Earplug-Induced Changes in Acoustic Reflex Thresholds Suggest that Increased Subcortical Neural Gain May Be Necessary but Not Sufficient for the Occurrence of Tinnitus

Publication date: Available online 16 March 2019Source: NeuroscienceAuthor(s): Hannah Brotherton, Charlotte Turtle, Christopher J. Plack, Kevin J. Munro, Roland SchaetteAbstractThe occurrence of tinnitus is associated with hearing loss and neuroplastic changes in the brain, but disentangling correlation and causation has remained difficult in both human and animal studies. Here we use earplugs to cause a period of monaural deprivation to induce a temporary, fully reversible tinnitus sensation, to test whether differences in subcortical changes in neural response gain, as reflected through changes in acoustic reflex thresholds (ARTs), could explain the occurrence of tinnitus.Forty-four subjects with normal hearing wore an earplug in one ear for either 4 (n = 27) or 7 days (n = 17). Thirty subjects reported tinnitus at the end of the deprivation period. ARTs were measured before the earplug period and immediately after taking the earplug out. At the end of the earplug period, ARTs in the plugged ear were decreased by 5.9 ± 1.1 dB in the tinnitus-positive group, and by 6.3 ± 1.1 dB in the tinnitus-negative group. In the control ear, ARTs were increased by 1.3 ± 0.8 dB in the tinnitus-positive group, and by 1.6 ± 2.0 dB in the tinnitus-negative group. There were no significant differences between the groups with 4 and 7 days of auditory deprivation.Our results suggest that either the subcortical neurophysiological ch...
Source: Neuroscience - Category: Neuroscience Source Type: research

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This article belongs to the special issue on SI: Tinnitus Hyperacusis
Source: Neuroscience - Category: Neuroscience Source Type: research
Publication date: Available online 8 March 2019Source: NeuroscienceAuthor(s): Hari M. Bharadwaj, Alexandra R. Mai, Jennifer M. Simpson, Inyong Choi, Michael G. Heinz, Barbara G. Shinn-CunninghamAbstractStudies in multiple species, including in post-mortem human tissue, have shown that normal aging and/or acoustic overexposure can lead to a significant loss of afferent synapses innervating the cochlea. Hypothetically, this cochlear synaptopathy can lead to perceptual deficits in challenging environments and can contribute to central neural effects such as tinnitus. However, because cochlear synaptopathy can occur without an...
Source: Neuroscience - Category: Neuroscience Source Type: research
Publication date: Available online 21 December 2018Source: NeuroscienceAuthor(s): Hannah Guest, Kevin J. Munro, Christopher J. PlackAbstractThe acoustic middle-ear-muscle reflex (MEMR) has been suggested as a sensitive non-invasive measure of cochlear synaptopathy, the loss of synapses between inner hair cells and auditory nerve fibers. In the present study, clinical MEMR thresholds were measured for 1-, 2-, and 4-kHz tonal elicitors, using a procedure shown to produce thresholds with excellent reliability. MEMR thresholds of 19 participants with tinnitus and normal audiograms were compared to those of 19 age- and sex-matc...
Source: Neuroscience - Category: Neuroscience Source Type: research
Conclusion: The MRI results with SWI were related to neurotological findings in patients suffering from sensorineural deafness with ataxia due to SS. Our findings support the integration of the SWI and 3D-CISS sequences into the MRI protocol for all patients referred for evaluation of the extent of SS.
Source: Otology and Neurotology - Category: ENT & OMF Tags: SENSORINEURAL HEARING LOSS AND TINNITUS Source Type: research
Conclusions: Patients with FMS have high levels of oxidative stress markers (GPx, NO, and MDA), highly frequent audiological symptoms with high hearing frequencies in audiometry, independent of disease severity.
Source: Nigerian Journal of Clinical Practice - Category: Rural Health Authors: Source Type: research
We describe a case of intravestibular ILS in which we included the ocular vestibular evoked myogenic potentials (oVEMPs) test in the diagnostic workup. The oVEMPs test is a relatively new neurophysiologic diagnostic modality that evaluates the superior vestibular pathway and the ascending contralateral pathway through the vestibulo-ocular reflex. In our case, a 65-year-old man presented with progressive right-sided sensorineural hearing loss, dizziness, and tinnitus and fullness in his right ear. Audiovestibular examination and MRI detected an intravestibular ILS on the right. We found that oVEMPs were absent on the contra...
Source: Ear, Nose and Throat Journal - Category: ENT & OMF Authors: Tags: Ear Nose Throat J Source Type: research
AbstractThe aim of this study was to investigate the possible role of cochlear outer hair cell function with TEOAE and DPOAE tests in patients with normal hearing and tinnitus. 25 tinnitus patients with normal hearing sensitivity selected as study group. Control group consist of 50 normal hearing subjects without tinnitus. All subjects had thresholds below 25 dBHL at frequencies 250 –8,000 Hz, tympanogram type A and normal acoustic reflex thresholds. TEOAE were recorded with click stimulus at 80 dB SPL at 1,000, 2,000, 3,000 and 4000 Hz. DPOAE were measured at frequencies 1,000–8,000 Hz and inten...
Source: Indian Journal of Otolaryngology and Head and Neck Surgery - Category: ENT & OMF Source Type: research
At the University of Michigan, scientists have developed a non-invasive technology to treat tinnitus, in most sufferers, by training the brain to “desynchronize” and to begin responding properly to real sounds. Their approach involves sti...
Source: Medgadget - Category: Medical Devices Authors: Tags: ENT Neurology Source Type: blogs
Abstract Animal models of tinnitus are essential for determining the underlying mechanisms and testing pharmacotherapies. However, there is doubt over the validity of current behavioural methods for detecting tinnitus. Here, we applied a stimulus paradigm widely used in a behavioural test (gap-induced inhibition of the acoustic startle reflex GPIAS) while recording from the auditory cortex, and showed neural response changes that mirror those found in the behavioural tests. We implanted guinea pigs (GPs) with electrocorticographic (ECoG) arrays and recorded baseline auditory cortical responses to a startling stimu...
Source: Brain Research - Category: Neurology Authors: Tags: Brain Res Source Type: research
We report a severe adverse event occurring in the course of a cohort study (ISRCTN13784335) aimed at measuring the efficacy and safety of venous stenting in the treatment of patients with medically refractory idiopathic intracranial hypertension (IIH). The patient was a 41-year-old woman who was not overweight, who presented with severe headache, grade 1 bilateral papilledema and transient tinnitus, refractory to medical treatment. Right transverse sinus stenting was successfully performed. Following surgery, the patient's state of consciousness decreased acutely with rapid and progressive loss of brainstem reflex. CT scan...
Source: Interventional Neuroradiology - Category: Radiology Tags: Interv Neuroradiol Source Type: research
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