Tinnitus

Photomed Laser Surg. 2017 Aug;35(8):427-431. doi: 10.1089/pho.2016.4240. Epub 2017 Mar 14.

Efficacy of Low-Level Laser Therapy in Subjective Tinnitus Patients with Temporomandibular Disorders.

Demirkol N1, Usumez A2, Demirkol M3, Sari F1, Akcaboy C4.

Author information

1
1 Department of Prosthodontics, Faculty of Dentistry, Gaziantep University , Gaziantep, Turkey .
2
2 Private Practice , ?stanbul, Turkey .
3
3 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Gaziantep University , Gaziantep, Turkey .
4
4 Department of Prosthodontics, Faculty of Dentistry, Gazi University , Ankara, Turkey .

Abstract

OBJECTIVE AND BACKGROUND:

Tinnitus is an apparent sound, perceived in the ear with no stimulus. It has been described as a sound originating from the brain. It affects 17% of the general population. Etiological factors for tinnitus include temporomandibular joint disorders (TMJ, TMD) and Costen’s syndrome. The aim of treatment is to eliminate the tinnitus or at least decrease its apparent volume.

MATERIALS AND METHODS:

In total, 46 patients referred to our department with bilateral subjective tinnitus with TMDs were selected for this study. Low-level laser therapy (LLLT) with an neodymium-doped yttrium aluminum garnet (Nd:YAG) (1064 nm) laser, LLLT with a diode laser (810 nm), and placebo treatment were applied to the patients. There were 15 patients each in the Nd:YAG and placebo groups and 16 patients in the 810nm diode laser group. LLLT was applied for 10 days, once per day. A visual analog scale (VAS) was used, with values between 0 and 10. VAS scores were recorded before treatment, on the last day of treatment, and 1 month after treatment. The VAS scores were the same on the last day of treatment and 1 month after treatment. The VAS scores before treatment and at 1 month after treatment were compared in a statistical analysis.

RESULTS:

There were statistically significant differences in the Nd:YAG laser (p=0.001) and 810 nm diode laser groups (p?=?0.005), but no difference in the placebo group (p=0.065).

CONCLUSIONS:

Both the Nd:YAG and 810 nm diode lasers were effective for the treatment of subjective tinnitus related to TMDs.

J Lasers Med Sci. 2017 Summer;8(Suppl 1):S38-S45. doi: 10.15171/jlms.2017.s8. Epub 2017 Aug 27.

Alterations in Auditory Electrophysiological Responses Associated With Temporary Suppression of Tinnitus Induced by Low-Level Laser Therapy: A Before-After Case Series.

Montazeri K1, Mahmoudian S1, Razaghi Z2, Farhadi M1.

Author information

1
Laboratory for Auditory Neuroscience, ENT and Head & Neck Research Center, Iran University of Medical Sciences, Tehran, Iran.
2
Laser Application in Medical Sciences Research Center (LAMSRC), Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Abstract

Introduction: Tinnitus is the phantom auditory perception of sound in the absence of an external or internal acoustic stimulus. The treatment is difficult due to multiple etiologies and great psychological influence. The purpose of this study was to determine alterations in auditory physiological and electrophysiological responses associated with temporary suppression of tinnitus induced by low-level laser (LLL) irradiation.

Methods: This study was conducted on 20 subjects with subjective tinnitus. All subjects signed the informed consent form and satisfied all the study eligibility criteria. Visual analog scale (VAS) for loudness, loudness matching of tinnitus (LMT), pitch matching of tinnitus (PMT), Persian-tinnitus questionnaire (P-TQ) and Persian-tinnitus handicap inventory (P-THI) were conducted pre- and post-low level laser therapy (LLLT) for all the subjects. Electrocochleography (ECochG) and distortion product otoacoustic emissions (DPOAEs) were recorded in 11 subjects. Continuous wave diode lasers, including red (630 nm) and infra-red (808 nm) were applied, and were both designed by the Canadian Optic and Laser (COL) Center. Twelve sessions of laser therapy were performed, 2 sessions per week for each subject. Total dose was 120 Joule/ ear/session.

Results: LLL irradiation could cause a significant decrease in subjective tests scores consisting of VAS for loudness, PMT, P-TQ, P-THI, but did not result in a significant improvement of objective evaluating parameters except for compound action potential (CAP) amplitude.

Conclusion: LLLT might be a subjectively effective treatment for short-term improvement of tinnitus. Defining a new protocol for optimizing LLLT parameters may be an option to improve parameters of objective tests.

Free Text of Article

Eur Arch Otorhinolaryngol. 2016 May 19. [Epub ahead of print]

Role of worry in patients with chronic tinnitus and sensorineural hearing loss: a preliminary study.

Caldirola D1, Teggi R2, Daccò S3, Sangiorgio E3, Bussi M2, Perna G3,4,5.

Author information

  • 1Department of Clinical Neurosciences, Villa San Benedetto Menni, Hermanas Hospitalarias, FoRiPsi, Via Roma 16, 22032, Albese con Cassano, Como, Italy. caldiroladaniela@gmail.com.
  • 2ENT Division, San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy.
  • 3Department of Clinical Neurosciences, Villa San Benedetto Menni, Hermanas Hospitalarias, FoRiPsi, Via Roma 16, 22032, Albese con Cassano, Como, Italy.
  • 4Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, University of Maastricht, Maastricht, The Netherlands.
  • 5Department of Psychiatry and Behavioral Sciences, Leonard Miller School of Medicine, University of Miami, Miami, FL, USA.

Abstract

Tinnitus-related distress appears to be more strongly associated with multiple psychological factors than with any perceptual properties of tinnitus. Prior studies have not investigated the role of worry in tinnitus sufferers. Worry is a dispositional cognitive trait that involves a pervasive, non-specific, future-oriented proneness to fretting, which can foster negative affective states and catastrophic thinking about a specific trouble when the trouble is actual and present. We examined the relationship between worry and self-perceived anxiety and depressive symptoms and handicap in 54 outpatients with chronic tinnitus and sensorineural hearing loss who had been previously recruited for a randomized double-blind study on the efficacy of transmeatal low-level laser therapy for tinnitus. We measured the current anxiety and depressive symptoms with the State-Trait Anxiety Inventory Form Y-1/Self-evaluation Depression Scale, the handicap with the Tinnitus Handicap Inventory, and the proneness to worry with the Penn State Worry Questionnaire. For the psychoacoustic tinnitus measures, we considered the loudness match and the minimum masking level. We found that tinnitus-related anxiety and depressive symptoms and handicap were significantly associated with proneness to worry (linear regression models, p < 0.01), whereas no associations were found with the psychoacoustic measures. This suggests the usefulness of worry assessment when managing chronic tinnitus in clinical practice. Early therapeutic interventions for reducing proneness to worry may facilitate better adaptation to tinnitus.

Ear Nose Throat J. 2015 Jan;94(1):32-6.

Effect of low-level laser therapy in the treatment of cochlear tinnitus: a double-blind, placebo-controlled study.

Dehkordi MA1, Einolghozati S, Ghasemi SM, Abolbashari S, Meshkat M, Behzad H.

Author information

1
Department of Otolaryngology, Mashhad Medical Sciences Branch, Islamic Azad University, Aria Hospital, 5th East Golestan St., Mashhad, Iran. drdehkordi@yahoo.com.

Abstract

Many treatments for chronic tinnitus have been attempted, but the condition remains difficult to cure, especially in the case of cochlear tinnitus. We conducted a prospective, double-blind, placebo-controlled study to assess the effect of low-dose laser therapy on chronic cochlear tinnitus. Our study population was made up of 66 patients-33 who received active laser treatment (case group) and 33 who received inactive dummy treatment (control group). Patients in the laser group received 5 mV with a wavelength of 650 nm for 20 minutes a day, 5 days a week, for 4 weeks. The controls followed the same schedule, but they were “treated” with an inactive device. The degree of tinnitus was evaluated before and after treatment in each group in three ways: (1) the Tinnitus Severity Index (TSI), (2) a subjective 10-point self-assessment scale for tinnitus loudness, and (3) the Tinnitus Evaluation Test (TET). At study’s end, we found no statistically significant differences between the case and control groups in the number of patients who experienced a reduction in TSI values (p = 0.589) or a reduction in subjective self-assessment scores (p = 0.475). Nor did we find any significant reductions in the loudness (p = 0.665) and frequency (p = 0.396) of tinnitus as determined by the TET. We conclude that 5-mV laser therapy with a wavelength of 650 nm is no better than placebo for improving hearing thresholds overall or for treating tinnitus with regard to age, sex, environmental noise level, and the duration of tinnitus.

Eur Arch Otorhinolaryngol. 2014 May;271(5):975-80. doi: 10.1007/s00405-013-2491-3. Epub 2013 Apr 19.

The effectiveness of transmeatal low-power laser stimulation in treating tinnitus.

Ngao CF1, Tan TS, Narayanan P, Raman R.

Author information

1
Department of Otorhinolaryngology, Faculty of Medicine, University Malaya Medical Centre, Lembah Pantai, 59100, Kuala Lumpur, Malaysia.

Abstract

The aim of this study is to examine the effectiveness of transmeatal low-power laser stimulation (TLLS) in treating tinnitus. This is a prospective, double-blinded, randomized, placebo-controlled trial. Patients with persistent subjective tinnitus as their main symptom were recruited into the study from the outpatient clinics. The recruited patients were randomized into the experimental group or TLLS+ group (patients in this group were prescribed to use TLLS at 5 mW at 650 nM wavelength for 20 min daily and oral betahistine 24 mg twice per day for a total of 10 weeks) and the control group or TLLS- group (patients in this group were prescribed with a placebo device to use and oral betahistine 24 mg twice per day for 10 weeks). All patients were required to answer two sets of questionnaires: the Tinnitus handicap inventory (THI) and visual analogue scales (VAS) symptoms rating scales, before starting the treatment and at the end of the 10-week treatment period. The total score of the THI questionnaire was further graded into five grades, grade 1 being mild and grade 5 being catastrophic. Wilcoxon-signed ranks test and Mann-Whitney test were used to compare and analyze the THI and VAS scores before and after treatment for each group. Changes with p value of <0.05 were considered as statistically significant. Chi square test was used to analyze the change of parameters in categorical forms (to compare between TLLS+ and TLLS-). Changes with p value of <0.05 were considered as statistically significant. Forty-three patients successfully and diligently completed their treatment. It was noted that using any condition of the device, TLLS+ or TLLS-, patient’s tinnitus symptoms improved in terms of THI scores (TLLS+, p value = 0.038; TLLS-, p value = 0.001) or VAS scores with a change of at least one grade (TLLS+, p value = 0.007; TLLS-, p value = 0.002) at p value <0.05 significant level. In contrast when TLLS+ group was compared with TLLS- group, no statistically significant result was obtained. In term of VAS scores, there seems to be no statistically significant improvement in patients’ annoyance, sleep disruption, depression, concentration and tinnitus loudness and pitch heard between the two groups. Transmeatal low-power laser stimulation did not demonstrate significant efficacy as a therapeutic measure in treating tinnitus.

J Lasers Med Sci. 2014 Spring;5(2):71-4.

Low level laser effect in treatment of patients with intractable tinnitus due to sensorineural hearing loss.

Mirvakili A1, Mehrparvar A2, Mostaghaci M2, Mollasadeghi A2, Mirvakili M1, Baradaranfar M1, Dadgarnia M1, Davari M1.

Author information

1
Department of Occupational Medicine, Shahid Sadoughi University of Medical Science, Yazd, Iran.
2
Department of Otorhinolaryngology, Shahid Sadoughi University of Medical Science, Yazd, Iran.

Abstract

INTRODUCTION:

Tinnitus is defined as a perception of sound without an external acoustic stimulus. Due to large number of causes and limited knowledge of its pathophysiology, tinnitus still remains an obscure symptom.

METHODS:

This was a cross-sectional study on 120 patients with tinnitus and sensorineural hearing loss who were randomly divided into two groups; one group received low-level laser and the second group used the same instrument but off, for 20 sessions of 20 minutes. A tinnitus handicap inventory (THI) and Visual Analog Scale (VAS) were used to evaluate the severity of patients’ symptoms. Severity and frequency of tinnitus were also determined using Audiometric tests.

RESULTS:

The average age of the 120 patients in the two groups of study were not statistically significantly different. The mean difference of severity of tinnitus between the two groups was statistically significant at the end of the study and 3 month after completion of treatment. The VAS and THI mean differences after the treatment were statistically significant between the two groups but not statistically significant after 3 months of completion the study.

CONCLUSION:

Low level laser radiation is effective for short-term treatment of Tinnitus caused by sensorineural hearing loss and its impact may be reduced over the time.

