Headache Differential

Headache assessment is a triage problem before it is a labeling problem. A familiar migraine pattern may support routine treatment, but a new feature can move the patient immediately toward emergency investigation. Migraine pain reflects trigeminovascular activation and CGRP release; secondary headaches arise from another process, such as hemorrhage, infection, raised intracranial pressure, venous thrombosis, or giant cell arteritis. The bedside questions are therefore: does this fit a primary headache, and is there a red flag that changes what must happen first? A normal neurological examination lowers concern in a typical recurrent pattern; it does not override thunderclap onset, papilledema, systemic illness, or a major pattern change.