Gap pre-pulse inhibition of the cortical auditory evoked potentials as a possible objective tinnitus assessment tool.

Objectives: The objective assessment tests overcome the variability of subjective methods. Cortical recordings with gap pre-pulse inhibition of the acoustic startle reflex stimulus have been used as objective tinnitus assessments in humans. This study aims to investigate this possible objective tinnitus test and compare gap-induced inhibition in different stimulus parameters and brain regions. Materials & Methods: Twenty People (18-50 years old) without hearing loss and tinnitus were included. The sound stimuli consisted of continuous background noise with a loud startle tone preceded by a silent gap (20 and 40 ms duration, 120 and 150 ms distance from the startle). The N1-P2 complex amplitude and topoplot maps were extracted in 27-channel cortical response recording after signal processing. Four brain regions of interest (ROI) of anterior-frontal, centro-frontal, right, and left temporal were investigated. Results: The results showed that the maximum inhibition occurred in a 40 ms gap duration and 150 ms distance in all 4 ROIs. In comparing ROIs, the centro-frontal and left temporal regions revealed the most inhibition (p<0.05). The decrease in the amplitude of the N1 and P2 in that region could also be traced in the 100 and 200 ms topoplots. Conclusion: Gap-induced inhibition was observed in all gap-embedded stimuli and all ROIs. However, the 40-150 mode and centro-frontal and left temporal regions had maximum inhibition in normal subjects. It provides a promising tool for objectively assessing tinnitus in humans with particular implications in children.

The Effect of Computer-Based Auditory Training on Speech-in-Noise Perception in Adults: a Systematic Review and Meta-Analysis.

To investigate the effectiveness of computer-based auditory training on speech-in-noise perception in adults. With no language restriction, 11 databases were searched from 1990 to 2020. We included any clinical trial studies with concurrent comparison groups that examined the effectiveness of computer-based auditory training programs in adults. The primary outcome was a speech in noise perception that was estimated using the "difference pretest-posttest-control" index (dppc2). The risk of bias was assessed using the Cochrane collaboration tool for assessing the risk of bias in randomized trials. The certainty of the evidence was investigated using the GRADE in two primary outcomes. Twenty three studies were included in two subgroups based on primary outcome: 12 studies with speech perception threshold and 11 studies with speech-in-noise test scores. Computer-based auditory training resulted in a speech in noise perception improvement (dppc2: -0.69, 95%CI: -1.11 to -0.26; I2 = 69.6%, p = 0.00) and (dppc2: 0.71, 95%CI: 0.38-1.03, I2: 17.8%, p = 0.27) respectively in both subgroups. 19 studies were judged to have a high risk of bias and 3 studies had a low risk of bias and the strength of the evidence was low in both primary outcomes. This finding indicates that computer-based auditory training can be a moderately effective intervention for speech-in-noise perception in adults. However, due to the low quality of primary studies and the low certainty of the evidence, the results are not yet definite. Prospero registration number: CRD42021233193. Supplementary Information: The online version contains supplementary material available at 10.1007/s12070-023-03920-0.

Use of Some Relevant Parameters for Primary Prediction of Brain Activity in Idiopathic Tinnitus Based on a Machine Learning Application.

INTRODUCTION: Tinnitus is one of the most common complaints, distressing about 15-24% of the adult population. Because of its pathophysiology heterogeneity, no curable treatment has been attained yet. Even though a neuromodulation management technique based on the tinnitus network model is currently being developed, it has not yet worked because the most involved brain areas still remain unpredictable from the patient's individual clinical and functional profile. A remarkable correlation between tinnitus network activity and the subjective measures of tinnitus like perceived loudness and annoyance and functional handicap is well established. Therefore, this study aimed to develop software for predicting the involved brain areas in the tinnitus network based on the subjective characteristics and clinical profile of patients using a supervised machine-learning method. METHODS: The involved brain areas of 30 tinnitus patients ranging from 6 to 80 months in duration were recognized by using QEEG and sLORETA software. There was a correlation between subjective information and those areas of activities in all rhythms by which we wrote our software. RESULTS: For verification and validation of the software, we compared and analyzed the results with SPSS data and the receiver operating characteristic (ROC) curves. CONCLUSIONS: The findings of this study confirmed the effectiveness of the software in predicting the brain activity in tinnitus subjects; however, some other important parameters can be added to the model to strengthen its reliability and feasibility in clinical use.