KEYWORDS:

laser therapylow-level; sensorineural hearing loss; tinnitus

Neurosci Lett. 2013 Jun 7;544:131-5. doi: 10.1016/j.neulet.2013.03.058. Epub 2013 Apr 11.

Trans-canal laser irradiation reduces tinnitus perception of salicylate treated rat.

Park YM1, Na WS, Park IY, Suh MW, Rhee CK, Chung PS, Jung JY.

Author information

1
Department of ORL-HNS, College of Medicine, Dankook University, Cheonan, Republic of Korea.

Abstract

The aim of this study was to find out the effect of low-level laser therapy (LLLT) on salicylate-induced tinnitus in the rat model. Fourteen Sprague-Dawley rats (8 weeks; 240-280 gm) were divided into 2 groups (study group, control group). Rats of both groups were treated with 400 mg/kg/day of sodium salicylate for 8 consecutive days. Tinnitus was monitored using GPIAS (Gap Prepulse Inhibition of Acoustic Startle) 2 h after first salicylate treatment, and every 24 h during 9 days of treatment. Rats in laser group were irradiated to each ear with wavelength of 830 nm diode laser (165 mW/cm(2)) for 30 min daily for 8 days. During salicylate treatment, rats of study group irradiated with low level laser showed significantly higher GPIAS values throughout the experiment. Therapeutic effect of LLLT is demonstrated in animal tinnitus model by means of GPIAS. Further experimental studies are needed to find possible mechanisms and better methods to improve LLLT efficacy.

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The Scientific World Journal
ScientificWorldJournal. 2013; 2013: 596076.
Published online 2013 Oct 28. doi:  10.1155/2013/596076
PMCID: PMC3830897

Efficacy of Low-Level Laser Therapy in the Management of Tinnitus due to Noise-Induced Hearing Loss: A Double-Blind Randomized Clinical Trial

Abolfazl Mollasadeghi, 1 Seyyed Jalil Mirmohammadi, 1 Amir Houshang Mehrparvar, 1 Mohammad Hossein Davari, 1Pedram Shokouh, 2 Mehrdad Mostaghaci, 1 Mohammad Hossein Baradaranfar, 3 and Maryam Bahaloo 4 , 5 ,*

Abstract

Background. Several remedial modalities for the treatment of tinnitus have been proposed, but an effective standard treatment is still to be confirmed. In the present study, we aimed to evaluate the effect of low-level laser therapy on tinnitus accompanied by noise-induced hearing loss. Methods. This was a double-blind randomized clinical trial on subjects suffering from tinnitus accompanied by noise-induced hearing loss. The study intervention was 20 sessions of low-level laser therapy every other day, 20 minutes each session. Tinnitus was assessed by three methods (visual analog scale, tinnitus handicap inventory, and tinnitus loudness) at baseline, immediately and 3 months after the intervention. Results. All subjects were male workers with age range of 30–51 years. The mean tinnitus duration was 1.85 ± 0.78 years. All three measurement methods have shown improved values after laser therapy compared with the placebo both immediately and 3 months after treatment. Laser therapy revealed a U-shaped efficacy throughout the course of follow-up. Nonresponse rate of the intervention was 57% and 70% in the two assessment time points, respectively. Conclusion. This study found low-level laser therapy to be effective in alleviating tinnitus in patients with noise-induced hearing loss, although this effect has faded after 3 months of follow-up. This trial is registered with the Australian New Zealand clinical trials registry with identifier ACTRN12612000455864).

1. Introduction

Tinnitus is defined as a sound in the ear(s) without any external auditory stimulus. About 15% of the general population experience at least one episode of tinnitus, which prevalence increases by age and reaches 85% in individuals older than 60 years [1]. This symptom is intolerable in nearly 20% of the cases [2]. Reaching as high as 67%, tinnitus is more prevalent among individuals suffering from hearing disorders [3].

Noise has such deleterious effects on hearing as noise-induced hearing loss (NIHL) is the second most common form of acquired hearing loss. It has long been recognized as a problem in noisy environments workers [4]. As a possible complication of NIHL, tinnitus is usually observed at frequencies equal to or higher than 3000 Hz, which is one octave band higher than the frequencies affected in NIHL. Its intensity is usually between 3 and 5 dB (occasionally up to 15 dB) [5].

Tinnitus may lead to such complications as depression, irritability, sleep disorders, and loss of concentration [6]. Although lacking a widely accepted treatment, various therapeutic modalities have been proposed thus far, including medications (such as sedatives, antiepileptics, antidepressants, antipsychotics, local anesthetics, antihistamines, and botulinum toxin A) [7], repetitive transcranial magnetic stimulation [8], transcutaneous electrical stimulation [9], and sound therapy [10]. Low-level laser therapy (LLLT) has recently been tried with promising results in outpatients with subjective tinnitus [2].

As known, laser has different usages in medicine such as wound healing, nerve and tissue repairing, pain control [11], and treating Meniere’s disease and tinnitus [12]. Although the exact mechanism of the effect of LLLT on tinnitus is not clearly understood, it has been proposed that it may be induced by increasing cell proliferation, growth factor secretion, improvement in inner ear blood flow, and/or activation of the hair cells mitochondria [2]. There is still some degree of controversy concerning the efficiency of LLLT in tinnitus. Some studies have shown positive effects [2, 11, 13, 14], but others have found no such effectiveness [15, 16].

Considering the fact that NIHL is a common disorder in industrial settings and tinnitus is its most common associated subjective complaint, we designed an interventional study to evaluate the effect of LLLT on tinnitus accompanied by NIHL.

2. Methods

2.1. Study Design and Population

The present study was a double-blind randomized clinical trial with the participation of patients referred to the occupational medicine clinic of Shahid Sadoughi University of Medical Sciences. Recruitment took place from September 2010 till September 2011.

One hundred volunteers younger than 50 years suffering from NIHL (defined as a bilateral sensorineural hearing loss, with the hearing threshold higher than 15?dB at least at one of the following frequencies: 3000, 4000, and 6000?Hz [4]) and tinnitus have enrolled to the study. The level of effect observed in a former study was used for the calculation of the sample size [2].

After baseline screening interview and examination, eleven participants were excluded from the study, yielding a final sample size of 89. Our main exclusion criteria were as follows: any history of exposure to ototoxic drugs/substances, psychotic disorders with auditory hallucination, acoustic trauma, head trauma, mumps, meningitis, Meniere’s disease, and having any contraindication for laser therapy [17].

Subjects were randomly allocated to either laser therapy or placebo groups. Randomization was done using a random digit table. According to the principles of double blindness, the study participants and operators who performed the assessment tests as well as the researchers who evaluated the outcomes were completely blinded to the groups.

After taking a thorough medical and occupational history, the microscopic examination of auditory meatus and tympanic membrane was performed. Afterwards, subjects underwent pure-tone audiometry performed at 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000?Hz frequencies (device: clinical audiometer, Interacoustic, AC40; headphone: TDH39, Denmark) in an acoustic chamber meeting the American National Standards Institute criterions [18]. Tympanometry was also accomplished for all participants (device: Tympanometer, Interacoustic, AZ26, Denmark). Subjects in the intervention group underwent laser therapy for 20 sessions, every other day, 20 minutes each session, which was a combination of protocols used in the previous studies [1, 2, 13]. A low-level laser beam with wave length of 650?nm and intensity of 5?mW was irradiated to the ear via mastoid bone (device: TINNImed, Switzerland). This device was connected to the ear by a soft silicone tip. The treatment sessions were performed for the subjects in placebo group with turned-off device.

A written informed consent was obtained from all participants before the enrolment. The protocol of the study was approved by the ethics committee of research vice chancellor of Shahid Sadoughi University of Medical Sciences.

2.2. Efficacy Assessments

We used the following three validated methods for the evaluation of outcome before treatment, immediately and 3 months after the termination of treatment: tinnitus visual analog scaling (VAS), tinnitus handicap inventory (THI), and tinnitus loudness measurement. Visual analog scale is scored on a 10-point scale, in which individuals select the lowest perceived loudness on a scale of 0 to 10 corresponding to an increasing level of loudness [19]. In THI scoring, 25 questions are asked from the patient and the severity of tinnitus is categorized as follows. Grade 1 (0–16): Slight (only heard in quiet environments); Grade 2 (18–36): Mild (easily masked by environmental sounds and easily forgotten with activities); Grade 3 (38–56): Moderate (noticed in the presence of background noise, although daily activities can still be performed); Grade 4 (58–76): Severe (almost always heard, leads to disturbed sleep patterns and can interfere with daily activities); Grade 5 (78–100): Catastrophic (Always heard, disturbed sleep patterns, difficulty with any activities) [20]. We used a translated version of the questionnaire into Persian, which was reviewed and modified by three experts to adapt our population culture. Loudness and frequency of tinnitus was assessed by audiometer. Pitch was matched by introducing two successive tones to the ear and the patient chose which one was closest to the tinnitus pitch. The loudness was assessed by matching it with the loudness of pure tone at each frequency in the contralateral ear according to the patient’s sensation.

2.3. Statistical Analysis

Data were analyzed by the Statistical Package for Social Sciences software version 15.0 (SPSS Inc, Chicago, Illinois, USA). We used independent-sample t-test for the comparison of mean tinnitus loudness between two groups in three occasions (baseline, immediately, and 3 months after intervention), and paired t-test for the comparison of treatment effect within each group in different occasions. Chi square test was also employed in the comparison of VAS and THI score changes between two groups.

3. Results

From 100 patients screened, 89 individuals were eligible for enrolment. Reasons for exclusion were as follows: exposure to ototoxic substances (n = 6), head injury (n = 2), consumption of ototoxic drug (n = 1), head trauma (n = 1), and childhood infection (n = 1). Figure 1 shows the flow diagram of the study. As demonstrated, 3 laser therapy- and 4 placebo-assigned participants have discontinued the trial due to personal reasons. Notably, no case of LLLT-attributable side effects was observed in our course of study.

Figure 1

Study flow diagram.

All cases were males with age range of 30 to 51 years (mean: 41.17 ± 5.89 years). Their mean duration of employment was 12.21 ± 1.77 years. Mean level of noise in the workplace (time weighted average for an 8-hour shift) was 87.60 ± 1.49?dBA. Tinnitus was bilateral in 49% of the cases, while 27 and 24 percent of subjects suffered from unilateral tinnitus in left and right ears, respectively. The mean tinnitus duration was 1.85 ± 0.78 years. As expected, there was not significant difference in terms of age (P = 0.88), employment duration (P = 0.83), workplace noise level (P = 0.78), and duration of tinnitus (P = 0.62) between two randomized study groups.

Participants were categorized based on the level of experienced changes in the severity of tinnitus quantified by VAS and total THI. Table 1 summarizes the results of between-group analyses of distribution of changes in different time intervals. As shown, LLLB was significantly more effective than placebo immediately and 3 months after treatment, which points to the efficacy of the study intervention. Nevertheless, tinnitus severity remained unchanged in 54% and 70% of patients immediately and 3 months after receiving LLLB (as measured by VAS).

Table 1

Comparison of changes in tinnitus visual analog scaling and tinnitus handicap inventory scores immediately and 3 months after intervention between groups.

According to Table 2, tinnitus loudness scores were comparable between two groups at baseline. After receiving LLLB, tinnitus loudness score was diminished in a U-shape manner with significantly lower scores than placebo in all time points.

Table 2

Comparison of tinnitus loudness between two groups at baseline, immediately and 3 months after intervention.

Changes in tinnitus loudness score were compared within and between groups in different time periods. As expressed in Table 3, LLLB reduced the loudness of tinnitus significantly in relation to the baseline values and compared with the placebo group in all time periods. A meaningful response was also detected in placebo-assigned individuals immediately after treatment, which still was significantly lower than that of the intervention group.

Table 3

Comparison of the changes of tinnitus loudness in 3 periods of assessment within and between groups.

4. Discussion

Previously published studies have reported the efficacy of LLLT in decreasing tinnitus to be between 15–67% [11]. Quantifying by VAS, our positive findings have been multiplied by some [2, 11, 13], while negated by other studies [15, 21]. Tauber et al. used 10 sessions of LLLT with two different wavelengths (635 and 839?nm) during two weeks which was different from our practice [11]. Okhovat et al. were treated patients with 20-minute sessions a day for 20 days using the same wavelengths to our study [2]. The most similar protocol to ours was used by Y?ld?r?m et al., with considerable improvements which sustained after two months [13].

