Cellular Processes Induced by HSV-1 Infections in Vestibular Neuritis.

Herpesvirus is a prevalent pathogen that primarily infects human epithelial cells and has the ability to reside in neurons. In the field of otolaryngology, herpesvirus infection primarily leads to hearing loss and vestibular neuritis and is considered the primary hypothesis regarding the pathogenesis of vestibular neuritis. In this review, we provide a summary of the effects of the herpes virus on cellular processes in both host cells and immune cells, with a focus on HSV-1 as illustrative examples.

Preoperative vestibular evoked myogenic potentials (VEMPs), caloric test, and pure tone audiometry to identify the vestibular nerve branch of schwannoma origin: preliminary results in a series of 26 cases.

Vestibular schwannoma (VS) is a benign tumor which develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a preoperative testing protocol with high accuracy to determine the nerve branch of origin. The nerve of origin was predicted on the basis of preoperative vestibular evoked myogenic potentials (VEMPs), caloric stimulation test, and pure tone audiometry on 26 recipients. The acquired data were entered into a statistic scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. Receiver operating characteristic (ROC) curves analysis of preoperative testing data showed the possibility of predicting the branch of origin. In particular, ROC curve of combined VEMPs absence, nystagmus detectable at caloric stimulation, and PTA < 75 dB HL allowed to obtain high accuracy for inferior vestibular nerve implant of the tumor (area under the curve-AUC = 0.8788, p = 0.012). In 24 of 26 cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. Preoperative audiological and vestibular evaluation can predict the vestibular tumor branch of origin with high accuracy. Despite the necessity of larger prospective cohort studies, these findings may change preoperative approach, possible functional aspects, and counseling with the patients.

Radial spoiled gradient T1 weighted imaging of the internal auditory canal: Is Scarpa's ganglion now an expected finding and source of fundal enhancement?

StarVIBE is a 3D gradient-echo sequence with a radial, stack-of-stars acquisition having spatial resolution and tissue contrast. With newer sequences, it is important to be familiar with sequence tissue contrasts and appearance of anatomical variants. We evaluated 450 patients utilizing this sequence; 35 patients demonstrated fluffy "cotton wool" enhancement at the internal auditory canal fundus without clear pathology. We favor this represents anatomic neurovascular enhancement that StarVIBE is sensitive to and is a touch-me-not finding.

Sperm-associated antigen 6 (Spag6) mutation leads to vestibular dysfunction in mice.

Spag6 encodes an axoneme central apparatus protein that is required for normal flagellar and cilia motility. Recent findings suggest that Spag6 plays a role in hearing and planar cell polarity (PCP) in the cochlea of the inner ear. However, a role for Spag6 in the vestibule has not yet been explored. In the present study, the function of Spag6 in the vestibule of the inner ear was examined using Spag6-deficient mice. Our results demonstrate a vestibular disorder in the Spag6 mutants, associated with abnormal ultrastructures of vestibular hair cells and Scarpa's ganglion cells, including swollen stereocilia, decreased crista in mitochondria and swollen Scarpa's ganglion cells. Immunostaining data suggests existence of caspase-dependent apoptosis in vestibular sensory epithelium and Scarpa's ganglion cells. Our observations reveal new functions for Spag6 in vestibular function and apoptosis in the mouse vestibule.

Arachnoid Cysts of the Internal Auditory Canal: Multiplanar Magnetic Resonance Imaging With Audio-Vestibular Correlates.

OBJECTIVES/HYPOTHESIS: To investigate prevalence, radiological characteristics, and functional correlates of arachnoid cysts (AC) of the internal auditory canal (IAC) region, including associations of nerve compression with auditory/vestibular symptoms and asymmetrical audiogram or vestibular testing. STUDY DESIGN: Retrospective study. METHODS: T2-weighted magnetic resonance imaging (MRI) studies of IACs were retrospectively analyzed from 1247 patients with asymmetric auditory or vestibular symptoms. Patients with radiological findings of AC of the IAC were identified. Multiplanar analysis was used to analyze cyst position in the IAC and assess nerve displacement or compression. Size, position, and presence of nerve compression were correlated with symptoms. RESULTS: Twenty-four patients had a cyst in the middle or fundus in the IAC. Diameter (P = .04) and position (P = .002) of AC were associated with symptoms. Sagittal analyses identified displacement versus compression (P = .003) more reliably than axial imaging. Symptom laterality was associated with the site of radiological abnormality. Vestibular nerve compression was associated with vertigo (P = .0001), and cochlear nerve compression was associated with auditory symptoms (P < .0001). CONCLUSIONS: In a retrospective series of patients undergoing MRI of IACs for asymmetric auditory or vestibular impairment, clinical symptom profile correlated with blinded assessment of IAC lesions. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:2323-2331, 2021.