The Effect of Combined Auditory Training on Concurrent Sound Segregation in Young old: A Single-Blinded Randomized Clinical Trial.

This study aimed to investigate the behavioral results of perceptual learning in young old using double-vowel discrimination tasks in combined auditory training programs. In a single-blind randomized clinical trial, 35 participants were randomly divided into three groups and received different auditory training programs for six sessions using the software. To compare the double-vowel discrimination score, CV in noise test, and reaction time to the first and second vowels pre- and post-intervention, an analysis of variance was conducted. The discrimination score in the double vowel task and CV in noise test improved after training with no significant difference between the groups. After auditory training, the lowest RT1 was observed in the first intervention group, whereas RT2 decreased only in the second intervention. The present study showed that combined auditory training programs are as effective as conventional auditory training programs in improving speech perception in the elderly. Modifications in the sensory cortex could be investigated using electrophysiological recordings, but this was not conducted because of the pandemic. Supplementary Information: The online version contains supplementary material available at 10.1007/s12070-023-03923-x.

Comodulation Masking Release in Tinnitus Frequency and One Lower Octave of Tinnitus Frequency.

Inhibitory function is the basis of many perceptual and non-perceptual abilities in the auditory system. In people with tinnitus, decreased inhibitory function in the central auditory system has been proven. This disorder is caused by an increase in neural activity caused by an imbalance between stimulation and inhibition. The aim of this study was to evaluate and compare inhibitory function in persons who had tinnitus, at and one octave lower than the tinnitus frequency. Studies show that inhibition has very important role in comodulation masking release. According to inhibitory dysfunction in people with tinnitus, in this study we assessed comodulation masking release in tinnitus frequency and one lower octave. Participants were divided into two groups. Group 1 consisted of 7 individuals with unilateral tonal tinnitus at 4 kHz and group 2 included 7 individuals with unilateral tonal tinnitus at 6 kHz. Paired test, in each group separately, showed that the comodulation masking release and Across Frequency comodulation masking release differed significantly between tinnitus frequency and one octave lower in each group (p < 0.05). In fact, the disinhibition in the area around the frequency of the tinnitus seems to be greater than the tinnitus frequency area. It seems that the results of CMRs can be used in planning and managing the treatment of people with tinnitus (such as sound therapy, etc.).

Vestibular Assessment in Patients with Persistent Symptoms of Mild Traumatic Brain Injury.

Aim: The estimated worldwide incidence of TBI is 10 million cases per year. Dizziness and imbalance are two common symptoms in mild TBI (mTBI). In about 10-15% of TBI patients, these symptoms remain for a long time and may show no recovery. These persistent symptoms may relate to different factors including vestibular abnormalities. The aim of this study is a vestibular assessment of patients with persistent symptoms of mTBI by different tests including computerized dynamic posturography. Materials and Methods: 21 patients with mTBI evaluated in this study. Patients were civilians with persistent symptoms. TBI did cause by blunt force trauma (mainly from falling) in the past 6 months. They had normal neurologic and musculoskeletal assessments and no temporal bone fracture. Several auditory and vestibular evaluations were performed for each patient. They included: case history, otoscopy, pure tone and speech audiometry, tympanometry, vestibular bedside examination (spontaneous nystagmus, gaze, saccade, pursuit, Dix-Hallpike maneuver, side-lying maneuver, roll, and Romberg test), cervical Vestibular Myogenic Evoked Potential (c-VEMP), Computerized Dynamic Posturography (CDP) and Dizziness Handicap Inventory (DHI). Results: Patients showed hearing loss in 10 (47.6%) and tinnitus in 4 (19.0%) cases. In ocular motor tests, patients had the most abnormal results in the pursuit test. 6 patients also had Benign Paroxysmal Positional Vertigo (BPPV) in the posterior canal. c-VEMP showed abnormal saccular function in 14 patients. In CDP, the composite scores were decreased relative to normal populations. Conclusion: vestibular tests showed abnormal results in most patients. Vestibular abnormality could relate to persisting symptoms of mTBI patients.

Metabotropic glutamate receptor: A new possible therapeutic target for cochlear synaptopathy.

