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Abstract: Objectives: This paper aims to determine the frequency of isolated labyrinthine infarction as an initial manifestation of anterior inferior cerebellar artery (AICA) territory infarction and discuss its clinical implication. Methods: We studied 54 consecutive patients with AICA infarction diagnosed by brain MRI from the acute stroke registry. Results: We identified 4 patients (7.4%) with AICA territory infarction who initially presented with vertigo and hearing loss mimicking acute labyrinthitis and subsequently suffered from delayed neurological deficits. All patients had normal brain MRIs including diffusion-weighted images at the time of isolated audiovestibular loss, but all subsequently exhibited acute infarct(s) in the AICA territory on follow-up brain MRIs when they developed additional neurological deficits. Conclusion: Labyrinthine infarction may be a warning sign of impending pontocerebellar infarction in the AICA territory. Our results indicate that even a classical peripheral presentation, e.g., acute hearing loss, and acute vertigo with unidirectional nystagmus, may be a manifestation of ischemic stroke in the posterior circulation. [Copyright &y& Elsevier]

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]

Diagnosis of combined peripheral and central vestibulopathy remains a challenge since the findings from peripheral vestibular involvements may overshadow those from central vestibular disorders or vice versa. The aim of this study was to enhance detection of these intriguing disorders by characterizing the clinical features and underlying etiologies. We had recruited 55 patients with combined peripheral and central vestibulopathy at the Dizziness Clinic of Seoul National University Bundang Hospital from 2003 to 2013. Peripheral vestibular involvement was determined by decreased caloric responses in either ear, and central vestibulopathy was diagnosed with obvious central vestibular signs or the lesions documented on MRIs to involve the central vestibular structures. Combined peripheral and central vestibulopathy could be classified into four types according to the patterns of vestibular presentation. Infarctions were the most common cause of acute unilateral cases while cerebellopontine angle tumors were mostly found in chronic unilateral ones. Wernicke encephalopathy and degenerative disorders were common in acute and chronic bilateral disorders. Twenty five (45.5%) patients showed only vestibular findings with or without auditory involvements, but association with gaze-evoked nystagmus, impaired smooth pursuit or central types of head shaking nystagmus indicated a central vestibular involvement in most of them (23/25, 92.0%). Given the requirements for urgent treatments and potentially grave prognosis of combined vestibulopathy, central signs should be sought even in patients with clinical or laboratory features of peripheral vestibulopathy. Scrutinized bedside evaluation, however, secured the diagnosis in almost all the patients with combined vestibulopathy. [ABSTRACT FROM AUTHOR]

Objective: To evaluate how often the positive sign of HINTS (Head-Impulse, Gaze Evoked Nystagmus, Test of Skew) appears in patients with acute peripheral vestibular lesion, HINTS findings were quantitatively measured and analyzed in patients with peripheral vestibulopathy accompanying spontaneous nystagmus.Methods: HINTS was evaluated in 14 vertigo patients with spontaneous nystagmus. Horizontal vestibulo-ocular reflex (VOR) gain was measured using the video head impulse test (vHIT). To evaluate gaze-evoked nystagmus (GEN), slow-phase velocities at different points of lateral gaze were measured and plotted, then the slope and its inverse value, the neural integrator time constant, were calculated. Skew deviation was tested using anaglyph filters to simulate the alternate cover test, and the degree and latency of vertical eyeball deviation were measured. The ABCD2 score was calculated to evaluate the risk of stroke.Results: Among 13 patients of peripheral vestibulopathy, 7 showed positive signs in HINTS (normal vHIT: 5, direction-changing GEN: 0, skew deviation: 3). One patient with a cerebellopontine angle tumor presented with both a peripheral and central pattern and showed positive HINTS findings (presence of direction-changing GEN). The mean VOR gain of patients with abnormal vHIT was 0.58±0.29 and 1.10±0.11 in the affected and contralateral side, respectively, while those in patients with normal vHIT were 1.04±0.21 and 1.13±0.12, respectively. The neural integrator time constant calculated from the mean slope of horizontal slow-phase velocity according to horizontal eye position was 42.9 s. The mean vertical eyeball deviation of patients with positive skew was 2.14±1.18° while uncovering the eye on the affected side, and -1.97±1.59° while uncovering the eye on the unaffected side. The median ABCD2 score of 14 patients was 2 (range, 1-3).Conclusions: HINTS findings were objectively measured in vertigo patients with spontaneous nystagmus. Although positive findings of HINTS have been recognized as a central sign, 54% (7/13) of cases with peripheral vestibulopathy showed positive HINTS signs. HINTS results should be interpreted carefully considering that a substantial proportion of peripheral vestibulopathy shows a positive HINTS sign. [ABSTRACT FROM AUTHOR]

• Falls were not associated with cVEMP or oVEMP abnormalities. • Falls were associated with higher MDS-UPDRS-III scores. • cVEMP and oVEMP amplitudes were not associated with disease duration or disease severity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Patients with isolated internuclear ophthalmoplegia (INO) frequently show abnormal ocular vestibular evoked myogenic potentials (VEMPs) in response to forehead tapping in the lesion side. [•] The medial longitudinal fasciculus (MLF) appears to contain the fibers for the otolith-ocular reflex from the contralateral ear. [•] The abnormal cervical VEMPs in some patients with isolated INO suggest a modulatory pathway for the inhibitory sacculocollic reflex descending in the MLF. [ABSTRACT FROM AUTHOR]

