Photobiomodulation therapy in improvement of harmful neural plasticity in sodium salicylate-induced tinnitus

Tinnitus is a common annoying symptom without effective and accepted treatment. In this controlled experimental study, photobiomodulation therapy (PBMT), which uses light to modulate and repair target tissue, was used to treat sodium salicylate (SS)-induced tinnitus in a rat animal model. Here, PBMT was performed simultaneously on the peripheral and central regions involved in tinnitus. The results were evaluated using objective tests including gap pre-pulse inhibition of acoustic startle (GPIAS), auditory brainstem response (ABR) and immunohistochemistry (IHC). Harmful neural plasticity induced by tinnitus was detected by doublecortin (DCX) protein expression, a known marker of neural plasticity. PBMT parameters were 808 nm wavelength, 165 mW/cm2 power density, and 99 J/cm2 energy density. In the tinnitus group, the mean gap in noise (GIN) value of GPIAS test was significantly decreased indicated the occurrence of an additional perceived sound like tinnitus and also the mean ABR threshold and brainstem transmission time (BTT) were significantly increased. In addition, a significant increase in DCX expression in the dorsal cochlear nucleus (DCN), dentate gyrus (DG) and the parafloccular lobe (PFL) of cerebellum was observed in the tinnitus group. In PBMT group, a significant increase in the GIN value, a significant decrease in the ABR threshold and BTT, and also significant reduction of DCX expression in the DG were observed. Based on our findings, PBMT has the potential to be used in the management of SS-induced tinnitus.

Electrophysiological and molecular changes following neuroprotective placental protein administration on tinnitus-induced rats

Objective

Despite 6%-20% of the adult population suffering from tinnitus, there is no standard treatment for it. Placenta extract has been used for various therapeutic purposes, including hearing loss. Here, we evaluate the effect of a novel neuroprotective protein composition (NPPC) extract on electrophysiological and molecular changes in the medial geniculate body (MGB) of tinnitus-induced rats.

Methods

To evaluate the protein analysis by western blot, the rats were divided into three groups: (1) saline group (intraperitoneal injection of 200 mg/kg saline twice a day for 28 consecutive days, (2) chronic Na-Sal group received sodium salicylate as in the first group, and (3) chronic treatment group (received salicylate 200 mg/kg twice daily for 2 weeks, followed by 0.4 mg NPPC daily from day 14 to day 28). Single-unit recordings were performed on a separate group that was treated as in group 4. Gap-prepulse inhibition of the acoustic startle (GPIAS) and pre-pulse inhibition (PPI) was performed to confirm tinnitus in all groups at the baseline, 14th and 28th days.

Results

Western blot analysis showed that the expression of γ-Aminobutyric acid Aα1 subunit (GABA Aα1), N-methyl-d-aspartate receptor subtype 2B (NR2B or NMDAR2B), α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors subunit GluR1 (GluR1), and α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors subunit GluR2 (GluR2) decreased after Na-Sal injection, while NPPC upregulated their expression. MGB units in rats with tinnitus showed decreased spontaneous firing rate, burst per minute, and a spike in a burst. After NPPC administration, neural activity patterns showed a significant positive effect of NPPC on tinnitus.

Conclusion

NPPC can play an effective role in the treatment of tinnitus in salicylate-induced rats, and MGB is one of the brain areas involved in these processes.

Level of Evidence

NA.

The human neuroprotective placental protein composition suppressing tinnitus and restoring auditory brainstem response in a rodent model of sodium salicylate-induced ototoxicity

The effect of neuroprotective placental protein composition (NPPC) on the suppression of tinnitus and the restoration of the auditory brainstem response (ABR) characteristics was explored in tinnitus-induced rats. The animals were placed into two groups: (1) the study group, rats received sodium salicylate (SS) at the dose of 200 mg/kg twice a day for two weeks, and then 0.4 mg of the NPPC per day, between the 14th and 28th days, (2) the placebo group, rats received saline for two weeks, and then the NPPC alone between the 14th and 28th days. The gap pre-pulse inhibition of the acoustic startle (GPIAS), the pre-pulse inhibition (PPI), and the ABR assessments were performed on animals in both groups three times (baseline, day 14, and 28). The GPIAS value declined after 14 consecutive days of the SS injection, while NPPC treatment augmented the GPIAS score in the study group on the 28th day. The PPI outcomes revealed no significant changes, indicating hearing preservation after the SS and NPPC administrations. Moreover, some changes in ABR characteristics were observed following SS injection, including (1) higher ABR thresholds, (2) lowered waves I and II amplitudes at the frequencies of 6, 12, and 24 kHz and wave III at the 12 kHz, (3) elevated amplitude ratios, and (4) prolongation in brainstem transmission time (BTT). All the mentioned variables returned to their normal values after applying the NPPC. The NPPC use could exert positive therapeutic effects on the tinnitus-induced rats and improve their ABR parameters.

Acoustic and optoacoustic stimulations in auditory brainstem response test in salicylate induced tinnitus

As a common debilitating disorder worldwide, tinnitus requires objective assessment. In the auditory brainstem response (ABR) test, auditory potentials can be evoked by acoustic or optoacoustic (induced by laser light) stimulations. In order to use the ABR test in the objective assessment of tinnitus, in this study, acoustic ABR (aABR) and optoacoustic ABR (oABR) were compared in the control and tinnitus groups to determine the changes caused by sodium salicylate (SS)-induced tinnitus in rat. In both aABR and oABR, wave II was the most prominent waveform, and the amplitude of wave II evoked by oABR was significantly higher than that of aABR. Brainstem transmission time (BTT), which represents the time required for a neural stimulation to progress from the auditory nerve ending to the inferior colliculus, was significantly shorter in oABR. In the tinnitus group, there was a significant increase in the threshold of both ABRs and a significant decrease in the amplitude of wave II only in the oABR. Based on our findings, the ABR test has the potential to be used in the assessment of SS-induced tinnitus, but oABR has the advantages of producing more prominent waveforms and significantly reducing the amplitude of wave II in tinnitus.

