Posterior inferior cerebellar artery aneurysm associated with fenestration of the vertebral artery--case report.

A 72-year-old male hospitalized for disturbance of consciousness and vomiting was found to have a left vertebral artery fenestration and a left posterior inferior cerebellar artery aneurysm. The aneurysm was successfully clipped through the lateral suboccipital approach and he recovered with minimal deficits. The association of vertebral artery fenestration and posterior inferior cerebellar artery aneurysm is rare, and their etiologies and relationship are discussed.