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Subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is bleeding in the area between the brain and the thin tissues that cover the brain, which is called the subarachnoid space. SAH can be caused by bleeding from an arteriovenous malformation, a bleeding disorder, bleeding from a cerebral aneurysm, a head injury, use of blood thinners or an unknown cause.

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

Subarachnoid hemorrhage caused by a cerebral aneurysm that ruptures occurs in about 40 to 50 out of 100,000 people over the age of 30. SAH due to aneurysm rupture is most common in people age 20 to 60 and is slightly more common in women.

Risks include:

  • Aneurysm in other blood vessels
  • Fibromuscular dysplasia and other connective tissue disorders
  • High blood pressure
  • History of polycystic kidney disease
  • Smoking
  • A strong family history of aneurysm

Common Symptoms

The main symptom of SAH is a severe headache that starts suddenly and is often worse near the back of the head. The headache may start after a popping or snapping feeling in the head.

Other symptoms include:

  • Decreased consciousness and alertness
  • Eye discomfort in bright light
  • Mood and personality changes, including confusion and irritability
  • Muscle aches, especially neck and shoulder pain
  • Nausea and vomiting
  • Numbness in part of the body
  • Seizure
  • Stiff neck
  • Vision problems, including double vision, blind spots or temporary vision loss in one eye
  • Eyelid drooping
  • Pupil size difference


Your doctor will do a brain and nervous system exam to look for signs of decreased nerve and brain function and an eye exam to look for decreased eye movements that may indicate damage to the cranial nerves.

If there is suspicion of SAH, your doctor will order a CT scan of the head. In about 5 to 10 percent of cases, the scan will be normal, especially if the bleed is small. If the CT scan is normal, your doctor will order a lumbar puncture.

Other diagnostic tests may include:

  • Cerebral angiography of blood vessels of the brain
  • CT angiography using contrast dye
  • Transcranial Doppler ultrasound to look at blood flow in the arteries of the brain
  • MRI
  • Magnetic resonance angiography (MRA)


The goals of treatment are to save your life, repair the cause of bleeding, relieve symptoms and prevent complications such stroke or permanent brain damage.

Surgery may be done to remove any large collection of blood, to relieve pressure on the brain if the SAH is due to an injury or to repair an aneurysm if the hemorrhage is due to aneurysm rupture.

In the event of an aneurysm, surgery may involve a craniotomy (cutting a hole in the skull) and aneurysm clipping or endovascular coiling (placing coils in the aneurysm to reduce the risk of further bleeding).

If no aneurysm is found, your healthcare team will observe your progress closely, and additional imaging tests may be ordered.

Treatment may also include:

  • Intravenous medications to control blood pressure
  • Nimodipine to prevent artery spasms
  • Painkillers and anti-anxiety medications to relieve headache and reduce pressure in the skull
  • Phenytoin or other medications to prevent or treat seizures

The outlook for patients with subarachnoid hemorrhage depends on a number of factors, including the location and amount of bleeding and any complications. Older age and more severe symptoms may lead to a poorer outcome.

Source: National Institutes of Health

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