An electrophysiological approach to tinnitus interpretation

Auris Nasus Larynx, 2011

Objectives: Tinnitus can be accompanied by depression, anxiety, insomnia, problems with auditory perception and poor general and mental health. This work was designed to evaluate the cognitive and psychological status in tinnitus patients using different subjective and objective measures. Methods: This work included 40 patients complaining of tinnitus without any vestibular complaints. Those patients were compared with 40 healthy age and sex matched controls. All subjects were evaluated through: basic audiologic evaluation, electrophysiological test (P300), oculomotor tests (smooth-pursuit, optokinetic, gaze and saccadic eye movements) and psychological evaluation (Hamilton depression and anxiety scales, Mini Mental Status Examination and Trail making tests). Results: Patients with tinnitus showed abnormalities at both electrophysiological and psychological levels when compared with normal subjects. Conclusion: This study provides evidences that different pathological mechanisms are involved in tinnitus generation which are more extensive than we thought.

Although a peripheral auditory (bottom-up) deficit is an essential prerequisite for the generation of tinnitus, central cognitive (top-down) impairment has also been shown to be an inherent neuropatho-logical mechanism. Using an auditory oddball paradigm (for top-down analyses) and a passive listening paradigm (for bottom-up analyses) while recording electroencephalograms (EEGs), we investigated whether top-down or bottom-up components were more critical in the neuropathology of tinnitus, independent of peripheral hearing loss. We observed significantly reduced P300 amplitudes (reflecting fundamental cognitive processes such as attention) and evoked theta power (reflecting top-down regulation in memory systems) for target stimuli at the tinnitus frequency of patients with tinnitus but without hearing loss. The contingent negative variation (reflecting top-down expectation of a subsequent event prior to stimulation) and N100 (reflecting auditory bottom-up selective attention) were different between the healthy and patient groups. Interestingly, when tinnitus patients were divided into two subgroups based on their P300 amplitudes, their P170 and N200 components, and annoyance and distress indices to their tinnitus sound were different. EEG theta-band power and its Granger causal neurodynamic results consistently support a double dissociation of these two groups in both top-down and bottom-up tasks. Directed cortical connectivity corroborates that the tinnitus network involves the anterior cingulate and the parahippocampal areas, where higher-order top-down control is generated. Together, our observations provide neurophysiological and neurodynamic evidence revealing a differential engagement of top-down impairment along with deficits in bottom-up processing in patients with tinnitus but without hearing loss.

International Journal of Otorhinolaryngology and Head and Neck Surgery

Background: Aiming to evaluate the recent theoretical postulates on tinnitus underscoring the role of thalamocortical neural tracts, the present study: explores middle latency response (MLR) as a possible physiological measure of tinnitus: thus investigates the predicted exaggeration of Pa-Na, Na-Pb interpeak amplitudes in tinnitus patients and; explores middle latency response (MLR) as a prognostic indicator of tinnitus retraining therapy (TRT), thus evaluates possible decrease in Pa-Na and Na-Pb amplitude after 2 weeks exposure to tinnitus retraining therapy.Methods: An experimental group was constructed by randomly assigning 30 patients with mean age 38.5 years and complaining of debilitating tinnitus but with normal hearing for the study. MLR was administered on patients with normal auditory brainstem response (ABR) and otoacoustic emission (OAE) both pre- and post-tinnitus retraining therapy. Results: Results demonstrated no significant effect on Pa, Na and Nb absolute and int...

Introduction: Tinnitus is a disturbing symptom and is often the main reason for otology referral. It is usually associated with hearing loss of varying aetiology, and is thought to begin in the cochlea, with later abnormal central activity. We hypothesise that tinnitus without hearing loss may be caused by central and subcortical abnormalities and altered outer hair cell function. Aim: To compare the auditory brainstem responses, middle latency responses and otoacoustic emissions in normal-hearing individuals with and without tinnitus. Methodology: The audiological test results of 25 normal hearing subjects with tinnitus (age 18–45 years) were determined, and compared with those of a control group. Results: A statistically significant difference was found between study group tinnitus ears vs control group ears, as regards wave I latency prolongation, shortening of wave V and absolute I–III and I–V interpeak latency, enlargement of wave Na and Pa amplitude, and distortion product and transient evoked otoacoustic emission signal-to-noise ratios. There was no statistically significant difference between unilateral vs bilateral tinnitus ears. Conclusion: The pathogenesis and optimum management of tinnitus are still unclear. It often occurs with primary ear disease, usually associated with hearing loss, but may occur in patients with normal hearing. Observed changes in auditory brainstem and middle latency responses indicate central auditory alterations. Tinnitus involves both peripheral and central activity, and complete audiological and neurophysiological investigation is required. Management should be based on both audiological and neurophysiological findings.

