Migraine equivalents and complicated migraine.

Migraine equivalents and complicated migraine are entities in which definition is difficult, presentations are pleomorphic, diagnosis is treacherous, pathophysiology is obscure, and treatment is uncertain. A useful principle is to regard them as diagnoses of exclusion that require aggressive and comprehensive investigation. Rational treatment consists of migraine prophylaxis using agents with minimal vasospastic potential and, in some cases, acetylsalicylic acid for platelet disaggregation. The prognosis for both complicated migraine and migraine equivalents is good; when patients with these diagnoses come to harm, it is often because the diagnosis is incorrect.