Vestibular Nerve Research Articles

Acceptability and feasibility of a vestibular nerve stimulation headset protocol in children with cerebral palsy

BackgroundResearch suggests electrical Vestibular Nerve Stimulation (VeNS) may improve balance for people with neurological impairments. This study aimed to assess the feasibility and acceptability of a VeNS headset protocol in children with cerebral palsy (CP).MethodsChildren aged 5–18 years with ambulant CP, their parents, and healthcare professionals were recruited via social media. Children completed a battery of balance tests and wore a sham VeNS headset one hour per day for four weeks. Perspectives on the balance tests and headset were ascertained from children, parents and healthcare professionals using semi-structured interviews. Interview data were analysed thematically.ResultsTwo families and four healthcare professionals participated. Balance outcome measures were fully completed and deemed acceptable. Adherence with wearing the headset was 89–100% but discomfort with self-adhesive electrodes was reported. Four themes emerged from interview data: headset issues, perceptions about VeNS, the importance of balance, and modifications for future study.ConclusionsAlthough the VeNS headset had high acceptability, the volunteer sample was small, potentially suggesting limited interest in VeNS as a treatment for children with CP, or reluctance to trial a ‘non-active’ headset. Recruitment via clinicians known to the family and use of an ‘active’ headset may increase participation in future research.

Application of Multiplanar Volume Reconstruction Technique for the Assessment of Electrode Location and Analysis of the Correlation to Cochlear Programming and Performance in Common Cavity Deformity

Purpose: Owing to the characteristic anatomy, cochlear implantation (CI) for common cavity deformity (CCD) has resulted in varied outcomes and frequent facial and vestibular nerve stimulation. The current study analyzed the correlation among the distance between each electrode and cavity wall (abbreviation, D), programming parameters, and performances outcomes.Materials and Methods: The current, retrospective study included 25 patients (27 ears) with CCD underwent CI. The multiplanar volume reconstruction (MPVR) techniques were employed to reconstruct and evaluate the postoperative temporal bone CT. The D and maximum comfortable level (MCL) 6 months after CI, facial and vestibular nerve stimulation, and outcomes 1, 2, and 3 years after CI pertaining to the questionnaires were documented and analyzed.Results: The patients were divided into symptomatic (10, 37%) and asymptomatic (17, 63%) groups according to with or without facial and vestibular nerve stimulation. The MCL pertaining to the symptomatic group was significantly lower than asymptomatic group, but Categories of Auditory Performance (CAP) scores 1 year after surgery was better (p < 0.05). The subjects were divided into flat (12, 44.4%) and curved (15, 55.6%) groups based on the contour of MCL map. The MCL and D were lower and shorter in the curved group than the flat group, and CAP score 1 year after surgery and Speech Intelligibility Rating (SIR) 3 years after surgery were better (p < 0.05).Conclusion: Although abnormal reactions such as facial and vestibular nerve stimulation were observed to be more frequent, lower MCL and better outcomes were observed in relation to the shorter D.

Vestibular Physical Therapy Evaluation of Individuals Exposed to Directed Energy.

Directed energy has been described as exposure to a unique sound/pressure phenomenon such as infrasonic or ultrasonic acoustic or electromagnetic energy. Following suspected sonic attacks on U.S. Embassies, a subset of individuals presented with a unique cluster of symptoms believed to have resulted from exposure to directed energy. The Joint Force does not have an established protocol to guide the vestibular physical therapy evaluation of individuals exposed to directed energy. Therefore, we sought to provide evidence-based guidance for conducting a comprehensive vestibular physical therapy evaluation in persons exposed to directed energy. A comprehensive search of relevant databases was performed from 2018 to the present. Four seminal articles were used to inform suggestions for clinical best practice. The physical therapist should ask open-ended questions to understand what the individual is experiencing and use key questions to focus attention on the mechanism of injury, symptom report, and symptom timeline. The physical therapist should perform an evaluation to determine if the peripheral vestibular apparatus (semicircular canals and otoliths), vestibular nerve, and/or central pathways have been affected by directed energy exposure. Components of the quantitative examination were selected because they provide information on health condition(s), body structure and function impairments, and activity limitations but require little to no specialized equipment. Evidence-based guidance for conducting a comprehensive vestibular physical therapy evaluation in individuals exposed to directed energy may aid in the identification and diagnosis of unconventional brain injury. This standardized approach can help physical therapists to evaluate complaints that do not match any previously known medical conditions but resemble brain injury or vestibular pathology.