Transcranial photobiomodulation in the management of brain disorders

Transcranial photobiomodulation (tPBM) is the process of delivering light photons through the skull to benefit from its modifying effect. Brain disorders are important health problems. The aim of this review was to determine the existing evidence of effectiveness, useful parameters, and safety of tPBM in the management of traumatic brain injury, stroke, Parkinson, and Alzheimer's disease as the common brain disorders. Four online databases, including Cochrane, Pub Med, Embase, and Google scholar were searched according to the Preferred Reporting Items for Systematic Reviews and meta-analyses (PRISMA) guidelines. 4728 articles were obtained in the initial search. Only those articles that were published until September 2020 and designed as randomized clinical trials (RCTs) or animal-controlled studies were included. 6 RCTs, 2 related supplementary articles, and 38 controlled animal studies met the inclusion criteria of this study. No RCTs were performed in the fields of Alzheimer's and Parkinson's diseases. The human RCTs and animal studies reported no adverse events resulted from the use of tPBM. Useful parameters of tPBM were identified according to the controlled animal studies. Since the investigated RCTs had no homogenous results, making an evidence-based decision for definite therapeutic application of tPBM is still unattainable. Altogether, these data support the need for large confirmatory well-designed RCTs for using tPBM as a novel, safe, and easy-to-administer treatment of brain disorders.

EVIDENCE BEFORE THIS STUDY

High prevalence and complications of brain disorders and also side effects of neuropsychiatric medications have encouraged researchers to find alternative therapeutic techniques which tPBM can be one of them. In present review we tried to determine the existing evidence of effectiveness, useful parameters, and safety of tPBM in the management of traumatic brain injury, stroke, Alzheimer, and Parkinson's disease as common brain disorders. Four online databases, including "Cochrane", "Pub Med", "Embase", and "Google scholar" were searched. Only those articles that were published until September 2020 and designed as RCTs or animal-controlled studies were included. Search keywords were the followings: transcranial photobiomodulation" OR "transcranial low-level laser therapy" AND "stroke" OR "traumatic brain injury" OR "Alzheimer" OR "Parkinson". Several studies have confirmed effectiveness of tPBM in treatment of different brain disorders but the level of evidence of its effectiveness remain to be determined.

ADDED VALUE OF THIS STUDY

In this study we systematically reviewed human RCTs to determine the existing evidence of tPBM effectiveness in management of four mentioned brain disorders. Since the outcomes of the reviewed RCTs were not homogeneous, further well-designed RCTs are required to decide more definitively on the evidence of this noninvasive and probably safe therapeutic intervention. We hypothesized that non-homogeneous outcomes could be due to inefficiency of PBM parameters. Controlled animal studies have the advantage of using objective tests to evaluate the results and compare them with the control group. We determined useful tPBM parameters based on these studies.

IMPLICATIONS OF ALL THE AVAILABLE EVIDENCE

This research is part of our main project of tinnitus treatment using photobiomodulation (PBM). Evidence of central nervous system involvement in tinnitus led us to believe that treatment protocol of tinnitus should also include transcranial PBM. The determined useful parameters can be helpful in designing more efficient tPBM protocols in the management of brain disorders and tinnitus as a common debilitating symptom that can be associated with these disorders.

Development and application of a tool to measure hearing health literacy of young people in the Islamic Republic of Iran

Background

A reliable and valid tool to assess hearing health literacy in Iranian young people is lacking.

Aims

This study aimed to develop a tool to assess the hearing health literacy of young people in the Islamic Republic of Iran and to use the tool to determine the hearing health literacy of a sample of Iranians aged 12-25 years.

Methods

A questionnaire was designed with three skill sections: obtaining health information, evaluating this information and applying it to benefit health. The validity and reliability of the tool were determined. Cluster sampling was used to select 50 urban clusters across the country from which 5000 Iranians aged between 12-25 years old were selected to complete the questionnaire.

Results

The final questionnaire had 22 items with scores ranging from 22 to 44. The Cronbach alpha was 0.65, and content validity ratio and index were 0.92 and 0.82, respectively. Of the 5000 questionnaires completed, 4890 were included in the analysis. The mean (standard deviation (SD)) age of the participants was 17 (SD 3) years and 45.9% were males. The mean score on the tool was 30.81 (SD 3.75), indicating inadequate health literacy (score 22-36). Only 137 (2.8%) participants had adequate health literacy (score 37-44). Statistically significant differences in mean hearing health literacy were seen for sex, age, years of education, occupation, marital status and income (P < 0.05).

Conclusions

Given the low level of hearing health literacy in Iranian young people, programmes to improve the ear and hearing health literacy are urgently needed.

Aberrant Frequency Related Change-Detection Activity in Chronic Tinnitus

Tinnitus is the perception of sound without the occurrence of an acoustic event. The deficit in auditory sensory or echoic memory may be the cause of the perception of tinnitus. This study considered the mismatch negativity (MMN) to investigate the potential difference between and within groups of persons with normal hearing (NH) and tinnitus. Using an auditory multi-feature paradigm to elicit the MMN, this study considered the MMN peak amplitude at two central frequencies for two MMN subcomponents. These central frequencies were 1 and 5 kHz, which the latter was closer to the perceived tinnitus frequency in the group with tinnitus. The deviants were higher frequency, lower frequency, higher intensity, lower intensity, duration, location (left), location (right), and gap. The pure tone audiometry (PTA) test and distortion product otoacoustic emissions (DPOAE) test showed no meaningful difference between the two groups. For the frontal subcomponent, the mean amplitudes of the MMN peak for the two groups illustrated less negative meaningful MMN peak amplitudes in the group of persons with tinnitus. For the supratemporal component at 5 kHz central frequency, amplitudes were lower for the group of persons with tinnitus, whereas for the central frequency of 1 kHz, most deviants exhibited meaningful differences. Additionally, within-group comparisons indicated that mean amplitudes for both groups were more negative at the central frequency of 1 kHz for the frontal MMN subcomponent. In comparison, the supratemporal component illustrated a lower peak amplitude at 5 kHz central frequency in the group of persons with tinnitus and no difference in the NH group, which is a unique observation of this study. Results of the between-groups are in accordance with previous studies and within-group comparisons consider the probability of decreasing the change detection capability of the brain. The results of this study indicate that increasing the frequency of the stimuli close to the tinnitus perceived frequencies decreases the prediction error, including the prediction error of the silence. Such a decrease may cause the prediction error of the spontaneous neural activity in the auditory pathway to exceed the silence prediction error, and as a result, increases the probability of occurrence of tinnitus in higher frequencies according to the predictive coding model.

