Changes in Audiometry Results Following Laser Therapy for Tinnitus

Aim: To demonstrate the effect of laser therapy in the treatment of tinnitus with changes in audiometric results. Method: This current study included a total of 30 patients (15 females and 15 males). A laser with a 650 nm wave length at 5 mW was applied to the ear with tinnitus complaint on every consecutive week day for 20 minutes with a break on weekends. The process was continued for 8 weeks and a total of 40 sessions were performed. Pure tone audiometric evaluation between 250-20000 Hz frequency ranges was performed prior to the therapy and was repeated right after and two months after the treatment.Tinnitus scoring was performed before and two months after laser therapy. The results, obtained following therapy, were statistically evaluated. Result: 50% of the patients were female, and 50% were male. The patients’ ages were between 20 and 74. In 7 of the patients, tinnitus was in the left ear, in 11 patients in the right ear and in 12 it was bilateral. The audiometric values of the patients were evaluated in 3 different conditions which included the values before therapy, values after therapy and values at 2 months following treatment. A greater difference was observed particularly in the frequencies above 8000 Hz. A significant difference was also detected in audiometry results after laser therapy (p<0,001). It was found that the difference between males and females was significant after laser therapy (p<0.001). Conclusion: The effect of laser therapy is still controversial. In our study, laser therapy seemed to be effective right after therapy. Although the audiometric values returned to pretreatment levels after 2 months, the tinnitus scores have remained lower compared to the pretreatment scores.


INTRODUCTION
Tinnitus is a sound felt in ears.These sounds are usually named as somatosounds.It can either be peripheral or have a more central auditory connection (1).The treatment of patients with chronic tinnitus is very troublesome and otologists are trying to find the most appropriate treatment (2).Management of tinnitus with sensorineural hearing loss is difficult.It can be treated by amplification (1).Biofeedback, cognitive therapy and tinnitus retraining therapy, physiotherapy and psychotherapy are other treatment modalities (1,3).
Many methods have been tried in the treatment of tinnitus and the results are quite variable.In a retrospective study done by Hahn, many treatment methods have been evaluated.The most effective treatment was found vinpocetine combined with physiotherapy, whereas infusion of pure lidocaine was found to be ineffective (3).
In recent years, laser technologies have been used in the treatment of tinnitus.The main mechanism that causes the therapeutic effects of laser is the increase in blood flow in the inner ear (4).ATP increase in the cell has been established experimentally with low power laser therapy (LPLT) (5).
The mechanism of action of low power laser has been reported as biophysiologic, rather than thermal.The primary area that absorbs laser irradiation is the mitochondria inside the neurons.Laser irradiation causes the protons to be released from the mitochondria into the cytoplasm.It is suggested that these protons inhibit the permeability of Na+/K+ channels and this in turn leads to a decrease in the frequency of action potential of the nerves (6).The increase in blood flow with suppression of the nerve action potential in sympathetic nerve action potential is one of the mechanisms of its effect (7,8).The improvement in the local microcirculation and the increase in oxygen flow to the hypoxic cells are considered to be due to the effect of LPLT (9).Laser therapy was performed with different wave lengths and intensities in literature.Some authors reported that low power laser was effective, and some other authors reported that no improvement was observed (6,10,11,12).
In our study, we evaluated 5 mW, 650 nm wave length laser application, not only by scoring, but also by audiometric evaluation in the 250-20000 Hz frequency range.

MATERIALS AND METHODS
30 patients, 15 males and 15 females, were included in this study following the approval of the institutional research ethics committee.Informed consents of all participants were obtained following a detailed explanation of all probable benefits and risks of the method.The patients were subdivided into 4 categories according to age groups (1st group: 20-30 years, 2nd.group: 31-40 years, 3rd group: 41-50 years, 4th group: 51 years and above).After ENT examination, laboratory tests, temporal CT and MRI studies were obtained.Patients with pathological laboratory or radiographic results were not included in the study.Laser therapy with 650 nm wave length laser at 5 mW was performed for all patients during 20 minutes per day for 8 weeks.Weekends

Tinnitus visual analog scale was:
1-Tinnitus exists in silence.8-Tinnitus is severe.Sometimes I wake up from tinnitus.9-Tinnitus is very severe.I feel depressed.I can't realize some social activities.10-Tinnitus is extreme.I can not work, I can not sleep and I always feel sick.In order to establish the effects of gender, age group, measurement results upon treatment, scores following this investigative laser therapy and the treatment results of different frequencies, SPSS 13.OV program was used by following GLM (General Linear Model) procedure.