Central vestibular compensation

Stable unilateral vestibular deficit (vestibular neuronitis being the most common example in clinical practice) causes an imbalance in the information reaching the two vestibular nuclei at the level of the brain stem. This inequality of in­for­ma­tion arriving from the inner ear or the vestibular nerve is interpreted by the central vestibular structures as a rotation towards the ear from which it receives more in­for­ma­tion, generating the natural balancing reactions – nys­tag­mus and vertigo, postural and walking imbalance. The phy­sio­lo­gical mechanism involved in the healing of such an injury is represented by the phenomenon of central ves­ti­bu­lar compensation, an expression of the plasticity of the cen­tral vestibular structures. This natural recovery pattern begins in the first days after the acute injury and is a long-last­ing process that allows good but incomplete recovery of dynamic deficits secondary to peripheral vestibular in­jury. This therapeutic window of the first week after onset should not be missed – initiation of phar­ma­co­lo­gical treat­ment (betahistine) from the first days and vestibular reha­bi­li­ta­tion pro­grams, both of which have been shown to facilitate and accelerate central vestibular compensation and en­su­ring ma­xi­mum patient’s recovery.

Surgical Management of Intractable Meniere's Disease.

Meniere's Disease (MD) is an inner ear disorder characterized by spontaneous recurrent vertigo, fluctuating sensorineural hearing loss, aural fullness and low-pitch tinnitus. Therapeutic management of MD includes dietary restriction and medical therapy. A minority of cases is characterized by frequent vertigo attacks, progressive hearing loss and persistent tinnitus even through the continuous medical treatments; this condition is called intractable MD and requires a therapeutic escalation from non-invasive medical treatment to surgical intervention. Invasive procedures include endolymphatic sac surgery, vestibular nerve section and labyrinthectomy. These procedures have a very high success rate on symptom control but may have a severe impact on the hearing function. However, the simultaneous combined approach of demolitive surgery and cochlear implantation may be a valid approach to treat symptoms of intractable MD and preserve hearing function. In the present study, we review current literature focusing on intractable MD to describe and discuss advantages and disadvantages of established and newly proposed surgical treatments for intractable MD.

Concordance of vestibular test batteries in patients with vestibular neuritis.

A growing number of vestibular function tests are utilized to differentiate and verify the diagnosis of vestibular neuritis. The aim of this study is to retrospectively investigate the consistency of the results of the objective vestibular test batteries in patients with a preliminary diagnosis of vestibular neuritis. We reviewed a total of 37 adult patients (mean age: 39.03 ± 11.67, 19 females, 18 males) who met the inclusion criteria with a prediagnosis of vestibular neuritis from 379 patients suffering vestibular symptoms. Caloric test (CVT), video head impulse test (vHIT), and ocular and cervical VEMP tests were compared with Cohen's kappa (Κ) analysis according to the likely affected part of the vestibular nerve. The highest statistically significant K value was found between horizontal vHIT and ocular VEMP (K = 0.707; good grade, p < 0.05). All the tests compared with CVT were poorly in agreement (K = 0.288; 0.262; 0.256 for HvHIT, oVEMP, AvHIT, respectively, p < 0.05). VEMP and vHIT tests have prominent diagnostic value and agree with each other for detecting and differentiating the types of vestibular neuritis. Further studies should aim to include cutting-edge technologies such as functional HIT and ocular counter roll test.