Alterations in Auditory Change Detection Associated with Tinnitus Residual Inhibition Induced by Auditory Electrical Stimulation

Background: Residual inhibition (RI) is a temporary phenomenon that happens following offset of appropriate complete or partial acoustical and electrical masking stimulations in people who experience tinnitus. The biologic mechanisms associated with RI are not yet fully understood. Few studies have been focused on RI. Auditory mismatch negativity (MMN) as a change-detection tool may be an appropriate tool to explore the processing changes because of tinnitus and RI.

Purpose: The purpose of this study was to investigate alterations in auditory change detection and auditory sensory memory related to RI induced by auditory electrical stimulation (AES) using MMN brain mapping in participants with tinnitus.

Research Design: This investigation was a single-blind randomized controlled clinical trial study. Participants were randomly assigned into two groups: AES and placebo electrical stimulation (PES).

Study Sample: Twenty-eight participants with chronic subjective tinnitus aged 22- to 45-yr-old participated in the study.

Intervention: After randomization, all participants received both AES and PES for 1 min in different sessions.

Data Collection and Analysis: Brain mapping of multifeature MMN paradigm was recorded from 29 scalp electrodes pre- and post-AES and PES. Following AES, participants were categorized into two groups: RI and nonresidual inhibition (NRI). The grand average MMN waveforms and isopotential topographic maps were obtained in RI, NRI, and PES groups.

Results: Three MMN parameters for five deviants of frequency, intensity, duration, location, and silent gap were compared among three groups of RI, NRI, and PES. Statistical analyses revealed significant between-subject effects for AES on MMN amplitude of frequency and duration deviant, MMN area under the curve of frequency, intensity, and duration deviants.

Conclusions: Presence of RI can reestablish change-detection mechanisms in the central auditory pathways. It is suggested that MMN is reliable for assessment of change-detection system in people with tinnitus. It can be a useful technique in monitoring effects of treatments and rehabilitation.

Impact of Acamprosate on Chronic Tinnitus: A Randomized-Controlled Trial

OBJECTIVES

Tinnitus is a common and distressing otologic symptom, with various probable pathophysiologic mechanisms, such as an imbalance between excitatory and inhibitory mechanisms. Acamprosate, generally used to treat alcoholism, is a glutaminergic antagonist and GABA agonist suggested for treating tinnitus. Thus, we aimed to evaluate the efficacy and safety of acamprosate in the treatment of tinnitus.

METHODS

The current randomized-controlled trial study included 20 subjects with chronic tinnitus. After performing psycho-acoustic, psychometric and electrophysiological evaluations, all studied tinnitus subjects were randomly divided into two groups of acamprosate and placebo. The first group received oral acamprosate (two tablets of 333 mg/d, three times a day), whereas the second group was given placebo treatment (two tablets, three times a day). After the first 30 days, all evaluations were repeated for the studied groups just in the same manner before the study. Subsequently, the final results of each evaluation were compared together with the baseline values.

RESULTS

Nine studied subjects randomly received acamprosate, whereas eleven others received a placebo. There was no significant improvement in the psycho-acoustic tests, except a decrease was observed in the pitch match of tinnitus (P = .039). For those subjects who were receiving acamprosate, a significant reduction was observed in tinnitus handicap inventory (P = .006), tinnitus questionnaire scores (P = .007), and the visual analog scores (P = .007) compared to the placebo group. There was a significant reduction in Action Potential latency (P = .048) as well as an increase in the amplitude of distortion product otoacoustic emissions at 4 kHz (P = .048).

CONCLUSIONS

The study results indicated a subjective relief of tinnitus as well as some degree of the electrophysiological improvement at the level of the cochlear and the distal portion of the auditory nerve among the subjects who received the acamprosate.

CLINICAL TRIAL REGISTRATION CODE

IRCT2013121115751N1.

The efficacy and safety of multiple sessions of multisite transcranial random noise stimulation in treating chronic tinnitus

Introduction

Objective

Methods

Results

Conclusions

Developing the Persian Version of Sensory Gating Inventory and Assessing Its Validity and Reliability

Introduction:

Sensory Gating Inventory (SGI) measures behavioral aspects of Sensory Gating (SG), which filters irrelevant sensory inputs into the higher cortex. It modifies sensitivity to sensory stimuli. Abnormal SG leads to overloading of information in the brain and its subsequent dysfunction. Electrophysiological techniques cannot assess the behavioral aspects of SG. We aimed to design the Persian version of SGI with high validity and reliability.

Methods:

After a forward and then backward translation of the original SGI, we assessed the content validity and construct validity of the Persian version. A total of 405 participants filled the Persian version of SGI. To assess test-retest reliability, 100 participants filled the inventory again 7–10 days later. The content validity ratio and index, as well as confirmatory factor analysis, were computed, too. Finally, the Cronbach’s alpha, Cohen’s kappa, and intraclass correlation coefficients were calculated.

Results:

The content validity ratios of all items of the inventory were more than 60%, which means that they were necessary according to the experts’ opinions. Confirmatory factor analysis confirmed the fitness of the 4-factor structure of the original Inventory. The test-retest reliability using the intraclass correlation coefficient and Cronbach’s alpha coefficients were also high for the four subscales. The Cohen’s kappa coefficients revealed moderate to substantial level of agreement between the first and second scores for all items.

Conclusion:

The Persian version of SGI has good and acceptable psychometric properties. It can be used as a valid and reliable tool for studying behavioral aspects of SG in Persian speaking population.

Correlation Analysis of the Tinnitus Handicap Inventory and Distress Network in Chronic Tinnitus: An EEG Study

INTRODUCTION

Tinnitus is a common disorder with a considerable amount of distress that affects the patient's daily life. No objective tools were approved for measuring tinnitus distress. It can be estimated only by subjective scales and questionnaires, albeit, the Electroencephalography (EEG) studies have reported some alterations regarding tinnitus distress network. This study aimed to investigate the correlation between Tinnitus Handicap Inventory (THI) and the recorded EEG data.