RESULTS
50% of the patients included into the study were female, and 50% were male.The patients' ages ranged between 20 and 74 and the arithmetic mean was 42.93+  12.814.In 7 of the patients, tinnitus was in the left ear, in 11 patients in the right ear and in 12 patients it was bilateral.The audiometric values of the patients were evaluated before therapy, after therapy and at 2 months following treatment (Table 1 and 2)(Figure 1).The tinnitus scores before and 2 months after therapy are given in Tables 1,2 and 3.
In the evaluation of audiometry results the difference between the results of females and males was not significant.A significant difference was also detected in audiometry results after laser therapy (p<0,001).It was found that the difference between males and females was significant after laser therapy (p<0.001).This situation was not observed before therapy and became evident following laser therapy.Lower scores were obtained after laser therapy compared to the scores before the intervention in statistical evaluation of tinnitus scores before and after laser therapy (Table 4 and 5)

DISCUSSION
Many studies have been performed upon the treatment of tinnitus.Many technological products have been tried along with many medical treatment modalities.Different treatment results have been reported.Furthermore, most of these reports have been evaluated subjectively, generally by different questions on the visual analog scale (VAS) (3,11).In our study, we tried to establish the effect of laser therapy upon tinnitus with a more objective method.For this purpose, we performed pure tone audiometric evaluation in 250-20000 Hz frequency range.These evaluations were repeated after therapy and 2 months following therapy.Results were statistically analyzed.Several complications may be seen following laser application.
In one study, sudden hear loss was reported in 1 patient, while dizziness was reported to have increased in another patient (10).In our study, we didn't observe any complication during laser treatment.
In the Hahn's study the audiometric improvement in tinnitus was established as 20 dB.In one patient tinnitus had disappeared, whereas in 1 patient it had worsened by 10 dB.While there was an audiometric improvement in 50.8%, tinnitus stayed the same in 47.5% of the cases.In 18 patients there was an improvement by 10 dB, in 22 patients by 20 dB, in 10 patients by 30 dB, in 6 patients by 40 dB, and in 5 patients by 50 dB.In our study, we established the effect of laser therapy upon hearing in the 250-20000 Hz frequency range.A greater difference was observed particularly in the frequencies above 8000 Hz.
The audiometric results obtained above this frequency displayed continuously increasing values.
Literature findings reveal that wave lengths, therapy duration, number of sessions and session intervals also differ in different studies.
Nakashima used 60 mW, 810 nm wave length laser transmeatally for 6 minutes for 1 day per week for a total duration of 4 weeks.Gungor used 5 mW, 650 nm wave length laser or placebo laser once a day 15 minutes for 1 week.Shiomi used 40 mW, 830 nm wave length laser for 9 minutes for 10 or more times once a week.Mirz, on the other hand, used 50 mW, 830 nm wave length laser in 10 minute sessions for 5 consecutive days, skipping the weekends and for 3 times reaching a total number of 15 sessions.
Hahn used 830 nm and 200 mW laser in 10 sessions for 3 weeks where each session lasted 10 minutes.It was reported that the higher improvement rate of tinnitus could be due to the use of higher intensity (200 mW) laser in comparison to other authors.Furthermore, every patient had been informed about the probable therapeutic effect of laser.This could have created a placebo effect on the patients.In conclusion, there was a 50.8% positive change in tinnitus (2,6,(10)(11)(12).
In our study, we applied 5 mW, 650 nm wave length laser to the patients' ears with tinnitus, for 20 minutes every day on five consecutive week days, with a break at weekends, reaching with a total duration of 8 weeks and a total number of 40 sessions.Pure tone audiometry in the 250-20000 Hz frequency range was performed before therapy, at the end of the therapy and 2 months after therapy.In addition, tinnitus scoring was performed before laser therapy and scoring was repeated 2 months after laser therapy.Statistical analysis was performed in order to establish the effects of treatment.
The difference between the results of females and males was not significant.A significant difference was also detected in audiometry results after laser therapy (p<0,001).It was found that the difference between males and females was significant after laser therapy (p<0.001).This situation was not observed before therapy and became evident following laser therapy.
Concerning the effect of age upon audiometric values before and after laser, the significance of the difference between groups showed the same distribution.The audiometric results obtained in the diseased and normal ears following laser therapy showed a statistically significant difference, as also observed in the situation before laser therapy (p< 0,001).In the results obtained at frequency changes after laser therapy (Table 2), the difference in the results with different letters in the same column was found to be statistically important (p< 0.001).The audiometric results in women following laser therapy showed a greater change with age.This became obvious after the intervention and reveals the effect of laser therapy.
The effect of laser therapy is still controversial.The controversy in laser therapy arises from the variable applications in treatment, the availability of different wave lengths, variable intensities and different application times.In our study, laser therapy seemed to be effective right after therapy and although the audiometric values returned to the pretreatment levels after 2 months, the tinnitus scores have remained lower compared to the pretreatment scores.In this study, we have followed up a 2 months intervention on certain days and have tried to establish the audiometric values before and after laser therapy.
The audiometric values that appeared after treatment and returned to pretreatment levels in a short time suggest that treatment may need to be performed for a longer duration longer follow-up periods may be necessary.In our opinion, the statistical evaluations performed after studies with long term laser applications can make substantial contributions to the evaluation of the effect of this treatment modality.We think that particularly the change in the interactions between gender, age, frequency, disease state etc. during laser therapy can be enlightening for the evaluations regarding laser therapy.

