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To evaluate pre- and post-operative semicircular canal function in patients with vestibular schwannoma (VS) by the video Head Impulse Test (vHIT). Nineteen patients with VS who underwent surgery were enrolled in this study. The gain in vestibulo-ocular reflex (VOR) and the degree of scatter in catch-up saccades were examined pre- and post-operatively for the semicircular canals in VS patients. Ten of 19 cases (52.6 %) with VS were defined as demonstrating both superior vestibular nerve (SVN) and inferior vestibular nerve (IVN) impairment from the results of pre-operative vHIT. Hearing level and subjective vestibular symptoms showed significant correlations with pre-operative semicircular canal function. Compared to pre-operative vHIT results, VOR gains within 1 month after surgery were significantly reduced in all three canals; however, significant differences had disappeared in the anterior and posterior semicircular canals at 6 months after surgery. Cases of unknown origin had a significantly greater reduction in posterior semicircular canal function after surgery compared with those with disease of IVN origin. As vHIT could evaluate pre-operative vestibular nerve impairment, post-operative VOR gain reduction and the degree of vestibular compensation, semicircular canal function evaluated by vHIT provides a good deal of useful information regarding VS patients undergoing surgery compared to caloric testing, and vHIT should be performed pre- and post-operatively for patients with VS. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the lateralization value of video head-impulse test (vHIT) for the diagnosis of vestibulopathy and to analyze cases showing dissociated results with caloric test.Methods: In total, 19 healthy volunteers and 92 dizzy patients who underwent both a caloric test and a vHIT were enrolled. Patients were divided into two groups depending on their fluctuating pattern of vertigo. The vestibulo-ocular reflex (VOR) gain and gain asymmetry (GA) of a vHIT as well as unilateral weakness (UW) and the sum of the slow-phase velocities (SPVs) of warm and cold irrigation of the same side were compared. A cutoff value of VOR gain of a vHIT was also calculated using a receiver-operating characteristic curve.Results: A VOR gain in an affected ear and GA of a vHIT showed a statistically significant correlation with UW in a caloric test. The cutoff value of a vHIT was determined to be 0.875, derived under the assumption that UW of a caloric test ≤25% is normal. However, the parameters of the two tests were dissociated in 18%.Conclusion: A VOR gain of vHIT is a valuable objective parameter with a lateralization value determining vestibular hypofunction. However, considering substantial dissociation between a vHIT and a caloric test, these tests can be complementary tools for the lateralization of vestibular impairment for the comprehensive evaluation of patients' VOR. [ABSTRACT FROM AUTHOR]

Globally, there are 3 million people living with multiple sclerosis (PLW-MS). A large proportion of PLW-MS have abnormal vestibular function tests that suggest central vestibular lesions. Yet, data regarding vestibular-ocular control in PLW-MS is limited. Thus, we aimed to further characterize compensatory saccade (CS) behavior in PLW-MS. We analyzed video head impulse data from four groups of six age- and sex-matched adults: people living with mild MS (PLW-mild-MS, people living with moderate MS (PLW-moderate-MS), people living with unilateral vestibular deafferentation (PLW-UVD), and healthy controls (HC). PLW-moderate-MS had lower lateral canal vestibulo-ocular reflex (VOR) gain bilaterally compared to PLW-mild MS (p < 0.001), HC (p < 0.001), and PLW-UVD (p < 0.001). CS frequency was higher for impulses towards the less affected side in PLW-moderate-MS versus the more (p = 0.01) and less (p < 0.001) affected sides in PLW-mild-MS. CS latency was shorter (p < 0.001) and CS peak velocity was lower (p < 0.001) with impulses towards the more affected side versus the less affected side in PLW-moderate-MS. However, CS peak velocity with impulses towards each side was similar in PLW-mild-MS (p = 0.12). Gaze position error (GPE) was larger after impulses towards the more affected side versus the less affected side in PLW-moderate-MS (p < 0.001) and PLW-mild-MS (p < 0.001). MS-related disability was moderately associated with VOR gain (p < 0.001) and GPE (p < 0.001). Additionally, we identified micro-saccades and position correcting saccades that were uniquely employed by PLW-MS as compensatory gaze stabilizing strategies. In PLW-MS, the characteristics of compensatory oculomotor behavior depend on the extent of residual VOR gain. [Display omitted] • People living with moderate multiple sclerosis often fail to generate compensatory saccades. • People living with mild multiple sclerosis tend to over-compensate for gaze position error. • The absence of saccades to compensate for low VOR gain may suggest internuclear ophthalmoplegia. [ABSTRACT FROM AUTHOR]

The video head impulse test (vHIT) is a diagnostic tool to examine patients experiencing dizziness by assessing the function of the semicircular canals. vHIT has been widely studied in adults but relatively less so in children. The aim of this study was to evaluate the causes of dizziness and the results of vHIT in children. We also identified factors that affect the vHIT results such as artifacts and technical errors. Retrospective review; Tertiary care center. A total of 39 patients who visited our clinic for dizziness from 2014 to 2017. The gain of vestibulo-ocular reflex, refixation saccades, and artifacts were analyzed using vHIT. We analyzed 691 individual vHIT traces and categorized the artifacts into 8 categories. Twenty-three males and 16 females were included. The mean age was 13.84 ± 2.60 years (range, 7–18). Common causes of dizziness were benign paroxysmal vertigo of childhood (25.6%), vestibular neuritis (20.5%), and vestibular migraine (17.9%). The sensitivity and specificity of vHIT based on the bithermal caloric test results were 40% and 94%, respectively. The analysis of vHIT traces revealed that the children had higher artifact ratios of vHIT than the adults. The main artifacts were high gain and blinking eyes. The vHIT results showed a higher percentage of artifacts in children than in the adults. More careful efforts are required to obtain more accurate results during the test, and it is necessary to check for technical errors while interpreting the results. [ABSTRACT FROM AUTHOR]