Subarachnoid Hemorrhage (SAH)

Subarachnoid hemorrhage is bleeding in the brain, in the space between the brain and the membrane that covers the brain.

Subarachnoid hemorrhage may be due to the following disorders:

  • Arteriovenous malformation (AVM) leading to bleeding
  • Use of blood thinners
  • A cerebral aneurysm that can bleed.
  • Head injury
  • A blood disorder that results in easy bleeding, such as hemophilia

Elderly people are are at risk of falling and hitting their heads. Among younger patients, a motor vehicle accident (MVA) is the most common injury leading to subarachnoid hemorrhage.

The risk of developing SAH increase in those:

  • with an aneurysm in other blood vessels
  • high blood pressure
  • who smoke
  • with a family history of aneurysms.

Symptoms of Subarachnoid Hemorrhage

A severe headache is the primary symptom. The headache usually starts suddenly and is often worse near the back of the head. Patients often describe it as the "worst headache ever" and unlike any other type of headache pain. The headache may start after a popping or snapping feeling in the head.

Other symptoms may include:

  • Decreased alertness
  • Eye discomfort in bright light (photophobia)
  • Visual problems, including double vision, blind spots, or temporary vision loss in one eye
  • Confusion and irritability
  • Stiff neck, neck pain and shoulder pain
  • Nausea and vomiting
  • Numbness in part of the body
  • Seizure

Diagnosis of Subarachnoid Hemorrhage

A physical exam may show signs of decreased nerve and brain function (focal neurologic deficit)

An eye exam may show decreased eye movements -- a sign of damage to the cranial nerves (in milder cases, no problems may be seen on an eye exam)

A CT scan can usually show signs of bleeding in the brain. A lumbar puncture (spinal tap) may also show blood in the cerebral spinal fluid (CSF).

Other tests that may be performed include:

  • Cerebral angiography
  • CT scan angiography
  • Transcranial Doppler ultrasound
  • Magnetic resonance imaging (MRI)
  • Magnetic resonance angiography (MRA)

Treatment of Subarachnoid Hemorrhage

Subarachnoid hemorrhage may require surgery to remove large collections of blood or relieve pressure on the brain if the hemorrhage is due to an injury.

Surgery may also be required to repair a cerebral aneurysm, if present. Surgical procedures to treat an aneurysm include:

  • craniotomy and aneurysm clipping
  • endovascular coiling -- placing coils in the aneurysm to reduce the risk of further bleeding

Surgery may need to be delayed If the person is critically ill. If the person is in coma or with decreased alertness, may require a shunt to drain fluid from the brain to relieve pressure. Additional life support and Intensive Care Unit procedures may be required.

A person who is is conscious may need to be on strict bed rest.

Medications may be prescribed to control symptoms, inlcuding:

  • blood pressure medications
  • calcium channel blockers (nimodipine) to prevent spasm (tightening) of the cerebral arteries
  • anticonvulstants to prevent or treat seizures


The outcome for a person with subarachnoid hemorrhage depends on several variables, including the location and the amount of bleeding. Generally, those who are older or with more severe symptoms suffer worse outcomes.

Repeat bleeding is a serious complication that worsens the outlook for recovery.

Reference: National Institute of Neurological Disorders and Stroke (NINDS)

Last updated: May 2, 2016.

This information is for general educational uses only. It may not apply to you and your personal medical needs. This information should not be used in place of a visit, call, consultation with or the advice of your physician or health care professional.

Communicate promptly with your physician or other health care professional with any health-related questions or concerns.

Be sure to follow specific instructions given to you by your physician or health care professional.

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