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Cerebellum (2013) 12:773775
DOI 10.1007/s12311-013-0480-0
LETTER TO THE EDITOR
Perverted Head Impulse Test in Cerebellar Ataxia
Seong-Hae Jeong & Ji-Soo Kim & In Chul Baek &
Jong Wook Shin & Hyunjin Jo & Ae Young Lee &
Jae-Moon Kim
Published online: 18 April 2013# Springer Science+Business Media New York 2013
Introduction
In the bedside head impulse test (HIT), the clinician identifies the catch-up saccades after head rotation as an indirect sign of vestibulo-ocular reflex (VOR) deficit [1]. Positive HIT can be observed in central vestibulopathies, in addition to peripheral vestibulopathies [24]. Recent reports proposed that a positive HIT in these patients with preserved caloric response is most likely due to cerebellar flocculus dysfunction, considering the findings of earlier studies related to high-frequency VOR [24]. Also, the dysconjugate upward eye deflection during yaw head impulse was also observed in patients with cerebellar disease [5, 6].
Here, we first documented video clips of upward trajectories during horizontal head impulses in a patient with cerebellar ataxia, i.e., perverted HIT, which could be another feature of positive HIT in central vestibulopathies.
Case
A 62-year-old woman presented with severe imbalance and dysarthria following fever, cough, and myalgia for 3 days.
She had taken antipsychotics such as lithium, carbamaze-pine, and clonazepam for about 10 years for the management of underlying bipolar disorder. At the emergency room, her vital signs were stable, with the exception of high temperature (up to 39 C). Scanning speech and severe truncal ataxia were noted. Spontaneous downbeat nystagmus (2/s) was observed without fixation, and it was augmented by downward gaze (2.7/s), lateral gaze (2.2/s), head shaking (6/s), and straight head-hanging position(13.5/s). The range of eye motion was normal. Slow saccades were noted in both the horizontal and vertical directions. The gain of smooth pursuit eye movements was also decreased. The downward smooth pursuit eye movements were more impaired than the upward ones. The patient showed upward trajectories during horizontal head impulses (Electronic Supplementary Material...