Optimized preoperative determination of nerve of origin in patients with vestibular schwannoma.

In vestibular schwannoma (VS) patients hearing outcome and surgery related risks can vary and depend on the nerve of origin. Preoperative origin differentiation between inferior or superior vestibular nerve may influence the decision on treatment, and the selection of optimal treatment and counselling modalities. A novel scoring system based on functional tests was designed to predict the nerve of origin for VS and was applied to a large number of consecutive patients. A prospective, double blind, cohort study including 93 patients with suspected unilateral VS was conducted at a tertiary referral centre. Preoperatively before tumor resection a functional test battery [video head-impulse test (vHIT) of all semicircular canals (SCC)], air-conducted cervical/ocular vestibular evoked myogenic potential tests (cVEMP, oVEMP), pure-tone audiometry, and speech discrimination was applied. Sensitivity and specificity of prediction of intraoperative finding by a preoperative score based on vHIT gain, cVEMP and oVEMP amplitudes and asymmetry ratios was calculated. For the prediction of inferior vestibular nerve origin, sensitivity was 73% and specificity was 80%. For the prediction of superior vestibular nerve origin, sensitivity was 60% and specificity was 90%. Based on the trade-off between sensitivity and specificity, optimized cut-off values of - 0.32 for cVEMP and - 0.11 for oVEMP asymmetry ratios and vHIT gain thresholds of 0.77 (anterior SCC), 0.84 (lateral SCC) and 0.80 (posterior SCC) were identified by receiver operator characteristic curves. The scoring system based on preoperative functional tests improves prediction of nerve of origin and can be applied in clinical routine.

Topography of the lesion in idiopathic sudden sensorineural hearing loss.

INTRODUCTION: Etiology of ISSNHL includes cessation of vascular perfusion, viral infection and cochlear membrane injury. Precise location of injury should be defined for a target-oriented treatment. Vestibular complaints in ISSNHL are hypothesized as involvement of vestibule. Vestibular complaints can be either due to involvement of inner ear or neural tract at any level. OBJECTIVES: In the present study we aimed to demonstrate involvement of vestibular organs in the absence of vestibular symptoms. It was aimed to evaluate superior and inferior vestibular neural pathways. METHODS: c-vemp and o-vemp were applied to patients suffering ISSNHL without vertigo. Pure tone averages, audiogram configurations, degree of hearing loss were analyzed. Latencies of P1 and N1 waves, amplitudes of P1-N1 waves were evaluated. Asymmetrical vemp wave patterns were compared between two ears regarding difference of PTA. RESULTS: Latencies of c-vemp waves were longer and amplitudes were smaller. o-vemp parameters were similar on both sides. Positive correlation was observed between c-vemp latencies and degree hearing loss. CONCLUSION: Inferior vestibular nerve pathway is affected in the absence of vertigo in ISSNHL with spared superior vestibular nerve pathway. Damage in IVN pathway correlates with degree of ISSNHL.

Larger tumor size and female gender suggest better tinnitus prognosis after surgical treatment in vestibular schwannoma patients with tinnitus.

