Despite the exceptional surgical and medical advances developed to combat aneurysms of the brain, this condition claims approximately 1 9,000 lives annually in the United States. However, new approaches are being developed that may reduce the death rate resulting from brain aneurysms.
A cerebral aneurysm is best described as a blister on the blood vessels in the brain, often present at birth. Studies show that as many as 5% of the population may have an aneurysm. However, most of these aneurysms will remain silent and produce few symptoms unless the blister grows. As the blister grows, its wall thins, eventually causing the outer layer of the vessel to burst. A common side effect of a ruptured aneurysm is irritation of surrounding blood vessels. This irritation causes blood vessels to go into spasms, initiating a stroke. Calcium channel blockers are now administered during a patient's recovery to prevent this side effect.
Cerebral aneurysms are not associated with any particular group in the population, occurring even in children and adolescents. Incidence of cerebral aneurysms peaks in persons between the ages of 35 and 65.
There are three main types of cerebral aneurysms: congenital, traumatic, and infectious. Although the congenital type seems to be present at birth, this does not mean brain aneurysms are necessarily a hereditary condition. The second type of aneurysm, traumatic, is uncommon. It results when a head injury causes partial disruption in an artery wall. Infectious aneurysms occur as a result of an infection that lodges in the cerebral artery and causes the vessel wall to disintegrate.
The initial mechanism behind aneurysmal formation remains controversial. Experts in neurology have three theories. The first proposes that aneurysms develop as a result of congenital defects in the middle layer of the cerebral artery. The second suggests that changes in the artery wall produces a weakness that permits the formation of an aneurysm. Supporters of the third theory believe that aneurysms result from both a congenital defect and a weakening of the wall structure.
Detection most often occurs as a result of spontaneous bleeding from blood vessels in the space surrounding the brain. This causes subarachnoid hemorrhage, a narrowing of blood vessels that reduces blood flow to segments of the brain. Several warning signs are present with this condition, including excruciating headaches, nausea, stiff neck, and, in extreme cases, loss of consciousness.
Because these signs are warning the body of a possible impending rupture of an aneurysm, the patient should see a doctor. In most cases, an angiogram will be administered. An important clue as to when an aneurysm might rupture is the aneurysm size; larger ones are more likely to burst. Therefore, the angiogram's ability to show the exact size and location of the aneurysm is indispensable to the doctor in assessing the patient's condition.
The goal of aneurysmal treatment is to prevent further rupture of the aneurysm while maintaining the regular flow of blood and oxygen to the brain. This is best accomplished by surgically placing a small metal clip at the base of the aneurysmal sac. Cases in which extreme swelling of the brain restricts access to the aneurysm, the surgery will be delayed for 8 to 10 days until the swelling of the brain has decreased and the patient's condition has improved. However, in cases where only minimal swelling has occurred, immediate surgery is an option.
The primary factor affecting survival following aneurysmal rupture is the length of time between the onset of bleeding and the time the patient's condition is assessed by a doctor. If the duration is too long, the risk of rebleeding is very high. Recurrence is most likely within the first 2 weeks after the initial bleeding.
Unfortunately, there are no known ways to eliminate cerebral aneurysms entirely. Research indicates, however, that situations that increase cerebral pressure, such as cocaine use, childbirth, exceptionally intense emotional stresses, or high blood pressure may increase the risk that an aneurysm in persons that already have the blister-like defect will burst.
To reduce the risk of aneurysmal rupture, pay attention to warning signs. People experiencing unusually violent headaches, nausea, vomiting, and head and neck pains should seek medical attention. Early detection is the key to survival.
For more information, contact a local physician or the Medical College of Pennsylvania, Department of Neurology, 3300 Henry Avenue, Philadelphia, PA 19129; 215-842-7095.