Tinnitus Group Research Articles

Tinnitus Identification based on Brain Network Analysis of EEG Functional Connectivity

Introduction: Tinnitus known as a central nervous system disorder is correlated with specific oscillatory activities within auditory and non-auditory brain areas. Several studies in the past few years have revealed that in the most tinnitus cases, the response pattern of neurons in auditory system is changed due to auditory deafferentation, which leads to variation of the brain networks. According to neuroimaging studies, the human brain is assumed as an organization with the different degree of small-worldness, which is a concept in graph theory. Such organization is able to optimize the functional integration and segregation and therefore efficiently transfer the information among its different pairs of nodes. Materials and Methods: In this paper, we introduce an approach to automatically distinguish tinnitus individuals from healthy controls based on whole-brain functional connectivity and network analysis. Eight participants with tinnitus and eight healthy individuals were included in the study. Resting state electroencephalographic (EEG) data were recorded using a 64-channel recorder. The functional connectivity analysis was applied to the EEG data using Weighted Phase Lag Index (WPLI) for various frequency bands in 2-44 Hz frequency range. The classification was performed on graph theoretical measures using support vector machine (SVM) as a robust classification method. Results: Experimental results showed that the variations of connectivity patterns in tinnitus group were observed within the frontal, temporal and parietal regions. Further, promising classification performance was achieved with a high accuracy, sensitivity, and specificity in all frequency bands. The best classification performance was observed in the beta2 frequency band with accuracy, sensitivity, and specificity of 100%. The results demonstrate that four graph theory based network measures i.e. node strength, clustering coefficient, local efficiency and characteristic path length could successfully discriminate tinnitus from healthy group. Conclusion: The results would be interpreted that the tinnitus network is more segregated but has weaker global efficiency compared to healthy group in high frequencies. In addition, tinnitus individuls presented lower segregation and greater integration relative to the healthy group in the theta frequency domain. As a conclusion, the tinnitus group shows a reduction of small-worldness as well as network integration in high-frequency bands. In general, our study provides substantial evidence that the tinnitus network can be successfully detected by consistent measures of the brain networks based on EEG functional connectivity.

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.

Normal hearing young adults with mild tinnitus: Reduced inhibition as measured through sensory gating.

Decreased central inhibition, possibly related to hearing loss, may contribute to chronic tinnitus. However, many individuals with normal hearing thresholds report tinnitus, suggesting that the percept in this population may arise from sources other than peripheral deafferentation. One measure of inhibition is sensory gating. Sensory gating involves the suppression of non-novel input, and is measured through cortical auditory evoked potential (CAEP) responses to paired stimuli. In typical gating function, amplitude suppression is observed in the second CAEP response when compared to the first CAEP response, illustrating inhibitory activity. Using this measure, we investigated central inhibitory processes in normal hearing young adults with and without mild tinnitus to determine whether inhibition may be a contributing factor to the tinnitus percept. Results showed that gating function was impaired in the tinnitus group, with the CAEP Pa component significantly correlated with tinnitus severity. Further exploratory analyses were conducted to evaluate variability in gating function within the tinnitus group, and findings showed that high CAEP amplitude suppressors demonstrated gating performance comparable to adults without tinnitus, while low amplitude suppressors exhibited atypical gating function.

Eyes and Ears: Cross-Modal Interference of Tinnitus on Visual Processing

The visual processing capacity of tinnitus patients is worse than normal controls, indicating cross-modal interference. However, the mechanism underlying the tinnitus-modulated visual processing is largely unclear. In order to explore the influence of tinnitus on visual processing, this study used a signal recognition paradigm to observe whether the tinnitus group would display a significantly longer reaction time in processing the letter symbols (Experiment 1) and emotional faces (Experiment 2) than the control group. Signal detection and signal recognition, which reflect the perceptual and conceptual aspects of visual processing respectively, were manipulated individually in different conditions to identify the pattern of the cross-modal interference of tinnitus. The results showed that the tinnitus group required a significantly prolonged reaction time in detecting and recognizing the letter symbols and emotional faces than the control group; meanwhile, no between-group difference was detected in signal encoding. In addition, any gender- and distress-modulated effects of processing were not found, suggesting the universality of the present findings. Finally, follow-up studies would be needed to explore the neural mechanism behind the decline in speed of visual processing. The positive emotional bias in tinnitus patients also needs to be further verified and discussed.Highlights:- The bottom-up visual processing speed is decreased in tinnitus patients.- Tinnitus primarily interferes with the detection of the visual signals in individuals.