Mixed results were also obtained by studies that have used tinnitus loudness score as their primary outcome measure. While this study in line with Tauber et al. [11], Gungor et al. [22], Newman et al. [20], and Shiomi et al. [23] has found tinnitus loudness to be improved after LLLT, two evaluations have failed to show the same efficacy [15, 16]. A noteworthy point to consider is the pronounced improvement reported by our patients after receiving placebo, which vanished at the end of the follow-up period. This observation, to our opinion, might be explained best by a placebo effect.

The results of total THI score in our study were in accordance with VAS results after LLLT and were consistent with the study of Cuda and Caria [14], but Teggi et al. did not show this change [15]. Table 4presents a detailed comparison between the findings of some relevant studies with what we found in our population. We suppose that the controversial results could be attributable to employing different treatment courses, as well as varied experiment settings. For instance, our patients received therapy in clinic, while Teggi et al. [15] gave the participants their course of treatment at home.

Table 4

Comparison of the design and results of some relevant studies with the present study.

Even though it remained higher compared with the baseline level and placebo group, we observed that the effect of LLLT attenuated after 3 months. Our finding was attenuated by another research with assessment period of 4 weeks and 6 months []. It seems that the efficacy of LLLT decreases over time, which may necessitates repeating the therapy. Further evidence, however, is needed for determining a proper time interval between sessions.

While most of the former comparable studies have not taken concomitant hearing disorders into consideration, we assessed the effect of LLLT on tinnitus in a background of sensorineural hearing loss. However, our results should be interpreted in the light of some limitations. The first limitation was our 3-month follow-up period that made it impossible to evaluate long-term outcomes of the studied intervention. Secondly, due to the fact that our study population comprised of male workers, the obtained results may hardly be generalized to other populations.

In conclusion, this study has provided evidence for the efficacy of LLLT in relieving NIHL accompanied tinnitus, an effect that was weakened after 3 months follow-up. Despite significant improving results, the LLLB treatment nonresponse rate was considerable which should be taken into account when considering this treatment method.

Conflict of Interests

The authors declare that there is no conflict of interests that would prejudice the impartiality of this work.

Acknowledgment

The authors would like to appreciate the cooperation of all the personnel of Shahid Rahnemoun hospital and Industrial Related Diseases Research Center, Yazd, Iran. This study was financially supported by a grant from Shahid Sadoughi University of Medical Sciences (Grant No.1563).

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ISRN Otolaryngol. 2013; 2013: 916370.
Published online 2013 Apr 23. doi:  10.1155/2013/916370
PMCID: PMC3658388

The Effect of Low-Level Laser Therapy on Hearing

Shawn S. Goodman, 1 ,* Ruth A. Bentler, 1 Andrew Dittberner, 2 and Ian B. Mertes 1
1Department of Communication Sciences & Disorders, The University of Iowa, Iowa City, IA 52242, USA
2GN Resound North America, Chicago, IL 60646, USA
*Shawn S. Goodman: ude.awoiu@namdoog-nwahs
Academic Editors: C. Y. Chien, K. Ishikawa, K. Parham, and A. D. Rapidis
Received 2013 Feb 9; Accepted 2013 Mar 27.

Abstract

One purported use of low-level laser therapy (LLLT) is to promote healing in damaged cells. The effects of LLLT on hearing loss and tinnitus have received some study, but results have been equivocal. The purpose of this study was to determine if LLLT improved hearing, speech understanding, and/or cochlear function in adults with hearing loss. Using a randomized, double-blind, placebo-controlled design, subjects were assigned to a treatment, placebo, or control group. The treatment group was given LLLT, which consisted of shining low-level lasers onto the outer ear, head, and neck. Each laser treatment lasted approximately five minutes. Three treatments were applied within the course of one week. A battery of auditory tests was administered immediately before the first treatment and immediately after the third treatment. The battery consisted of pure-tone audiometry, the Connected Speech Test, and transient-evoked otoacoustic emissions. Data were analyzed by comparing pre- and posttest results. No statistically significant differences were found between groups for any of the auditory tests. Additionally, no clinically significant differences were found in any individual subjects. This trial is registered with ClinicalTrials.gov (NCT01820416).

1. Introduction

Low-level laser therapy (LLLT) has been practiced for over 20 years in Europe and has more recently been introduced in the United States as a treatment for pain and postsurgical tissue repair. It has been proposed that laser energy in the red and near-infrared light spectrum may aid in the repair of tissue damage. A proposed mechanism for this therapeutic effect is the stimulation of mitochondria in the cells to produce more energy through the production of adenosine triphosphate [1–3].

It has been postulated that LLLT may improve cochlear function. Animal studies have found that laser stimulation can induce anatomic and physiologic changes in the cochlea. Rhee et al. [4] reported that rat hair cells were repaired with LLLT following noise exposure. Wenzel et al. [5] found that laser stimulation increased basilar membrane stiffness (and therefore resonant frequency) in guinea pigs. The authors suggested that this could allow lower-frequency regions of the cochlea (where auditory function is typically less compromised) to respond to higher frequency sounds.

Studies in humans have investigated the effects of LLLT on both hearing loss and tinnitus, with equivocal results. Some studies have found an improvement in hearing thresholds and tinnitus symptoms (e.g., [6–10]), while others have found no significant effect of LLLT (e.g., [11–15]). The reason for the discrepancy in findings is not known, but likely involves multiple factors such as study design, subject characteristics, LLLT methodology, and outcome measures used to assess the effects of LLLT.

Further research on the effect of LLLT on hearing in humans appears warranted. Although some studies showed improvements in hearing thresholds, no published study to date has examined the effect of LLLT on speech understanding and only one has examined the effect on cochlear function via otoacoustic emissions [11]. Pilot data from HearingMed (unpublished) found that LLLT improved word recognition scores in subjects with hearing loss relative to a placebo group, which motivated the current study. The purpose of the current study was to assess the effect of LLLT on hearing in terms of auditory sensitivity, speech understanding, and cochlear function. A randomized, double-blind, placebo-controlled trial design was implemented using the laser therapy protocol suggested by the HearingMed study.

2. Materials and Methods

2.1. Subjects

In order to accurately detect possible changes in hearing status due to laser treatment, it was necessary to avoid using subjects whose hearing might fluctuate due to other factors. Before potential subjects were enrolled in the study, they were asked a list of screening questions to determine eligibility. The questions were chosen to ensure stable hearing, as well as to address possible safety issues. All subjects were also required to have normal middle ear function, as assessed by 226?Hz tympanograms.

A total of 35 adult subjects were enrolled in the study. Two subjects withdrew from the study due to loss of interest and/or scheduling difficulty. The data from three additional subjects were not included in the analysis. One subject yielded unreliable audiometric and speech understanding data, speech scores could not be obtained from one subject with a profound hearing loss, and calibration problems compromised data from the third subject. Data from the remaining 30 subjects were included in the analyses. The experimental protocol was approved by the Institutional Review Board of The University of Iowa, and written informed consent was obtained from all participants.

2.2. Laser Device

An Erchonia EHL laser (Erchonia Medical, Inc.) was used to provide the laser stimulation. The device was a portable (9?? × 5?? × 1??) unit that consisted of a hand-held probe and a main body. The probe contained two laser diodes. One diode produced light in the green part of the visible light spectrum (532?nm wavelength), and the other diode produced light in the red part of the visible light spectrum (635?nm wavelength). Both diodes produced energy levels of 7.5?mW (class IIIb). The laser beams from both diodes were dispersed through lenses to create parallel line-generated beams, rather than spots. The 532?nm light was constant, and the 635?nm light was pulsed, with frequencies of 15 and 33?Hz. The pulsing alternated between frequencies every 30 seconds. A second Erchonia EHL device served as the placebo. It was identical to the treatment device, except that the laser diodes were replaced with nonfunctioning standard light-emitting diodes.

2.3. Study Design

2.3.1. Groups

The study used three groups: treatment, placebo, and control. Subjects were pseudorandomly assigned to one of the three groups. Initial group assignment was random with occasional adjustment to ensure that the three groups were similar in terms of number of participants, female/male ratio, mean age of participants, and mean pure-tone audiometric thresholds. The composition of each group is shown in Table 1.

Table 1

Group characteristics.

The treatment group received the laser treatment protocol (described in Section 2.4) using the functional laser device. The placebo group also received the laser treatment protocol, but using the nonfunctioning laser device. The control group made similarly timed visits to the laboratory but received no real or feigned “treatment.” The study used a repeated-measures design, with each subject taking a battery of pretests, followed by treatment (laser, sham laser, or nothing), followed by a battery of posttests.

2.3.2. Timeline

The pretest, treatment sessions, and posttest took place in three scheduled visits within a 7–10-day period for each subject. On the first visit, the pretests were administered, followed immediately by the treatment session. Subjects in the treatment group received laser treatment with the functioning laser device. Subjects in the placebo group received laser treatment with the nonfunctioning device. Subjects in the control group simply sat in a comfortable chair and had a short conversation with the researcher. All subjects returned for a second treatment session 2-3 days after the first visit. Subjects returned for the third and final treatment 2-3 days after the second treatment session. Immediately after the third treatment, the posttest battery was administered.

2.3.3. Blinding

Subjects did not know whether they were in the treatment or placebo groups, and the researchers administering the laser treatments did not know whether they were using the treatment or placebo device. Appropriate laser safety goggles (Laservision, style F12, filter 000131.000) were worn by subjects and the researchers administering the laser treatment. The goggles had lenses rated OD 6+ @ 510–680?nm, which blocked all visible laser light. The goggles also hugged the face firmly, preventing laser light from entering from the side.

To further avoid potential bias in the test results, the research team was divided into two groups. Two team members administered the laser therapy independently of two other team members that administered the battery of auditory tests. The members who administered the auditory tests also performed scheduling and group assignments. Groups were simply identified by colors; so, the testers did not know which treatment (laser, placebo, or control) any subject was receiving. The testers were not present during treatment sessions. The team members giving the laser therapy did not know which laser device was functioning and which was the placebo. A fifth member of the research team, not otherwise involved in the study, assigned the functioning and placebo laser devices to two of the color groups and was responsible for checking the devices weekly to ensure that the functioning laser device was working.

2.4. Laser Treatment Protocol

The LLLT treatment protocol was based on a pilot study conducted by HearingMed (unpublished) showing improvement of word recognition scores following LLLT. Subjects in the treatment group had the low-level laser applied for approximately 4 minutes to the area around both pinnae, the back of the neck, and the top of the head. Subjects in the placebo group received the same protocol, except that the disabled laser device was used. Subjects in the control group simply sat in a comfortable chair and conversed with the research team member for a few minutes, and no treatment of any kind was administered. The laser was applied as described in the following steps and as shown in Figure 1.

Figure 1

Visual depiction of the laser treatment. Each step is described in detail in the text. The white circle represents the subject’s head. The double black lines represent the laser beams on the subject’s head. The white arrows show the directional movement 

Step 1 —

The laser was centered on the right temporomandibular joint, just anterior to the external auditory meatus of the ear, at a distance of approximately 2 inches from the surface of the skin. The hand-held probe was rotated from vertical to horizontal and back continuously for 15 seconds.

Step 2 —

The laser was positioned on midline of cervical spine with the beams running vertically from external occipital protuberance to the seventh cervical vertebrae. The hand-held probe was held at a distance of approximately 3 inches from the surface of the skin and continuously swept horizontally back and forth for 30 seconds.

Step 3 —

The left temporomandibular joint was stimulated, as described in Step 1.

Step 4 —

The laser was positioned on top of the head with the beams running across the head from ear to ear. The probe was held at a distance of approximately 2 inches from the surface of the head and continuously swept back and forth from the forehead to the occipital protuberance for 30 seconds.

Step 5 —

The laser was centered on the right external auditory meatus, with the probe held at a distance of approximately 2 inches from the surface of the pinna. The probe was rotated from vertical to horizontal and back continuously for 60 seconds.

Step 6 —

The laser was positioned over the cervical spine with the beams running horizontally. The probe was held at a distance of approximately 2 inches from the surface of the skin and continuously swept up and down from the occipital protuberance to the top of the shoulders for 15 seconds.

Step 7 —

The left external auditory meatus was stimulated, as described in Step 5.

2.5. Auditory Test Battery

The auditory test battery consisted of three assessments: pure-tone audiometry, speech understanding, and transient-evoked otoacoustic emissions (TEOAEs). These tests were chosen to examine different aspects of hearing; pure-tone audiometry assessed auditory sensitivity in quiet, speech testing assessed speech processing in noise, and otoacoustic emissions assessed the physiological state of the cochlea.