METHODS

A total of 33 chronic tinnitus cases (9 females) with the mean age of 42.67 years were recruited. Their THI scores were collected, and a 3-minute EEG recorded with eye closed at resting-state. The correlation analysis was performed on THI scores and the current density in the selected Region of Interests (ROIs) concerning the distress network for the eight frequency bands. The patients grouped depending on the THI cutoff point of 56 into low and high THI groups, and then the groups were compared for source analysis and functional connectivity between ROIs using standardized low-resolution brain electromagnetic tomography.

RESULTS

A significant positive correlation was seen between THI scores and the electrical activity in the Anterior Cingulate Cortex (ACC), the prefrontal cortex, and the parahippocampus for an alpha band (P<0.05) and in the ACC for beta (P<0.01). Source analysis showed significant differences with increased activity in the high THI group for alpha, beta and gamma bands. Functional connectivity was also elevated in the high THI group between the ROIs in alpha and beta bands.

CONCLUSION

THI can be a useful tool for measuring tinnitus distress, and it has a high correlation with EEG data.

Toward An Exploration of Habituating to Tinnitus: Perspectives on Sensory Gating

BACKGROUND

Some tinnitus participants habituate to their tinnitus, but some others do not and complain of its annoyance so much. It has been suggested that tinnitus is a habituation deficit. Habituation and the ability to ignore a sensory input depend on the normal function of filtering mechanism of sensory gating.

PURPOSE

The purpose of this study was to compare behavioral aspects of sensory gating in normal and tinnitus participants to search for the reason why some tinnitus participants habituate to their tinnitus but some others do not.

RESEARCH DESIGN

This investigation was an observational case-control study.

STUDY SAMPLE

There were 60 tinnitus participants who were categorized into two tinnitus groups (30 compensated tinnitus participants and 30 decompensated tinnitus participants) based on the complaint of tinnitus annoyance, visual analog scale (VAS) for tinnitus loudness, annoyance, and awareness, scores on Tinnitus Questionnaire (TQ), and Tinnitus Handicap Inventory (THI). Also, there were 30 normal hearing participants without tinnitus as the normal control group.

DATA COLLECTION AND ANALYSIS

Sensory Gating Inventory (SGI), TQ, THI, and VAS was obtained from all participants. THI, TQ, VAS, and SGI total scores and their factors were compared among the groups. Correlations between SGI scores with THI, TQ, and VAS score were calculated.

RESULTS

The results showed that SGI total score and the scores of its four factors were significantly higher in decompensated tinnitus participants compared with compensated tinnitus participants and normal controls. Also, there was a positive correlation between SGI perceptual modulation factor and TQ emotional distress factor and with the VAS for loudness in decompensated tinnitus group.

CONCLUSIONS

These results suggested that tinnitus associated with behavioral aspects of sensory gating and decompensated tinnitus may be a result of deficient sensory gating.

The potential role of auditory prediction error in decompensated tinnitus: An auditory mismatch negativity study

INTRODUCTION

Some tinnitus subjects habituate to their tinnitus but some others do not and complain of its annoyance tremendously. Normal sensory memory and change detection processes are needed for detecting the tinnitus signal as a prediction error and habituation to tinnitus. The purpose of this study was to compare auditory mismatch negativity as the index of sensory memory and change detection among the studied groups to search for the factors involving in the perception of tinnitus and preventing habituation in decompensated tinnitus subjects.

METHODS

Electroencephalography was recorded from scalp electrodes in compensated tinnitus, decompensated tinnitus, and no tinnitus control subjects. Mismatch negativity was obtained using the oddball paradigm with frequency, duration, and silent gap deviants. Amplitude, latency, and area under the curve of mismatch negativities were compared among the three studied groups.

RESULTS

The results showed lower mismatch negativity amplitude and area under the curve for the higher frequency deviant and for the silent gap deviant in decompensated tinnitus group compared to normal control and compensated tinnitus group.

CONCLUSIONS

This study revealed a deficit in sensory memory and change detection processing in decompensated tinnitus subjects. This causes persistent prediction errors; tinnitus signal is consistently detected as a new signal and activates the brain salience network and consequently prevents habituation to tinnitus. Mismatch negativity is proposed as an index for monitoring tinnitus rehabilitation.

The investigation of semantic memory deficit in chronic tinnitus: a behavioral report

Introduction

Tinnitus is a central auditory disorder in which different processing systems are involved as a network. One of these networks is memory. Previous studies have demonstrated some deficits in various types of memory in chronic tinnitus.

Objectives

The main purpose of the present study was to investigate the semantic memory, which is not yet investigated in the tinnitus population.

Methods

In this case–control study, 15 subjects with chronic tinnitus and 16 matched healthy controls were included. 40 semantically related and 40 semantically unrelated word pairs were presented to the participants in a counter-balanced fashion. They were asked to make decision about their semantic relatedness. Then the participants’ reaction times and the accuracy of responses were calculated.

Results

Mean of reaction times were significantly longer in the tinnitus group (M = 1034 ms, SD = 0.31) compared to the control group (Mean = 1016 ms, SD = 0.13), p < 0.05. However, no significant difference was found for the mean percentage of correct responses between the two groups.

Conclusion

The current study provided behavioral evidence that chronic tinnitus can affect the semantic memory. Such behavioral outcomes may provide new insights into more research activities in the field of electrophysiology and neuroimaging in the tinnitus population.

Cognitive Memory Comparison Between Tinnitus and Normal Cases Using Event-Related Potentials

About 20 percent of people above 60 years old suffer from tinnitus though no definitive treatment has been found for it. Evaluation of electrical brain activity using Event-Related Potentials (ERPs) is one of the methods to investigate the underlying reasons of tinnitus perception. Previous studies using ERPs suggest that the precognitive memory in tinnitus groups is negatively affected in comparison to the normal hearing groups. In this study, cognitive memory has been assessed using visual and auditory P300 response with oddball paradigm. Fifteen chronic tinnitus subjects and six normal hearing subjects participated in the experiment. T-test with significance level of 0.05 was applied on amplitude and latency of auditory and visual P300 for all electroencephalography (EEG) channels separately to compare tinnitus and normal hearing groups where the tinnitus group showed meaningful lower amplitude of auditory P300 peak in three EEG channels.