Changes in the regional shape and volume of subcortical nuclei in patients with tinnitus comorbid with mild hearing loss.

Tinnitus, the perception of sound without an external source, is a prevalent disease, but its underlying mechanism has not been fully elucidated. Recent studies have suggested the involvement of subcortical nuclei in tinnitus generation. We investigated changes in the local shape and volume of subcortical nuclei in relation to tinnitus. The participants included 53 patients with tinnitus and 52 age- and gender-matched normal controls. Individual 3D T1-weighted structural images were obtained using 3-T magnetic resonance imaging. Surface-based vertex analysis (SVA) was performed with automated segmentation of the bilateral caudate nuclei, putamina, nucleus accumbens, thalami, pallidum, hippocampi, amygdalae, and brainstem. The scalar distances from the mean surface and volumes of 15 nuclei were compared between the tinnitus and control groups and correlated with tinnitus handicap score (THI) and tinnitus duration. SVA revealed regional contractions in the accessory basal and lateral nuclei of the right amygdala and expansions in the left medial and right ventral posterior nuclei and lateral dorsal nucleus of both thalami. The surface distances of the right nucleus accumbens were positively correlated with tinnitus duration, while those of the left nucleus accumbens and left hippocampus were negatively correlated with THI. Regional atrophy of the amygdala may indicate self-modulation of emotional response regulation to diminish tinnitus-related emotional distress. Thalamic regional expansion may signify dysfunctional auditory gating in the thalamus, where inhibition of the tinnitus signal at the thalamus level is disrupted due to abnormal changes in the limbic system, ultimately leading to the tinnitus percept.

A Comprehensive Study of Oxidative Stress in Tinnitus Patients.

Oxidative stress is considered to be one of the molecular changes that are the underlying causes of tinnitus. The aim of this study was to investigate the dynamic thiol/disulphide homeostasis as a new oxidative stress parameter in tinnitus patients as well as to investigate thelipid hydroperoxide (LOOH),total antioxidant status (TAS),total oxidant status (TOS) andoxidative stress index (OSI) parameters and compare the results with the results of the healthy control group. A prospective controlled trial was performed on tinnitus patients in Harran University hospital. A total of 70 subjects, including 35 tinnitus patients and 35 healthy individuals participated in this study. Their total thiol, native thiol levels and LOOH, TAS, TOS levels were measured in plasma of all tinnitus patients and healthy volunteers participants. TOS and OSI levels were significantly increased, and TAS levels were significantly lower in the patient groups compared with the control group (p < 0.01). Native thiol levels and Native thiol/total thiol ratios were significantly lower in the tinnitus group compared to the control group (p < 0.01). Disulphide level and disulphide/native thiol and disulphide/total thiol ratios were significantly higher in the patients (p < 0.01). Also, LOOH ratios were significantly higher in the tinnitus group (p < 0.01). The results of this study reveal that in tinnitus cases, the oxidative stress and antioxidant enzyme imbalance were more significant than in healthy control group. The nature of the relationship between oxidative stress and tinnitus should be clarified with larger studies.

Does changes in mismatch negativity after tinnitus retraining therapy using tinnitus pitch as deviant stimulus, reflect subjective improvement in tinnitus handicap?