2.5.1. Pure-Tone Audiometry

Pure-tone thresholds were measured in 5?dB steps at six audiometric frequencies (0.25, 0.5, 1, 2, 4, and 8?kHz). Audiometry was conducted using custom software written in MATLAB (MathWorks) that implemented a method of adjustment psychophysical paradigm [], with stimuli presented via ER-2 insert earphones (Etymotic Research). Thresholds for each subject were averaged to yield two measurements. The pure-tone average (PTA) was the average of the thresholds at 0.5, 1, and 2?kHz (Figure 2). The high-frequency average (HFA) was the average of the thresholds at 2, 4, and 8?kHz (Figure 3).

Figure 2

Distribution of pretest audiometric PTA for each group. The y-axis has been flipped to resemble an audiogram. Dotted horizontal lines indicate the median. Boxes demark the 25th and 75th percentiles. Asterisks show actual data points. (Data with identical 
Figure 3

Distribution of pretest audiometric HFA for each group. Group means: 45.8, 44.8, 38.6?dB HL for treatment, placebo, and control groups, respectively. Figure format is the same as described in Figure 2.

2.5.2. Speech Understanding

The Hearing in Noise Test (HINT) [] was used to determine the signal-to-noise ratios (SNRs) for the subsequent speech testing. This test is a prerecorded, adaptive measure of sentence speech reception thresholds in noise. Subjects are asked to repeat 20 sentences presented in a background of speech-shaped noise. For this experiment, the noise was fixed at a level of 65?dBA, and the speech level was adjusted adaptively based on the listener’s responses. The speech presentation level across sentences 5 through 20 was averaged to obtain the level at which the listener achieved a 50% correct performance (SNR50). The SNR50 score obtained during pretesting (Figure 4) was used to set the SNRs for the Connected Speech Test (CST) for each subject, as described below.

Figure 4

Distribution of pretest HINT SNR50 scores for each group. Group means: 2.1, 0.7, and ?0.5?dB for treatment, placebo, and control groups, respectively. These values were used to set the signal-to-noise ratio for both the CST pre- and posttests. 

The CST [] provides objective quantification of the intelligibility of connected speech. The stimuli are a collection of passages about common topics. Each passage contains recordings of 9 or 10 sentences spoken by a female talker of average intelligibility. Subjects are asked to listen and repeat the sentences. Scoring is based on the number of key words repeated by the listener out of 25 key words per passage. The passages are embedded in multitalker babble. The SNR used in the present study was the SNR50 obtained from the pretested HINT, plus 4?dB. Scores were averaged across several test passages to produce a measure of intelligibility.

2.5.3. Otoacoustic Emissions

Transient-evoked otoacoustic emissions (TEOAEs) are physiologic measures of the cochlea’s response to a click-like acoustic stimulus []. TEOAEs were measured using an ER-10C probe microphone system (Etymotic Research). Transient stimuli containing energy from 1 to 8?kHz were used. A double-evoked paradigm [] was used to cancel the stimulus and extract TEOAEs. Probe clicks were presented at a level of 87?dB peak-equivalent SPL, and the higher-level suppressor was presented 12?dB higher than the probe. Approximately 2000 recordings were made from each ear, and the recordings were averaged after artifact rejection.

TEOAEs were filtered into two bands: 1-2?kHz and 2–8?kHz. These frequency bands were chosen to correspond with the audiometric analyses and in this paper are referred to as the TEOAE PTA (1-2?kHz) and the TEOAE HFA (2–8?kHz). The distribution of pretest TEOAE amplitudes is shown for each frequency band in Figures ?Figures55 and ?and6.6. It was discovered during data analysis that some of the earlier subjects were tested using probe and suppressor levels that were much lower than intended. These subjects were therefore omitted from the data shown later and from subsequent analyses involving TEOAEs. These subjects’ data were retained for the audiometry and speech test analyses.

Figure 5

Distribution of pretest TEOAE PTA amplitudes (1-2?kHz). N = 10 (5 subjects), 12 (6 subjects), and 12 (6 subjects) for the treatment, placebo, and control groups, respectively. Figure format is the same as described in Figure 2.
Figure 6

Distribution of pretest TEOAE HFA (2–8?kHz) amplitudes. Figure format is the same as described in Figure 2.

3. Results

Data were obtained from both ears of each subject. Since no obvious differences were seen between left and right ears, data from both ears were combined in the following analyses. Strictly speaking, this likely violates the statistical assumption of independent sampling, since the test results from left and right ears of a single subject are likely to be highly correlated. None of the statistical tests used in the analyses are robust to the assumption of independent sampling, and the effect of including both ears is likely to be that of artificially increasing the sample size, making it more likely that a statistically significant result will be found. All statistical tests were conducted using a significance level of ? = 0.05.

3.1. Pure-Tone Audiometry

Changes in the low-frequency pure-tone thresholds (PTA) were calculated by subtracting each subject’s pretest PTA from their posttest PTA. Changes in the high-frequency pure-tone thresholds were computed in the same way using the HFA thresholds. Negative values indicated an improvement in thresholds after treatment, and positive values indicated a worsening. Figures ?Figures77 and ?and88 show the distribution of change in thresholds for PTA and HFA, respectively.

Figure 7

Change in the audiometric PTA. Change calculated as posttest minus pretest; negative values indicate improvement in thresholds. N = 18 (9 subjects), 20 (10 subjects), and 22 (11 subjects) for the treatment, placebo, and control groups, respectively. Figure 
Figure 8

Change in the audiometric HFA. Change calculated as posttest minus pretest; negative values indicate improvement in thresholds. Figure format is the same as described in Figure 2.

Changes in PTA and HFA across the three groups were compared statistically. Analysis of variance was used to test the null hypothesis that the population means of the groups are all equal. Use of ANOVA requires four assumptions: (1) data are from groups with normally distributed populations; (2) data are from groups with equal population variances; (3) groups are independent; (4) data within groups are independent and randomly sampled. The test is robust to the first and second assumptions if the number of samples in each group is large and equal or nearly equal. The test is never robust to the third and fourth assumptions. The sample sizes in this data set (N = 18, 20, and 22) were probably large enough and close enough to the same size to meet the first two assumptions. Additionally, the sampled data did not suggest high skewness or kurtosis. The third assumption was assumed to have been met. As discussed at the beginning of Section 3, the fourth assumption was likely violated.

An analysis of variance showed no difference between group means for changes in PTA (F(2,57) = 0.09, P = 0.913) or for HFA (F(2, 57) = 1.33, P = 0.274). These results are shown in tabular form in Tables ?Tables22and ?and3.3.

Table 2

ANOVA for difference between audiometric PTA group means.
Table 3

ANOVA for difference between audiometric HFA group means.

3.2. Speech Understanding

Before computing changes in CST performance, scores were first transformed into rationalized arcsine units (rau) []. Changes in rau scores were calculated by subtracting each subject’s score obtained during the pretest from their score obtained during the posttest. Positive values indicate an improvement in speech understanding after treatment, and negative values indicate a decline. Figure 9 shows the distribution of change in rau scores for each group.

Figure 9

Change in CST scores expressed as rationalized arcsine units. Change calculated as posttest minus pretest; positive values indicate improvement in speech intelligibility. Figure format is the same as described in Figure 2.

Changes in rau scores across the three groups were compared statistically. Analysis of variance was used to test the null hypothesis that the population means of the groups are all equal. The assumptions required by ANOVA were discussed previously. As they apply to the rau difference data, the sample sizes were probably large enough and close enough to the same size to meet the first two assumptions. However, the sampled data do suggest the possibility that the groups are differently skewed (sk = 0.471, ?1.40, ?0.55 for the treatment, placebo, and control groups, resp.). A Kruskal-Wallis test was therefore also performed to compare the medians of the groups. The Kruskal-Wallis test technically requires the assumption that the populations of the different groups are identical. The test is robust to all differences except differences in variability between groups. The test is reasonably robust to differences in variability if the sample sizes are equal. While the sample sizes in this data set were not exactly equal, they were close to the same. Additionally, the standard deviations, which are reasonable estimates of variability, were reasonably similar (SD = 13.06, 16.04, 10.55 for the treatment, placebo, and control groups, resp.).

An analysis of variance showed no difference between group means for changes in rau score (F(2,57) = 2.20, P = 0.120). The Kruskal-Wallis test showed no difference between group medians for changes in rau score (Kw(2) = 4.04, P = 0.133). These results are shown in tabular form in Tables ?Tables44 and ?and5.5.

Table 4

ANOVA for difference between CST group means, expressed in rationalized arcsine units.
Table 5

Kruskal-Wallis test for difference between CST group medians, expressed in rationalized arcsine units. This test was performed on scores transformed to ranks. The ranks assigned to tied scores were the average of the ranks those scores would have had 

3.3. Transient-Evoked Otoacoustic Emissions

Changes in the lower-frequency TEOAE amplitudes were calculated by subtracting each subject’s TEOAE PTA obtained during the pretest from their TEOAE PTA obtained during the posttest. Changes in the higher-frequency TEOAE amplitudes (TEOAE HFAs) were computed in the same way. Because TEOAEs are generated as a byproduct of outer hair cell function, significant positive values would theoretically be indicative of an improvement in outer hair cell function after treatment, and significant negative values would indicate a worsening. Figures ?Figures1010 and ?and1111 show the distribution of change in TEOAE amplitude for the lower and higher frequency bands, respectively.

Figure 10

Change in TEOAE PTA amplitudes (1-2?kHz). Change calculated as posttest minus pretest; positive values indicate improvement. Figure format is the same as described in Figure 2.
Figure 11

Change in TEOAE HFA (2–8?kHz) amplitudes. Change calculated as posttest minus pretest; positive values indicate improvement. Figure format is the same as described in Figure 2.

Changes in TEOAE PTA and TEOAE HFA across the three groups were compared statistically. Analysis of variance was used to test the null hypothesis that the population means of the groups are all equal. Regarding the assumptions required by ANOVA, the smaller sample sizes of the TEOAE data set were probably not large enough to make the test robust to the assumption of normality. The groups in the TEOAE PTA data set (Figure 7) appeared to be normally distributed and had equal variances (skew = ?0.67, ?0.06, ?0.5; kurtosis = ?0.47, ?1.2, ?0.8; SD = 2.8, 2.8, 3.0, for the treatment, placebo, and control groups, resp.). The third assumption was assumed to have been met. As discussed at the beginning of Section 3, the fourth assumption was likely violated.

There is no theoretical reason to expect the higher-frequency TEOAE data to be distributed differently from the lower-frequency data; however, the groups in the TEOAE HFA data set (Figure 8) were skewed, with the control group being skewed in the opposite direction to the other two groups (skew = ?0.95, ?0.94, 0.92, for the treatment, placebo, and control groups, resp.). Because of this, a Kruskal-Wallis test was also performed to test the null hypothesis that the population medians of the groups are all equal, in addition to computing a standard analysis of variance.

Analysis of variance showed no difference between group means for changes in TEOAE PTA (F(2,31) = 0.133, P = 0.876) or for TEOAE HFA (F(2,31) = 0.20, P = 0.819). These results are shown in tabular form in Tables ?Tables66 and ?and7.7. In addition, the Kruskal-Wallis test showed no difference between group medians for changes in TEOAE HFA (Kw(2) = 4.04, P = 0.133). These results are shown in tabular form in Table 8.

Table 6

ANOVA for difference between TEOAE PTA group means.
Table 7

ANOVA for difference between TEOAE HFA group means.
Table 8

Kruskal-Wallis test for difference between CST group medians, expressed as rationalized arcsine units. The ranks were assigned as described in Table 5.

4. Discussion

4.1. Clinical Significance and Statistical Power

None of the three measures of hearing (audiometric thresholds, speech recognition test, or otoacoustic emissions) showed a statistically significant difference between the treatment, placebo, or control groups. Although a statistically significant difference between the groups might be detected with a larger sample size, such statistical significance may not necessarily be clinically meaningful. As discussed later, no individuals showed any clinically significant changes on any of the auditory tests.

4.1.1. Pure-Tone Audiometry

From a clinical standpoint, a pure-tone threshold change of 10?dB or greater is generally considered significant []. Changes of a smaller magnitude are considered to be within normal clinical variability and are not suggestive of any significant alteration in hearing ability. As can be seen in Figures ?Figures66 and ?and7,7, changes in PTA and HFA were less than 10?dB for all subjects in all groups, and the changes were evenly split in the positive and negative directions. It is worth noting that a similar pattern was seen in individual frequencies: of the 300 audiometric measurements made (5 audiometric frequencies (0.5 to 8?kHz), left and right ears, 30 subjects), only one measurement showed a change greater than 10?dB. A single subject in the treatment group showed an improvement of 25?dB at 0.5?kHz in one ear. The other ear showed a 5?dB decrease. No improvement was seen in this subject’s speech scores or otoacoustic emissions. The most plausible explanation is that the large threshold improvement was artifactual, in that the audiometric testing was always under the control of the subject. To summarize the audiometric test results, in addition to group means being the same, no individual subjects showed a clinically significant change in thresholds.

