Contralateral suppression of otoacoustic emissions in a clinical sample of children with auditory processing disorder.

OBJECTIVE: The suppression of evoked otoacoustic emissions (EOAE) may serve as a clinical tool to evaluate the medial olivocochlear (MOC) reflex, which is thought to aid speech discrimination (particularly in noise) by selectively inhibiting cochlear amplification. The present study aimed to determine if contralateral transient evoked otoacoustic emission (TEOAE) suppression was present in a clinical sample of children with listening difficulties with and without auditory processing disorder (APD). DESIGN: A three-group, repeated measure design was used. STUDY SAMPLE: Forty three children aged 8-14 years underwent an auditory processing assessment and were divided into three groups: children with reported listening difficulties with APD, children with reported listening difficulties without APD, and children with normal hearing. APD was defined as per British Society of Audiology. RESULTS: TEOAE suppression was present in all three participant groups. No significant group, age or ear effects were observed for TEOAE suppression in dB or as a normalised index. CONCLUSION: Contralateral TEOAE suppression method could not be used as a clinical tool to identify APD in this study's participating children and did not support the hypothesised link between reduced MOC function and general listening difficulties in background noise in children with or without APD.

[The clinical manifestations and neurophysiological features of long-lasting paroxysmal vertigo:theanalysis of the original observations].

The objective of the present study was to elucidate specific features of etiology and pathophysiology of recurring chronic vestibular dysfunction. It included 90 patients with this pathology of whom 24 (26.6%) presented with vascular compression of the vestibulocochlear nerve diagnosed by means of high-field MRI. This method revealed the high frequency of positionally-dependent vestibular dysfunction associated with neurovascular interactions. Analysis of the state of vestibular dysfunction during the attack-free periods demonstrated the signs of latent vestibular dysfunction in 20 (83.3%) patients. The results of the study provide additional information on the prevalence of vascular compression of the vestibulocochlear nerve in the patients presenting with recurrent chronic dizziness; moreover, they make it possible to evaluate the state of vestibular function and develop the new diagnostic criteria for vestibular paroxismia.

Vestibular involvement in peripheral neuropathy: a review.

OBJECTIVE: This paper reviews the current literature on involvement of the vestibular division of the eighth cranial nerve in peripheral neuropathies. The literature abounds with references to auditory neuropathy, which is frequently related to more generalized neuropathies, but there is a marked paucity of work regarding vestibular neuropathy. A brief overview of neuropathies and the anatomy of the vestibulocochlear nerve provide the background for a review of the literature of vestibular nerve involvement in a range of neuropathies. DESIGN: A literature search including textbooks, and peer-reviewed published journal articles in online bibliographic databases was conducted. STUDY SAMPLE: Two databases for medical research were included in this review. RESULTS: The review of the literature indicates that vestibular involvement is a common and consistent finding in many peripheral neuropathies of different aetiologies. Specifically, if patients present unsteadiness/ataxia out of proportion to objective signs of somatosensory loss or muscle weakness. CONCLUSION: This review concludes that vestibular neuropathy, is common in peripheral neuropathy and should be identified to optimize patient management and rehabilitation.

Tumors of the nervous system and hearing loss: Beyond vestibular schwannomas.

Hearing loss is a common side effect of many tumor treatments. However, hearing loss can also occur as a direct result of certain tumors of the nervous system, the most common of which are the vestibular schwannomas (VS). These tumors arise from Schwann cells of the vestibulocochlear nerve and their main cause is the loss of function of NF2, with 95 % of cases being sporadic and 5 % being part of the rare neurofibromatosis type 2 (NF2)-related Schwannomatosis. Genetic variations in NF2 do not fully explain the clinical heterogeneity of VS, and interactions between Schwann cells and their microenvironment appear to be critical for tumor development. Preclinical in vitro and in vivo models of VS are needed to develop prognostic biomarkers and targeted therapies. In addition to VS, other tumors can affect hearing. Meningiomas and other masses in the cerebellopontine angle can compress the vestibulocochlear nerve due to their anatomic proximity. Gliomas can disrupt several neurological functions, including hearing; in fact, glioblastoma multiforme, the most aggressive subtype, may exhibit early symptoms of auditory alterations. Besides, treatments for high-grade tumors, including chemotherapy or radiotherapy, as well as incomplete resections, can induce long-term auditory dysfunction. Because hearing loss can have an irreversible and dramatic impact on quality of life, it should be considered in the clinical management plan of patients with tumors, and monitored throughout the course of the disease.