Objectives: Cochlear synaptopathy is a common cause of auditory disorders in which glutamate over-activation occurs. Modulating glutamatergic pathways has been proposed to down-regulate post-synaptic excitation. Materials and Methods: 12-guinea pigs as sham and test groups were exposed to a 4-kHz noise at 104 dB SPL, for 2 hr. Pre-exposure intra-tympanic injection with LY354740 and normal saline 9% was applied in the test and sham groups. The amplitude growth of ABR-wave-I and wave-III latency shift with noise were considered in pre- and post-exposure times. The synapses were observed by transmission electron-microscopy. Results: ABR thresholds recovered 1-week post-exposure in both groups. The reduction of wave-I amplitude at 4, 6, and 8 kHz were statistically different between pre- and 1- day post-exposure and recovered mostly in the sham group. The amount of latency shift in masked ABR was different between pre- and all post-exposure, and the response could not be detected at higher than 50 dB SL noise. However, the response detectability increased to 60 dB SL noise, and the significance of differences between pre- and post-exposure persisted only at the high level of noise in the test group. In electron-microscopy of sham samples, the size of the ribbon was larger, spherical with an irregularity, and hollow. The post-synaptic density was thicker and missed its flat orientation. Conclusion: The higher slope of the ABR-wave I amplitude, the more tolerance of noise in masked ABR, concomitant with the histological finding that revealed less synaptic damage, confirmed the therapeutic effect of LY354740 in cochlear synaptopathy.

Regularity of background auditory scene and selective attention: A brain oscillatory study.

There are scarce data related to the facilitative effects of regularity encoding on auditory selective attention during every day listening conditions. Therefore, present study aimed to investigate how temporal and spectral regularities of background auditory stream affect auditory selective attention at both levels of brain neural oscillatory activities and involved cortical locations. EEG was recorded in healthy young adults listening to two concurrent auditory streams including background and foreground ones in three conditions differing for background auditory stream which was characterized by having spectral or temporal sound regularities and random structure. The neural sources of EEG bands during recognizing target sounds in the foreground stream were determined via standardized Low-Resolution brain Electromagnetic Tomography (sLORETA). Sound regularities of the background auditory stream had no significant effect on the EEG relative power during the task of selective attention. In all conditions, there was a significant increase in the relative power of EEG alpha and beta frequency bands. sLORETA localized significant increase of mentioned bands in the precuneus of parietal lobe; medial frontal gyrus of frontal lobe and insula of sub-lobar in temporal regularity, spectral regularity and random conditions respectively. These results revealed that although temporal and spectral acoustic regularities of competitor auditory stream had no facilitative effect on alpha-related brain processing during selective attention, different brain cortical locations were activated with the introduction of these regularities. This result might provide preliminary evidence for some degree of brain neural specialization in the processing of temporal and spectral regularities during auditory selective attention tasks.

Vestibular Hypersensitivity in Patients with Chronic Noise Exposure.

It has been demonstrated that high-intensity noise exposure adversely affects the human balance function. The Tullio phenomenon (TP) refers to sound-induced imbalance which is resulted from hypersensitivity of vestibular end organs to normal acoustic stimuli. Although different etiologies have been attributed to TP, evidence on the role of excessive noise exposure in the development of this symptom is limited. The present study aims to assess the vestibular functions in patients manifesting TP symptom who were exposed to long-term excessive noise levels. This was an analytic cross-sectional study conducted on 17 males diagnosed with TP with a history of chronic noise-induced hearing loss (TP group) and 17 healthy individuals. All subjects in both groups underwent complete otological, videonystagmography (VNG), and cervical vestibular myogenic potential (cVEMP) assessments. The most common complaint in TP subjects was vertigo and imbalance. During the VNG assessment, we found abnormal positional nystagmus and caloric irrigation (vestibular hyperfunction) results in 4 (23.53%) and 9 (52.94%) patients, respectively. Seven (41.17%) patients indicated cVEMP thresholds which were abnormally lower than the normal values ( ≤ 70 dB HL). However, when both VNG and cVEMP results were considered together, the abnormal rate reached 70.58% (12 of 17 cases). Our findings showed that both the semicircular canal as well as otolith stuctures could be affected in TP patients with a history of chronic noise exposure.

Shannon entropy measures for EEG signals in tinnitus.