Background: Tinnitus is a subjective auditory phantom phenomenon which can be highly distressing. About 63%-75% vestibular schwannoma (VS) had a symptom of tinnitus.Objectives: To investigate the tinnitus maintenance mechanism from the view of tinnitus change after surgical treatment in VS patients.Material and methods: We conducted a retrospective study of VS patients with tinnitus from August 2008 to February 2019 and did follow-ups on their changes of tinnitus after surgery.Results: Among 298 VS cases, 201 of them had tinnitus symptom (67.4%). No statistical difference in the surgical approach was found between the tinnitus poor outcome and good outcome groups (p = .14), and statistical difference was found in gender (p = .04) and tumor size (p = .01) between the two groups. Binary logistic regression analysis revealed that gender (odds ratio [OR], 2.12; 95% CI, 1.10-4.08 [p = .03]) and tumor size (OR, 2.22; 95% CI, 1.16-4.24 [p = .02]) emerged as a significant and independent factor associated with the good outcome of tinnitus.Conclusions and significance: The results of this study confirmed that the cochlear nucleus of the brainstem and above part of the brainstem may play an important role in the maintenance of tinnitus.

Vestibular Nerve Atrophy After Vestibular Neuritis - Results from a Prospective High-Resolution MRI Study.

PURPOSE: Sudden unilateral peripheral vestibular deficit is mostly termed vestibular neuritis (VN), even if its cause or the exact location of the lesion remains unclear. Thus, therapy is mostly symptomatic. We aimed to prove if there is peripheral atrophy after VN with persistent canal paresis. METHODS: After approval by the ethics committee and according to the declaration of Helsinki and with informed consent, ten patients with persistent canal paresis after VN and ten age-matched healthy controls were included. High-resolution measurement (in-plane resolution 0.2 mm) of the internal auditory canal (IAC) using a 3 D CISS sequence at 3 Tesla was performed. The course of the pertaining nerves was reconstructed in the 3 D dataset and the measurement was performed at 60 % of the length of the IAC. The cross-sectional areas of the superior (SVN) and inferior vestibular nerve (IVN) were taken independently by two blinded readers. RESULTS: The interrater difference regarding the area was 22 %. We found significant atrophy of the SVN with a 24 % smaller area (p = 0.026) and found a smaller ratio of SVN/IVN on the symptomatic side (p = 0.017). Concerning single subject data, only 5 patients showed extensive atrophy of the NVS, while 5 patients did not. The time since symptom onset did not significantly influence the atrophy. CONCLUSION: MRI measuring of the area of the NVS after VN could detect atrophy after VN. However, only 5 patients exhibited marked atrophy, while the other 5 patients did not. With the background of stringent inclusion criteria (more than 6 months of symptom duration and proven persistent canal paresis), one has to wonder if there might be different etiologies behind the apparently identical symptoms. KEY POINTS: · MRI measuring of the area of the NVS after VN could detect atrophy after VN. · Only half of the 10 researched patients showed atrophy, while the other patients did not. · There are different etiologies to be suspected for VN. CITATION FORMAT: · Freund W, Weber F, Schneider D et al. Vestibular Nerve Atrophy After Vestibular Neuritis - Results from a Prospective High-Resolution MRI Study. Fortschr Röntgenstr 2020; 192: 854 - 861.

Location of Small Intracanalicular Vestibular Schwannomas Based on Magnetic Resonance Imaging.

Vestibular schwannomas (VSs) were proposed to arise from the glial-Schwann cell junction within the internal auditory canal (IAC). However, otopathology studies indicate that VS may arise anywhere along the course of the vestibular nerve. Recent studies suggested that the majority of tumors are located centrally within the IAC with an equal distribution near the porus acusticus and the fundus. However, these studies analyzed tumors of all sizes, obscuring their precise origin. Herein, we aim to quantify the position of small intracanalicular tumors (<5 mm), assessing hearing outcomes and growth patterns in relation to tumor position. Of the 38 small intracanalicular tumors analyzed, 61% originated closest to the fundus, 34% at the midpoint, and only 5% closest to the porus acusticus. Tumors were observed with serial magnetic resonance imaging for 3.37 ± 2.65 years (mean ± SD) without intervention. Our findings indicate a lateral predominance of small VS within the IAC, an independence between tumor location and hearing outcomes, and further support the slow natural progression of VS.

Vestibular Implantation and the Feasibility of Fluoroscopy-Guided Electrode Insertion.

