Thunderclap headache

Purpose of Review: A thunderclap headache is a very severe headache that reaches its maximum intensity within 1 minute. Patients with thunderclap headache must be evaluated emergently and comprehensively to rule out underlying disorders that can be associated with high mortality and morbidity, determine the cause for the thunderclap headache, and initiate targeted therapy. This review presents an up-to-date summary on the clinical presentation, diagnostic evaluation, and causes of thunderclap headache. Recent Findings: Numerous etiologies for thunderclap headaches have been identified, with the most common causes being subarachnoid hemorrhage and reversible cerebral vasoconstriction syndrome. Other relatively common causes include cervical artery dissection, cerebral venous sinus thrombosis, and spontaneous intracranial hypotension. Although ''primary'' thunderclap headache is typically accepted to exist, it may be that such cases represent missed diagnoses of underlying causes. The urgent evaluation of the patient with thunderclap headache includes brain CT, followed by lumbar puncture if the brain CT is nondiagnostic. If a diagnosis is not reached following brain CT and lumbar puncture, brain MRI and imaging of the brain and cervical vasculature are indicated. Summary: Patients with thunderclap headache require an emergent and comprehensive evaluation to identify the underlying cause and to initiate appropriate therapy.