Presents as a sudden severe headache, often described as "the worst headache of life," with nausea, vomiting, and photophobia.
Examination can be normal or may reveal altered consciousness, meningismus, intraocular hemorrhages, or focal findings.
Computed tomography (CT) indicated if subarachnoid hemorrhage is clinically suspected. Lumbar puncture is indicated if CT is unrevealing. Cerebral angiography confirms the presence of aneurysms.
Initial stabilization followed by surgical clipping or endovascular coil embolization is standard therapy.
Complications are common and include rebleeding, acute hydrocephalus, and delayed cerebral ischemia.
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space and is an emergency. The most common cause of nontraumatic SAH is intracranial aneurysm.  Aneurysmal SAH causes substantial morbidity and mortality. When a cerebral aneurysm ruptures, blood flows into the subarachnoid space, sometimes seeping into brain parenchyma and/or ventricles. The sudden increase in intracranial pressure, as well as the destructive and toxic effects of blood on brain parenchyma and cerebral vessels, accounts for most complications.
Neurology and Neurosurgery
Washington University School of Medicine
SK is an author of a reference cited in this monograph.
Dr Salah Keyrouz would like to gratefully acknowledge Dr Michael N. Diringer, a previous contributor to this monograph. MND is an author of a number of references cited in this monograph.
Department of Neurology and Rehabilitation
University of Illinois at Chicago
VA declares that he has no competing interests.
PM declares that he has no competing interests.
Aggregate Professor of Neurosurgery
Department of Clinical Neuroscience
University of Palermo
GG declares that he has no competing interests.
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