Brain Waves Evaluation of Sound Therapy in Chronic Subjective Tinnitus Cases Using Wavelet Decomposition

Management and treatment of subjective tinnitus is an ongoing focus of research activities. One of the most viable assessments of such treatment is the evaluation of brain activity in addition to patient response and clinical assessment. This study focuses on sound therapy and evaluation of patients’ electroencephalogram (EEG) in order to verify the potency of this approach. Broadband sound therapy was applied to nineteen participants aging from 25 to 64 and suffering from chronic subjective tinnitus to study the difference of brain activity, a) before fake treatment, b) after fake treatment and c) after the main treatment, using EEG and Visual Analog Scale (VAS) for evaluating Residual Inhibition (RI). Four features were extracted using 4-level wavelet decomposition with Symlet 8 as its mother wavelet. For the “After the main treatment” stage, the mean value of wavelet coefficients for the last wavelet level, which corresponded to delta band of EEG, was lower in the FC3 channel based on Two-Sample T-Test with significance level of 0.01, as compared to the same channel of the “before the treatment” stage, for cases in which decreased tinnitus loudness were reported.

The Persian version of auditory word discrimination test (P-AWDT) for children: Development, validity, and reliability

OBJECTIVE

Auditory discrimination of speech sounds is an important perceptual ability and a precursor to the acquisition of language. Auditory information is at least partially necessary for the acquisition and organization of phonological rules. There are few standardized behavioral tests to evaluate phonemic distinctive features in children with or without speech and language disorders. The main objective of the present study was the development, validity, and reliability of the Persian version of auditory word discrimination test (P-AWDT) for 4-8-year-old children.

METHODS

A total of 120 typical children and 40 children with speech sound disorder (SSD) participated in the present study. The test comprised of 160 monosyllabic paired-words distributed in the Forms A-1 and the Form A-2 for the initial consonants (80 words) and the Forms B-1 and the Form B-2 for the final consonants (80 words). Moreover, the discrimination of vowels was randomly included in all forms. Content validity was calculated and 50 children repeated the test twice with two weeks of interval (test-retest reliability). Further analysis was also implemented including validity, intraclass correlation coefficient (ICC), Cronbach's alpha (internal consistency), age groups, and gender.

RESULTS

The content validity index (CVI) and the test-retest reliability of the P-AWDT were achieved 63%-86% and 81%-96%, respectively. Moreover, the total Cronbach's alpha for the internal consistency was estimated relatively high (0.93). Comparison of the mean scores of the P-AWDT in the typical children and the children with SSD revealed a significant difference. The results revealed that the group with SSD had greater severity of deficit than the typical group in auditory word discrimination. In addition, the difference between the age groups was statistically significant, especially in 4-4.11-year-old children. The performance of the two gender groups was relatively same.

CONCLUSION

The comparison of the P-AWDT scores between the typical children and the children with SSD demonstrated differences in the capabilities of auditory phonological discrimination in both initial and final positions. It supposed that the P-AWDT meets the appropriate validity and reliability criteria. The P-AWDT test can be utilized to measure the distinctive features of phonemes, the auditory discrimination of initial and final consonants and middle vowels of words in 4-8-year-old typical children and children with SSD.

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

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.

Association of genetic variations in the mitochondrial DNA control region with presbycusis

Background

The prominent role of mitochondria in the generation of reactive oxygen species, cell death, and energy production contributes to the importance of this organelle in the intracellular mechanism underlying the progression of the common sensory disorder of the elderly, presbycusis. Reduced mitochondrial DNA (mtDNA) gene expression and coding region variation have frequently been reported as being associated with the development of presbycusis. The mtDNA control region regulates gene expression and replication of the genome of this organelle. To comprehensively understand of the role of mitochondria in the progression of presbycusis, we compared variations in the mtDNA control region between subjects with presbycusis and controls.

Methods

A total of 58 presbycusis patients and 220 control subjects were enrolled in the study after examination by the otolaryngologist and audiology tests. Variations in the mtDNA control region were investigated by polymerase chain reaction and Sanger sequencing.

Results

A total of 113 sequence variants were observed in mtDNA, and variants were detected in 100% of patients, with 84% located in hypervariable regions. The frequencies of the variants, 16,223 C>T, 16,311 T>C, 16,249 T>C, and 15,954 A>C, were significantly different between presbycusis and control subjects.

Conclusion

The statistically significant difference in the frequencies of four nucleotide variants in the mtDNA control region of presbycusis patients and controls is in agreement with previous experimental evidence and supports the role of mitochondria in the intracellular mechanism underlying presbycusis development. Moreover, these variants have potential as diagnostic markers for individuals at a high risk of developing presbycusis. The data also suggest the possible presence of changes in the mtDNA control region in presbycusis, which could alter regulatory factor binding sites and influence mtDNA gene expression and copy number.

The relationship between ultra-high frequency thresholds and transient evoked otoacoustic emissions in adults with tinnitus

Background: The possible role of cochlear function in tinnitus generation is still a matter of debate. To assess the role of outer hair cell dysfunction in tinnitus and its possible relationship with ultra-high frequency (UHF) hearing sensitivity, transient evoked otoacoustic emissions (TEOAE) and UHF hearing thresholds were investigated in normal hearing individuals with and without tinnitus. Methods: Eighteen individuals with tinnitus and 22 without tinnitus participated in this study. TEOAE was recorded with click stimulus at 80 dBpeSPL. UHF pure tone audiometry was performed at 10, 12.5, 16, and 18 kHz. Results: TEOAE was significantly abnormal in 72.2% of the tinnitus, and 18.2% of the control groups (p=0.001). The individuals with tinnitus had significantly poorer UHF hearing sensitivity compared to the control group at 12.5 and 18 kHz (p≤0.048). There was a stronger correlation between increasing UHFs hearing threshold and decreasing SNRs of TEOAEs in the tinnitus group compared to the controls. Conclusion: Our study revealed poorer UHF hearing thresholds and more TEOAE abnormalities in normal hearing individuals with tinnitus compared to the controls. Perhaps the alterations in the basal cochlea, following a decrease in UHF hearing sensitivity, affect OAEs that are originated from more apical cochlear parts in tinnitus ears more than non-tinnitus ears.

