Subarachnoid Hemorrhage

Find your care

Our expert neurosurgery team is committed to providing the finest and most comprehensive patient care. For help finding a neurosurgeon, call 310-825-5111.

About Subarachnoid Hemorrhage

General Information

  • Subarachnoid hemorrhage (SAH) involves bleeding into the space between the surface of the brain, or pia mater, and the arachnoid, one of three coverings of the brain.
  • Trauma is the most common cause of spontaneous SAH, and 75 percent to 80 percent of spontaneous SAHs involve ruptured brain aneurysms. Other causes of SAH include arteriovenous malformation (AVM), vascular inflammation affecting the central nervous system, and carotid artery dissection.
  • The Incidence of SAH in North America ranges from 10 to 28 per 100,000 people, with approximately 28,000 new hemorrhages per year.
  • Factors leading to higher risk of SAH include high blood pressure, cigarette smoking, oral contraceptives, pregnancy and child birth, and cocaine abuse.
  • SAH occurs in 25 percent to 40 percent of individuals with a moderate or severe head injury (a Glasgow Coma Scale score of 3 to 12).
  • Complications of SAH requiring specific diagnosis and treatment are vasospasm and hydrocephalus.


  • The most common symptom is a sudden severe headache, often characterized as "the worst headache of my life." This headache occurs in up to 97 percent of cases.
  • Other symptoms include vomiting, fainting, temporary loss of consciousness during the headache, and blurred or double vision.
  • The presence of blood circulating in the subarachnoid space also may lead to neck stiffness and low back pain due to irritation of nerve roots in the lower back.


  • A computed tomography (CT) brain scan will detect SAH in 95 percent of cases.
  • A lumbar puncture to test cerebrospinal fluid is used in questionable cases.
  • Cerebral angiography can locate the source of bleeding 80 percent to 85 percent of the time in confirmed cases. Sometimes a second angiography is needed.


  • Once the cause of the subarachnoid hemorrhage is found, it needs to be treated right away.
  • Aneurysms and AVMs require treatment specific to those disorders.
  • Treatment generally occurs in three phases:
    1. Early intensive care focuses on support of vital functions of the body, preventing high blood pressure, renewed bleeding and seizures.
    2. Surgery to stop the bleeding within 24 to 36 hours of onset of symptoms.
    3. Late intensive care treats vasospasm by elevating blood pressure and blood volume.


  • Despite vast improvement in prognosis for patients with subarachnoid hemorrhage, about one third to half may die or be left with impaired brain function.
  • Prognosis depends largely on how badly the person was affected at first and if vasospasm develops.


  • Vasospasm
    • General information: Cerebral vasospasm, or the spasmodic constriction of blood vessels in the brain, is a common symptom following SAH. Vasospasm typically occurs six to eight days after the SAH.
    • Symptoms: Symptoms include confusion or decreased level of consciousness with speech disturbances or weakness.
    • Diagnosis: Vasospasm can be diagnosed non-invasively at the UCLA Cerebral Blood Flow Laboratory with transcranial Doppler or with an angiogram.
    • Treatment:Options include increasing blood volume and pressure, calcium channel blockers to prevent spasm, and medication or angioplasty to open constricted arteries.
  • Hydrocephalus
    • General information: Acute hydrocephalus, an abnormal accumulation of cerebrospinal fluid in the brain, occurs in 15 percent of patients with SAH.
    • Diagnosis: The initial CT scan can show the dilated ventricles.
    • Treatment: Treatment involves using a catheter to drain the excess fluid. A small percentage of patients develop chronic hydrocephalus, which requires surgical placement of a shunt to drain fluid.

The Neuro-ICU cares for patients with all types of neurosurgical and neurological injuries, including stroke, brain hemorrhage, trauma and tumors. We work in close cooperation with your surgeon or medical doctor with whom you have had initial contact. Together with the surgeon or medical doctor, the Neuro-ICU attending physician and team members direct your family member's care while in the ICU. The Neuro-ICU team consists of the bedside nurses, nurse practitioners, physicians in specialty training (Fellows) and attending physicians. UCLA Neuro ICU Family Guide