BACKGROUND AND AIM: Tinnitus is known as a common clinical symptom, and it comprehensively is essential to understand the underlying mechanisms. Time-varying EEG is considered an appropriate technique to explore brain regions and related activities, and nonlinear methods may extract the irregularities in the EEG signal and gather more expanded information. Therefore, we studied Shannon Entropy in EEG raw data obtained from normal subjects and compared it to data from chronic tinnitus sufferers before and after an intervention. METHODS: From the qEEG database of Iran University of Medical Sciences, the School of Rehabilitation Sciences, we have selected 23 healthy and 24 chronic tinnitus subjects. Nineteen subjects of the tinnitus group had benefited from a complete course of sound therapy (binaural beat for a month). QEEGs were measured with a 27-channel EEG amplifier in the sitting and eye-closed position for 3 min. Shannon entropy was investigated for all electrodes separately and compared among groups using a one-way ANOVA statistical test. FINDINGS: Our results revealed a significant difference between healthy and tinnitus subjects (p < 0.05). Post-hoc comparisons using the Bonferroni test showed increased entropy in the tinnitus group for all electrodes (p < 0.05) at low frequencies and most electrodes at mid frequencies. In addition, after the intervention, paired t-test showed a reduction in entropy to somehow above normal control levels for all electrodes at low-frequencies. Such results were accompanying clinical improvement after the intervention. CONCLUSION: The increased entropy in tinnitus patients might reflect the chaotic behavior of the brain. Nonlinear methods in EEG studies (Entropy) could be of great importance in understanding tinnitus neurophysiology and might potentially be a suitable criterion for clinical practice.

Thyroid-Stimulating Hormone and Free Thyroxine Alterations in Subjects with Occupational Hearing Loss.

CONTEXT AND AIM: Occupational hearing loss (OHL) is caused by exposure to industrial noise. Alterations in the thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels are related to hearing loss. The purpose of this study is to investigate the TSH and FT4 level alterations in OHL. METHODS AND MATERIAL: Among 428 subjects, 144 male workers with normal hearing (NH), noise-induced hearing loss (NIHL), and high tone loss (HTL) (N = 48 in each group) were included in this study. All the subjects had normal TSH and FT4 levels. RESULTS: The TSH level is higher in the HTL and NIHL groups in comparison to NH, but it is only significant in the HTL group. The FT4 level is significantly lower in the NIHL group; however, the lower FT4 level in the HTL group is not significant when compared to the NH group. DISCUSSION: The NIHL group may turn into the HTL group over time. This process could be monitored by alteration in their TSH and FT4 levels. CONCLUSIONS: Alterations in the TSH and FT4 levels could be considered as a pathophysiology for OHL. More research is required to investigate the electrophysiological, physiological, and histological correlations of TSH and FT4 and different types of hearing loss caused by noise exposure.

The Relationship between Psychoacoustic and Electrophysiological Assessments of Temporal Resolution.

BACKGROUND: Temporal resolution is essential to speech acoustic perception. However, it may alter in individuals with auditory disorders, impairing the development of spoken and written language. The envelope of speech signals contains amplitude modulation (AM) that has critical information. Any problem reducing the listener's sensitivity to these amplitude variations (auditory temporal acuity) is likely to cause speech comprehension problems. The modulation detection threshold (MDT) test is a measure for evaluating temporal resolution. However, this test cannot be used for patients with poor cooperation; therefore, objective evaluation of MDT is essential. PURPOSE: The main aim of this study is to find the association between the auditory steady-state response (ASSR) and psychoacoustic measurement of MDT at different intensity levels and to assess the amplitude and phase of ASSR as a function of modulation depth. DESIGN: This was a correlational research. STUDY SAMPLE: Eighteen individuals (nine males and nine females) with normal hearing sensitivity, aged between 18 and 23 years, participated in this study. DATA COLLECTION AND ANALYSIS: ASSR was recorded at fixed AM rates and variable AM depths for carrier frequencies of 1,000 and 2,000 Hz with varying intensities. The least AM depth, efficient to evoke an ASSR response, was interpreted as the physiological detection threshold of AM. The ASSR amplitude and phase, as a function of AM depth, were also evaluated at an intensity level of 60 dB hearing level (HL) with modulation rates of 40 and 100 Hz. Moreover, the Natus instrument (Biologic Systems) was used for the electrophysiological measurements. An AC40 clinical audiometer (Intra-acoustic, Denmark) was also used for the psychoacoustic measurement of MDT in a similar setting to ASSR, using the two-alternative forced choice method. Pearson's correlation test and linear regression model and paired t-test were used for statistical analyses. RESULTS: A significant positive correlation was found between psychoacoustic and electrophysiological measurements at a carrier frequency of 1000 Hz, with a modulation rate of 40 Hz at intensity levels of 60 dB HL (r = 0.63, p = 0.004), 50 dB HL (r = 0.52, p = 0.02). A significant positive correlation was also found at a carrier frequency of 2000 Hz, with a modulation rate of 47 Hz at 60 dB HL (r = 0.55, p = 0.01) and 50 dB HL (r = 0.67, p = 0.002) and a modulation rate of 97 Hz at 60 dB HL (r = 0.65, p = 0.003). Moreover, a significant association was found between the modulation depth and ASSR amplitude and phase increment at carrier frequencies of 1,000 and 2000 Hz, with modulation rates of 40 and 100 Hz. CONCLUSION: There was a significant correlation between ASSR and behavioral measurement of MDT, even at low intensities with low modulation rates of 40 and 47 Hz. The ASSR amplitude and phase increment was a function of modulation depth increase. The findings of this study can be used as a basis for evaluating the relationship between two approaches in the clinical population.