2 -
Tinnitus is not constant, but remarkable in daily life.3-Tinnitus is almost constant.4-Tinnitus is constant and sometimes irritating.5-Tinnitus is constant and usually irritating but not affective to daily activity or sleep.6-Tinnitus effects my daily communication and sometimes going to sleep takes several minutes.7-I have always-unpleasant sound.It affects sometimes my job.I can sleep only with medication.

Table 1 .
Distribution of the Least Square Analysis (LSA-General Linear Model Analysis) (LSM) and significance assessment findings for audio results before laser therapy over age, and frequency subgroups.
LSM: Least squares means; SE: Standard error; a, b, c, d, e, f, g, h, j, k, ŧ: the difference between LSMs expressed with a different letter in the same column is significant (NS: Not significant; *** p < 0,001).

Table 2 .
Distribution of the Least Square Analysis (LSA-General Linear Model Analysis) (LSM) and significance assessment findings for audiological evaluation after laser therapy over age and frequency subgroups.
LSM: Least squares means; SE: Standard error; a, b, c, d, e, f, g, h, j, k, ŧ: the difference between LSMs expressed with a different letter in the same column is significant (ns: Not significant; *** p < 0,001).

Table 3 .
Distribution of the Least Square Analysis (LSA-General Linear Model Analysis) (LSM) and significance assessment findings for audiological evaluation at 2 months after laser therapy over gender, age, disease state, and frequency subgroups.
LSM: Least squares means; SE: Standard error; a, b, c, d, e, f, g, h, j, k, ŧ: the difference between LSMs expressed with a different letter in the same column is significant (NS: Not significant; *** p < 0,001).

Table 4 .
Distribution of the Least Square Analysis (LSA-General Linear Model Analysis) (LSM) and significance assessment findings for tinnitus scoring results before laser therapy over gender, age, disease state and frequency subgroups.

Table 5 .
Distribution of the Least Square Analysis (LSA-General Linear Model Analysis) (LSM) and significance assessment findings for tinnitus scoring results after laser therapy over gender, age, disease state and frequency subgroups.