Subarachnoid hemorrhage is a type of stroke that occurs when a blood vessel ruptures and blood quickly fills the area immediately surrounding the brain and spinal cord called the subarachnoid space. This space contains the cerebrospinal fluid, which cushions and bathes the brain and spinal cord. This life-threatening condition, which requires emergency medical care, may increase the pressure around the brain and can interfere with its function.

Subarachnoid Hemorrhage

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Subarachnoid hemorrhage occurs in about 30,000 Americans each year and is most common in people between the ages of 35-65. It is usually caused by:

  • Serious head injury
  • Rupture of cerebral aneurysms and other blood vessel deformities at the base of the brain (spontaneous subarachnoid hemorrhage); such defects are usually present since birth.
  • Bleeding disorders
  • Illicit drug use (especially cocaine and amphetamines)

Risk Factors

The following factors increase your chances of developing subarachnoid hemorrhage. If you know you have any of these risk factors, tell your doctor:

  • Disorders associated with weakened blood vessels, including polycystic kidney disease , fibromuscular dysplasia, or connective tissue disorders
  • Past history of aneurysms
  • High blood pressure increases the risk of aneurysm rupture
  • Smoking
  • Moderate to heavy alcohol consumption
  • Estrogen deficiency


If you experience any of these symptoms do not assume it is due to subarachnoid hemorrhage. These symptoms may be caused by other, less serious health conditions. If you experience any one of them, however, get medical care right away.

  • A very sudden, excruciating headache (frequently described as the "worst headache of my life”)
  • Brief loss of consciousness
  • Seizures
  • Nausea
  • Weakness on one side of your body
  • Unexplained numbness or tingling
  • Slurred speech or other speech disturbance
  • Visions problems, such as double vision, blind spots, or temporary vision loss on one side
  • Stiff neck or shoulder pain
  • Confusion


Your doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include the following:

  • CT scan of the head—a type of x-ray that uses a computer to make pictures of structures inside the head
  • Lumbar puncture (spinal tap)—a procedure to determine if there is blood in the cerebrospinal fluid
  • Angiogram—a type of x-ray; images of the blood vessels of the brain are taken after dye is injected in the bloodstream


Subarachnoid hemorrhage is a serious condition requiring initial treatment in the intensive care unit. Despite treatment, approximately 25%-30% of patients with this condition die.

The aim of treatment is to stop the bleeding, limit damage to the brain, and reduce the risk of recurrence. If bleeding results from a cerebral aneurysm, a surgeon will usually attempt to stop it using various techniques. Patients receive medications to insure proper blood flow to the rest of the brain and must remain at absolute bed rest to prevent additional bleeding. Once the situation is stabilized, patients undertake a vigorous rehabilitation program.

If you are diagnosed with a subarachnoid hemorrhage, follow your doctor's instructions.


Aneurysms present since birth cannot be prevented. Since they are so rare, doctors do not recommend screening for them. However, not smoking and controlling blood pressure can theoretically reduce the risk of a rupture if an aneurysm exists. If an unruptured aneurysm is discovered by chance in a young individual, it will usually be removed surgically if possible.

The consistent use of seatbelts and motorcycle helmets can reduce the risk of subarachnoid hemorrhage from head trauma .