BMC ear, nose, and throat disorders, 2017

To date, a large number of acoustic therapies have been applied to treat tinnitus. The effect that produces those auditory stimuli is, however, not well understood yet. Furthermore, the conventional clinical protocol is based on a trial-error procedure, and there is not a formal and adequate treatment follow-up. At present, the only way to evaluate acoustic therapies is by means of subjective methods such as analog visual scale and ad-hoc questionnaires. This protocol seeks to establish an objective methodology to treat tinnitus with acoustic therapies based on electroencephalographic (EEG) activity evaluation. On the hypothesis that acoustic therapies should produce perceptual and cognitive changes at a cortical level, it is proposed to examine neural electrical activity of patients suffering from refractory and chronic tinnitus in four different stages: at the beginning of the experiment, at one week of treatment, at five weeks of treatment, and at eight weeks of treatment. Four o...

Neural Regeneration Research, 2015

Frontiers in Aging Neuroscience

The auditory brainstem response (ABR) in tinnitus subjects has been extensively investigated over the last decade with the hopes of finding possible abnormalities related to the pathology. Despite this effort, the use of the ABR for tinnitus diagnosis or as an outcome measure is under debate. The present study reviewed published literature on ABR and tinnitus. The authors searched PubMed, MedLine, Embase, PsycINFO, and CINAHL, and identified additional records through manually searching reference lists and gray literature. There were 4,566 articles identified through database searching and 151 additional studies through the manual search (4,717 total): 2,128 articles were removed as duplicates, and 2,567 records did not meet eligibility criteria. From the final 22 articles that were included, ABR results from 1,240 tinnitus subjects and 664 control subjects were compiled and summarized with a focus on three main areas: the participant characteristics, the methodology used, and the outcome measures of amplitude and/or latency of waves I, III, and V. The results indicate a high level of heterogeneity between the studies for all the assessed areas. Amplitude and latency differences between tinnitus and controls were not consistent between studies. Nevertheless, the longer latency and reduced amplitude of wave I for the tinnitus group with normal hearing compared to matched controls was the most consistent finding across studies. These results support the need for greater stratification of the tinnitus population and the importance of a standardized ABR method to make comparisons between studies possible.

The international tinnitus journal, 2009

Quantitative electroencephalography (QEEG) is the technique whereby brain electrical activity in individuals is recorded as they sit quietly with their eyes closed. The electrical activity is quantified with a variety of statistical measures to characterize the huge variation in combinations of emissions from the brain. Neuroscience research has demonstrated that such resting brain activity measures may be consistently altered in conditions such as depression or dementia. A wide variety of ongoing efforts are attempting to find characterizations that reliably denote other neurological conditions. In research on tinnitus, a variety of groups have been working to characterize QEEG changes related to the presence of the abnormal sensation of sound and to the emotional distress associated with it. QEEG changes related to the tinnitus percept are in the gamma electroencephalography (EEG) band recorded from temporal lobes. Clinical depression has a reliable marker in the depression of pos...

Neuroreport, 2002

Increased spontaneous activity and aberrant neural synchrony is thought to be the underlying cause of tinnitus. The perceived pitch of tinnitus may be dictated by frequency specific neural fibers of the subcortical pathway, or the projection of altered cortical activity by-way-of tonotopic reorganizations. Subcortical neural activity in relation to tinnitus was characterized using ABR measurements. In the present study, 11 patients (21 ears) with constant tonal tinnitus underwent a two-part experiment. Experiment 1 involved click ABR measurements and included two experimental groups: tinnitus with normal hearing from 2000-4000 Hz (GI) and tinnitus with hearing loss within the range of 2000-4000 Hz (GII). Experiment 2 utilized tone burst ABRs matched to each participant's perceived tinnitus pitch and included two experimental groups: tinnitus with normal hearing at the tinnitus pitch (GIa) and tinnitus with hearing loss at the tinnitus pitch (GIIa). These groups were compared to a control group (GIII) of ten monaurally tested (10 ears) participants with normal hearing thresholds at 250-20000 Hz and no tinnitus. Click ABR results indicate significantly prolonged V-III IPLs for GI and GII and a significantly extended absolute V latency for GII only. Tone burst ABRs matched to tinnitus pitch revealed significantly prolonged absolute latencies and IPLs at three of the seven frequencies for GIIa. ABR threshold seeking was completed and revealed negative eHL values for two of the four different stimuli for GI and GIa and four of the eight stimuli for GII and GIIa. Click ABRs results are suggestive of upper brainstem abnormalities for both groups. While GI demonstrated prolonged V-III IPLs, no significant differences were found for GIa. This suggests that there is no frequency specific subcortical characteristic associated with tinnitus with normal hearing. Frequency specific properties for subcortical activity could not be characterized due to varying results of GIIa.