Acute Vestibular Syndrome with Ocular Tilt Reaction Due to Bacterial Labyrinthitis

This is a patient who initially presented with the acute vestibular syndrome (AVS, e.g., acute prolonged vertigo, spontaneous nystagmus) and right sided hearing loss, and was diagnosed with bacterial labyrinthritis. Her HINTS (Head Impulse, Nystagmus, Test of Skew) testing indicated a central etiology based on the presence of a skew deviation. In fact, there was a complete ocular tilt reaction - 1) skew deviation with right hypotropia (ipsilateral to the affected ear), 2) right head tilt, and 3) ocular counterroll (excylodeviation OD and incyclodeviation OS). Nystagmus was unidirectional (left-beating or contralesional), and there was a + head impulse test to the ipsilesional side, which are both typically seen with peripheral pathology. However, if any of the 3 ocular motor/vestibular tests suggest a central localization, the etiology must be assumed to be central until proven otherwise. Although a skew deviation is classically a central sign, rarely a severe peripheral utricular injury (e.g., bacterial labyrinthitis) can result in diplopia and a clinically evident skew deviation. MRI was done at one week, which did not demonstrate abnormalities of the posterior fossa, specifically regarding the central utricle-ocular motor pathways.