Objective: The objective of this research was to study the ability of Mismatch Negativity response parameters to assess the habituation after Tinnitus Retraining Therapy through comparing MMN parameters before and after TRT and comparing MMN in tinnitus patients to non-tinnitus patients, and correlating MMN parameters to subjective measures of tinnitus.Methodology: This research included two groups: a tinnitus group of 30 tinnitus patients who were compared with a control group that consisted of well-matched 10 normal adult subjects. All participants were subjected to full history taking, audiological examination, and MMN test. Tinnitus patients were further assessed for tinnitus severity using the Tinnitus Handicap Inventory (THI), tinnitus analyses including pitch and loudness matching, with the PMF as the deviant stimulus for the MMN test.Results: The MMN latencies were significantly shorter and the MMN amplitudes were significantly greater in the tinnitus group before TRT than the control group. The MMN amplitude after TRT has significantly decreased and the MMN latency has significantly been prolonged in both ears after TRT compared with before TRT. The MMN amplitude improvement matched the subjective improvement measured subjectively by the THI.Conclusion: Tinnitus patients showed abnormality in central auditory processing mechanisms involved in pre-attentive change detection of tinnitus-related neuronal activity. This MMN abnormality showed improvement after habituation using TRT. So, we recommend adding the MMN test in evaluating tinnitus patients objectively before and after TRT for monitoring the treatment progress, together with the usual subjective measures for assessment of the degree of tinnitus severity.

COMT and the neurogenetic architecture of hearing loss induced tinnitus

As the COMT polymorphism is especially prominent in the prefrontal cortex and has been associated with auditory gating, we hypothesize that tinnitus patients with this polymorphism have altered activity in the ventromedial prefrontal/anterior cingulate areas that modulates the tinnitus percept. To test this, we recruited a total of 40 tinnitus subjects and 20 healthy controls for an EEG study. A comparison between tinnitus subjects and healthy controls and their frequency of being Val/Val genotype or Met carriers (including Val/Met and Met/Met genotype) shows no significant effect, suggesting that the distributions for the tinnitus and healthy groups are similar. Our results show that an interaction between the amount of hearing loss and the COMT Val158Met polymorphism can increase susceptibility to the clinical manifestation of tinnitus. We further demonstrate that the parahippocampus becomes involved in tinnitus in patients with hearing loss that are Met carriers. In these patients, the parahippocampus sends more tinnitus information to the pregenual anterior cingulate cortex and auditory cortex that is specifically related with increased loudness. At the same time, the pregenual anterior cingulate cortex, which normally functions as a gatekeeper, is not cancelling this auditory information, ultimately leading to increased tinnitus loudness.

Accuracy of the of the PROMIS-57 questionnaire to identify significant depressive and anxiety symptoms among patients on hemodialysis

The prevalence of panic disorder (PD) reportedly is up to fivefold higher in people with tinnitus than it is in the general population. The brain networks in the two conditions overlap but the pathophysiological link remains unclear. In this study the electrophysiological brain activity is investigated in adults with non-pulsatile tinnitus with and without concurrent PD.Resting-state EEGs of 16 participants with non-pulsatile tinnitus and PD were compared with those of 16 peers with non-pulsatile tinnitus without PD and as many healthy controls. The sLORETA technique was used to identify group-specific electrophysiological frequencies in the brain and to approximate the brain regions where differences occurred. The influence of distress was investigated and functional connectivity charted using the Region-of-Interest (ROI) approach (amygdala, anterior cingulate cortex (ACC), insula, precuneus).The comorbid group showed significantly diminished theta activity (p < 0.05) in the precuneus (BA7) compared to the tinnitus group without PD as well as in another region of the precuneus (BA31) as compared to the controls. Higher levels of distress influenced results in the tinnitus group without PD, while in those with PD a diminished connectivity was observed between the dorsal ACC and the other three ROIs as contrasted to the controls.Adults with non-pulsatile tinnitus and concurrent PD show differential brain activity patterns to tinnitus only sufferers and healthy controls. Higher levels of distress may modulate brain activity in the absence of PD. Screening for distress is recommended in both clinical and research settings.

The Association Between Cochlear and Retrocochlear Disorders with Tinnitus with Normal Hearing Thresholds.