Recent research has shown promising results for the development of a clinically feasible vestibular implant in the near future. However, correct electrode placement remains a challenge. It was shown that fluoroscopy was able to visualize the semicircular canal ampullae and electrodes, and guide electrode insertion in real time. Ninety-four percent of the 18 electrodes were implanted correctly (<1.5 mm distance to target). The median distances were 0.60 mm, 0.85 mm, and 0.65 mm for the superior, lateral, and posterior semicircular canal, respectively. These findings suggest that fluoroscopy can significantly improve electrode placement during vestibular implantation.

Superior vestibular neuritis: improved detection using FLAIR sequence with delayed enhancement (1 h).

INTRODUCTION: Vestibular neuritis is the second cause of vertigo and new imaging protocols using delayed FLAIR with double-dose of gadolinium are proposed for its diagnosis. Our aim is to demonstrate that a single dose of gadolinium is sufficient. METHODS: Thirty-three patients with a unilateral vestibular neuritis are compared to a control group. All patients underwent a FLAIR sequence, 1 hour after intravenous injection of a single dose of gadolinium, on a 1.5 Tesla MRI. Two radiologists analyzed the enhancement intensity of the superior (sup VN) and inferior vestibular nerve (inf VN) and ratios to the signal of the cerebellum were calculated (supVN/C). The statistics were performed using Bayesian analysis. RESULTS: A strong enhancement of the sup VN was observed on the pathological side in 85% of patients with vestibular neuritis. The average signal intensity of the pathological sup VN (139 units ± 44) was more than two times the average intensity in the control group (58.5 units ± 5). The average ratios supVN/C were significantly different between the pathological side in vestibular neuritis (2.43 units ± 0.63) and the control group [1.16 ± 0.14 (Pr(diff > 0) = 1)]. A delayed enhancement > 71.5 units had a sensitivity of 96% and a specificity of 100% for the diagnosis of superior vestibular neuritis. CONCLUSION: A delayed FLAIR sequence, acquired 1 hour after a single dose of gadolinium injection, is a useful method for the diagnosis of vestibular neuritis. An enhancement of the sup VN > 71.5 units was in favor of the diagnosis.

Peripheral Vestibular System Histopathologic Changes following Head Injury without Temporal Bone Fracture.

OBJECTIVE: Vestibular symptoms such as dizziness and vertigo are common after head injury and may be due to trauma to the peripheral vestibular system. The pathophysiology of peripheral vestibular symptoms following head injury without temporal bone (TB) fracture, however, is not well understood. Herein, we investigate the histopathology of the peripheral vestibular system of patients who sustained head injury without a TB fracture. STUDY DESIGN: Otopathology study. SETTING: Otopathology laboratory. SUBJECTS AND METHODS: TB of subjects with a history of head injury without TB fractures were included and evaluated by light microscopy. Specimens were assessed for qualitative and quantitative characteristics, such as number of Scarpa's ganglion cells in the superior and inferior vestibular nerves, vestibular hair cell and/or dendrite degeneration in vestibular end organs, presence of vestibular hydrops, and obstruction of the endolymphatic duct. RESULTS: Five cases (n = 5 TBs) had evidence of vestibular pathology. There was a decrease of 48.6% (range, 40%-59%) in the mean count of Scarpa's ganglion cells as compared with that of normative historical age-matched controls. Moderate to severe degeneration of the vestibular membranous labyrinth was identified in the posterior, superior, and lateral canals in several cases (50%, n = 4 TBs). The maculae utriculi and sacculi showed mild to severe degeneration in 2 cases. Additional findings include vestibular hydrops (25%, n = 2 TBs) and blockage of the endolymphatic duct (n = 1 TB). CONCLUSIONS: Otopathologic analysis of patients with a history of head injury without TB fracture demonstrated peripheral vestibular otopathology. Future studies are necessary to determine if otopathology findings are directly attributable to head injury.

Bilirubin-induced neurotoxic and ototoxic effects in rat cochlear and vestibular organotypic cultures.

