Subarachnoid hemorrhage

Christopher Kramer MD (

Dr. Kramer of the University of Chicago has no relevant financial relationships to disclose.

James R Brorson MD (Dr. Brorson of the University of Chicago received consulting fees from the National Peer Review Corporation and Medico-legal Consulting.)
Steven R Levine MD, editor. (

Dr. Levine of the SUNY Health Science Center at Brooklyn has no relevant financial relationships to disclose.

Originally released April 10, 1995; last updated April 6, 2020; expires April 6, 2023

This article includes discussion of subarachnoid hemorrhage and subarachnoid haemorrhage. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Subarachnoid hemorrhage is among the most devastating neurologic events, and yet the outcome can be very favorable in well-managed cases. Here, clinical features and treatment of spontaneous subarachnoid hemorrhage are reviewed. Evolving trends in the emergency room diagnosis of subarachnoid hemorrhage are critically discussed. Secondary complications of subarachnoid hemorrhage, including aneurysm rebleeding, hydrocephalus, hyponatremia, seizures, delayed cerebral ischemia, and associated cardiopulmonary ailments play a major role in determining outcome, and their management is discussed. Recommendations from published national guidelines for the management of aneurysmal subarachnoid hemorrhage are included.

Key points


• Subarachnoid hemorrhage, often occurring from rupture of an intracranial aneurysm, constitutes a life-threatening neurologic emergency.


• Subarachnoid hemorrhage typically presents with a sudden severe headache and neck stiffness, and can be complicated by fatal rebleeding, arterial vasospasm producing ischemia, seizures, metabolic derangements, and venous thrombosis.


• The diagnosis of subarachnoid hemorrhage is usually confirmed by a noncontrast head CT, which has very high sensitivity in the initial hours following headache onset. Failure to diagnose subarachnoid hemorrhage can have fatal consequences.


• Traditionally a lumbar puncture has been recommended after a negative head CT when subarachnoid hemorrhage is suspected, but there is an evolving acceptance of noninvasive evaluation for aneurysm with CT angiogram when initial plain CT is negative for a suspected hemorrhage.


• Securing of the underlying ruptured aneurysm with surgical clipping or endovascular coiling should be performed as soon as possible to limit the chance of aneurysm rebleeding.


• Treatment in a specialized neurointensive care setting is necessary to address the diverse possible complications including delayed cerebral ischemia and metabolic derangements.

Historical note and terminology

Subarachnoid hemorrhage is a devastating condition, often resulting in severe neurologic disability or death, in which blood extravasates into the subarachnoid space between the arachnoid membrane and the pia mater. The majority of nontraumatic subarachnoid hemorrhages are due to the rupture of saccular intracranial aneurysms. Early autopsy descriptions of aneurysmal subarachnoid hemorrhage included “Observations on the Sanguineous Apoplexy” of Giovanni Morgagni (1682-1771) and the documentation of bilateral carotid aneurysms in a patient presenting with apoplexy and headache by Gilbert Blane (1749-1834) (DiLuna et al 2004). However, it was not until the end of the 19th century, due in part to the more detailed description of the signs and symptoms of subarachnoid hemorrhage and the advent of the lumbar puncture procedure, that the diagnosis of subarachnoid hemorrhage could be made. In 1927, Egaz Moniz was the first to successfully carry out cerebral angiography, enabling confirmation of the diagnosis of ruptured intracranial aneurysm in those patients presenting with signs and symptoms of subarachnoid hemorrhage (Moniz et al 1928). In 1973, computed tomography was introduced, allowing for direct noninvasive visualization of intracranial contents, thus facilitating the diagnosis of subarachnoid hemorrhage. Craniotomy with microsurgical clip obliteration was the main treatment method for aneurysms until 1991, when Guglielmi introduced the endovascular occlusion of aneurysm with electrolytically detachable coils (Connolly et al 2012). Since then, new advances in endovascular treatment have emerged, providing a widening array of options for treating aneurysms with challenging anatomy or location.

The content you are trying to view is available only to logged in, current MedLink Neurology subscribers.

If you are a subscriber, please log in.

If you are a former subscriber or have registered before, please log in first and then click select a Service Plan or contact Subscriber Services. Site license users, click the Site License Acces link on the Homepage at an authorized computer.

If you have never registered before, click Learn More about MedLink Neurology  or view available Service Plans.

Find out how you can join MedLink Neurology