MEDICAL SURFARI: BRAIN ANEURYSMS

The blood that circulates through the vascular system of our bodies is oxygen-rich and carries a variety of nutrients necessary to sustain our health.

However, when blood escapes the vascular system either due to trauma or a spontaneously ruptured blood vessel it does not have such wonderful qualities and attributes. Extravasated blood (blood outside the vascular system) may be very irritating to the surrounding body tissues causing swelling and damage.

This is especially true of the brain.

One of the most severe and life-threatening conditions is the rupture of a cerebral (brain) aneurysm. An aneurysm is a weak area within the wall of one of the arteries supplying the brain. Over time this thin weak area may become thin enough that under conditions of high blood pressure or straining it may rupture.

This rupture causes a bleeding stroke that we refer to as a subarachnoid aneurysmal hemorrhage (SAH). This occurs about 30,000 times a year in the United States.

Aneurysms usually don't exhibit any outward symptoms until after they have ruptured. When an aneurysm ruptures it produces cataclysmic headache that patients often prescribes as "the worse headache of my life."

Nausea and vomiting, avoidance of bright light, stiff neck and sometimes double vision or even unconsciousness almost always accompany this. Approximately 10 percent of the people with this type of hemorrhage will die before making it to the hospital and 40 to 50 percent die within the first few days after they hemorrhage.

Of the 50 to 60 percent that survive the initial hemorrhage and make, less than half will eventually return to their normal activities. This condition is truly a neurosurgical emergency and warrants expert treatment. In patients who make it to the hospital surviving the initial hemorrhage, the bleeding has usually stopped due to a blood clot patch that has formed over the aneurysm.

The biggest risk for these patients is the risk of re-rupture. If this occurs there is at least a 70 percent chance of death.

Two tests are usually required to confirm the diagnosis of a ruptured aneurysm. A CT scan of the brain often demonstrates this type of hemorrhage relatively well. An angiogram or (arteriogram blood vessel) x-ray must be performed to identify the precise location of the aneurysm.

This then serves as the neurosurgeon's road map to locate and obliterate the aneurysm. Aneurysms resembles balloons in that they usually have a neck that can be crossed-clamped with a small spring clip thereby preventing blood flow into the aneurysm. This usually cures the problem, and requires a technically demanding brain operation through a small scalp incision and opening in the skull.

In some exceedingly large aneurysms or in those that can not be safely accessed, small balloons or spring coils may be delivered through a blood vessel catheter to block or reduce the flow into the aneurysm.

The peak age for aneurysmal SAH is about 55 to 60 years. Approximately 20 percent occur between the ages of 15 to 45 years. The risk factors for SAH include high blood pressure, cigarette smoking, oral contraceptives, advanced age and cocaine abuse. Cocaine abuse causes sudden rises in blood pressure sometimes resulting in blood vessel rupture.

Not all aneurysms will rupture. In patients with an aneurysm that has not ruptured it is estimated that the chance of rupture is approximately 1 to 2 percent per year and this is cumulative. Two groups of people are most commonly screened for the development of aneurysms in the brain -- with a family history of aneurysm especially first-degree relatives who have had an (SAH) and those with a condition called autosomal polycystic kidney disease.

The incidence of brain aneurysms in these groups is between 5 and 10 percent. As with most disease early detection is most beneficial as treatment of unruptured aneurysms is associated with much lower rates of death and injury than treatment after an aneurysm has ruptured.

World Wide Web Resources

Aneurysm Answers

http:www.stroke.org/Education/Aneurysm.html

The National Stroke Association provides this web site which has comprehensive information for the public on cerebral aneurysms, including prevention and risk factors.

Family Guide: Neuromedicine

http://www.hsc.missouri.edu/~neuromedicine/aneurysm.shtml

This web site provided by the University of Missouri-Columbia provides basic answers to questions you might have on signs and symptoms, diagnostic tests and treatment options.