4.1.2. Speech Understanding

When considering clinically significant changes in CST scores, it is necessary to know the critical difference of the scores, expressed in rau. Cox et al. [] suggested that critical differences for this test should be derived from the measured within-subject standard deviation. They reported a 95% critical difference for hearing-impaired subjects of about 15.5?rau. Humes et al. [] pointed out that the subjects in the Cox et al. study had a considerable amount of practice before the variability was measured. For the Humes et al. study, in which subjects received no practice with the CST, a 95% critical difference of 32.2?rau was determined. The present research is similar to the Humes et al. study, in that subjects received no practice prior to the data collection. Further, the standard deviation of the rau differences in control group of the present study was 10.55?rau, which is similar to the standard deviation of 11.5?rau found in the Humes et al. study. Examination of the distribution of rau scores for the control group (Figure 9) also supported using a 95% critical difference of somewhere between 25 and 30?rau.

From Figure 9, it can be seen that there were three data points that exceeded a critical difference value of 25. Two of these were in the negative direction (suggesting a decrease in speech intelligibility), and one was in the positive direction. Since the critical value represents a 95% confidence interval, it can be expected that in any given sample, approximately 5% of the scores will exceed the critical value simply by chance. In the current sample, about 3 scores would be expected to exceed the critical value (0.05 ? 60 = 3). Further, these large changes occurred in only one ear of three different subjects, while changes in their other ears did not approach significance (?5.48, ?11.56, and ?5.49?rau). Finally, these large rau changes did not cooccur with significant changes in audiometric thresholds or TEOAEs. To summarize the CST results, in addition to group means being the same, no subgroup of individual subjects showed a clinically significant change in speech understanding.

4.1.3. Otoacoustic Emissions

When considering clinically significant change in TEOAEs, an amplitude change of 6?dB or greater might be considered significant given the test-retest reliability in normal populations []. As can be seen in Figures ?Figures1010 and ?and11,11, none of the measurements made a change of at least 6?dB in the positive direction, which would indicate significant improvement in TEOAEs. As with the other tests, in addition to group means being the same, no subgroup of individual subjects showed a clinically significant change in TEOAE amplitude.

4.2. Comparison with Previous Studies

As described in Section 1, conflicting results on the effect of LLLT on hearing have been reported. The current results are further evidence that LLLT does not have an effect on hearing status. In the current study, care was taken to blind the subjects, the researchers administering the treatment, and the researchers administering auditory testing. It appears that some previous studies were less careful about controlling for placebo effect and potential researcher bias. Future studies should also implement double-blinding, as well as control and placebo groups. Other factors may also explain the discrepancy in findings. Some previous studies may have achieved much greater laser penetration by using animal models [] and isolated cochleae []. The current study, involving external irradiation of human subjects, likely involved less stimulation of structures associated with hearing. While a transmeatal approach to irradiation [] would have achieved greater penetration, such an approach represents a less practical delivery method and is not commonly used by holistic practitioners of LLLT. Differences in laser wavelength and dosage may also contribute to variable results across studies.

4.3. Limitations of Current Study

As discussed previously, several statistical assumptions must hold true in order to report valid statistics (normality, equal variance, independence, and random sampling). Since the current study was intended to be a feasibility study, it was anticipated that by randomly sampling individuals with documented sensorineural hearing loss, some evidence of an intervention effect would be measureable, if any existed. Since no effect could be demonstrated across a number of outcomes for any individual subjects, the study was terminated.

In this feasibility study, the timeline was fixed as per the pilot data from the manufacturer of the device. It is possible that the treatment number, treatment protocol, or even the duration of the entire data gathering was insufficient to show an intended effect.

The laser device was checked weekly, as per the manufacturer’s guidelines. It is possible, though unlikely, that the laser diode or the total output power varied between subject applications, all of which took place within a 7–10-day period.

5. Conclusions

No statistically significant effect of LLLT on auditory function was found, as assessed by pure-tone audiometry, speech understanding, and TEOAEs. Additionally, no individual subjects showed any clinically significant change. It remains possible that other methods of LLLT could have an effect on hearing. Further research elucidating the anatomic and physiologic bases for therapeutic effects of LLLT on hearing are needed before further clinical testing is warranted.

References

1. Karu TI. Molecular mechanism of the therapeutic effect of low-intensity laser radiation. Lasers in the Life Sciences1988;2(1):53–74.
2. Wilden L, Karthein R. Import of radiation phenomena of electrons and therapeutic low-level laser in regard to the mitochondrial energy transfer. Journal of Clinical Laser Medicine and Surgery1998;16(3):159–165. [PubMed]
3. Kujawa J, Zavodnik L, Zavodnik I, Buko V, Lapshyna A, Bryszewska M. Effect of low-intensity (3.75–25?J/cm2) near-infrared (810?nm) laser radiation on red blood cell ATPase activities and membrane structure. Journal of Clinical Laser Medicine and Surgery2004;22(2):111–117. [PubMed]
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8. Gungor A, Dogru S, Cincik H, Erkul E, Poyrazoglu E. Effectiveness of transmeatal low power laser irradiation for chronic tinnitus. Journal of Laryngology and Otology2008;122(5):447–451. [PubMed]
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ISRN Otolaryngol. 2012 Apr 9;2012:132060. doi: 10.5402/2012/132060. Print 2012.

Low-level laser therapy in patients with complaints of tinnitus: a clinical study.

Salahaldin AH1, Abdulhadi K, Najjar N, Bener A.

Author information

1
ENT and Head and Neck Surgery Department, Audiology and Balance Unit, Rumaillah Hospital and Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar.

Abstract

OBJECTIVE:

The objective of the study was to investigate the effectiveness of low-level laser therapy (LLLT) in treating patients who were suffering from long-term complaints of tinnitus with well-understood etiology and who were not responding to conventional therapy in Qatar.

DESIGN:

This is a prospective clinical study conducted during the period from May 2010 and February 2011.

SETTING:

Audiology Clinic, Outpatient Department, Hamad General Hospital.

SUBJECTS AND METHODS:

The study included 65 patients aged 15-76 years with chronic unilateral or bilateral tinnitus with a minimum duration of illness of one year. The investigation included 101 ears of 65 patients. A 5?mW laser with a wavelength of 650?nm was applied transmeatally for 20 minutes once daily for 3 months. The study was based on a face-to-face interview with a designed questionnaire that recorded the diagnosis of patients, clinical evaluation and audiometric test results, and side effects of low-level laser therapy (LLLT) and scored their symptoms loudness on five-point scale every two weeks. A decrease of one scale point regarding the loudness duration and degree of annoyance of tinnitus was accepted to represent an improvement; at the same time, a pure tone audiometric test was carried out and the results recorded. In addition, a record of the side effect was taken.

RESULTS:

Over half of the patients (56.9%) had some form of improvement in their tinnitus symptoms. Mild improvement was reported in 33.8% of patients, moderate improvement was reported in 16.9%, and full improvement was reported in 6.15%. Of the patients who reported dizzy spells as a symptom of their tinnitus condition, 27.7% reported mild improvement and 16.9% reported full improvement. Common side effects of LLLT were noted among 20% of patients; however, all of them were mild and disappeared within a few days.

CONCLUSION:

Low-level laser therapy was found to be useful for treatment of chronic tinnitus.

Vestn Otorinolaringol.  2011;(1):39-40.

The application of supravascular laser irradiation of blood for the treatment of cochleovestibular disorders.

[Article in Russian]
Lapchenko AS, Kucherov AG, Levina IuV, Ivanets IV, Krasiuk AA, Kadymova MI.

Abstract

A total of 165 patients presenting with neurosensory impairement of hearing and Meniere’s disease were treated by supravascular (extracorporeal) laser irradiation of blood. The study undertaken to evaluate the efficacy of this treatment confirmed its beneficial effect in patients with acute hearing disorders. It was equally effective as regards elimination of labyrinthine hydropsis in patients presenting with Meniere’s disease. The method proved less efficacious for the management of long-standing hearing impairement and chronic loss of hearing, but it can be used to prevent the development of these conditions.

J Res Med Sci.  2011 Jan;16(1):33-8.

Low-level laser for treatment of tinnitus: a self-controlled clinical trial.

Okhovat A, Berjis N, Okhovat H, Malekpour A, Abtahi H.

Department of Otorhinolaryngology, School of Medicine, Isfahan University of Medical Science, Isfahan, Iran.

Abstract

BACKGROUND: Despite the high prevalence and morbidity, tinnitus still remains an obscure symptom. We assessed the efficacy of low-level laser for treatment of tinnitus.

METHODS: It was a self controlled clinical trial study on 61 outpatients with subjective tinnitus. The patients were irradiated with a 650-nm, 5-mW soft laser for twenty days and twenty minutes per day. The sensation of tinnitus was measured on a Visual Analog Scale (VAS) before and two weeks after treatment and they were compared by means of Wilcoxon signed ranktest.

RESULTS: Thirty-eight (62.3%) patients were men and twenty-three (37.7%) were women. Fourteen patients (31.8%) worked in noisy environment. The VAS mean difference before and after the treatment was statistically significant (p < 0.0001). The best treatment effect was in the youngest group and there were significant differences between this group and the middle age and older groups (p = 0.018 and 0.001, respectively). The mean VAS score reduction was not statistically significant between male and female patients (p = 0.23). Also, the treatment outcome according to the noise level in patient’s workplaces was not significantly different in women (p = 0.693), but it was significant in men (p = 0.029).

CONCLUSIONS: Transmeatal low-level laser irradiation is effective for the treatment of tinnitus and some variables like age and job can affect the treatment outcome.

J Laryngol Otol. 2008 May;122(5):447-51. Epub 2007 Jul 12.

Effectiveness of transmeatal low power laser irradiation for chronic tinnitus.

Gungor A, Dogru S, Cincik H, Erkul E, Poyrazoglu E.

Department of Otolaryngology, Haydarpasa Military Hospital, Istanbul, Turkey.

OBJECTIVE: To evaluate effectiveness of 5 mW laser irradiation in the treatment of chronic tinnitus. STUDY DESIGN: Prospective, randomised, double-blind study.Methods:This investigation included 66 ears in 45 patients with chronic unilateral or bilateral tinnitus. A 5 mW laser with a wavelength of 650 nm, or placebo laser, was applied transmeatally for 15 minutes, once daily for a week. A questionnaire was administered which asked patients to score their symptoms on a five-point scale, before and two weeks after laser irradiation. A decrease of one scale point, regarding the loudness, duration and degree of annoyance of tinnitus, was accepted to represent an improvement. RESULTS: The loudness, duration and degree of annoyance of tinnitus were improved, respectively, in up to 48.8, 57.7 and 55.5 per cent of the patients in the active laser group. No significant improvement was observed in the placebo laser group. CONCLUSION: Transmeatal, low power (5 mW) laser irradiation was found to be useful for the treatment of chronic tinnitus.

EMLA Laser Health J 2007;2:46-67
European Medical Laser Association (EMLA)

Combined non-invasive laser – Egb 761 therapy of chronic tinnitus

A. Hahn
Head of ENT Clinic of the 3rd Medical Faculty, Charles University, Prague, CZ

The treatment of patients with chronic tinnitus is very problematic and therefore otologists are trying to discover more suitable courses of therapy. In this study we wanted to evaluate the outcome of using a combination of EGb 761 and soft laser therapy.

We examined 120 patients with an average duration of tinnitus of 10 years. The patients underwent pure-tone audiometry, speech audiometry and objective audiometry tests. The intensity and frequency of tinnitus was also determined. EGb 761 was administered 3 weeks before starting soft laser therapy. Patients underwent 10 sessions of laser therapy, each lasting for 10 min. An improvement in tinnitus was audiometrically confirmed in 50.8% of patients.

Acta Odontol Scand. 2006 Apr;64(2):89-96.

Long-term effect on tinnitus by treatment of temporomandibular disorders: a two-year follow-up by questionnaire.

Tullberg M1, Ernberg M.

Author information

1
Department of Clinical Oral Physiology, Institute of Odontology, Karolinska Institutet, Huddinge, Sweden. marie.tullberg@brahekliniken.se

Abstract

OBJECTIVE:

The aim of the study was to investigate the presence of symptoms and signs of temporomandibular disorders (TMD) in patients with tinnitus and to evaluate the effect of TMD treatment on tinnitus in a long-term perspective in comparison with a control group of patients on a waiting list.

MATERIAL AND METHODS:

One-hundred-and-twenty patients with tinnitus were subjected to a clinical examination of the masticatory system and whether they had co-existing TMD to TMD treatment. Ninety-six patients had TMD, most frequently localized myalgia. Seventy-three of these completed the treatment and responded to a questionnaire 2 years later. Fifty patients with tinnitus who were on the waiting list served as a control group.