Exposure to high levels of bilirubin in hyperbilirubinemia patients and animal models can result in sensorineural deafness. However, the mechanisms underlying bilirubin-induced damage to the inner ear, including the cochlear and vestibular organs, remain unknown. The present analyses of cochlear and vestibular organotypic cultures obtained from postnatal day 3 rats exposed to bilirubin at varying concentrations (0, 10, 50, 100, or 250 µM) for 24 h revealed that auditory nerve fibers (ANFs) and vestibular nerve endings were destroyed even at low doses (10 and 50 µM). Additionally, as the bilirubin dose increased, spiral ganglion neurons (SGNs) and vestibular ganglion neurons (VGNs) exhibited gradual shrinkage in conjunction with nuclei condensation or fragmentation in a dose-dependent manner. The loss of cochlear and vestibular hair cells (HCs) was only evident in explants treated with the highest concentration of bilirubin (250 µM), and bilirubin-induced major apoptosis most likely occurred via the extrinsic apoptotic pathway. Thus, the present results indicate that inner ear neurons and fibers were more sensitive to, and exhibited more severe damage following, bilirubin-induced neurotoxicity than sensory HCs, which illustrates the underlying causes of auditory neuropathy and vestibulopathy in hyperbilirubinemia patients.

A Case of Bilateral Atrophy of the Inferior Vestibular Nerves.

: We report a case of a 62-year-old woman who was found to have bilateral atrophy of the inferior vestibular nerves on magnetic resonance imaging (MRI) after presenting to our clinic with 6 years of intermittent vertigo and residual unsteadiness. The nerve atrophy may be associated with an episode of vestibular neuritis, a common cause of vertigo that exclusively involves the inferior vestibular nerve in less than 3% of cases. While MRI may demonstrate vestibular nerve enhancement in cases of acute vestibular neuritis, no single MRI finding has been demonstrated consistently among cases of acute or chronic vestibular neuritis. Physical therapy is likely an effective long-term treatment for this patient to achieve central compensation for symptomatic relief.

Histopathology of the Inner Ear in Charcot-Marie-Tooth Syndrome Caused by a Missense Variant (p.Thr65Ala) in the MPZ Gene.

Charcot-Marie-Tooth (CMT) syndrome is a clinically and genetically heterogeneous group of neuropathies affecting both peripheral motor and sensory nerves. Progressive sensorineural hearing loss, vestibular abnormalities, and dysfunction of other cranial nerves have been described. This is the second case report of otopathology in a patient with CMT syndrome. Molecular genetic testing of DNA obtained at autopsy revealed a missense variant in the MPZ gene (p.Thr65Ala), pathogenic for an autosomal-dominant form of CMT1B. The temporal bones were also prepared for light microscopy by hematoxylin and eosin and Gömöri trichome stains, and immunostaining for anti-myelin protein zero. Pathology was consistent with a myelinopathy of the auditory, vestibular, and facial nerves bilaterally. The pathophysiology of cranial nerve dysfunction in CMT is unknown. Findings in the current case suggested, at least in cranial nerves 7 and 8, that a myelinopathy may be causative.

Preoperative determination of nerve of origin in patients with vestibular schwannoma.

BACKGROUND: Vestibular schwannoma (VS) is a benign tumor that develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a novel scoring system that was designed to determine the nerve of origin. METHODS: The nerve of origin was predicted based on video head impulse assessments of all semicircular channels, together with cervical/ocular vestibular-evoked myogenic potential tests. The acquired data were entered into a scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. RESULTS: The novel scoring system was applied to five consecutive patients undergoing surgical VS treatment. In one case, no determination was possible. In all other cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. CONCLUSION: The scoring system predicts the nerve of origin and will be evaluated in a larger prospective cohort study of VS patients in the near future.

[Preoperative determination of nerve of origin in patients with vestibular schwannoma. German version]. / Präoperative Bestimmung des Ursprungsnervs von Vestibularisschwannomen.

BACKGROUND: Vestibular schwannoma (VS) is a benign tumor that develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a novel scoring system that was designed to determine the nerve of origin. METHODS: The nerve of origin was predicted based on video head impulse assessments of all semicircular channels, together with cervical/ocular vestibular-evoked myogenic potential tests. The acquired data were entered into a scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. RESULTS: The novel scoring system was applied to 5 consecutive patients undergoing surgical VS treatment. In one case, no determination was possible. In all other cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. CONCLUSION: The scoring system predicts the nerve of origin and will be evaluated in a larger prospective cohort study of VS patients in the near future.