Tinnitus is the perception of hearing the sound without any sound stimulus. It is a symptom of abnormality in a form of conductive disorder when it comes from the outer ear canal and middle ear. A tinnitus complaint has a normal hearing threshold but it has been not fully recognized its causes. Thus, an objective evaluation is needed to locate the abnormality by using OAE and BERA test. To analyze the association of TEOAE, DPOAE, and BERA to locate cochlear and retrocochlear disorders in tinnitus patients with normal hearing threshold. The study was conducted from August to November 2010 until the number of samples was fulfilled in Outpatient Clinic and Audiology Unit in Department of Otolaryngology-Head and Neck Surgery, Dr. Soetomo General Hospital Surabaya. The inclusion criteria in this study included: patients aged 20-50years old, hearing threshold of ≤ 25dB, type A tympanogram. The comparison and the association test of TEOAE, DPOAE and BERA in tinnitus group were: TEOAE-BERA analysis result using Mc Nemar obtained p = 0.006, Kappa p = 0.047, likelihood ratio p = 0.066, and the result of DPOAE-BERA analysis using Mc Nemar obtained p = 0.008, Kappa p = 0.439, likelihood ratio p = 0.336. There was a difference in the results of DPOAE examination between tinnitus patients with normal hearing threshold and the control group. There was no difference in TEOAE and BERA test results between tinnitus patients with normal hearing threshold and the control group. This indicates an abnormality in the cochlear.

The investigation rate and influence factors of tinnitus with chronic suppurative otitis media

Objective:To investigate the incidence of tinnitus and its influencing factors in patients with chronic suppurative otitis media, and to provide clinical data for the study of the pathogenesis of tinnitus.Method:The clinical data of 77 patients with chronic suppurative otitis media who underwent modified radical mastoidectomy and tympanoplasty were investigated. When tinnitus and otitis media happened in the same side,then the tinnitus is judged to be otitis media related. Patients were further divided into otitis media related tinnitus and the no tinnitus groups. The differences of tinnitus severity, sleep disturbance, migraine (migraine features), snoring and gastroesophageal reflux were compared between the two groups in tinnitus occurrence and classification.Result:The incidence of otitis media related tinnitus was 55.8%(43/77). Most of the tinnitus happened(33/43) later than the occurrence of otitis media for several years or even decades. There were 43 cases of tinnitus associated with otitis media, and 31 cases without tinnitus. Between the groups, significant differences were observed in migraine features, and the P value is 0.011, while no significant differences were noticed in the severity of hearing loss and sleep disorders, snoring, gastroesophageal reflux. Ranking of otitis media related tinnitus was positively related to the degree of hearing loss, especially the bone conduction threshold. With Spearman rank correlation test,P values of mean value(250Hz,500Hz,1kHz,2kHz,4kHz), middle frequency (1kHz, 2kHz)and high frequency (4kHz) of bone conduction threshold were 0.010,0.019 and 0.003, and the correlation coefficients were 0.391,0.356 and 0.443, respectively.Conclusion:The occurrence of tinnitus in patients with otitis media may not be consistent with the time of otitis media, and theoretically later than the occurrence of otitis media is more reasonable. Whether tinnitus occurs in patients with otitis media is not related to sleep disorders, the degree of air conduction and bone conduction hearing loss, but is related to migraine features. The severity of tinnitus associated with otitis media is associated with bone conduction hearing loss.

Differential electrophysiological correlates of panic disorder in non-pulsatile tinnitus

AimsThe prevalence of panic disorder (PD) reportedly is up to fivefold higher in people with tinnitus than it is in the general population. The brain networks in the two conditions overlap but the pathophysiological link remains unclear. In this study the electrophysiological brain activity is investigated in adults with non-pulsatile tinnitus with and without concurrent PD. MethodsResting-state EEGs of 16 participants with non-pulsatile tinnitus and PD were compared with those of 16 peers with non-pulsatile tinnitus without PD and as many healthy controls. The sLORETA technique was used to identify group-specific electrophysiological frequencies in the brain and to approximate the brain regions where differences occurred. The influence of distress was investigated and functional connectivity charted using the Region-of-Interest (ROI) approach (amygdala, anterior cingulate cortex (ACC), insula, precuneus). ResultsThe comorbid group showed significantly diminished theta activity (p < 0.05) in the precuneus (BA7) compared to the tinnitus group without PD as well as in another region of the precuneus (BA31) as compared to the controls. Higher levels of distress influenced results in the tinnitus group without PD, while in those with PD a diminished connectivity was observed between the dorsal ACC and the other three ROIs as contrasted to the controls. ConclusionsAdults with non-pulsatile tinnitus and concurrent PD show differential brain activity patterns to tinnitus only sufferers and healthy controls. Higher levels of distress may modulate brain activity in the absence of PD. Screening for distress is recommended in both clinical and research settings.