Electrophysiological and phonological change detection measures of auditory word processing in normal Persian-speaking children

OBJECTIVE

Auditory phoneme discrimination is a basic and important prerequisite for acquiring speech, reading, and spelling skills. Children, who are unable to perceive auditory phoneme discrimination, cannot develop phonemic representations. Therefore, the early identification of these deficits and application of effective therapeutic approaches is a necessity. We need to assess appropriately word or sound discrimination in normal populations using an objective passive task such as mismatch negativity (MMN). Therefore, the aim of the present study was to investigate MMN responses using speech stimuli (words) in 6-7 year-old normal Persian-speaking children.

METHODS

Ten right-handed Persian-speaking children with normal visual and auditory acuity, aged from 6 to 7 years, participated in the study. Recording of electroencephalography (EEG) was done by 64 A g/AgCl electrodes. A new auditory paradigm was used with three deviant stimuli (/gam/,/jam/, and/tam/) which differed in the first consonant from a repeated standard word (/dam/). A total of 1500 stimuli, 750 standards and 750 deviants (250 each deviant), were presented by Cogent 2000 running in MATLAB software using two loud speakers.

RESULTS

MMN peaked over the fronto-central sites at around 380-424 ms after the onset of the stimulus. The comparison of the MMN amplitudes elicited by three deviants revealed a significant "initial phoneme type" effect in Fz and Cz (p < 0.05). This negativity was found to be larger for manner and voicing deviants compared with that of the place of articulation (p < 0.001) on midline scalps. The comparison of the MMN latencies revealed no significant main effect of all variables (p > 0.05). Also, the results revealed that only the MMN amplitude for the/gam/deviant correlated with the percentage of correct responses (R = -0.86, p < 0.01).

CONCLUSION

The current study showed that words can elicit MMN responses in ∼200 ms after the onset of changes. We can objectively evaluate children's neural speech sound discrimination using the developed paradigm in a natural word context. This paradigm can be useful objectively for investigating distinctive features of sounds and phonological discrimination development in normal children.

The potential role for use of mitochondrial DNA copy number as predictive biomarker in presbycusis

OBJECTIVES

Age-related hearing impairment, or presbycusis, is the most common communication disorder and neurodegenerative disease in the elderly. Its prevalence is expected to increase, due to the trend of growth of the elderly population. The current diagnostic test for detection of presbycusis is implemented after there has been a change in hearing sensitivity. Identification of a pre-diagnostic biomarker would raise the possibility of preserving hearing sensitivity before damage occurs. Mitochondrial dysfunction, including the production of reactive oxygen species and induction of expression of apoptotic genes, participates in the progression of presbycusis. Mitochondrial DNA sequence variation has a critical role in presbycusis. However, the nature of the relationship between mitochondrial DNA copy number, an important biomarker in many other diseases, and presbycusis is undetermined.

METHODS

Fifty-four subjects with presbycusis and 29 healthy controls were selected after ear, nose, throat examination and pure-tone audiometry. DNA was extracted from peripheral blood samples. The copy number of mitochondrial DNA relative to the nuclear genome was measured by quantitative real-time polymerase chain reaction.

RESULTS

Subjects with presbycusis had a lower median mitochondrial DNA copy number than healthy subjects and the difference was statistically significant (P=0.007). Mitochondrial DNA copy number was also significantly associated with degree of hearing impairment (P=0.025) and audiogram configuration (P=0.022).

CONCLUSION

The findings of this study suggest that lower mitochondrial DNA copy number is responsible for presbycusis through alteration of mitochondrial function. Moreover, the significant association of mitochondrial DNA copy number in peripheral blood samples with the degree of hearing impairment and audiogram configuration has potential for use as a standard test for presbycusis, providing the possibility of the development of an easy-to-use biomarker for the early detection of this condition.

Auditory middle latency responses differ in right- and left-handed subjects: an evaluation through topographic brain mapping

PURPOSE

To investigate the association of handedness with auditory middle latency responses (AMLRs) using topographic brain mapping by comparing amplitudes and latencies in frontocentral and hemispheric regions of interest (ROIs).

METHOD

The study included 44 healthy subjects with normal hearing (22 left handed and 22 right handed). AMLRs were recorded from 29 scalp electrodes in response to binaural 4-kHz tone bursts.

RESULTS

Frontocentral ROI comparisons revealed that Pa and Pb amplitudes were significantly larger in the left-handed than the right-handed group. Topographic brain maps showed different distributions in AMLR components between the two groups. In hemispheric comparisons, Pa amplitude differed significantly across groups. A left-hemisphere emphasis of Pa was found in the right-handed group but not in the left-handed group.

CONCLUSION

This study provides evidence that handedness is associated with AMLR components in frontocentral and hemispheric ROI. Handedness should be considered an essential factor in the clinical or experimental use of AMLRs.

The relationship between treatment of mental disorder and chronic tinnitus

INTRODUCTION

Comorbidity of chronic tinnitus and mental disorders may result in more disability.

OBJECTIVES

This research provides an evaluation about the effects of medically treated comorbid mental disorder on chronic tinnitus.

MATERIALS AND METHODS

Fifty-five patients diagnosed with chronic tinnitus and mental disorders were randomly requited by producing a before-after design. They underwent three months of drug therapy for comorbid mental disorders by psychiatrists. Study instruments are Tinnitus Handicap Inventory, Tinnitus Questionnaire, Loudness Match Tinnitus, Hamilton Depression Rating Scale, Beck Anxiety Inventory, The Structured Clinical Interview and Symptom Check List -90.

