Acute sensorineural hearing loss with vertigo due to vascular events in the vertebrobasilar system is diagnostically challenging, especially if signs of central nervous system involvement are minimal. We report herein on the clinical course and diagnostic process of a 60-year-old woman who presented with acute sensorineural hearing loss and vertigo caused by a dissecting aneurysm in the vertebral artery. Brain magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), single-photon emission computed tomography (SPECT), and a lumbar puncture revealed a dissecting aneurysm in the left vertebral artery with no evidence of ischemic lesions or subarachnoid hemorrhage. Dysfunction in the cerebellum was suggested by saccadic pursuit and truncal ataxia. The patient underwent anticoagulant therapy for 1 year, following which the isolated cavity of the dissecting aneurysm reduced in size as observed on brain MRI. In addition, significant improvements were seen in her gait and hearing level. The patient can now walk normally and has suffered no relapse of symptoms. (152 words)