Excitation of the Auditory System as a Result of Non-invasive Extra-Cochlear Stimulation in Normal Subjects and Tinnitus Patients.

One of possible approach that may suppress tinnitus is electrical stimulation of the ear. At first invasive techniques were used (promontory or round window stimulation), nowadays a non-invasive method, namely hydrotransmissive electric stimulation (ES) through external acoustic canal, has been developed. The aim of the study is to investigate the effect of applying ES with positive and negative current polarities on the ears of healthy subjects and on the tinnitus ears of patients with tinnitus. This comparison further clarifies the mechanisms of operation of non-invasive extra-cochlear ear ES. A second aim is to assess the effects of ES on tinnitus in tinnitus patients. The material was composed of two groups: tinnitus group—49 patients suffering from tinnitus, and healthy students group—34 healthy individuals. ES was performed with the use of a custom-made apparatus. The active, silver probe–was immersed inside saline filling external ear canal. The passive electrode was placed on the forehead. Positive and next negative DC stimulation was provided with the use following frequencies: 0.25, 1, 2, 3, 4, 5, 6, 7, 8 kHz. We checked for the presence of the auditory percept (AP) and, if AP was present, the minimum current amplitude necessary to produce AP was measured. In our research both positive and negative polarities were efficient to evoke AP in the participants. This effect, however, was more pronounced for positive polarity in no tinnitus and normal hearing individuals (healthy students group). In the tinnitus group, current intensity needed to evoke AP was higher than in the healthy students group. However, comparing normal hearing vs. hearing loss patients within the tinnitus group, we did not observe the relationship between hearing threshold and current intensity evoking AP. Afterwards, we analyzed the effect of multi-frequency ES on tinnitus. It appeared to be effective in 75% of tinnitus ears (with a high score of disappearance–22%). Our study proved that extracochlear ES with positive and negative current was efficient to stimulate the auditory system. Stimulating tinnitus ears with two polarities we obtained a higher ratio of improvement (75%) comparing to positive stimulations.

Targeting Heterogeneous Findings in Neuronal Oscillations in Tinnitus: Analyzing MEG Novices and Mental Health Comorbidities.

Tinnitus is a prevalent phenomenon and bothersome for people affected by it. Its occurrence and maintenance have a clear neuroscientific tie and one aspect are differences in the neuronal oscillatory pattern, especially in auditory cortical areas. As studies in this field come to different results, the aim of this study was to analyze a large number of participants to achieve more stable results. Furthermore, we expanded our analysis to two variables of potential influence, namely being a novice to neuroscientific measurements and the exclusion of psychological comorbidities. Oscillatory brain activity of 88 subjects (46 with a chronic tinnitus percept, 42 without) measured in resting state by MEG was investigated. In the analysis based on the whole group, in sensor space increased activity in the delta frequency band was found in tinnitus patients. Analyzing the subgroup of novices, a significant difference in the theta band emerged additionally to the delta band difference (sensor space). Localizing the origin of the activity, we found a difference in theta and gamma band for the auditory regions for the whole group and the same significant difference in the subgroup of novices. However, no differences in oscillatory activity were observed between tinnitus and control groups once subjects with mental health comorbidity were excluded. Against the background of previous studies, the study at hand underlines the fragility of the results in the field of neuronal cortical oscillations in tinnitus. It supports the body of research arguing for low frequency oscillations and gamma band activity as markers associated with tinnitus.

Effect of distress on transient network dynamics and topological equilibrium in phantom sound perception

Distress is a domain-general behavioral symptom whose neural correlates have been under investigation for a long time now. Although some studies suggest that distress is encoded by changes in alpha activity and functional connectivity between specific brain regions, no study that we know has delved into the whole brain temporal dynamics of the distress component. In the current study, we compare the changes in the mean and variance of functional connectivity and small-worldness parameter over 3 min of resting state EEG to analyze the fluctuation in transient stable states, and network structure. On comparing these measures between healthy controls and patients experiencing low and high levels of distress due to a continuous ringing in the ear (tinnitus), we observe an increase in fluctuation between transient stable states characterized by an increase in both variance of functional connectivity and the small-worldness parameter. This results in a possible increase in degrees of freedom leading to a paradoxical equilibrium of the network structure in highly distressed patients. This may also be interpreted as a maladaptive compensation to look for information in order to reduce the hyper-salience in highly distressed individuals. In addition, this is correlated with the amount of distress only in the high distress tinnitus group, suggesting a catastrophic breakdown of the brain's resilience. Distress not only accompanies tinnitus, but other disorders such as somatic disorders, fibromyalgia, post-traumatic stress disorder, etc. Since the current study focuses on a disorder-general distress symptom, the methods and results of the current study have a wide application in different neuropathologies.