Analysis of the anatomical features of vestibular nerve canal based on 10 μm otology CT

Objective: To analysis the anatomical features of normal vestibular nerve canal based on 10 μm otology CT. Methods: Sixty-seven patients (103 ears) underwent 10 μm otology CT examinations in Department of Radiology, Beijing Friendship Hospital, Capital Medical University from September 2020 to March 2021 were retrospectively recruited. There were 24 males and 43 females, aged from 18 to 70 (40±17) years. According to the morphology of the inferior vestibular nerve canal, it can be divided into four types as follows: uniform straight type, curved type, ampullary type and direct connection. The anatomical variables of the superior vestibular nerve canal (external orifice, isthmus and internal orifice widths, canal length, angle with labyrinthine segment of the facial nerve) and inferior vestibular nerve canal (widths of the externaland internal orifice, canal length, angles with long axis of the vestibule and the modiolus) between the different sides, genders and canal morphologies were analyzed and compared, respectively. Results: 100% superior vestibular nerve canals and 75.7% (78/103) inferior vestibular nerve canals are clearly depicted by otology CT. The left-side ear presented with larger internal orifice diameter of the superior vestibular neve canal [(1.46±0.47) mm vs (1.31±0.41) mm], and a smaller angle between the inferior vestibular neve canal and the modiolus [(41.6±16.9)° vs (51.6±21.0)°] than the right-side ear (all P<0.05, respectively), respectively. Compared to females, males demonstrated larger internal orifice of the superior vestibular nerve canal [(1.55±0.37) mm vs (1.28±0.36) mm, P<0.05]. The uniform straight type of the inferior vestibular nerve canal was the most common type (62.1%, 64/103), followed by the direct connection (19.4%, 20/103), and the ampullary type was the least common type (4.9%, 5/103). There were significant differences in external diameter and angles with the long axis of the vestibule and the modiolus between the four morphologies of the superior vestibular nerve canal (all P<0.05, respectively). Conclusion: Ten μm otology CT is capable of depicting normal vestibular nerve canal clearly. Quantitative measurement of the normal vestibular nerve canal can provide references for the imaging diagnosis and preoperative evaluation of lesions in this area.

Effect and mechanism of BDNF/TrkB signaling on vestibular compensation

ABSTRACT Brain-derived neurotrophic factor (BDNF) regulates neuronal plasticity by targeting the tyrosine kinase B receptor (TrkB) receptor, but limited researches concentrate on the role of BDNF/TrkB signaling in vestibular compensation. In this study, rats with unilateral vestibular dysfunction were established by unilateral labyrinthectomy (UL) and infusion with siBDNF or 7, 8-Dihydroxyflavone (7,8-DHF, a TrkB receptor agonist). The behavioral scores of rats with vestibular deficits were determined and the rotarod test was performed after UL. BDNF and TrkB levels after UL were determined by western blot and quantitative reverse transcription PCR (qRT-PCR). 5-bromo-2ʹ-deoxyuridine (BrdU)-positive cells (newly generated cells) and GAD67-positive cells (GABAergic neurons) were identified by immunohistochemistry. Glial fibrillary acidic protein (GFAP) (astrocyte marker)-positive cells were identified and GABA type A receptor (GABAAR) expression was detected by immunofluorescence. We found that after UL, BDNF and TrkB levels were up-regulated with a maximum value at 4 h, and then progressively down-regulated during 4 h ~ 7 d. Blocking BDNF/TrkB signaling inhibited the recovery from vestibular deficits, decreased the numbers of newly generated cells and astrocytes in medial vestibular nucleus (MVN), inferior vestibular nerve (IVN), superior vestibular nerve (SVN) and lateral vestibular nucleus (LVN), and disrupted the balances of GABAergic neurons and GABAAR expressions in the left (lesioned) side and right (intact) side of MVN, whereas activation of BDNF/TrkB signaling caused opposite results. The current study indicated that BDNF/TrkB signaling avails vestibular compensation, depending on the number of newly generated cells and astrocytes, the rebalance of GABAergic neurons, and GABAAR expression in bilateral MVN.

