Intermittent downbeat nystagmus due to vertebral artery compression.

Downbeat nystagmus (DBN) uncommonly occurs as a transient phenomenon, and it rarely occurs in patients with cerebrovascular disease. We observed a patient with intermittent DBN and lightheadedness due to transient obstruction of his dominant vertebral artery when he turned his head to his left side. Surgical removal of an osteophyte at the site of the angiographically demonstrated lesion relieved his symptoms.