Vertebrobasilar insufficiency is a functional deficit of the inner ear, brainstem, cerebellum and other tissues due to impaired blood supply to the vertebrobasilar system. The common symptom is vertigo, but there are usually other brainstem manifestations, such as perioral numbness, transient hearing loss, diplopia, nystagmus, dysarthria, ataxia, and bilateral cone bundle signs. Exclusion of inner ear and vagal pathology is sufficient to confirm the diagnosis. Common etiologies are vertebrobasilar artery sclerosis and compression of the vertebral artery by degenerative changes of the cervical spine. Trauma to the vertebral artery, theft of blood from the subclavian artery, or theft of blood due to occlusion of the carotid artery can also cause symptoms of inadequate blood supply to the vertebrobasilar artery.