RESULTS

Three months medical treatment puts forward the argument that among mental disorders, anxiety and major depressive disorder demonstrate a significant reduction. Pearson Correlation coefficient ostensibly reveals that there is no significant relationship between mental disorders and tinnitus severity. The statistics lend support to profound effect of major depressive disorder as a key factor on tinnitus disability exacerbation. Medical treatment also touches on issue such as tinnitus severity, its disabling effects and TQ subscales that statistics shows significant trends in their reduction.

CONCLUSION

Findings lay emphasis on tinnitus severity reduction and connection might be established between alleviated mental disorders comorbidity and the improvement of quality of life.

Alterations in early auditory evoked potentials and brainstem transmission time associated with tinnitus residual inhibition induced by auditory electrical stimulation

INTRODUCTION

Residual inhibition (RI) is the temporary inhibition of tinnitus by use of masking stimuli when the device is turned off.

OBJECTIVE

The main aim of this study was to evaluate the effects of RI induced by auditory electrical stimulation (AES) in the primary auditory pathways using early auditory-evoked potentials (AEPs) in subjective idiopathic tinnitus (SIT) subjects.

MATERIALS AND METHODS

A randomized placebo-controlled study was conducted on forty-four tinnitus subjects. All enrolled subjects based on the responses to AES, were divided into two groups of RI and Non-RI (NRI). The results of the electrocochleography (ECochG), auditory brain stem response (ABR) and brain stem transmission time (BTT) were determined and compared pre- and post-AES in the studied groups.

RESULTS

The mean differences in the compound action potential (CAP) amplitudes and III/V and I/V amplitude ratios were significantly different between the RI, NRI and PES controls. BTT was significantly decreased associated with RI.

CONCLUSION

The observed changes in AEP associated with RI suggested some peripheral and central auditory alterations. Synchronized discharges of the auditory nerve fibers and inhibition of the abnormal activity of the cochlear nerve by AES may play important roles associated with RI. Further comprehensive studies are required to determine the mechanisms of RI more precisely.

Community-based newborn hearing screening programme for early detection of permanent hearing loss in Iran: An eight-year cross-sectional study from 2005 to 2012

Objectives

We here present the results of the first eight years of the newborn hearing screening programme in Iran, with a view to establishing the prevalence of hearing impairment among infants, and the efficacy of the programme.

Methods

A total of 3,350,995 infants were screened using the series method of transient evoked otoacoustic emissions (TEOAEs)/automated auditory brainstem responses (AABRs), between 2005 and 2012. The infants were first tested for TEOAEs (three times). Based on the results of this test, the positive cases were referred to the next stage, where they were tested for AABRs. If they also tested positive on AABRs, they were referred to the diagnostic and rehabilitation stages.

Results

Results of this study indicated an infant hearing impairment prevalence of 3 per 1000. Although this rate was as high as 5 per 1000 in the early years of the programme, it decreased to 2.6 per 1000 in the last year. The absolute referral rate was 14.5% in the first stage, which decreased to 0.9% and 0.2% in the second and the third stages, respectively. The follow-up rate was 70% in the first stage, which increased up to 73% and 85% in the second and the third stages, respectively.

Conclusion

The study results suggest that the prevalence of hearing impairment in infants in Iran is comparable with that in developed and developing countries, and that the series TEOAEs/AABRs method used in the screening programme in Iran is efficient.

Correlation between brain cortex metabolic and perfusion functions in subjective idiopathic tinnitus

OBJECTIVES

Subjective tinnitus has associated with abnormal brain metabolism and perfusion found in functional imaging studies by fluorodeoxyglucose (FDG) and technetium99m (TC99m). But there is no study evaluating the association of brain metabolism and perfusion abnormalities in a group of these subjects. The aim of this study was to investigate if there is any significant correlation between the brain perfusion and metabolism abnormalities in subjects with tinnitus.

MATERIALS AND METHODS

In this cross-sectional study, 52 patients were undergone TC99m-ECD single photon emission computerized tomography (SPECT) scan and F18-FDG positron emission tomography (PET). The results of PET and SPECT scanning were fused with MRI to accurate anatomical localization of abnormalities. The analysis was performed using Kendal's correlation, t-test and chi square.

RESULTS

Assessing these 52 tinnitus subjects (containing 42 males [76.4%]) showed that a significant correlation was found between the brain metabolic function and perfusion (p value 0.001).

Human cytomegalovirus infection leads to elevated levels of transplant arteriosclerosis in a humanized mouse aortic xenograft model

Recent findings emphasized an important role of human cytomegalovirus (HCMV) infection in the development of transplant arteriosclerosis. Therefore, the aim of this study was to develop a human peripheral blood lymphocyte (hu-PBL)/Rag-2(-/-) γc(-/-) mouse-xenograft-model to investigate both immunological as well as viral effector mechanisms in the progression of transplant arteriosclerosis. For this, sidebranches from the internal mammary artery were recovered during coronary artery bypass graft surgery, tissue-typed and infected with HCMV. Then, size-matched sidebranches were implanted into the infrarenal aorta of Rag-2(-/-) γc(-/-) mice. The animals were reconstituted with human peripheral blood mononuclear cells (PBMCs) 7 days after transplantation. HCMV-infection was confirmed by Taqman-PCR and immunofluorescence analyses. Arterial grafts were analyzed by histology on day 40 after transplantation. PBMC-reconstituted Rag-2(-/-) γc(-/-) animals showed splenic chimerism levels ranging from 1-16% human cells. After reconstitution, Rag-2(-/-) γc(-/-) mice developed human leukocyte infiltrates in their grafts and vascular lesions that were significantly elevated after infection. Cellular infiltration revealed significantly increased ICAM-1 and PDGF-R-β expression after HCMV-infection of the graft. Arterial grafts from unreconstituted Rag-2(-/-) γc(-/-) recipients showed no vascular lesions. These data demonstrate a causative relationship between HCMV-infection as an isolated risk factor and the development of transplant-arteriosclerosis in a humanized mouse arterial-transplant-model possibly by elevated ICAM-1 and PDGF-R-β expression.