Analysis of interpeak latencies of brainstem auditory evoked potential waveforms during microvascular decompression of cranial nerve VII for hemifacial spasm.

OBJECT: Microvascular decompression (MVD) of the facial nerve is an effective treatment for patients with hemifacial spasm. Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) during MVD can reduce the incidence of hearing loss. In this study the authors' goal was to evaluate changes in interpeak latencies (IPLs) of Waves I-V, Waves III-V, and Waves I-III of BAEP Waveforms I, III, and V during MVD and correlate them with postoperative hearing loss. To date, no such study has been performed. Hearing loss is defined as nonuseful hearing (Class C/D), which is a pure tone average of more than 50 dB and/or speech discrimination score of less than 50%. METHODS: The authors performed a retrospective analysis of IPLs of BAEPs in 93 patients who underwent intraoperative BAEP monitoring during MVD. Patients who did not have hearing loss were in Class A/B and those who had hearing loss were in Class C/D. RESULTS: Binary logistic regression analysis of independent IPL variables was performed. A maximum change in IPLs of Waves I-III and Waves I-V and on-skin change in IPLs of Waves I-V increases the odds of hearing loss. However, on adjusting the same variables for loss of response, change in IPLs did not increase the odds of hearing loss. CONCLUSIONS: Changes in IPL measurements did not increase the odds of postoperative hearing loss. This information might be helpful in evaluating the value of IPLs as alarm criteria during MVD to prevent hearing loss.

Assessment of vestibulocochlear organ function in patients meeting radiologic criteria of vascular compression syndrome of vestibulocochlear nerve--diagnosis of disabling positional vertigo.

BACKGROUND: This study sought to assess the vestibulo-cochlear organ in patients meeting radiologic criteria of vascular compression syndrome (VCS) of the eighth cranial nerve. MATERIAL/METHODS: The authors performed a retrospective analysis of 34 patients (18 women, 16 men; mean age, 49 years) treated in between 2000 and 2007, with VCS of the eighth cranial nerve by MRI. Contrasted magnetic resonance imaging identified an anterior inferior cerebellar artery vascular loop adhering to the vestibule-cochlear nerve in all 34 cases. All patients were given pure tone audiometry, distortion product otoacoustic emissions, auditory brainstem response, and electroneurographic examinations. RESULTS: Most-common symptoms were unilateral hearing loss (82%), unilateral tinnitus (80%), and dizziness (74%). Most-frequent abnormalities in performed examinations were specific auditory brainstem response changes (interpreted according to Möller's criteria) in 86% of cases and sensorineural hearing loss in pure tone audiometry (82%). Abnormal changes in electronystagmography were found in the absence (12%) or weakness (35%) of a caloric response. No patients were surgically treated. CONCLUSIONS: Significantly, there is no more weakness or absence of the caloric response of a vestibular organ in a patient with vascular compression of the vestibulo-cochlear nerve. Despite an absence of electrophysiologic testing of vestibular organ dysfunction, most examined patients (meeting the radiologic criteria of VCS of the eighth cranial nerve) had subjective symptoms like vertigo and dizziness. Disabling positional vertigo should be considered in the differential diagnosis of vertigo when accompanied by tinnitus or deafness.

[Cochlear-vestibular disorders in the patients presenting with chronic purulent otitis media].