RESULTS:

Eighty percent of the patients had signs of TMD, most commonly myofascial pain. Forty-three percent of the patients reported that their tinnitus was improved at the 2-year follow-up, 39% that it was unchanged, and 17% that it was impaired compared to before the treatment. Twelve percent of the subjects in the control group reported that their tinnitus was improved compared to 2 years previously, 32% that it was unchanged, and 56% that it was impaired. The difference between groups was significant (chi(2): p<0.001).

CONCLUSION:

The results of this study showed that TMD symptoms and signs are frequent in patients with tinnitus and that TMD treatment has a good effect on tinnitus in a long-term perspective, especially in patients with fluctuating tinnitus.

Lasers Med Sci. 2003;18(3):154-61

Transmeatal cochlear laser (TCL) treatment of cochlear dysfunction: a feasibility study for chronic tinnitus.

Tauber S, Schorn K, Beyer W, Baumgartner R.

Department of Otolaryngology, Head and Neck Surgery, Ludwig-Maximilians-University of Munich, D-81377 Munich, FRG. drtauber@yahoo.de

Low-level-laser-therapy (LLLT) targeting the inner ear has been discussed as a therapeutic procedure for cochlear dysfunction such as chronic cochlear tinnitus or sensorineural hearing loss. Former studies demonstrate dose-dependent biological and physiological effects of LLLT such as enhanced recovery of peripheral nerve injuries, which could be of therapeutic interest in cochlear dysfunction. To date, in patients with chronic tinnitus mastoidal and transmeatal irradiation has been performed without systematic dosimetric assessment. However, light-dosimetric studies on human temporal bones demonstrated that controlled application of laserlight to the human cochlea depends on defined radiator position within the external auditory meatus. This feasibility study first presents a laser application system enabling dose-controlled transmeatal cochlear laser-irradiation (TCL), as well as preliminary clinical results in patients with chronic cochlear tinnitus. The novel laser TCL-system, consisting of four diode lasers (lambda=635 nm-830 nm) and a new specific head-set applicator, was developed on the basis of dosimetric data from a former light-dosimetric study. In a preliminary clinical study, the TCL-system was applied to 35 patients with chronic tinnitus and sensorineural hearing loss. The chronic symptoms persisted after standard therapeutic procedures for at least six months, while retrocochlear or middle-ear pathologies have been ruled out. The patients were randomised and received five single diode laser treatments (lambda=635 nm, 7.8 mW cw, n=17 and lambda=830 nm, 20 mW cw, n=18) with a space irradiation of 4 J/cm2 site of maximal cochlear injury. For evaluation of laser-induced effects complete otolaryngologic examinations with audiometry, tinnitus masking and matching, and a tinnitus-self-assessment were performed before, during and after the laser-irradiation. The first clinical use of the TCL-system has been well tolerated without side-effects and produced no observable damage to the external, middle or inner ear. Changes of tinnitus loudness and tinnitus matching have been described. After a follow-up period of six months tinnitus loudness was attenuated in 13 of 35 irradiated patients, while two of 35 patients reported their tinnitus as totally absent. Hearing threshold levels and middle ear function remained unchanged. Further investigations by large double-blind placebo-controlled studies are mandatory for clinical evaluation of the presented TCL-system and its therapeutic effectiveness in acute and chronic cochlear dysfunction.

ON THE EFFECTIVENESS OF LOW LEVEL LASER LIGHT (LLLL) IN THE INNER EAR

 

Reproduced here through permission of Dr. Lutz Wilden
Examined by pre- and posttherapeutical audiometry courses of air and bone conductions
Lutz Wilden*
*Private office Dr. med. Lutz Wilden, Kurallee 16, D-94072 Bad Füssing, Tel:+49 8531 980198, Fax:+49 8531980119, e-mail: info@dr.wilden.de.

(db = decibel; j = joule; kc = kilocycle; nm = nanometer)

ABSTRACT
A) The objective of the study was the documentation of the biostimulative effects of LLLL in high energetical dosages (measured in j) by audiometry changes of a statistically relevant number of patients. B) The energy was transmitted with 3 laser diodes with a wave length of 830 nm and 3 diodes with a wave length of 635 nm; it was administered via meatus and mastoid. The examination and therapy included 348 patients and 215 right and 187 left inner ear organs (cochlea). 171 organs were female, 231 were male. Their average age at the beginning of the therapy was 56.9 years; the average duration of their disease was 5.9 years. 97.3 % suffered from tinnitus. The examination started on 24 june 1996 and ended on 9 february 1999. The average treatment phase lasted 61.5 days. The average duration of the therapy was 11.8 hours; the average quantity of the transmitted energy was 6732 j. Before every therapy series with LLLL the patients actual hearing capacity (air and bone conductions) was examined by audiometry. At the end of each therapy series their hearing capacity was examined by the same method for a second time. The statistical analysis consisted of the arithmetical evaluation of a mean value of all test data over 12 frequencies as far as air and bone conductions were concerned, the drawing up of frequency intervals (low = 0.125, 0.25, 0.5 and 0.75 kc, middle = 1, 1.5, 2 and 3 kc, and high = 4, 6, 8 and 12 kc) and the grouping of the patients according to age, duration of the disease, quantity of the transmitted energy and the relative total reduction of the necessary sound volume in db. In cases of deafness 125 db were used as an auxiliary numeric value. C) The hearing capacity of the patients was ameliorated in all frequency sectors (average value = 20.6 %). The best db-reductions were obtained in the low frequency sector (9.3 db) and in the high frequency sector (11.2 db). There was a close (and biologically plausible) correlation as far as the amelioration of the hearing capacity and the age of the patients and the duration of their disease were concerned; this correlation was the higher, the more energy was transfered on the whole. D) If LLLL is administered in sufficiently high dosages to the inner ear (cochlea), it is possible to obtain and document medicinically significant biostimulative effects.
Introduction
According to a study of the university of Cologne1) by 2030 every second German will be suffering from impairments of the inner ear. Even at the present time, the number of people all over the world, who are inflicted with long-standing impairments or acute diseases of the inner ear, amounts to millions. The basic diagnostic for the documentation of the functional quality of the cochlea is the audiometry. The correlation of organopathological examinations of the cochlea and pathological audiometry results is illustrated by scientific papers2)
The audiometry belongs to the diagnostical standard equipment of medical offices and acousticians and is universally being used as a basic diagnostic by trade operative associations and industrial medicine for the purpose of examinations and appraisements. This is why it seemed approriate to use this method, which is both economical and easy on the patient, to verify the biostimulative effects of LLLL on the inner ear.
Nowadays, the prevailing measures to give therapy to patients with a reduced hearing capacity are the administration of non-specific medicaments that stimulate the blood circulation respectively the utilization of technical equipment such as sound amplifiers (hearing aids) or – in severe cases – electronically operated artificial inner ear appliances.
At present, a therapy that ameliorates the biological qualitiy of the sensory cells of the cochlea and thus increases the hearing capacity is being cold-shouldered by the overwhelming majority of physicians.
Although the manifold clinical and experimental studies of the international low level laser literature3) include examinations of the therapy of inner ear diseases 4) and the penetration capacity of LLLL into the inner ear 5), so far there was no statistical inquiry about the therapy with high dosages of LLLL, which is backed up by a sufficient amount of audiometrical data and takes into account a statistically relevant number of patients respectively inner ear organs.
Material and methods
The data of this study were collected from patients, whose further treatment – within the scope of conventional therapies – was predominantly regarded as futile when they started the low level laser therapy (LLLT). The patients all received an out-patient treatment, which consisted exclusively of a monotherapy. They were advised to take reasonable prophylactic measures against noise during (and after) the therapy. Possibly existing medicamentous or masker therapies were discontinued. Patients with hearing aids were advised to reduce the adjustments according to their improving hearing quality.
The energy was transmitted by 3 laser diodes with a wave length of 830 nm und 3 diodes with a wave length of 635 nm; it was administered via meatus and mastoid. The statistical analysis consisted of the arithmetical evaluation of a mean value of all audiometrical data over 12 frequencies as far as air and bone conductions were concerned, the drawing up of frequency intervals (low = 0.125, 0.25, 0.5 and 0.75 kc, middle = 1, 1.5, 2 and 3 kc, and high = 4, 6, 8 and 12 kc and the grouping of the patients according to age, duration of the disease, quantity of the transmitted energy and the relative total reduction of the necessary sound volume in db. In cases of deafness 125 db were used as an auxiliary numeric value.

In the case of the initial audiometrical results (pretherapeutical findings) the evaluation of the mean value of all readings reveals a clearly reduced average course of the hearing curves of the air and bone conductions over all frequencies, with low points in the frequency sector around 6 kc and the frequency sector around 12 kc (sensorineural hardness of hearing, oblique descension).

As expected, the bone conduction is situated above the air conduction in all frequencies. Occasional intersections of the air and bone conductions are only to be found in the frequency sector between 6 and 8 kc; this phenomenon, which is known from individual audiometries and can be observed on the mean curve, is due to an increasing loss of the differentiation capacity of the cochleas sensory cells within the range of higher-grade biological quality reductions of the organ of Corti.

In the case of the final audiometrical results (posttherapeutical findings) the evaluation of the mean value of all readings reveals a clearly and symmetrically ameliorated average course of the hearing curves of the air and bone conductions over all frequencies as compared with the pretherapeutical course (amelioration of the sensorineural hardness of hearing with a reduction of the oblique descension). As expected, the bone conduction is once again situated above the air conduction in all frequencies; the intersection phenomena in the frequency sector between 6 and 8 kc show a downward tendency.

The diagram of the average total reduction (db) of the air and bone conductions shows a significant amelioration of the hearing capacity in the low and high frequency sector and a more pronounced amelioration of the air conduction as compared with the bone conduction in the lower frequency sector.

Clinically, this can be interpreted to the effect that, apart from its general therapeutical value, the LLLL also exerts a positive influence on the widespread sound conduction disturbances in this frequency sector, which are indicated by degenerative changes of the middle ear (for instance, otosclerotic processes.)

The highest reduction is to be found in the low frequency sector (9.3 db when there are 0.25 kc in the air conduction; 6.4 db when there are 0.124 kc in the bone conduction) and in the high frequency sector (10.9 db when there are 12 kc in the air conduction; 11.2 db when there are 12 kc in the bone conduction).
The average reduction (improved hearing) of the sound pressure necessary for the perception of sounds within a given frequency totals a mean value of 7.2 db over all frequenciesair(air = 7.8 db; bones = 6.7 db). Altogether, this corresponds with an average amelioration of the hearing capacity of<20.6 %(air = 20.5%;bones = 20.6%); for further figures compare appendix, table1.

The comparison of all pre- and posttherapeutical readings over all frequencies reveals statistically highly significant results in the case of the air and bone conductions.

The values of the air conduction, which are slightly higher as those of the bone conduction, indicate that the LLLL has additional positive therapeutical effects on the sound conducting structures of the middle ear.

The grouping of the readings according to age groups and 3 frequency intervals results in findings that are biologically plausible as far as both the air and the bone conductions is concerned. In other words, the patient group with the highest average age (72.4 years) finds itself in the most disadvantageous starting position; the patient group with the lowest average age (37.9 years) finds itself in the most advantageous starting position.

This applies to all 3 frequency intervals. The data also show that – in spite of the respective starting position – all age groups profit from the biostimulative effects of the LLLL in a relatively equal way. This holds good for both the air and the bone conduction.

If one takes into consideration the energy quantity (j) transmitted in order to reach these results, it is obvious that the eldest age group needs the largest quantity of transfered energy. However, this seems to be biologically plausible as well.

As to the grouping of the readings according to the duration of the disease and 3 frequency intervals, the patient group with the shortest duration of the disease (0.6 years) has the best initial values and obtains the best final results with the smallest quantity of transfered energy. The patient group with the longest duration of the disease (14.5 years) has the poorest initial values and furthermore needs the largest quantity of transfered energy. This holds good for both the air and the bone conduction over all frequencies. At the same time, a detailed analysis of the data reveals that – in spite of the respective duration of the disease – all patient groups profit from the biostimulative effects of the LLLL in a relatively equal way. It has to be emphasized, though, that once again the most difficult patient group (average duration of the disease 14.5 years) needed the largest quantity of transfered energy.
The grouping of the readings according to energy quantities reveals a clear correlation between the total quantity of the transfered energy and the therapeutical results that were obtained. The larger the quantitity of transfered energy, the higher the db-reductions that could be observed. This applies to both the air and the bone conduction in all 3 frequency intervals.
Fig. 6b clearly shows the correlative (parallel) connection between the total quantity of transfered energy and the total reduction.