The anticipation and inheritance pattern of c.487A>G mutation in the GJB2 gene

Mutations in the GJB2 gene are the most common causes of hereditary hearing loss. This study reveals some facts about the inheritance pattern of M163V in the GJB2 gene. This study was performed on two different families with non-syndromic hearing loss. We screened the GJB2 coding region with direct sequencing. There was a substitution of A to G in exon 2 at nucleotide 487 (M163V). This mutation was heterozygous in fathers and children while mothers were normal. Fathers of both families showed late onset hearing impairment, but there was early onset hearing loss in the children, which was more severe compared to the fathers. M163V has been reported as an unknown heterozygous mutation that leads to failure of the homotypic junctional channel formation. Another mutation in this codon is M163L, with an autosomal dominant inheritance, which impairs trafficking through the plasma membrane, resulting in cell death. Assessment of the familial pedigree has revealed anticipation in phenotype and autosomal dominant inheritance. These data in addition to the high conservation of methionine residue in mammalian species suggest that M163V is inherited with an autosomal dominant pattern. Therefore, the risk of inheritance will increase. Genetic counselors and otologists should prioritize the evaluation and prevention of this disorder in patients.

Pattern of brain blood perfusion in tinnitus patients using technetium-99m SPECT imaging

BACKGROUND AND PURPOSE

Tinnitus is associated with an increased activity in central auditory system as demonstrated by neuroimaging studies. Brain perfusion scanning using single photon emission computed tomography (SPECT) was done to understand the pattern of brain blood perfusion of tinnitus subjects and find the areas which are mostly abnormal in these patients.

MATERIALS AND METHODS

A number of 122 patients with tinnitus were enrolled to this cross-sectional study. They underwent SPECT and magnetic resonance imaging (MRI) of brain, and the images were fused to find the regions with abnormal perfusion.

RESULTS

SPECT scan results were abnormal in 101 patients (83%). Most patients had bilateral abnormal perfusion (N = 65, 53.3%), and most subjects had abnormality in middle-temporal gyrus (N = 83, 68%) and temporoparietal cortex (N = 46, 37.7%). Patients with multifocal involvement had the least mean age than other 2 groups (patients with no abnormality and unifocal abnormality) (P value = 0.045).

CONCLUSIONS

Brain blood perfusion pattern differs in patient with tinnitus than others. These patients have brain perfusion abnormality, mostly in auditory gyrus (middle temporal) and associative cortex (temporoparietal cortex). Multifocal abnormalities might be due to more cognitive and emotional brain centers involvement due to tinnitus or more stress and anxiety of tinnitus in the young patients.

Persian language version of the "Tinnitus Handicap Inventory": translation, standardization, validity and reliability

Tinnitus is a debilitating condition that is widespread yet difficult to successfully diagnose and treat. This symptom can seriously affect the individual's life quality.

OBJECTIVES

The aim of current study was to compose and validate a Persian version of the Tinnitus Handicap Inventory (THI-P).

MATERIALS AND METHODS

The linguistic validation of the original version of THI into Persian version (THI-P) included translation, back translation and data gathering. The THI-P was administered to 112 tinnitus subjects. Age, gender, medical history and tinnitus characteristics were recorded as baseline information. All participants complained of chronic unilateral or bilateral subjective idiopathic tinnitus lasting for at least 6 months before consulting about their tinnitus.

RESULTS

There was no significant difference between gender, age, hearing impairment and total score and subscales of THI-P. Pearson product-moment correlations revealed adequate test-retest reliability for the THI-P (r = 0.96). Cronbach's-alpha coefficient indicated adequate internal stability of the THI-P (r= 0.943), with a total item correction varying between r=0.939 and r=0.944, indicating its reproducibility.

CONCLUSION

The present study proved the internal consistency/ coherency of the Persian version of THI (THI-P). This provides satisfactory application in clinical/research environments.

Functional brain abnormalities localized in 55 chronic tinnitus patients: fusion of SPECT coincidence imaging and MRI

Tinnitus is often defined as the perception of sounds or noise in the absence of any external auditory stimuli. The pathophysiology of subjective idiopathic tinnitus remains unclear. The aim of this study was to investigate the functional brain activities and possible involved cerebral areas in subjective idiopathic tinnitus patients by means of single photon emission computerized tomography (SPECT) coincidence imaging, which was fused with magnetic resonance imaging (MRI). In this cross-sectional study, 56 patients (1 subject excluded) with subjective tinnitus and 8 healthy controls were enrolled. After intravenous injection of 5 mCi F18-FDG (fluorodeoxyglucose), all subjects underwent a brain SPECT coincidence scan, which was then superimposed on their MRIs. In the eight regions of interest (middle temporal, inferotemporal, medial temporal, lateral temporal, temporoparietal, frontal, frontoparietal, and parietal areas), the more pronounced values were represented in medial temporal, inferotemporal, and temporoparietal areas, which showed more important proportion of associative auditory cortices in functional attributions of tinnitus than primary auditory cortex. Brain coincidence SPECT scan, when fused on MRI is a valuable technique in the assessment of patients with tinnitus and could show the significant role of different regions of central nervous system in functional attributions of tinnitus.

Pulsatile tinnitus and carotid artery atherosclerosis

This cross-sectional study was designed to determine the prevalence of carotid artery atherosclerosis in patients with pulsatile tinnitus. All patients who had pulsatile tinnitus and presented to the otolaryngology clinic of Rasoul Akram Hospital, Iran University of Medical Sciences, and to some other private hospitals and clinics were referred to a tertiary referral center. From November 1999 to September 2003, 34 patients with pulsatile tinnitus underwent a clinical evaluation. Color Doppler ultrasonography was performed in all patients. Atherosclerotic carotid artery disease (ACAD) was found to be a cause of pulsatile tinnitus in four patients (11.76%). The mean age of these patients was higher than that of the other patients (59 vs. 34 years). All patients had at least one risk factor for ACAD. In three patients, pulsatile tinnitus was the first manifestation of ACAD; in two of these, this symptom occurred when the stenosis affected more than 70% of the artery's diameter. ACAD should be considered in evaluation of all patients with pulsatile tinnitus and associated cardiovascular risk factors. As pulsatile tinnitus may be the sole manifestation of severe carotid artery stenosis, immediate color Doppler ultrasonographic study is recommended in those patients with risk factors and in the elderly.