Brainstem Representation of Auditory Overshoot in Guinea Pigs Using Auditory Brainstem Responses.

Objective: It is easier for a listener to detect a brief tonal signal presented in a longer masking noise by increasing the delay between the signal and the masker. This phenomenon (overshoot) is influenced by a reduction in cochlear amplification and to date, there is no objective tool to investigate it. Therefore, a different paradigm of the auditory brainstem response (ABR) was utilized to measure auditory overshoot. It was assumed that increasing the delay onset time (DOT) between a signal and a masker reduces the latencies of waves I and III. Materials & Methods: Sixteen normal young male guinea pigs were tested. A tone burst stimulus (signal: 16 kHz, 5ms in duration) and wide-band noise (masker: 0.1-8.0 kHz, 100ms in duration) at three DOTs were used. To diminish the effect of the noise on waves, waveforms were subtracted from those derived from the noise burst alone. The absolute latency of the waves I and III, inter-peak latency of the waves I-III, and amplitude ratio of the waves III/I were compared for the 0, 30, and 100ms DOTs and five signal-to-noise ratios. Results: The latencies of increased from the 0 to 30ms DOT and then decreased from the 30 to 100ms DOT (p < 0.001). No significant changes were observed in the latency waves at the 100ms DOT compared to the 0ms DOT (p > 0.005). Moreover, there were no significant differences between the three DOTs regarding the inter-peak latency and amplitude ratio of the waves (p <0.005). Conclusion: The study results showed an overshoot-like electrophysiological effect using ABR. Therefore, an objective test was used to investigate auditory cochlear gain.

A Dose-Effect Study of Cisplatin Ototoxicity in Albino Guinea Pigs.

INTRODUCTION: Cisplatin is one of the most commonly used antineoplastic drugs; nonetheless, its ototoxic dose-limiting side effects have remained a significant challenge in clinical practice. The recognition of the exact template of hearing loss induced by multiple low doses of cisplatin could be of great help in managing the treatment process. The present study aimed to investigate the effects of multiple doses of this drug on the auditory system. MATERIAL AND METHODS: The present study was performed using an experimental guinea pig model in four groups as follows:1- 0.9% sodium chloride solution, 2- total dose of 7.5 mg/kg Cisplatin, 3- total dose of 10 mg/kg Cisplatin, and 4- total dose of 12.5 mg/kg cisplatin. The drugs were injected as 2.5 mg/kg/daily IP access in all groups. The auditory brainstem response (ABR) test was performed before the treatment and after every injection on a daily basis up to 72 h after the last injection. RESULTS: There was dose-dependent significant hearing loss in all evaluated frequencies in three cisplatin groups. The general template of induced hearing loss during experimental days was almost the same in groups Cis7.5 and Cis10. In Cis 12.5 group, there was a jump in the threshold shift on the 5th day of the experiment and an upward trend in the function. CONCLUSION: As evidenced by the obtained results, the monitoring of hearing loss after every injection in patients who receive the drug and detecting the exact dose-dependent pattern of the induced hearing loss is of great help in controlling its undesirable destructive side effects on the auditory system.

Bilateral Carotid Artery Occlusion and Cochlear Oxidative Stress and Hearing Loss in Rats.