The author presents statistical information concerning the prevalence of chronic purulent otitis media. Characteristics of typical complaints are described with special reference to cochlear-vestibular disorders in patients presenting with epitympanitis. The results of detailed analysis of the causes of cochlear-vestibular disorders in the patients with chronic purulent otitis media during the preoperative and postoperatve periods are reported.

Acoustic Reflexes in Aural Atresia Patients: Evidence of an Intact Efferent System?

OBJECTIVE: To record crossed acoustic reflex thresholds (xART's) postoperatively from patients after surgical repair of unilateral congenital aural atresia (CAA). To seek explanations for when xARTs can and cannot be recorded. We hope to understand the implications for this central auditory reflex despite early afferent deprivation. METHODS: Patients who underwent surgery to correct unilateral CAA at a tertiary academic medical were prospectively enrolled to evaluate for the presence of xART. Preoperative ARTs in the normal (non-atretic) ear, and postoperative ipsilateral ARTs (stimulus in the normal ear) and contralateral ARTs (stimulus in the newly reconstructed atretic ear; record in the normal ear) were measured at 500, 1000, and 2000 Hz. RESULTS: Four of 11 patients with normal ipsilateral reflex thresholds preoperatively demonstrated crossed acoustic reflexes postoperatively (stimulus in reconstructed ear; record from normal ear). Four other patients demonstrated normal ipsilateral thresholds preoperatively but did not have crossed reflexes postoperatively. No reflexes (pre- or postoperatively) could be recorded in 3 patients. Crossed reflex threshold is significantly correlated with the postoperative audiometric threshold. There was no correlation between ipsilateral and contralateral reflex thresholds. CONCLUSION: Crossed acoustic reflexes can be recorded from some but not all postoperative atresia patients, and the thresholds for those reflexes correlate with the postoperative pure tone threshold. The presence of acoustic reflexes implies an intact CN VIII-to-opposite CN VII central reflex arc despite early unilateral sound deprivation.

Retro-labyrinthine Lesion Site Detected by Galvanic Vestibular Stimulation Elicited Vestibular-evoked Myogenic Potentials in Patients with Auditory Neuropathy.

OBJECTIVE: Auditory neuropathy (AN) is a unique pattern of hearing loss with preservation of hair cell function. The condition is characterized by the presence of otoacoustic emissions (OAE) or cochlear microphonic (CM) responses with severe abnormalities of the auditory brainstem response (ABR). The vestibular branches of the VIII cranial nerve and the structures innervated by it can also be affected. However, the precise lesion sites in the vestibular system are not well characterized in patients with AN. METHODS: The air-conducted sound (ACS) vestibular-evoked myogenic potentials (VEMPs) and galvanic vestibular stimuli (GVS)-VEMPs were examined in 14 patients with AN. RESULTS: On examination of VEMPs (n=14, 28 ears), the absent rates of ACS-cervical VEMP (cVEMP), ACS-ocular VEMP (oVEMP), GVS-cVEMP, GVS-oVEMP and caloric test were 92.9% (26/28), 85.7% (24/28), 67.9% (19/28), 53.6% (15/28), and 61.5% (8/13), respectively. Impaired functions of the saccule, inferior vestibular nerve, utricle, superior vestibular nerve, and horizontal semicircular canal were found in 25.0% (7/28), 67.9% (19/28), 32.1% (9/28), 53.6% (15/28) and 61.5% (8/13) patients, respectively. On comparing the elicited VEMPs parameters of AN patients with those of normal controls, both ACS-VEMPs and GVS-VEMPs showed abnormal results in AN patients (such as, lower presence rates, elevated thresholds, prolonged latencies, and decreased amplitudes). CONCLUSION: The study suggested that patients with AN often have concomitant vestibular disorders. Retro-labyrinthine lesions were more frequently observed in this study. GVS-VEMPs combined with ACS-VEMPs may help identify the lesion sites and facilitate detection of areas of vestibular dysfunction in these patients.

