Visual Phenomena Associated With Migraine and Their Differential Diagnosis.

BACKGROUND: Visual phenomena are of many different kinds; their differential diagnosis is usually possible with directed history-taking. In this review, we describe common visual phenomena that must be distinguished from a migraine aura.
METHODS: This review is based on publications retrieved by a selective search in PubMed and the Web of Knowledge/Science, with special attention to the current classification of the International Headache Society and the recommendations of the German Migraine and Headache Society. The following search terms were used: "visual phenomena/phenomenon," "migraine aura," and "persistent/complication/ long-lasting/ongoing."
RESULTS: The most helpful questions for differential diagnosis are whether the symptoms are present in one eye only or in both, whether their onset was sudden or over minutes or days, and whether the phenomenon has occurred only once or repeatedly, or is persistently present. A visual aura associated with migraine must be distinguished, in rare cases, from an isolated epileptic aura, from cerebral/retinal ischemia, or from visual snow. Further differential diagnoses include a persisting perceptual disturbance after hallucinogen use (HPPD, "hallucinogen persisting perception disorder") and the Charles Bonnet syndrome (CBS); the latter arises as a consequence of severely impaired vision. Posterior reversible encephalopathy syndrome (PRES) is rare and generally reveals itself over its further course through the appearance of additional clinical manifestations. Primary ophthalmological causes can usually be readily identified and classified by ophthalmological examination.
CONCLUSION: Patients with visual phenomena typically consult physicians from various medical specialties. A correct differential diagnosis can be made based on the history if the physician views the symptoms in their overall context to determine the particular disease entity that is responsible.