Direction-changing spontaneous nystagmus in cerebellopontine angle tumour

The most common symptoms of tumours involving the cerebellopontine angle (CPA) are unilateral sensorineural hearing loss, dizziness, and asymmetric tinnitus. While the clinical manifestations have been well documented in previous studies, the nystagmus findings in these patients have not been thoroughly investigated yet. This study aimed to investigate the incidence of direction-changing spontaneous nystagmus in patients with CPA tumours, evaluate their radiologic characteristics, and gain insight into the mechanisms underlying nystagmus. Direction-changing spontaneous nystagmus was observed in 6 out of 83 patients (7%) with CPA tumours during the 7-year period. Temporal bone magnetic resonance imaging findings revealed the presence of an intrameatal mass in CPA tumours in all six patients with direction-changing spontaneous nystagmus. Vestibular schwannomas were confined within the internal auditory meatus in four patients, and petroclival meningiomas extended into the internal auditory meatus in two patients. The mechanism of direction-changing spontaneous nystagmus may be explained as paroxysmal secondary central hyperactivity in the vestibular nucleus due to the long-standing pressure effect in the vestibular nerve by tumours, or by ephaptic discharges in the vestibular nerve.

Spontaneous Resolution of Ocular Tilt Reaction

A 30-year-old man presented to the ophthalmologic clinic with sudden onset of vertical and torsional diplopia. Concomitant skew deviation with right hypertropia was observed. Funduscopy revealed that the fovea was located above the lower edge of the optic disc in the right eye; incyclotorsion was present. Conversely, the fovea was located below the lower edge of the optic disc in the left eye; excyclotorsion was present. He was diagnosed to have ocular tilt reaction (OTR). Neurological examination was unremarkable. Cranial magnetic resonance imaging demonstrated no abnormalities and no evidence of acute ischemia, demyelination, or vestibular nerve abnormality. The patient was followed without any treatment. One month later, his diplopia had disappeared. Incyclotorsion in the right eye and excyclotorsion in the left eye were also improved. Torsional deviation is difficult to detect with a standard eye exam. A fundus photograph is useful for diagnosis in such cases if it can be obtained.

Sensitivity of Romberg Test in Diagnosis of Peripheral Vestibular Disorders in Comparison with Caloric Test: Psychometric Study

Introduction: Romberg test is one of the balance screening tests. Since this test does not require special equipment, it is widely used in the evaluation of people suffering from balance disorders. This study aimed to determine the sensitivity of the Romberg test for the diagnosis of peripheral vestibular dysfunction compared with the caloric test that is the gold standard for the diagnosis of horizontal semicircular canal/superior vestibular nerve disorders. Materials and Methods: This study was a cross-sectional-comparative study and the sample was selected from those who referred to the audiology clinic of the School of Rehabilitation Sciences, Tehran University of Medical Sciences, Tehran, Iran. Romberg test with closed eyes was performed in 47 people suffering from unilateral or bilateral peripheral vestibular disorders (25 women and 22 men, mean age: 43.80 ± 4.46 years) whose lesion was confirmed by caloric test. The results were recorded in the participants’ history files and the files were reviewed. Chi-square test was used to compare the results. The sensitivity of Romberg test was determined in comparison with their caloric test results. Results: Only 5 participants had abnormal Romberg results, while 35 patients showed unilateral caloric weakness and 12 had bilateral deficits. Therefore, Romberg's sensitivity was 10.64%. There was no significant correlation between Romberg results and duration of disease. Conclusion: Romberg test seems to have low sensitivity in diagnosis of peripheral vestibular disorders. Therefore, vestibular tests with higher sensitivity are recommended for the diagnostic purposes and caloric test may not be replaced by Romberg test.