Cerebellopontine angle arachnoid cyst containing ectopic choroid plexus--case report.

We present a rare and interesting case of a cerebellopontine angle cyst containing ectopic choroid plexus tissue in a 26 year-old female. Surgical resection was performed, and histological examination confirmed the presence of choroid plexus in the cyst wall. This is the first reported case of ectopic choroid plexus at the cerebellopontine angle in an adult. We present the case and review the literature.

Patient-reported involvement of the eighth cranial nerve in giant cell arteritis.

INTRODUCTION: The frequency of eighth nerve lesions in patients with giant cell arteritis (GCA) has rarely been examined. However, sudden onset deafness has been recorded as a presenting feature of GCA on several occasions. This study sought to establish how common this and other symptoms of eighth nerve involvement are in a large retrospective survey. METHODS: We contacted 170 patients with GCA and 250 matched PMR patients, inviting them to participate in a questionnaire survey of symptoms of eighth nerve dysfunction. We compared the presence of deafness, tinnitus, loss of balance and vertigo in both groups and examined the relationship between the onset of these symptoms and other features of GCA. RESULTS: A total of 317 patients were recruited. The percentage of patients with symptoms of possible vestibulocochlear disease prior to commencement of steroid therapy was significantly greater among GCA patients than PMR patients for all domains. Hearing loss which was twice as common in GCA as in PMR (53% vs 26%) [p = 0.001]. Deafness was concurrent in 35% of GCA patients with other symptoms and 45% reported colocation with headache. Recovery with steroids occurred in 56% of these. CONCLUSION: Symptoms of eighth nerve dysfunction are present in over half of patients with GCA. Recovery with steroids was predicted by concurrence with headache in terms of both timing and location. It appears that eighth nerve involvement, especially acute hearing loss, is a not infrequent feature of GCA and often responds well to steroid therapy. Clinicians should enquire about these symptoms when evaluating a patient for possible GCA.Key Points• Deafness is a frequent presenting feature of giant cell arteritis.• Vertigo, tinnitus and loss of balance are also often reported by GCA sufferers.• Steroid therapy is more likely to relieve these symptoms if they are ipsilateral and concurrent with headache.

NLRP3 inflammasome activation in human vestibular schwannoma: Implications for tumor-induced hearing loss.

Vestibular schwannoma (VS) is the fourth most common intracranial tumor, arising from neoplastic Schwann cells of the vestibular nerve and often causing debilitating sensorineural hearing loss (SNHL) and tinnitus. Previous research suggests that the abnormal upregulation of inflammatory pathways plays a highly significant, though infrequently described role in VS pathobiology, and that VS-associated SNHL is due not only to mechanical compression of the auditory nerve but also to differences in the intrinsic biology of these tumors. We hypothesize that patients who present with poor hearing associated with VS experience a more robust inflammatory response to this tumor than VS patients who present with good hearing. To investigate this hypothesis, we conducted a comprehensive pathway analysis using gene expression data from the largest meta-analysis of vestibular schwannoma microarray data, comprising 80 tumors and 16 healthy peripheral nerves. We identified the NLRP3 inflammasome as a novel target worthy of further exploration in VS research and validated this finding at the gene and protein expression level in human VS tissue using qRT-PCR and immunohistochemistry. To date, NLRP3 inflammasome activation has not been reported in VS, and this finding may represent a new and potentially significant therapeutic avenue. Notably, after analysis of 30 VSs, we observe that overexpression of key components of the NLRP3 inflammasome is preferentially associated with tumors that produce increased hearing loss in VS patients. Therefore, therapeutic development for VS should include considerations for minimizing NLRP3-associated inflammation to best preserve hearing.

Auditory nerve is affected in one of two different point mutations of the neurofilament light gene.