Even if expressed in percentages, the mean values of the respective groupings demonstrate that the smallest amount of transfered energy (6188 j) results in the lowest relative reduction (5.4 %), whereas the largest quantitity of transfered energy (9007 j) brings about the highest relative reaction (46.4 %).

The highest correlation coefficient of 0.91 (relative total reduction in relation to total quantity of transfered energy) thus confirms the observations implied by the foregoing groupings according to age, duration of the disease and total quantity of transfered energy.

In the whole course of the therapy no side effects whatsoever could be observed.

In some of the cases, however, the LLLT of the inner ear organ presented in this paper caused specific individual reactions such as temporary vertigo respectively the disappearance of an existing otogenic vertigo, the momentary appearance respectively disappearance of a sensation of pressure in the ear and changes respectively the reduction or disappearance of a prevailing dysacusia and/or tinnitus, which had to be interpreted correctly with regard to the patient.

 

Conclusions

If LLLL is transmitted to the inner ear (cochlea) in sufficiently high dosages, it is possible to obtain and document medicinically significant biostimulative effects.

In this respect, the results of the study at hand not only refer to the fundamental working model of the cellular energy transfer6) from 1998, which was based on quantum mechanics, but confirm its conclusions as well, namely, that cellular regeneration processes do take place, if the mitochondria in question are stimulated to an increased production of adenosine triphosphate (ATP) by sufficiently large quantities of LLLL.

To what extent subsequent LLLTs lead to additional organic betterments (on average > than 20.6 %) is left up to future studies. The same applies for an augmentation of the total quantity of the transfered energy in the course of the treatment phases or per unit; in the latter case further technological developements on the part of the laser industry are indispensable, though.

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– J. Kert and L. Rose (1989). Cinical Laser Therapy, Low Level Laser Therapy. D”nemark: Veksoe
– Pekka J. Pöntinen (1992). Low Level Laser Therapy as a medical treatment modality. A manual for Physicians, Dentists, Physiotherapists and Veterinary Surgeons. Tampere: Art Upo Ltd.
– D. Baxter (1994). Therapeutic Lasers. Edinburg: Churchill Livingstone
– G. Ambronn, R. Muxeneder and U. Warnke (1995). Laser- und Magnetfeldtherapie in der Tiermedizin. Jena/Stuttgart: Gustav Fischer Verlag
– Pekka J. Pöntinen and R. Pothmann(1998). Laser in der Akupunktur. Grundlagen, Indikation und Technik für die Akupunktur – Schwerpunktpraxis. Stuttgart: Hyppocrates Verlag
– Tiina Karu (1998). The Science of Low-Power Laser Therapy. Amsterdam: Gordon and Breach Science Publishers
– 2 nd Congress World Association for Laser Therapy (1998), September 2-5. Abstracts. Kansas City: University of Kansas Medical Center
– Jan TunÈr and Lars Hode (1999). Low Level Laser Therapy. Clinical Practice and Scientific Background. Gr”ngesberg: Prima Books
4.- Y. Shiomi, H. Takahashi, I. Honjo, H. Kojima, Y. Naito and N. Fujiki (1995). Efficacy of transmeatal low power laser irridiation on tinnitus: a preliminary report. Auris Nasus Larynx. 24: pp. 39-42
– L. Wilden and D. Dindinger (1996). Treatment of chronic complex diseases of the inner ear with Low Level Laser Therapy. Laser Therapy. 8 (3)
– Lutz Wilden and Michaela Fritsch (1997). Tinnitus lindern durch Laserlicht. Wiesbaden: Dr. Werner Jopp Verlag
5.- Wolfgang Beyer, Reinhold Baumgartner and Stefan Tauber (1997). Dosinetric analysis for low-level-lasertherapy (LLLT) of the human inner ear at 593nm and 633nm. Munich: Forschungsbericht der Ludwig-Maximilians-Universität
6.- Lutz Wilden and Rainer Karthein (1998). Import of Radiation Phenomena of Electrons and Therapeutic Low-Level Laser in Regard to the Mitochondrial Energy Transfer. Journal of Clinical Laser in Medicine and Surgery. 16 (3), pp. 159-165

EMLA Laser Health J 2007;2:46-67
European Medical Laser Association (EMLA)

Laser therapy in the combined treatment of hyperacusis, a prospective clinical study.

P. A. Mikael Bäckman – Audio Laser-Kliniken, Hovmantorp, Sweden
homepage: www.alir.nu/medicin
email: email: mica@mail.nu

Abstract

Patients suffering from hyperacusis were treated twice a week with a combination of therapeutic laser, pulsed electromagnetic field and the control and adjustment of Reactive Oxygen Species (ROS). 245 observations in 42 ears on 26 patients were measured before therapy and after 10-20 therapeutic sessions. One group was evaluated in short-term follow-up (immediately after therapy), another group was evaluated in long-term follow-up (4-6 months after therapy). The average improvement for the pain thresholds was 17.02 dB. An average improvement of 10 dB or more was obtained in 40 ears. In the long-term follow-up group the average result was 22.84 dB and in the short-time follow-up group it was 14.50 dB. All ears improved. Between 177-504 J of laser light was administrated via meatus acusticus. The pulsed electromagnetic field applicator generated a magnetic field of a maximum of 100 µT and it was placed behind the ear, over the area of the mastoid bone. ROS were measured and controlled by administrating different sorts of antioxidants such as Ginkgo biloba.

[Low-energy laser radiation in the combined treatment of sensorineural hearing loss and Meniere’s disease]

[Article in Russian]
Pal’chun VT, Lapchenko AS, Kadymova MI, Kucherov AG.

59 patients with neurosensory hypoacusis and 45 with Meniere’s disease underwent helium-neon laser intra- or supravascular radiation of blood. The treatment proved effective in acute neurosensory hypoacusis and Meniere’s disease. In chronic neurosensory hypoacusis the effect was insignificant.

Comprehensive therapy of patients suffering from tinnitus.

Prochazka M, Tejnska R.

37 patients suffering from tinnitus (age 18-86 years) were treated in three ways: 1. Rehabilitation: mobilisation, physical training, physiotherapy. 2. Same as 1 but with placebo laser added. 3. Same as 1 but with functional laser added. Laser used was 830 nm 300 mW. 2-3 treatments per week were given, total 10 treatments. Treatment protocol: 90 J/cm2 CW on mastoideus, 45 J/cm2 5 Hz on mastoideus, 50 J/cm2 CW on acoustic duct, 25 J/cm2 5 Hz on acoustic duct. Tebokan Egb 761 ginko medication was added to treatment. Results were classified as no effect/less than 50% relief/more than 50% relief/no more tinnitus. The percentwise outcome for the three groups was: 1. 29.4/44.1/17.6/8.9 2. 25.8/48.4/25.8/0 3. 19.4/19.4/35.5/25.8

Auris Nasus Larynx. 1997;24(1):39-42.

Efficacy of transmeatal low power laser irradiation on tinnitus: a preliminary report.

Shiomi Y, Takahashi H, Honjo I, Kojima H, Naito Y, Fujiki N.

Department of Otolaryngology, Faculty of Medicine, Kyoto University, Japan.

Thirty-eight patients suffering from tinnitus resistant to several medical therapies for more than 6 months were treated by low power laser irradiation. A 40 mW laser with a wavelength of 830 nm was irradiated via their external auditory meatus toward the cochlea for 9 min once a week, 10 times or more. Patients were asked to score their symptoms on a 5 point scale before and after the treatment for a subjective evaluation of the effect. The results were estimated by the change of the loudness and duration of tinnitus, and the degree of annoyance due to tinnitus. Although only 26% of the patients had improved duration, loudness and degree of annoyance were relieved in up to 58 and 55%, respectively, without major complication. Laser therapy seemed to be worth trying on patients with intractable tinnitus.

Auris Nasus Larynx. 1997; 24 (1): 39-42.

Promising results using LLLT for tinnitus and inner ear diseases

Shiomi et al. used a 40 mW GaAlAs laser in a group of 38 patients suffering from tinnitus, resistant to several medical therapies for more than six months. 21.6 J was given each time through the auditory meatus toward the cochlea. Ten treatments or more were given. Only 26% of the patients reported improved duration, but 58% had  reductiont of loudness and 55% reduced annoyance. The authors conclude: ”Laser therapy seemed to be worth trying on patients with intractable tinnitus”. Editorial note: The results can be improved if much higher doses are given. Dr. Lutz Wilden of Bad Füssing, Germany reported on his 6 years of experience at a recent lecture before the members of the Swedish Laser Medical Society (Stockholm, May 1998). Dr. Wilden is using three different lasers. One is directed through the meatus, two are positioned over the mastoid. Total dosage 2000-4000 (sic) joules per treatment (60 minutes per session, 30 minutes per ear). Doses may seem very high, but the thick bone behind the ear absorbs about 95% of the energy before reaching the inner ear. For more info, see http://home.t-online.de/gbl-hc/ez.

TINNITUS AND VERTIGO – A CASE FOR THE DENTIST?

Jan Tunér DDS Grängesberg, Sweden. E-mail: jan@tuner.nu

The correlation between tinnitus/vertigo and cranomandibular disorders (CMD) has been known for quite some time, yet few dentists seem to be aware of this. It is not natural for the dentist to ask, nor for the patient to inform the dentist about such a situation since it does not appear to be a dental indication. However, quite a number of tinnitus/vertigo patients will be releived of their symptoms if a proper CMD treatment is performed. Low level lasers have been used to treat tinnitus patients with reasonable success, if sufficient energy and suitable treatment technique is used. These lasers have also proved themselves successful in the treatment of CMD. It is obvious, therefore, that low level laser therapy is an appropriate treatment modality for the yet undefined subgroup of tinnitus/vertigo patients with a CMD background. Laser therapy will reduce pain levels, ease muscular spasms and revert the vicious circle. In some cases laser therapy alone will produce astonishing results, in others it has to be combined with traditional occlusal stabilisation procedures. It is important for doctors to be aware of this subgroup of tinnitus patients since traditional therapies, and even laser therapy of the inner ears, will be ineffective if the CMD is not diagnosed and treated. This presentation will look at the literature documentation for laser therapy of tinnitus/vertigo.

Light dosimetry and preliminary clinical results for low level laser therapy in cochlear dysfunction.

Beyer W et al.

The light distribution inside the cochlear windings produced by irradiation of the tympanic membrane was quantitatively measured ex vivo for wavelengths of 593, 612, 635, 690, 780 and 805 nm by means of video dosimetry. The transmission of light across the tympanic cavity and the promontory depends strongly on the wavelength. Spatial intensity variations of a factor of 10 and more inside the cochlear windings have been measured. The clinical study was performed with 30 patients suffering from chronic permanent tinnitus. 5 irradiations within 2 weeks each with a space irradiation of 4J/cm2 were applied at the cochlear position to be treated. Diode lasers of 635 or 830 nm, 15 patients each, were used. During and after irradiation there was no significant change of hearing. However, 40% of the patients reported a slight to significant attenuation of the tinnitus loudness of the treated ear. There was no difference between the two wavelength groups. A double blind controlled study is in preparation.

Otology & neurotology 2002; 23 (3): 296-300.

 

Transmeatal low-power laser irradiation for tinnitus.

Nakashima T, Ueda H, Misawa H et al.

To evaluate effectiveness of 60mW laser irradiation in the treatment of tinnitus. Prospective, randomised double-blind study. This investigation included 68 ears in 45 patients with disabling unilateral or bilateral tinnitus. The active or placebo laser treatment was administered trans-meatally once a week for 6 minutes. Laser irradiation was performed four times during a 4-week period. A questionnaire was administered to evaluate the loudness, duration, quality, and annoyance of tinnitus before and after irradiation. The loudness and pitch match for tinnitus were obtained, and distortion product otoacoustic emissions were also examined.: No significant difference was observed between the active and placebo laser groups with regard to outcome of loudness, duration, quality, and annoyance of tinnitus. In one patient who received active laser treatment, acute hearing deterioration occurred after the third irradiation. Transmeatal low-power laser irradiation with 60 mW is not effective for the treatment of tinnitus.

Lasers Med Sci. 2003;18(3):154-61.

Transmeatal cochlear laser (TCL) treatment of cochlear dysfunction: a feasibility study for chronic tinnitus.

Tauber S, Schorn K, Beyer W, Baumgartner R.

