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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 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]

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]

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]