Severe Headache

Clinical Overview

Clinical Definition: Acute severe headache is a highly prevalent emergency department presentation requiring swift, methodical neurological differentiation to rule out lethal structural intracranial pathologies, preeminently Subarachnoid Hemorrhage (SAH), from benign functional cephalgias. Clinical Significance: Constitutes globally up to 2-4% of all ED volume. Morbidity severity scales dramatically with the presence of the "Thunderclap Headache" phenomenology—defined as instantaneous pain reaching absolute maximum explosive intensity generally under 5 minutes. High-Morbidity Differentials: Aneurysmal SAH, Bacterial Meningitis/Viral Encephalitis, Cerebral Venous Sinus Thrombosis (CVST), and Giant Cell Arteritis (GCA) carrying catastrophic irreversible neuro-ophthalmologic sequelae.