Significance of scintillating scotoma of late onset.

Scintillating hemianopic scotomas are usually caused either by migraine or, more rarely, vertebral-basilar insufficiency. We report two patients in whom this symptom was probably caused by platelet microthrombi in pial vessels of the visual cortex. These patients were similar in that they had scintillating scotomas which began after the age of fifty and abnormal platelet aggregability. Since increased platelet aggregability is associated with cerebral vascular accidents and is treatable, older patients who develop teichopsias should have appropriate hematological tests.