INTRODUCTION: This study aimed to evaluate the effects of bilateral carotid artery occlusion on cochlear oxidative stress and hearing status in rats. METHODS: The rats were divided into two sets. The first set was used for electrophysiological recording (click and 4 kHz tone burst auditory brainstem responses and electrocochleography) on the day before surgery and then on the first, fourth, and seventh days after surgery. Animals of the second set were used for biochemical analysis. The cochlea of animals in the second set was collected on the first, fourth, and seventh days after carotids occlusion for biochemical analysis. For the control groups, no carotids occlusion was done. For ischemia induction, both common carotid arteries were occluded for 20 minutes. RESULTS: Electrophysiological analysis showed that burst auditory brainstem thresholds significantly elevated after common carotid arteries occlusion on the first, fourth, and seventh days after surgery with abnormal electrocochleography results at 75%, 70%, and 85% on the first, fourth, and seventh days after surgery, respectively. The electrophysiological finding confirmed by biochemical results that showed malondialdehyde and nitric oxide levels increased and superoxide dismutase and catalase activities decreased after occlusion in cochlea tissue. CONCLUSION: This study showed that bilateral common carotid artery occlusion increases cochlear oxidative stress and induces hearing loss in rats.

The efficacy and safety of multiple sessions of multisite transcranial random noise stimulation in treating chronic tinnitus / Eficácia e segurança de múltiplas sessões de estimulação transcraniana por ruído aleatório multissítio no tratamento do zumbido crônico

Abstract Introduction: Random noise stimulation was reported as the more effective and safer type of electrical stimulation techniques in relieving tinnitus symptoms. The multisite protocol of transcranial random noise stimulation has shown additional favorable effects. Objective: Here we will discuss the role of applying eight sessions of multisite transcranial random noise stimulation in decreasing tinnitus loudness and annoyance without exerting additional adverse effects. Methods: Twenty-nine subjects (8 female), the mean age of (45.34 ± 9.57) with chronic tinnitus received transcranial random noise stimulation in the multisite protocol, 10 min of auditory-transcranial random noise stimulation applied over the T3, T4 preceded by 10 min of prefrontal-transcranial random noise stimulation applied over F4, FP1. In the first group, only one session was applied and the multiple-sessions group contained eight repeated sessions. Visual analog scale scores for loudness and distress were recorded before and immediately after the treatment. Multivariate repeated measure ANOVA test was used and minimal detectable change calculated. Results: There was a statistically and clinically significant reduction in tinnitus loudness and annoyance in both groups (p < 0.05, effect size (η 2) > 0.8), while the amount of annoyance suppression in the multiple-sessions group was significantly greater than the single-session group. The patients of the multiple-sessions transcranial random noise stimulation group reported an improvement in their sleep and lower tinnitus handicap inventory scores without experiencing any additional adverse effects of the intervention. Conclusions: The results of this study showed a substantial improvement in tinnitus symptoms by using the multiple sessions of transcranial random noise stimulation in the multisite protocol without producing any additional side effects. We suggest further clinical trials with long-term follow-up be investigated.

Resumo Introdução: Tem sido relatado que a estimulação transcraniana por ruído aleatório é um tipo mais eficaz e seguro de técnica de estimulação elétrica no alívio dos sintomas do zumbido. O protocolo multissítio da estimulação transcraniana por ruído aleatório mostrou efeitos favoráveis adicionais. Objetivo: Discutir o papel da aplicação de oito sessões de estimulação transcraniana por ruído aleatório multissítio na diminuição da intensidade (loudness) do som e incômodo (annoyance) do zumbido sem causar efeitos adversos adicionais. Método: Vinte e nove indivíduos com zumbido crônico (oito do sexo feminino), com média de 45,34 ± 9,57 anos, receberam estimulação transcraniana por ruído aleatório no protocolo multissítio, 10 minutos de estimulação transcraniana por ruído aleatório-auditivo aplicado no T3, T4 precedido por 10 min de estimulação transcraniana por ruído aleatório pré-frontal aplicado sobre F4, FP1. No primeiro grupo, apenas uma sessão foi aplicada e o grupo de múltiplas sessões recebeu oito sessões. Os escores da escala visual analógica para a intensidade do som (loudness) e incômodo (annoyance) do zumbido foram registrados antes e imediatamente após o tratamento. O teste Anova multivariada para medidas repetidas foi utilizado e a mudança mínima detectável foi calculada. Resultados: Houve uma redução estatisticamente e clinicamente significante na intensidade e incômodo do zumbido em ambos os grupos (p < 0,05; tamanho do efeito (η2) > 0,8), embora o nível de supressão do incômodo no grupo de sessões múltiplas tenha sido significantemente maior do que no grupo de sessão única. Os pacientes do grupo estimulação transcraniana por ruído aleatório com múltiplas sessões relataram uma melhoria no sono e menores escores no tinnitus handicap inventory, sem experimentar quaisquer efeitos adversos adicionais da intervenção. Conclusão: Os resultados deste estudo mostraram uma melhora substancial nos sintomas do zumbido utilizando múltiplas sessões de estimulação transcraniana por ruído aleatório no protocolo multissítio sem produzir quaisquer efeitos colaterais adicionais. Sugerimos que novos ensaios clínicos com seguimento de longo prazo sejam realizados.

