Persistent trigeminal artery as a cause of dizziness.

Complaints of vertigo and dizziness are common problems referred to otolaryngologists for evaluation. Awareness of uncommon causes of dizziness increases the physician's ability to diagnose and treat these patients. We present the case of a middle-aged woman who presented with episodes of vertigo and symptoms suggestive of vertebrobasilar insufficiency. These symptoms were the result of a persistent trigeminal artery (PTA) and occlusive carotid artery disease. A PTA is a carotid-basilar anastomosis that has been reported to be demonstrated on 0.1% to 0.6% of all cerebral angiograms. Persistence of this vessel usually leads to hypoplasia or agenesis of the ipsilateral posterior communicating artery, and leaves the internal carotid artery as the main source of blood supply to the region of the upper brainstem. The appearance and clinical significance of this unusual condition will be discussed.