Persistent positive visual phenomena in migraine.

Ten patients with migraine developed persistent positive visual phenomena lasting months to years. The complaints were similar in their simplicity and involvement of the entire visual field and usually consisted of diffuse small particles such as TV static, snow, lines of ants, dots, and rain. Neurologic and ophthalmologic examinations were normal, and EEGs were normal in eight of eight patients tested. MRI was normal in all patients except one who had nonspecific biparietal white matter lesions and another with a small venous angioma. Treatment of this unusual complication of migraine was unsuccessful.