Acute Vestibular Syndrome With Skew Deviation and Positive Head Impulse Test Due to a Demyelinating Lesion

This is a patient who initially presented with the acute vestibular syndrome (AVS, e.g., acute prolonged vertigo, spontaneous nystagmus). ; See https://collections.lib.utah.edu/details?id=187730 for additional history. ; Her HINTS (Head Impulse, Nystagmus, Test of Skew) testing indicated a central etiology based on the presence of a skew deviation and gaze-evoked (direction-changing) nystagmus. However, she also had a + head impulse test (HIT), which is typically a peripheral sign. 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. In the AVS, a negative (normal) HIT is more helpful since it is highly suggestive of a central etiology. A + HIT at the bedside must be seen to diagnose a peripheral etiology like vestibular neuritis with a high degree of confidence, although a + HIT can be occasionally seen with central or vascular etiologies, especially with labyrinthine ischemia or a lesion involving the vestibular nucleus. Her MRI showed an acute demyelinating plaque involving the left lateral medulla.