Abstract: Paroxysmal reversal of spontaneous nystagmus has rarely been described. Herein, we report recurrent bouts of vertigo and oscillopsia in association with reversed spontaneous nystagmus in a patient with prior surgical resection of the cerebellar vermis due to medulloblastoma and subsequent labyrinthine damage. The symptoms almost completely resolved with carbamazepine. The episodes may be ascribed to paroxysmal reversal of the vestibular asymmetry due to intermittent decompensation by the deficient cerebellum. [Copyright &y& Elsevier]

The clinical features of a lesion confined to the superior cerebellar peduncle (SCP) have not been defined well in human. A 92-year-old woman suddenly developed mild dysarthria and severe imbalance from an isolated unilateral SCP infarction, and examination showed ipsiversive ocular torsion, severe ipsilesional limb ataxia, and truncal ipsipulsion. These findings are well consistent with those observed in monkeys when the SCP was severed. In addition to the dentate-rubro-thalamic projections, the SCP appears to contain the fibers involved in the control of eye motion in the roll plane. [ABSTRACT FROM AUTHOR]

Highlights • Amplitude of cervical vestibular-evoked myogenic potentials (cVEMP) representing saccule-related neural function decreases with ageing. • Decreased estimated glomerular filtration rate (eGFR) is associated with reduced cVEMP amplitudes. • The deleterious effect of free T4 on cVEMP amplitude occurs in younger subjects but not in older ones. Abstract Objective This study attempted to identify systemic factors for age-related decline in neural function originating from the saccule using cervical vestibular-evoked myogenic potentials (cVEMP) parameters. Methods We recruited 129 symptomatic vertiginous patients who did not have known disorder affecting the cVEMP pathway (mean age = 52.4 ± 13.9). The indicators of saccule-related neural function were the sum of normalized cVEMP amplitude (SNA) and the average of p13 latency on both sides (average latency, AL). Any associations between cVEMP and systemic factors were evaluated using a linear regression. Result SNA decreased with ageing (p < 0.001) in univariable regression. The estimated glomerular filtration rate (eGFR) was positively associated with SNA (p = 0.002). Hematocrit, C-reactive protein, vitamin D, and free thyroxine (T4) showed a trend of association with SNA (p < 0.2). SNA was associated with ageing, increased free T4, and decreased eGFR in multivariable analysis. In the subgroup analysis, SNA was significantly associated with free T4 in younger patients (mean age = 41.5 ± 9.91) but not in the older ones (mean age = 63.5 ± 6.54). AL did not show any significant associations with systemic factors. Conclusion Decreased eGFR and increased free T4 as well as aging may be risk factors for decline of saccule-related neural function. Significance Neural function originating from the saccule may be affected by systemic factors. [ABSTRACT FROM AUTHOR]

Objective Perverted downbeat head-shaking nystagmus (pdHSN) has been considered a sign of central pathology. Two hypotheses have been advanced as the mechanisms of pdHSN without proper validation. This study aimed to elucidate the mechanism of pdHSN. Methods Eighteen patients with pdHSN due to central lesions were subjected to analyses of their oculographic characteristics. The peak velocity, temporal features including the duration and time constant (TC), rotational axis of pdHSN were analyzed. To determine the most relevant mechanism of pdHSN, we compared the TCs of pdHSN with those of downbeat nystagmus after vertical head-shaking in four subjects, and with the TCs of horizontal head-shaking nystagmus (HSN) in three subjects who had both horizontal and downbeat nystagmus after head-shaking. Results The duration of pdHSN ranged from 14 to 25 s and the estimated TC was from 3.9 to 7.8 s. When the data were pooled after the intensities of the nystagmus in each patient were normalized, the TC was 5.2 (95% CI = 5.0–5.4) seconds from nonlinear regression test. The rotational vectors of pdHSN ( n = 8) were mostly aligned between the anterior semicircular canals. The estimated TC of downbeat nystagmus after vertical head-shaking (5.8 s) was similar to that of pdHSN (6.0 s) in four subjects tested. In contrast, the TC of horizontal HSN (10.9 s) was significantly larger than that of pdHSN (4.9 s) in three subjects. Conclusions The characteristics of TCs of HSN in our patients with central lesions suggest that pdHSN is due to enhanced activities of the central anterior canal pathway. Significance pdHSN is a sign indicative of central pathology causing cerebellar dysfunction, especially when it associated with other neuro-otological signs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rats well tolerate global cerebral ischemia up to 20min during 4-vessel occlusion. [•] Among the vestibular structures, the medial vestibular nucleus (MVN) is most vulnerable to ischemia in rats. [•] The frequent occurrence of isolated vascular vertigo in human is supported by the selective ischemic vulnerability of MVN confirmed in this experiment. [•] The 4-vessel occlusion adopted in the study may be easily utilized to induce posterior circulation ischemia in rats. [ABSTRACT FROM AUTHOR]

Abstract: A 74-year-old woman with sudden vertigo and dysarthria showed spontaneous nystagmus beating rightward, upward and clockwise. She also exhibited dysfunction of the left utricle and superior and horizontal canals, which was documented by head impulse and heave tests, measurements of ocular torsion and subjective visual vertical tilt, bithermal caloric tests, and rotation axis analysis of the spontaneous nystagmus. In contrast, functions of the left posterior canal, saccule, and cochlea were remained intact, as evidenced by normal head impulse test, audiometry and vestibular evoked myogenic potential. MRI revealed an acute infarction in the left lateral pons of anterior inferior cerebellar artery (AICA) territory. Our patient with AICA infarction showed isolated damage to the superior vestibular labyrinth or its afferents with preservation of the inferior vestibular labyrinth and auditory function. Our patient provides further evidence that isolated damage to the superior vestibular labyrinth or its afferents may be a mechanism of isolated vascular vertigo. [Copyright &y& Elsevier]