Resection of Vestibular Schwannoma Through Middle Cranial Fossa Approach with Endoscopic Assistance

We sought to report the outcome of resection of vestibular schwannomas (VSs) originating from the inferior vestibular nerve that extended into the fundus of the internal auditory canal through the middle cranial fossa (MCF) approach with endoscopic assistance. Seven patients with VSs who underwent resection through MCF approach with endoscope assistance and 12 patients with conventional microsurgery in our department were enrolled in this study. These patients' characteristics were acquired, and the surgical outcomes, as well as postoperative complications, were evaluated. In the endoscope group, the VS was first removed by a conventional microscopic procedure and then an endoscope was used to find and remove any residue lesions. In 3 of 7 patients, residue tumor in the space below transverse crest was found and completely removed under endoscope. Six of 7 patients (85.7%) had House-Brackmann grade I at the time of last follow-up in the endoscope group compared with 10 of 12 patients (83.3%) in the conventional microsurgery group. Serviceable hearing was successfully maintained in 2 of 3 patients (66.7%) in the endoscope group compared with 6 of 10 patients (60%) in the conventional microsurgery group. Total resections were achieved in all the patients (100%) in the endoscope group compared with 9 of 12 patients (75%) in the conventional microsurgery group. Using an endoscope in VS resection through the MCF approach could facilitate complete removal of the lesion while minimizing the risk of hearing loss and facial paralysis. The endoscope-assisted MCF approach is especially suitable for removing an intracanalicular VS with lateral extension involving the space below the transverse crest.

Usefulness of vestibular evoked myogenic potentials in diagnosis of peripheral vestibular disorders

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Vestibular evoked myogenic potentials (VEMP) are electromyographic responses to high-intensity acoustic stimuli to test vestibular system, otolith function and integrity of inferior vestibular nerve. These are easy to perform and non-invasive. In this study, we aimed at clinical application of VEMP to evaluate common peripheral vestibular disorders.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Prospective observational study carried in ENT department during January 2015-November 2016 over 40 patients in age group between 30-70 years with history of vertigo who underwent regular neuro-otological examination and VEMP.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Of these, 25 diagnosed with BPPV, 11 with Meniere’s disease, and four with vestibular neuritis. Eight patients showed delayed VEMP responses. 28 (70%) patients had normal VEMP, 12 (30%) had abnormal VEMP responses. Out of 25 patients suffering from benign paroxysmal positional vertigo (BPPV) posterior semi-circular canal was involved in 20 (80%) patients and lateral semi-circular canal in 5 (20%) patients.&lt;strong&gt; &lt;/strong&gt;Abnormal VEMP was found in 5 (20%) patients involving posterior semi-circular canal and in 1 (20%) patient involving lateral semi-circular canal. In patients with Meniere’s disease stage I, Meniere’s disease was observed in 7 (63.6%), stage II in 2 (18.1%), and stage IV disease in 1 (9.09%) patient. In these patients, abnormal VEMP was found in 3 (42.8%) of 7 stage I, 1 (50%) of 2 stage II and 1 (100%) of stage IV patients.&lt;strong&gt; &lt;/strong&gt;One (20%) patient had abnormal VEMP responses during study.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;VEMP are short-latency EMG that evaluates saccule and inferior vestibular nerve in peripheral vestibular nervous system. VEMP should be considered as complementary test along with conventional vestibular function tests in patients with peripheral vertigo.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;

Activation of Raf signalling in NF2-null Schwann cells leads to sustained proliferation; an investigation of a new and inducible model for human schwannoma