OBJECTIVE: To define auditory nerve and cochlear functions in two families with autosomal dominant axonal Charcot-Marie-Tooth (CMT). METHODS: Affected members in two families with different point mutations of NF-L gene were screened with auditory brainstem responses (ABRs). Those with abnormal ABRs were further investigated with clinical, neurophysiological and audiological procedures. The point mutations of NF-L gene involved were Glu397Lys in 8 affected members of the family with AN, and Pro22Ser in 9 affected members of the family without AN. RESULTS: ABRs and stapedial muscle reflexes were absent or abnormal in affected members of only one family consistent with auditory neuropathy (AN). In them, audiograms, otoacoustic emissions, and speech comprehension were normal. Absent or abnormal ABRs were consistent with slowing of conduction along auditory nerve and/or brainstem auditory pathway. Wave I when present was of normal latency. CONCLUSIONS: Auditory nerve involvement in the presence of normal cochlear outer hair cell activity is asymptomatic in one of two families with CMT disorder with different point mutations of the NF-L gene. The nerve disorder is consistent with altered synchrony and slowed conduction. SIGNIFICANCE: The absence of "deafness" may reflect the ability of central mechanisms to compensate for the slowly developing auditory nerve abnormalities.

Remote tentorium meningioma causing sudden sensorineural deafness.

BACKGROUND: Sudden sensorineural deafness is a well-known symptom mostly of unknown etiology. CASE DESCRIPTION: A case of sudden sensorineural deafness is reported to be caused by a small, remote, ipsilateral tentorial meningioma not compressing the vestibulocochlear nerve or auditory tract. Surgical resection of the meningioma immediately restored the patient's hearing. CONCLUSION: The authors hypothesize that the sudden sensorineural deafness resulted from a growing meningioma inducing a neurovascular compression of the vestibulocochlear nerve, the vertebral artery already being in close relationship with the vestibulocochlear nerve in the premorbid phase. Resection of the meningioma allows for an autodecompression of this vascular conflict resulting in hearing restoration.

Objective findings with malpositioning of a nucleus 24RE(CA) cochlear implant.

BACKGROUND: Proper intracochlear placement of cochlear implant electrode arrays is believed to be important for optimum speech perception results. However, objective tests of cochlear implant function typically provide little or no information about the intracochlear placement of the array. We report the results for a variety of objective tests, including averaged electrode voltage (AEV) measurements, in a patient where the electrode array had folded up on itself during insertion. PURPOSE: To determine whether any of the objective measures provided evidence of incorrect electrode placement. RESEARCH DESIGN: Objective test data are reported for a patient with an incorrectly positioned electrode array, prior to and following reimplantation, and compared to data obtained in 42 patients with normal insertions. STUDY SAMPLE: One patient with an incorrectly placed electrode array, prior to and following reimplantation, and a sample of 42 implant recipients with correct insertions. INTERVENTION: The patient with the malpositioned electrode array was explanted and reimplanted. The results for the first and the second implant, with regards to objective test results, are compared. The results are also compared to the data obtained on 42 implant recipients with normal insertions. DATA COLLECTION AND ANALYSIS: The objective test data (primarily AEV data) are compared with AEV results obtained in 42 patients with normal electrode insertions. RESULTS AND CONCLUSIONS: Although the electrode array had folded up on itself during insertion, intraoperative electrode impedances and VIII nerve responses, as well as postoperative electrically evoked auditory brainstem responses, were within normal limits. However, averaged electrode voltages, obtained with the Nucleus Crystal Integrity Test system, were abnormal and consistent with a low-impedance pathway between the apical and middle portions of the electrode array.

The recordability of two sonomotor responses in young normal subjects.

