脳底動脈解離後に生じた高度感音難聴例

Abstract

A 55-year-old woman suddenly noticed right hearing loss and tinnitus. Several days later, she lost consciousness, and was referred to Ehime Prefectural Central Hospital. Computed tomography (CT) showed subarachnoidal hemorrhage at the right cerebellopontine angle. However, subsequent CT-angiography and four-vessel cerebral angiography could not detect the exact cause of hemorrhage, such as aneurysm and arterial dissection. When she regained consciousness a few days later, she noticed worsening of right hearing loss and dizziness. Pure-tone audiogram showed complete deafness in the right ear. Distortion product otoacoustic emission and auditory brainstem response were not elicited in the right ear. Caloric test demonstrated canal paresis of the right ear with normal response in visual suppression. There were no neurological deficits other than right VIIIth nerve damage. Cerebral infarction and vasospasm were negative in magnetic resonance imaging (MRI) and MR-angiography performed on the 5th day. One month after onset, four-vessel angiogram demonstrated stenosis of the basilar artery near the branching site of AICA. These findings suggested that her deafness and disequilibrium were due to inner ear ischemia caused by dissection of the basilar artery, which also caused subarachnoidal hemorrhage.