Isolated Flocculus Infarction Mimicking Acute Labyrinthitis

Acute vestibular syndrome characterized by vertigo, spontaneous nystagmus, and postural instability is caused by a unilateral injury to either peripheral or central vestibular structures. However, central vestibular syndromes, such as labyrinthine ischemia due to occlusion of anterior inferior cerebellar artery (AICA), may cause abrupt unilateral labyrinthine dysfunction that mimics peripheral vestibulopathy. Here we report an AICA infarction with isolated flocculus lesion on magnetic resonance imaging mimicking acute labyrinthitis with vertigo, unidirectional horizontal-torsional nystagmus, ipsilesional sensorineural hearing impairment, and positive head-thrust test without any typical findings of floccular lesion. J Korean Neurol Assoc 29(3):241-245, 2011