• Home

Home > Medical Reference > Encyclopedia (English)

Toggle: English / Spanish

Subarachnoid hemorrhage

• Overview
• Symptoms
• Treatment
• Prevention

Definition:

Subarachnoid hemorrhage is bleeding in the area between the brain and the thin tissues that cover the brain. This area is called the subarachnoid space.

Alternative Names:

Hemorrhage - subarachnoid

Causes, incidence, and risk factors:

Subarachnoid hemorrhage can be caused by:

• Bleeding from an arteriovenous malformation (AVM)
• Bleeding disorder
• Cerebral aneurysm rupture
• Head injury
• Unknown cause (idiopathic)
• Use of blood thinners

Injury-related subarachnoid hemorrhage is often seen in the elderly who have fallen and hit their head. Among the young, the most common injury leading to subarachnoid hemorrhage is motor vehicle crashes.

Subarachnoid hemorrhage due to rupture of a cerebral aneurysm occurs in approximately 10-15 out of 10,000 people. However, some studies suggest that number may be slightly lower. Subarachnoid hemorrhage due to rupture of a cerebral aneurysm is most common in persons age 20 to 60. It is slightly more common in women than men.

Risks include:

• Aneurysms in other blood vessels
• Disorders associated with aneurysm or weakened blood vessels
• Fibromuscular dysplasia (FMD) and other connective tissue disorders
• High blood pressure
• History of polycystic kidney disease
• Smoking

A strong family history of aneurysms may also increase your risk.

References:

Kirmani JF, Alkawi A, Ahmed S, et al. Endovascular treatment of subarachnoid hemorrhage. Neurol Res . 2005;27 Suppl 1:103-7.

Edlow JA. Diagnosis of subarachnoid hemorrhage. Neurocrit Care . 2005;2(2):99-109.

Bird S. Failure to diagnose: subarachnoid haemorrhage. Aust Fam Physician . 2005 Aug;34(8):682-3.

Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice . 5th ed. St. Louis, Mo: Mosby; 2002:2362-2363.

• Review Date: 6/7/2007
• Reviewed By: Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.