Reduced sound-evoked and resting-state BOLD fMRI connectivity in tinnitus.

The exact neurophysiological basis of chronic tinnitus, which affects 10-15% of the population, remains unknown and is controversial at many levels. It is an open question whether phantom sound perception results from increased central neural gain or not, a crucial question for any future therapeutic intervention strategies for tinnitus.We performed a comprehensive study of mild hearing-impaired participants with and without tinnitus, excluding participants with co-occurrences of hyperacusis. A right-hemisphere correlation between tinnitus loudness and auditory perceptual difficulty was observed in the tinnitus group, independent of differences in hearing thresholds. This correlation was linked to reduced and delayed sound-induced suprathreshold auditory brain responses (ABR wave V) in the tinnitus group, suggesting subsided rather than exaggerated central neural responsiveness. When anatomically predefined auditory regions of interest were analysed for altered sound-evoked BOLD fMRI activity, it became evident that subcortical and cortical auditory regions and regions involved in sound detection (posterior insula, hippocampus), responded with reduced BOLD activity in the tinnitus group, emphasizing reduced, rather than increased, central neural gain. Regarding previous findings of evoked BOLD activity being linked to positive connectivities at rest, we additionally analysed r-fcMRI responses in anatomically predefined auditory regions and regions associated with sound detection. A profound reduction in positive interhemispheric connections of homologous auditory brain regions and a decline in the positive connectivities between lower auditory brainstem regions and regions involved in sound detection (hippocampus, posterior insula) were observed in the tinnitus group. The finding went hand-in-hand with the emotional (amygdala, anterior insula) and temporofrontal/stress-regulating regions (prefrontal cortex, inferior frontal gyrus) that were no longer positively connected with auditory cortex regions in the tinnitus group but were instead positively connected to lower-level auditory brainstem regions. Delayed sound processing, reduced sound-evoked BOLD fMRI activity and altered r-fcMRI in the auditory midbrain correlated in the tinnitus group and showed right hemisphere dominance as did tinnitus loudness and perceptual difficulty. The findings suggest that reduced central neural gain in the auditory stream may lead to phantom perception through a failure to energize attentional/stress-regulating networks for contextualization of auditory-specific information. Reduced auditory-specific information flow in tinnitus has until now escaped detection in humans, as low-level auditory brain regions were previously omitted from neuroimaging studies.Trial registration: German Clinical Trials Register DRKS0006332.

Effects of Spirulina on GABA Receptor Gene Expression in Salicylate-Induced Tinnitus.

The function of γ-amino butyric acid receptor (GR) was related with tinnitus. But, the effects of Spirulina platensis water extract (SP) on the mRNA expression of GRAβ3 in mice with tinnitus were still unclear. Eighteen SAMP8 mice were divided into the control group (intraperitoneal injection of saline, once per day), the tinnitus group (intraperitoneal injection of salicylate, 300 mg/kg body weight once per day), and the spirulina group [intraperitoneal injection of salicylate, 300 mg/kg body weight and oral SP supplementation (1000 mg/kg body weight) once per day]. Effects of SP on the mRNA expression of GRAβ3 in the cochlea and brain of mice were studied for 4 days. Compared to the control group, the tinnitus group had significantly higher tinnitus scores and lower mRNA expression of GRAβ3 gene in the cochlear, brainstem, hippocampus and parahippocampus, temporal lobes, and the frontal lobes. On the other hand, the spirulina group had significantly lower tinnitus scores and higher GRAβ3 gene expression than the tinnitus group in all tested areas. SP could reduce salicylate-induced tinnitus possibly via increasing the salicylate-induced down-regulation of GRAβ3 gene expression.

