Persistent migraine aura in an adolescent girl.

A 14-year-old girl presented with a prolonged migraine visual aura of several weeks' duration. Symptoms gradually resolved over a 6-week period, with no recurrence of visual aura over a 20-month follow-up period. Although there is significant overlap between the features of stereotypical and persistent migraine auras, or "visual snow," the latter tend to be unformed and can occupy the entire visual field of both eyes. To our knowledge, this phenomenon has been reported only twice before in children. Recognition of its features will allow the pediatric ophthalmologist to differentiate persistent visual aura from visual hallucinations.