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.

Subarachnoid hemorrhage can be caused by:

• Bleeding from an arteriovenous malformation (AVM)
• Bleeding disorder
• Bleeding from a cerebral aneurysm
• 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. 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
• Fibromuscular dysplasia (FMD) and other connective tissue disorders associated with aneurysm or weakened blood vessels
• High blood pressure
• History of polycystic kidney disease
• Smoking

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

The main symptom is a severe headache that 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:

• Sudden or decreased consciousness and alertness
• Difficulty or loss of movement or feeling
• Mood and personality changes, including confusion and irritability
• Muscle aches (especially neck pain and shoulder pain)
• Nausea and vomiting
• Photophobia (light bothers or hurts the eyes)
• Seizure
• Stiff neck
• Vision problems, including double vision, blind spots, or temporary vision loss in one eye

Additional symptoms that may be associated with this disease:

• Eyelid drooping
• Eyes, pupils different size
• Sudden stiffening of back and neck, with arching of the back (Opisthotonos; not very common)
• Seizures

A physical exam may show a stiff neck due to irritation by blood of the meninges, the tissues that cover the brain. Except those in a deep coma, persons with a subarachnoid hemorrhage may resist neck movement.

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

An eye exam will be performed. Decreased eye movements can be a sign of damage to the cranial nerves. In milder cases, no problems may be seen on an eye exam.

If your doctor thinks you may have a subarachnoid hemorrhage, a head CT scan (without dye contrast) should be immediately done. In some cases, the scan may be normal, especially if there has only been a small bleed. If the CT scan is normal, a lumbar puncture (spinal tap) must be performed. Patients with SAH will have blood in their spinal fluid.

CT scan angiography (using contrast dye) may be done to look for evidence of and aneurism.

Cerebral angiography of blood vessels of the brain is better than CT angiography to show small aneurysms or other vascular problems. This test can pinpoint the exact location of the bleed and can tell if there are blood vessel spasms.

Transcranial doppler ultrasound is used to look at blood flow in the arteries of the brain that run inside the skull. The ultrasound beam is directed through the skull. It can also detect blood vessel spasms and may be used to guide treatment.

Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) are occasionally used to diagnose a subarachnoid hemorrhage or find other associated conditions.

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

If the hemorrhage is due to an injury, surgery is done only to remove large collections of blood or to relieve pressure on the brain.

If the hemorrhage is due to the rupture of an aneurysm, surgery is needed to repair the aneurym. If the patient is critically ill, surgery may have to wait until the person is more stable. Surgery may involve a craniotomy (cutting a hole in the skull) and aneurysm clipping, which closes the aneurysm, or endovascular coiling, a procedure in which coils are placed within the aneurysm to reduce the risk of further bleeding.

If no aneurysm is found, the person should be closely watched by a health care team and may need repeated imaging tests.

Treatment for coma or decreased alertness status may be needed. This may include special positioning, life support, and methods to protect the airway. A draining tube may be placed into the brain to relieve pressure.

If the person is conscious, strict bed rest may be advised. The person will be told to avoid activites that can increase pressure inside the head. Such activities include bending over, straining, and suddenly changing position. The doctor may prescribe stool softeners or laxatives to prevent straining during bowel movements.

Blood pressure will be strictly controlled. This requires medicines given through an IV line. The medicine often requires frequent adjustments. A medicine called calcium channel blocker is used to prevent blood vessel spams.

Pain killers and anti-anxiety medications may be used to relieve headache and reduce intracranial pressure. Phenytoin or other medications may be used to prevent or treat seizures.

How well a patient with subarachnoid hemorrhage does depends on a number of different factors, including the location and extent of the bleeding, as well as any complications. Older age and more severe symptoms from the beginning are associated with a poorer prognosis.

Complete recovery can occur after treatment, but death may occur in some cases even with aggressive treatment.

Repeated bleeding is the most serious complication. If a cerebral aneurysm bleeds for a second time, the outlook is significantly worsened.

Changes in consciousness and alertness due to a subarachnoid hemorrhage may become worse and lead to coma or death.

Other complications include:

• Stroke
• Seizures
• Medication side effects
• Complications of surgery

Go to the emergency room or call the local emergency number (such as 911) you have symptoms of a subarachnoid hemorrhage.

Identification and successful treatment of an aneurysm would prevent subarachnoid hemorrhage.

Zivin J. Hemorrhagic cerebrovascular disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 432.