Auditory Related Resting State fMRI Functional Connectivity in Tinnitus Patients: Tinnitus Diagnosis Performance.

The purpose of the present study was to investigate functional connectivity in tinnitus patients with and without hearing loss, and design the tinnitus diagnosis performance by resting state functional magnetic resonance imaging (rs-fMRI). Nineteen volunteers with normal hearing without tinnitus, 18 tinnitus patients with hearing loss, and 11 tinnitus patients without hearing loss were enrolled in this study. The subjects were evaluated with rs-fMRI, and region of interests (ROIs) based correlation analyses were performed using the CONN toolbox version 16 and SPM version 8. The correlation coefficients from individual level results were converted into beta values. With a beta threshold of more than 0.2, 91% of all possible connections between auditory-related ROIs (Heschl's gyrus, planum temporale, planum polare, operculum, insular cortex, superior temporal gyrus) in the control group remained intact, whereas 83 and 66% of such connections were present in the hearing loss and the normal-hearing tinnitus group. However, between non-auditory-related ROIs, the rates of intact connections at a beta threshold of more than 0.2 were 17% in the control group, and 16 and 15% in the tinnitus groups. When resting state fMRI positive is defined as less than 9% of all possible connections between auditory-related ROIs with a beta threshold of more than 0.7, the sensitivity and specificity of tinnitus diagnosis is 86 and 74%, respectively. The associations between auditory-related networks are weakened in tinnitus patients, even if they have normal hearing. It is possible that rs-fMRI can be a tool for objective examination of tinnitus, by focusing the auditory-related areas.

The Impact of Tinnitus on N-Back Performance in Normal Hearing Individuals.

Tinnitus sufferers commonly report concentration difficulties. Despite several previous studies investigating this, the underlying cause and the role of hearing status remains unclear. To investigate whether there are any differences between normal hearing individuals with and without tinnitus in terms of working memory capacity, and whether working memory capacity correlates with high-frequency hearing thresholds. Participants had their hearing thresholds measured (0.125-16 kHz) and performed a visual n-back test. All participants completed the Hospital Anxiety and Depression Scale, in addition tinnitus participants filled out the Tinnitus Questionnaire. Sixty-two individuals participated, 31 had tinnitus (tinnitus group) and 31 did not have tinnitus (control group). Groups were age- and sex matched, and all participants had normal hearing thresholds (20 dB HL or better at 0.125-8 kHz). Friedman test of differences among repeated measures was conducted on the collected data of n-back performance, and Mann-Whitney U-test was used to compare groups. Age-corrected correlations were calculated for high-frequency hearing and each n-back condition. We found no significant differences between the groups in terms of n-back task performances, except for the 2-back condition where the tinnitus group performed significantly better than the controls (p = 0.007). Furthermore, we found high-frequency hearing thresholds of the best ear (10-16 kHz) to correlate with performances at more demanding n-back conditions (p = 0.029 for 1-back and p = 0.015 for 2-back). This suggests that presence of tinnitus might not imply poorer working memory capacity and that deteriorated high-frequency hearing thresholds.

An evaluation of magnetic resonance imaging with histogram analysis in patients with idiopathic subjective tinnitus.

OBJECTIVE:Tinnitus is defined as the perception of sound in the ears without any acoustic stimulus. It has still not been determined whether tinnitus originates peripherally, centrally, or from several locations. The aim of the study was to determine any possible cochlear pathology in patients with normal hearing and tinnitus of unspecified etiology.METHODS:The study included 22 patients who presented at the clinic with the complaint of idiopathic subjective tinnitus that had been ongoing for at least 1 year. A total of 44 ears were included; 28 with tinnitus and 16 healthy ears. Unilateral tinnitus was determined in 16 patients and bilateral in six patients. The temporal magnetic resonance imaging (MRI) and audiogram results of the patients were retrieved from the hospital records. The MRI histogram measurement was made automatically and calculated for each ear separately.RESULTS:Entropy was found to be significantly higher in the control group and distribution was lower (p>0.01). In the tinnitus group, distribution was found to be broader, and kurtosis was statistically significantly greater (p<0.001).CONCLUSION:MRI histogram analysis can be considered as a method to be used in the clinical evaluation of the determination of possible cochlear pathology in ears with tinnitus.