Abstract Aims The NF2 gene encodes the tumour suppressor Merlin, which is deleted in 100% of patients with the familial tumour predisposition syndrome neurofibromatosis type 2 but also in 70% of those who develop sporadic schwannomas. The Raf-TR mouse model uses a tamoxifen-inducible Raf-kinase/ oestrogen receptor fusion protein (Raf-TR) expressed in myelinating Schwann cells to mimic a nerve injury response in Schwann cell by activating Raf/MEK/ERK signalling in the absence of peripheral nerve injury. We will assess whether Raf/MEK/ERK activation on an NF2 null background leads to tumourigenesis within the vestibular nerves and dorsal root ganglia (DRGs), two tumour sites identified in the Periostin-Cre mouse model in which schwannoma formation is spontaneous, with a view to generating an inducible NF2 null schwannoma mouse model. Method Mice with a Schwann cell specific loss of Merlin were crossed with mice carrying a tamoxifen-inducible Raf-TR gene to generate Raf-TR+/-; P0-Cre+/-; NF2fl/fl (Cre+) mice which were NF2 null and compared to Raf-TR+/-; P0-Cre-/-; NF2fl/fl (Cre-) littermate controls. Mice were injected with tamoxifen or vehicle for five consecutive days and their vestibular nerves and dorsal root ganglia (DRGs) were analysed at various timepoints . An EdU proliferation assay was used to quantify the proliferation in the vestibular ganglia, as well as the DRGs. Rates of proliferation were compared to Cre- age-matched littermate controls treated with tamoxifen or vehicle. Results In the Periostin-Cre NF2 null schwannoma model, tumours form spontaneously in the DRGs and vestibular ganglia. In our new model, we see a clear increase in proliferation at 21 d post-injection in the NF2 null (Cre+) tamoxifen-treated mice compared to control (Cre-) tamoxifen-treated controls in both DRGs and vestibular ganglia. Cre- tamoxifen-treated mice do not show increased proliferation compared to Cre- vehicle controls. Taken together, this shows that activation of the Raf/MEK/ERK pathway in Schwann cells only causes a sustained proliferation response on an NF2 null background in the DRGs and vestibular ganglia. We are assessing later timepoints to further characterise tumour development in these mice. Conclusion Combining the Raf-TR mouse model to create a demyelinating phenotype with an NF2 null background leads to vastly increased rates of proliferation at the sites of schwannoma tumourigenesis within the peripheral nervous system: the DRGs and the vestibular ganglia. The high proliferation in the vestibular ganglia in particular is similar to the development of vestibular schwannomas in patients with Neurofibromatosis type 2. The new mouse model used in this study shows potential to be very useful as an inducible schwannoma tumour model, in which we can study the early events of tumour formation.

Three - dimensional fluid attenuated inversion recovery sequence on 3 tesla magnetic resonace imaging in cranial nerve pathologies: Two case reports

Three - dimensional fluid attenuated inversion recovery sequence (3D-FLAIR) was introduced as a practical sequence which helps to reduce the cerebrospinal fluid pulsation and flow artefacts of conventional 2D acquisition and brings contiguous slices, ability in reformatting in variable planes which are typical features of 3D acquisition. 3D - FLAIR has been applied on assessing several neurologic pathologies. In this article, we introduce the application of 3D - FLAIR sequence without contrast enhancement on detecting abnormalities of cranial nerve pathology by presenting two cases, acute vestibular neuritis and facial nerve palsy. We suggest that 3D - FLAIR is the relatively useful sequence in detecting cranial nerve pathologies.

Retrosigmoid approach for giant cystic vestibular schwannoma: subperineural dissection technique for facial nerve preservation.

In this illustrative video, the authors demonstrate retrosigmoid resection of a giant cystic vestibular schwannoma using the subperineural dissection technique to preserve facial nerve function. This thin layer of perineurium arising from the vestibular nerves is used as a protective buffer to shield the facial and cochlear nerves from direct microdissection trauma. A near-total resection was achieved, and the patient had an immediate postoperative House-Brackmann grade I facial nerve function. The operative nuances and pearls of technique for safe cranial nerve and brainstem dissection, as well as the intraoperative decision and technique to leave the least amount of residual adherent tumor, are demonstrated.The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21128

Acute vestibular disorders: Stroke or not?

