Subarachnoid Hemorrhage Affects 30,000 Americans
It happens suddenly: an excruciating headache, accompanied by neck pain, nausea, or vomiting. The sudden buildup of pressure the person feels in his or her head may cause rapid loss of consciousness or death. The event is a subarachnoid hemorrhage (SAH), which affects more than 30,000 Americans each year. Bret Michaels, the 47-year-old frontman for the band Poison, is, unfortunately, one of those statistics.
A subarachnoid hemorrhage is a type of stroke that typically is caused by abnormalities of the arteries at the base of the brain. These abnormalities, called cerebral aneurysms (saclike widening of an artery), tend to rupture when the blood vessel wall becomes weak. According to the Brain Aneurysm Foundation, about 40 percent of people who experience a major rupture also experience the warning signs.
Subarachnoid hemorrhage can be caused by a number of factors, including presence of a bleeding disorder, head injury, use of blood thinners, a cerebral aneurysm, or arteriovenous malformation (AVM; an abnormal connection between veins and arteries, usually congenital). Risk factors, according to the National Institutes of Health, include aneurysms in other blood vessels, high blood pressure, history of polycystic kidney disease, and smoking.
When the brain aneurysm ruptures, it bleeds into the subarachnoid space, which is the compartment that surrounds the brain. This causes a subarachnoid hemorrhage. In most cases, the bleeding stops rather quickly. However, if any of the blood makes contact with brain cells, the cells can become damaged. If any of the blood leaks into the cerebrospinal fluid in the subarachnoid space, the accumulated blood can form a clot, which can damage or destroy nearby brain cells.
One complication of SAH is hydrocephalus. Blood from the ruptured aneurysm can block circulation of the cerebrospinal fluid, which can result in increased pressure on the brain. If the open spaces in the brain (ventricles) become enlarged, the patient develops hydrocephalus, which is characterized by confusion, lethargy, and incontinence.
Vasospasm can occur as a complication of SAH as well. Vasospasm is a narrowing of the blood vessels around the base of the brain, and it typically develops 5 to 8 days after the initial hemorrhage. Medications can reduce the threat of vasospasm, and it can resolve within several days.
Fifty percent of people who experience an SAH die within minutes of a massive hemorrhage. About 25 percent of patients suffer delayed death, while the remaining 25 percent usually survive with varying degrees of long-term brain deficits.
The goals of treatment of SAH are to repair the cause of bleeding, relieve symptoms, and prevent complications, including permanent brain damage. Hemorrhage caused by a ruptured aneurysm is treated with surgery to repair the aneurysm. An SAH caused by an injury usually involves surgery to remove the accumulated blood or to relieve pressure on the brain.
Prognosis depends on the location and extent of the hemorrhage, and the presence of any complications. Patients who are older and who have more severe symptoms from the beginning usually have a poorer prognosis. Repeated bleeding is the most serious complication. A cerebral aneurysm that bleeds for a second time greatly reduces the chances of survival from subarachnoid hemorrhage.
The Brain Aneurysm Foundation
National Institutes of Health
University of Maryland Medical Center