Perverted Head Impulse Test in Cerebellar Ataxia
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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 . Positive HIT can be observed in central vestibulopathies, in addition to peripheral vestibulopathies [2, 3, 4]. 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 [2, 3, 4]. 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.
KeywordsCerebellar Ataxia Head Impulse International Cooperative Ataxia Rate Scale Cerebellar Disease Head Impulse Test
Conflict of interest
All authors report no disclosures.
The video demonstrates upward deflection during horizontal head impulse. (WMV 4513 kb)
Dissociated gain of vertical head impulse, i.e., decreased during upward pitch and increased during downward pitch, is shown on video clip. (WMV 1772 kb)
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