Acute vestibular syndrome of severe vertigo, nausea/vomiting, spontaneous nystagmus and postural imbalance is commonly due to viral or post-viral inflammation of the vestibular nerve or labyrinth. However, similar symptoms and signs may occur in cerebellar or brainstem strokes in which vertigo may be an isolated or the initial symptom without other focal neurologic deficits. Since cerebellar or brainstem strokes may be fatal, it is important to recognize acute vestibular syndrome of vascular etiologies.

Drop Attack Treated by Microvascular Decompression of the Superior Vestibular Nerve.

We report a case of cochleovestibular neurovascular compressive syndrome (CVCS)-induced drop attack treated with microvascular decompression (MVD) of the superior vestibular nerve. This report discusses the merits of surgical intervention through a review of related literature. A 58-year-old woman was referred to our clinic with a chief complaint of intermittent, strong, right-sided tinnitus lasting for a few seconds immediately prior to drop attack. Magnetic resonance imaging (MRI) showed bilateral neurovascular contact between the anterior inferior cerebellar artery (AICA) and the vestibulocochlear nerve. Based on MRI findings, history of present illness, and response to anticonvulsants, CVCS was suspected, and surgical decompression on the right side was subsequently performed. The patient became asymptomatic immediately after the surgery, and the vestibular-evoked myogenic potentials were normalized. No recurrence was reported during a 1-year follow-up period.

The Effect of Somatosensorial System on Vestibular System.

The aim of this study was to investigate the effects of the somatosensory system on the vestibular system and the interconnected ways they work together to maintain balance. The study was conducted on 54 individuals (27 females and 27 males), aged between 18-25years. vHIT as well as cVEMP tests were used to evaluate the participants. Tests were carried out while sitting, standing on firm surface and standing on foam respectively. According to the posterior vHIT results, there was a significant difference between VOR gains obtained while sitting and standing on firm surface in right side as well as on the left side (p < 0,01). Moreover, when VOR gains in standing on firm and standing on foam results were compared to each other, statistical significance was found right and left posterior canals (p < 0,05). Concerning the results obtained from VEMP, a statistically significant difference was seen in the comparison of P1-N1 amplitudes of the right side on firm surface and standing on foam (p < 0,01). When the inputs from somatosensorial system are disturbed, the parts of the vestibular system that are primarily affected are the posterior SSC, saccule and inferior vestibular nerve. This can be interpreted as the inferior vestibular nerve being more affected than the superior vestibular nerve when posture is disturbed due to somatosensory cues being unavailable or unstable.

Vestibular-Evoked Cerebral Potentials.

The human vestibular cortex has mostly been approached using functional magnetic resonance imaging and positron emission tomography combined with artificial stimulation of the vestibular receptors or nerve. Few studies have used electroencephalography and benefited from its high temporal resolution to describe the spatiotemporal dynamics of vestibular information processing from the first milliseconds following vestibular stimulation. Evoked potentials (EPs) are largely used to describe neural processing of other sensory signals, but they remain poorly developed and standardized in vestibular neuroscience and neuro-otology. Yet, vestibular EPs of brainstem, cerebellar, and cortical origin have been reported as early as the 1960s. This review article summarizes and compares results from studies that have used a large range of vestibular stimulation, including natural vestibular stimulation on rotating chairs and motion platforms, as well as artificial vestibular stimulation (e.g., sounds, impulsive acceleration stimulation, galvanic stimulation). These studies identified vestibular EPs with short latency (<20 ms), middle latency (from 20 to 50 ms), and late latency (>50 ms). Analysis of the generators (source analysis) of these responses offers new insights into the neuroimaging of the vestibular system. Generators were consistently found in the parieto-insular and temporo-parietal junction—the core of the vestibular cortex—as well as in the prefrontal and frontal areas, superior parietal, and temporal areas. We discuss the relevance of vestibular EPs for basic research and clinical neuroscience and highlight their limitations.