Department of Otolaryngology, Head and Neck Surgery, Ludwig-Maximilians-

University of Munich, D-81377 Munich, FRG. drtauber@yahoo.de
Low-level-laser-therapy (LLLT) targeting the inner ear has been discussed as a therapeutic procedure for cochlear dysfunction such as chronic cochlear tinnitus or sensorineural hearing loss. Former studies demonstrate dose-dependent biological and physiological effects of LLLT such as enhanced recovery of peripheral nerve injuries, which could be of therapeutic interest in cochlear dysfunction. To date, in patients with chronic tinnitus mastoidal and transmeatal irradiation has been performed without systematic dosimetric assessment. However, light-dosimetric studies on human temporal bones demonstrated that controlled application of laserlight to the human cochlea depends on defined radiator position within the external auditory meatus. This feasibility study first presents a laser application system enabling dose-controlled transmeatal cochlear laser-irradiation (TCL), as well as preliminary clinical results in patients with chronic cochlear tinnitus. The novel laser TCL-system, consisting of four diode lasers (lambda=635 nm-830 nm) and a new specific head-set applicator, was developed on the basis of dosimetric data from a former light-dosimetric study. In a preliminary clinical study, the TCL-system was applied to 35 patients with chronic tinnitus and sensorineural hearing loss. The chronic symptoms persisted after standard therapeutic procedures for at least six months, while retrocochlear or middle-ear pathologies have been ruled out. The patients were randomised and received five single diode laser treatments (lambda=635 nm, 7.8 mW cw, n=17 and lambda=830 nm, 20 mW cw, n=18) with a space irradiation of 4 J/cm2 site of maximal cochlear injury. For evaluation of laser-induced effects complete otolaryngologic examinations with audiometry, tinnitus masking and matching, and a tinnitus-self-assessment were performed before, during and after the laser-irradiation. The first clinical use of the TCL-system has been well tolerated without side-effects and produced no observable damage to the external, middle or inner ear. Changes of tinnitus loudness and tinnitus matching have been described. After a follow-up period of six months tinnitus loudness was attenuated in 13 of 35 irradiated patients, while two of 35 patients reported their tinnitus as totally absent. Hearing threshold levels and middle ear function remained unchanged. Further investigations by large double-blind placebo-controlled studies are mandatory for clinical evaluation of the presented TCL-system and its therapeutic effectiveness in acute and chronic cochlear dysfunction.

Used by the kind permission of the Czech Society for the Use of Laser in Medicine, www.laserpartner.org

The Role of LLLT in Treatment of Tinnitus

Laser Partner, 26.2.2002

Miroslav Prochazka, M.D.

Head doctor of the Jarov Private Rehab Clinic, Prague, CZ

tusita@mbox.vol.cz

Abstract

Comprehensive laser rehabilitation therapy of tinnitus has proven successfull and beneficial for treatment of this widespread civilization disease. Its long-term results are convincing, bringing significant relief to 36 per cent of patients and even leaving remarkable 26 per cent of patients without any symptoms (see Miroslav Prochazka, Ales Hahn: Comprehensive Laser Rehabilitation Therapy  of Tinnitus: Long-Term Double Blind Study on a Group of 200 Patients in 3 Years, Laser Partner No. 51/2002). With the results mentioned above we can really speak about a breakthrough. This study brings an additional overview of the role of LLLT (Low Level Laser Therapy) in the treatment. Our results enable us to pinpoint laser as the leading element in the overall therapy of tinnitus.

Introduction

Tinnitus is an auditory perception apearing without an objective sonic source from the outer environment. Tinnitus can be subjective (heard only by the patient) and objective (sound can be even heard also by others). Our study, however, deals with patients suffering from subjective tinnitus only. According to literature, fifteen per cent of entire population have experienced at least a tinitus episode some time, its incidence and severity rising with age up to approx. eighty-five per cent of population older than 60.

Our clinic has been treating tinnitus for more than 5 years. We have published three studies on this particular issue, and we are of the opinion that our results are being followed in several countries (Brasil, Cyprus, Sweden, Switzerland, Slovakia, Turkey, Japan, Germany etc.) and implemented in numerous clinics with significant results. Studies published by these clinics show results which are almost identical with our experience.

Our last study on a group of 200 patients in the course of three years was finalized in February 2002 and published in June 2002. Since there have always been efforts to evaluate an exact role of LLLT in treatment of tinnitus, apart from medication and physiotherapeutic manipulation of neck vertebra as an integral part of the comprehensive therapy, we have decided to create a separate group of patients to be treated only with laser. This was only possible thanks to our vast experience and long involvement in tinnitus treatments.

Materials and methods

Our group consisted of 72 patients, 49 males, 23 females, age ranging between 16 to 92 years. The age and sex is given in Table 1.

SEX  /  AGE 16 – 20 21 – 30 31 – 40 41 – 50 51 – 60 61 +
Male 2 4 6 9 13 15
Female 0 1 4 5 6 7
Total 2 5 10 14 19 22

Prior to the application of LLLT, all the patients underwent the following pre-therapy examination:

1. Anamnesis (aimed especially at the fact whether tinnitus was caused by an acoustic trauma, as well as at genetic predisposition)

2. Subjective evaluation of suffering

3. Clinical examination (otoneurology, axial skeleton, nystagm, blood pressure)

4. Technical examination (audiogram, x-ray of neck vertebra, ENG, tinnitometry)

5. Laboratory testing

Audiograms were taken in all the patients prior to the therapy. After the therapy audiograms were taken in 62.5 per cent, i. e. 45 patients, showing a slight improvement. Audiogram provides only for numeric range of perception of frequency of sounds, however it does not give us an objective evaluation of quality of hearing. Furthermore, the patients do not see the main improvement in a wider range of frequency of sounds, this remains usually on a similar level, but the main benefit is the absence of the additional burdening sound caused by tinnitus. Therefore the patients can better analyze sounds in general, their hearing is “refreshed” as they usually describe the result of the therapy.

Typical audiograms of patients with tinnitus before and after therapy shown on Picture 1.

MAESTRO/CCM device (manufactured by MediCom, Prague) was used for the study, with an infrared laser probe (830 nm) and power output 300 mW. The following application dosages and frequency modulations were applied on the following points:

1.         meatus acusticus externus – in the direction of the axis of the auditory duct – continuous beam 50 J/cm2 followed by 25  J/cm2, frequency modulation of 5 Hz (Picture 2),

2.         processus mastoideus – directed on the center, the vector of the beam in the direction of counter-lateral orbit, continuous beam 90  J/cm2 , followed by 45 J/cm2 with 5 Hz pulse frequency (Picture 3).

We strictly appeal to maintain the direction of the vector of aiming the beam – in fact the target structure of the helix is a shape of several square milimeters.

Picture 2:

Irradiation of meatus acusticus externus

Picture 3:

Irradiation of processus mastoideus

At the beginning, attendance was scheduled to 10 procedures in total, twice a week. Having completed the first series, patients returned after 2 – 3 months for another two series, each consisting of 5 – 6 therapies, once a week.

Evaluation

Level of subjective complaints was evaluated according to three scales:

  • Percentage scale – complaints evaluated 100 per cent at the beginning of therapy (Blue), according to the level of relief decreased (Green) to 80, 70 etc. per cent, possible acceleration of problems (Red) goes up to 110, 120 etc. per cent, no tinnitus equals 0 per cent
  • Five-grade scale – analogous to pain scales, reaching from Gr. I = No tinnitus to Gr. 5 = tinnitus interfering all activities

Grade I = No tinnitus

Grade II = No interfering sound perceived during the day, only in evenings, causing no discomfort

Grade III = Interfering sound perceived during the day, interrupting drowse only

Grade IV = Interrupting drowse and sleep, interfering sound causing discomfort during the day

Grade V = Unbearable discomfort, interfering all activities

  • Graphic scale – Patient marking 0 to 10, accompanied by a simple graphics showing face grimaces according to his/her amount of subjective hardship.

In order to simplify the effect of therapy as much as possible the results were divided in four groups:

  1. Patients with no effect of comprehensive therapy
  2. Less than 50 per cent relief
  3. More than 50 per cent relief
  4. No more tinnitus, patient free of the disease.

This evaluation is identical with our previous study, and it enabled us to compare easily the results of both studies.

Results

The results obtained are shown in Table 2.

Result Patients Per cent
No effect 15 20.8
Less than 50 % relief 19 26.4
More than 50 % relief 22 30.6
No more tinnitus 16 22.2
Total 72 100

It was interesting to compare our latest results (LLLT only) with those of our previous studies, i. e. our study made in 1998, long-term study between 1999 – 2001, and the initial study aimed at LLLT only. Comparison is contained in Table 3.

Result 1998 1999 – 2001 LLLT only
No effect 19.4 % 16.0 % 20.8 %
Less than 50 % relief 19.4 % 15.0 % 26.4 %
More than 50 % relief 35.5 % 43.0 % 30.6 %
No more tinnitus 25.8 % 26.0 % 22.2 %

 

Discussion

Hippocratic Oath orders us to treat patients to the best of our knowledge and ability. Since our long-term experience in comprehensive treatment of tinnitus has been based on the triad of physiotherapeutic manipulation, medication, and LLLT, we were at a loss whether we would not harm our patients in a way, giving them only a part of the treatrment, mere LLLT. We have to declare, that we have selected patients during the introductory examination, sorting out patients whose x-ray indicated a possibility of tinnitus caused by vertebral blockades. On the other hand, this selection led to a more pure evaluation of the role of LLLT in the treatment of tinnitus, leaving out both a possible cause and a corresponding treatment.

We have been positively surprised that in general the ratio of individual four groups remained similar. The number of patients with no effect of LLLT slightly increased (by 4.8 per cent when compared to the long-term study, by 1.4 per cent in comparison to the original study of 1998). This is obviously caused by the absence of medication and physiotherapy, showing their supportive efect.

In the group evaluating improvement as less than 50 per cent the leading role of LLLT can be evidenced best. More than one-fourth of all patients (26.4) report improvement after therapy performed with LLLT only, which is a result better than those in both previous studies (19.4 and 15.0) .

Impressive results have also been obtained in the last two groups , when we imagine more than one half of all patients reporting significant and/or total relief of tinnitus (30.6 + 22.2 = 52.8 per cent).

Conclusion

22.2 per cent patients suffering from tinnitus never more after treatment with therapeutic laser is a great success of LLLT. It only confirms the leading role of LLLT within comprehensive laser rehabilitation therapy of tinnitus. On the other hand we must stress the necessity to apply the two remaining parts of our therapeutic triad as well, since medication and physiotherapeutic manipulation are integral parts of the general care of our patients, and we should not deprive the suffering of the means and methods capable of bringing them more relief, which we are aware of.

Literature and references
  • Tejnska, R., Prochazka, M.: Non Invasive Laser in Therapy of Tinnitus, Laser Partner 4/2000, Prague 2000.
  • Simunovic, Z. et al.: Lasers in medicine and dentistry, Vitagraf Rijeka, 2000. Hahn, A. et al.: Combined Laser – Egb 761 Tinnitus Therapy, Acta Otolaryngol 2001, Suppl. 545, 92-93.
  • Shiomi, Y. et al.: Efficacy of Transmeatal Low Power Laser Irradiation on Tinnitus: a preliminary report, Auris Nasus Larynx, 1997, 24, 39-42.
  • Chomete, G. et al.: Effect of the Laser on Gingival Tissue. I. J Biol Buccale 1987, 15, 45-49.
  • Tunér, J., Hode, L.: Low Level Lasertherapie Clinical Practice and Scientific Background, Grängesberg 1999.
  • Petrek, M., Hubacek, J., Ordeltova, M.: Innunomodulatory Effects of Lasertherapy in the Treatment of Chronic Tonsilitis, Acta Universitatis Palackianae Olomucensis, T. 129, 1991.
  • Hubacek, J.: Experience with the Use of LLLT in ENT Medicine, Laser Partner 22/2000, Prague 2000
  • Prochazka, M.: Case Histories of Patients Suffering from Tinnitus Treated by Comprehensive Rehabilitation Therapy incl. LLLT, Laser Partner 40/2001, Prague 2001.
  • Prochazka, M., Hahn, A.: Comprehensive Laser Rehabilitation Therapy of Tinnitus – Long-Term Double Blind Study on a Group of 200 Patients in 3 Years, Laser Partner 51/2002, Prague 2002.
  • Declaration von Helsinki des Weltarztsbundes, Pharm. ind. 52, 1990, 12, 1497 – 1498.
  • Wilden, L., Dindiger, D.: Treatment of Chronic Complex Diseases of the Inner Ear, Laser Therapy 4/1996.
  • Ohshiro, T., Ogata, H., Yoshida, M. et al: Penetration Depths of 830 nm Diode Laser Irradiation in the Head and Neck Assessed Using a Radiography Phantom Model and Wavelength-specific Imaging Film, Laser Therapy 8/1996.