BACKGROUND: It has been reported that up to 40% of patients over age 60 fail to generate a vestibular evoked myogenic potential (VEMP; Su et al, 2004). When this occurs it is difficult to determine whether the absent VEMP represents evidence of bilateral impairment of the vestibulocollic reflex pathway or a normal age-related variant (i.e., idiopathic absence). PURPOSE: The purpose of the present investigation was to determine whether both VEMPs and PAMs could be recorded reliably in a sample of neurologically and otologically intact young adults. If both could be obtained with high reliability in normal subjects, then the bilateral presence of PAM in the bilateral absence of VEMP, at least in younger patients, could be used to support the contention that the absent VEMP represented evidence of bilateral impairment. RESEARCH DESIGN: A descriptive study. STUDY SAMPLE: Attempts were made to record both the VEMP and a second sonomotor response, the postauricular muscle potential (PAM) from 20 young adults. RESULTS: Results showed both the VEMP and the PAM were present in 90% of the ears. Both the VEMP and PAM responses were bilaterally absent for one subject. Also, the VEMP and PAM were unilaterally absent for two subjects. Subjects who generated VEMPs also generated a PAM in at least one ear. CONCLUSIONS: The present investigation represents an initial step in the determination of whether the presence of PAMs in the absence of VEMPs can be used as a method of validating the presence of an impairment affecting the vestibulocollic reflex pathway.

A daily alternating method for comparing different signal-processing strategies in hearing aids and in cochlear implants.

BACKGROUND: Although we always want to select the best signal-processing strategy for our hearing-aid and cochlear-implant patients, no efficient and valid procedure is available. Comparisons in the office are without listening experience, and short-term take-home trials are likely influenced by the order of strategies tried. PURPOSE: The purpose of this study was to evaluate a new procedure for comparing signal-processing strategies whereby patients listen with one strategy one day and another strategy the next day. They continue this daily comparison for several weeks. We determined (1) if differences existed between strategies without prior listening experience and (2) if performance differences (or lack there of) obtained at the first listening experience are consistent with performance after two to three months of alternating between strategies on a daily basis (equal listening experience). RESEARCH DESIGN: Eight subjects were tested pretrial with a vowel, sentence, and spondee recognition test, a localization task, and a quality rating test. They were required to listen to one of two different signal processing strategies alternating between strategies on a daily basis. After one to three months of listening, subjects returned for follow-up testing. Additionally, subjects were asked to make daily ratings and comments in a diary. RESULTS: Pre-trial (no previous listening experience), a clear trend favoring one strategy was observed in four subjects. Four other subjects showed no clear advantage. Post-trial (after alternating daily between strategies), of the four subjects who showed a clear advantage for one signal processing strategy, only one subject showed that same advantage. One subject ended up with an advantage for the other strategy. Post-trial, of the four subjects who showed no advantage for a particular signal processing strategy, three did show an advantage for one strategy over the other. CONCLUSION: Patients are willing to alternate between signal processing strategies on a daily basis for up to three months in an attempt to determine their optimal strategy. Although some patients showed superior performance with initial fittings (and some did not), the results of pre-trial comparison did not always persist after having equal listening experience. We recommend this daily alternating listening technique when there is interest in determining optimal performance among different signal processing strategies when fitting hearing aids or cochlear implants.

[Regeneration of hair cells and auditory neurons in the ear]. / Régénération des cellules ciliées et des neurones auditifs de l'oreille.

Most of deafness have a neuro-sensory origin and are characterized by a loss of hair cells and auditory neurons in the spiral ganglion. At the moment, hearing aids are the only treatment available. To restore hearing in a patient suffering from deafness, it is necessary to study the mechanisms that might lead to the regeneration of neurosensory structures of the inner ear. HAIR CELL REGENERATION: The production of hair cells and supporting cells is terminated during embryonic development of the cochlea in mammals. However, several recent arguments suggest that new hair cells can be produced by the sensory epithelium of mammals. We first identified the presence of progenitor cells in the organ of Corti. In a second approach, the molecular mechanisms underlying the production of new hair cells have been studied. NEURONAL REGENERATION: The study of the development of the ear, cultures of neurons and analysis of animals invalidated for specific genes reveal that a number of growth factors are important for the maintenance and repair of neurons in the inner ear. These molecules induce the survival of auditory neurons in vitro and in vivo. The signaling pathways intra-cellular are analyzed with a better understanding of the mechanisms that lead to survival or death of neurons hearing and with the identification of new pharmacological agents that promote survival of neurons hearing in diseases of the inner ear. These molecules can be administered locally in the inner ear. IN CONCLUSION: Recent studies on the regeneration of neurosensory structures of the inner ear suggest that eventually it will be possible to replace the hair cells in the cochlea of mammals and to reinnervate them by auditory neurons in order to restore hearing in patients suffering from deafness.