Multisite transcranial Random Noise Stimulation (tRNS) modulates the distress network activity and oscillatory powers in subjects with chronic tinnitus.

Tinnitus is a common disorder in which auditory and non-auditory areas are involved as a network. Therefore, the multisite protocol of brain stimulation (tRNS) seems effective in relieving tinnitus symptoms. This study aimed to verify the modulatory effects of multisite tRNS on the tinnitus network. Thirty-two tinnitus-suffering patients received two consecutive sessions of tRNS (SHAM+ REAL) applied over the T3, T4 (the auditory cortex group) and F4, FP1 followed by T3, T4 (the multisite group). A 3-min resting-state EEG was recorded before and immediately after each session. After the multisite-tRNS real session, there was a significantly increased power in the alpha-1 band at the auditory and prefrontal cortex accompanied by decreased power in the delta and beta-2 bands in the prefrontal cortex. Standardized low-resolution brain electromagnetic tomography (sLORETA) showed a significant decrease in beta-2 activity in the prefrontal cortex, anterior cingulate cortex, and the parahippocampus and decreased alpha connectivity between the right prefrontal cortex and the left auditory cortex. No significant effects were noticed for the sham session. This study showed that tRNS has modulatory effects on the electrical activity of the brain and that targeting prefrontal and auditory areas in sequence could modulate the distress network and multiple hubs in the tinnitus network.

The comparison of the comodulation masking release (CMR) in individuals with and without chronic tinnitus.

In comodulation masking release (CMR), the auditory signal threshold improves when maskers far from the frequency of the target signal are coherently amplitude-modulated. Studies show that inhibitory function may play a role in CMR. In individuals who have tinnitus, decreasing inhibitory functioning in auditory central nervous system has been documented. Therefore, in this study, the purpose was to evaluate CMR in individuals suffering from tinnitus and compare CMR findings with those who do not have tinnitus. Seventeen normal-hearing individuals (without tinnitus) and 13 individuals having unilateral tonal tinnitus (4000 or 6000 Hz) with normal or near to normal hearing participated in this study. All participants were 20 to 50 years of age and underwent comodulated (CM), unmodulated (UM), and reference (RF) threshold measurements and then the CMRs (CMR and Across Frequency CMR; AF-CMR) were calculated. An ANOVA showed that the CM thresholds were statistically different between groups, while the RF and UM thresholds were not statistically different. CMR (CMR & AF-CMR) function was higher in those without tinnitus compared to unilateral tinnitus sufferers. Due to the inhibitory role of the auditory central nervous system in CMR, it appears that tinnitus and CMR both may be influenced by inhibitory function.

Asymmetric Flankers in Comodulation Masking Release.

BACKGROUND AND OBJECTIVES: Detection of auditory signals may be improved when maskers far from the frequency of the target signal are coherently amplitude-modulated. This improvement of signal detection is called comodulation masking release (CMR). In the CMR experiments, flankers have been usually arranged symmetrically. In practice, we will be confronted with a problem by using symmetric flankers due to the limited output of clinical audiometers, especially at high-frequency. We aimed to check whether flanker arrangement has any effect on the amount of CMR, especially when there is no flankers with a frequency higher than the signal. Subjects and. METHODS: Eighteen normal hearing listeners ranging in age from 20 to 46 years old participated. Symmetric (2-2) and asymmetric (3-1 and 4-0) flankers were used and then the amount of CMR compared among them. RESULTS: Our results showed in the same numbers of flankers, there were no statistically CMR differences between symmetric and asymmetric arrangement. Also when we did not have a flanker at a frequency higher than the signal and all flankers were placed below the signal, there was no statistically difference with the symmetric arrangement. CONCLUSIONS: The asymmetry of the flankers and also omitting the flankers with a frequency higher than the signal, have no effect on CMR results. We concluded that CMR can be considered by using clinical audiometer.

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.