"Release hallucinations" as the major symptom of posterior cerebral artery occlusion: a report of 2 cases.

Visual hallucinations were the presenting symptoms in 2 patients with probable infarcts in the territory of a posterior cerebral artery. They occurred in areas of paracentral scotomas, right in Patient 1 and left in Patient 2. In Patient 1 they were formed, prolonged, and not apparently related to past experience. In Patient 2 they were at first paroxysmal and unformed, with more prolonged metamorphopsia; later there appeared to be palinoptic formed images, possibly postictal in nature. Such hallucinations appear to be of a "release" type, and may be more common than is generally appreciated in patients with posterior cerebral artery occlusion.