Tinnitus in vascular conflict of the eighth cranial nerve: a surgical pathophysiological approach to ABR changes.

Some forms of tinnitus are associated with a blood vessel being in close contact with the auditory nerve near its entrance into the brainstem. The outcome of operations for tinnitus, moving the blood vessel off the nerve (microvascular decompression operations, MVD) is less successful than microvascular decompression operations for other vascular conflict syndromes (hemifacial spasm, HFS, and trigeminal neuralgia, TGN). No generally accepted criteria exist for the selection of candidates for MVD for tinnitus. A pathophysiological approach for interpreting auditory brainstem response (ABR) changes is proposed as a basis for selection of tinnitus patients for the MVD operation. We followed changes in the ABR and the tinnitus in 78 patients with unilateral tinnitus, who had indications of having vascular conflicts of the eighth nerve. In 18 of these patients a blood vessel was removed of the auditory nerve and in 9 of these a correlation could be made between preoperative and postoperative clinical changes and ABR changes. In this retrospective study we found abnormalities in the amplitude of peak II and the interpeak latency (IPL) I-III of the ABR that were related to the duration of their tinnitus and its intensity. While no ABR changes could be detected during the first 2 years, after that period a decrease of the amplitude of peak II occurred, and a prolongation the IPL of peak I-III occurred in patients whose peak II had disappeared. The rate of IPL I-III increase slows down after 10 years. IPL I-III prolongation correlates with ipsilateral hearing loss at tinnitus frequency and worsens in time. This correlates with a worsening of the tinnitus associated with the worsening of the IPL I-III. Tinnitus frequency correlates to the frequency of maximal hearing loss and the more the hearing loss at tinnitus frequency the worse the tinnitus. Postoperative improvement of tinnitus correlated with postoperative improvement of peak II and postoperative improvement of hearing loss at the tinnitus frequency correlated with postoperative IPL I-III improvement. It is concluded that interpreting ABRs from a pathophysiological point of view can be beneficial for surgeons performing MVDs for tinnitus, especially with regard to timing of the surgery and interpretation of symptom presentation.

Delayed vestibular evoked responses to the eyes and neck in a patient with an isolated brainstem lesion.

OBJECTIVE: Two recently described tests of the vestibular system, vestibular evoked myogenic potentials (VEMPs) and ocular vestibular evoked myogenic potentials (OVEMPs), test the descending and ascending vestibular brainstem pathways, respectively. We describe a case of a patient in whom these investigations localised the lesion and suggested its nature. METHODS: VEMPs (to clicks and short duration galvanic stimulation) and OVEMPs (to clicks) were recorded. RESULTS: Click- and galvanic-evoked VEMPs were delayed on the left side (by approximately 5-6 ms), and click-evoked OVEMPs were similarly delayed (by approximately 4 ms) following left-sided stimulation. Repeat testing 21 months later showed partial resolution. CONCLUSIONS: The observed delays in evoked potentials suggested a demyelinating lesion. Furthermore, the similarity in delayed responses to neck and extraocular muscles was suggestive of a lesion at the root entry zone of the vestibulocochlear nerve. SIGNIFICANCE: VEMPs and OVEMPS may thus provide information about the location and nature of lesions affecting central vestibular pathways.