Transient Positive Horizontal Head Impulse Test in Pregabalin Intoxication.

Head impulse test (HIT) is helpful to understanding high-frequency vestibulo-ocular reflex in patients with dizziness and imbalance. There are some reports on abnormal HITs in cerebellar disorder. To our knowledge, there was no report of transient bilateral positive head impulse related to antiepileptic drugs. A 65-year-old woman developed dizziness and imbalance after treatment with pregabalin for pain control of radiation cystitis. Neurological examination exhibited positive bilateral HIT results, in addition to ataxia and gaze-evoked rebound nystagmus. Pregabalin intoxication can evoke transient positive horizontal head impulse test as another indicator of cerebellar dysfunction.