Head-Shaking Aids in the Diagnosis of Acute Audiovestibular Loss due to Anterior Inferior Cerebellar Artery Infarction

Objective: To determine the patterns and diagnostic value of head-shaking nystagmus (HSN) in patients with acute audiovestibular loss. Method: Eighteen patients underwent evaluation of spontaneous nystagmus, gaze-evoked nystagmus, HSN, head impulse test, ocular tilt reaction, subjective visual vertical, bithermal caloric tests, and pure-tone audiogram. The findings were compared with those of 21 patients with labyrinthitis. Results: Fifteen patients (83%) exhibited HSN, and the horizontal HSN usually beat contralesionally (10/14, 71%). However, 9 (50%) patients also showed patterns of central HSN that included perverted HSN (n = 7), HSN in the opposite direction of spontaneous nystagmus (n = 4), and HSN beating towards unilateral canal paresis or abnormal head impulse testing (n = 3). Overall, central HSN, gaze-evoked nystagmus, and normal head impulse testing were specific for anterior inferior cerebellar artery (AICA) infarction. Moreover, central HSN was the only sign that indicated stroke in 1 of our patients with isolated audiovestibular syndrome. Lesion subtraction analyses revealed that damage to the flocculus was relatively frequent in patients with perverted HSN. Conclusions: In AICA infarction, HSN was common with both peripheral and central patterns. Careful evaluation of HSN may provide clues for AICA infarction in patients with acute audiovestibular loss. Copyright (C) 2012 S. Karger AG, Basel