Introduction

Aneurysm can occur on blood vessels anywhere in the human body.  However, brain or intracranial aneurysms have a unique significance because of the variable pattern cerebrovascular anomalies.  About 90 percent of the blood supply reaches the brain through the two carotid arteries and the remaining 10 percent from the vertebral arteries.  The human brain receives about 15% of the cardiac output although the brain accounts for only 2.5% of the body weight.  The notoriety of intracranial aneurysm compared to all lesions in the brain is the unpredictable behavior of aneurysm at different locations in the brain, the high mortality 50% when they rupture, the peak incident of rupture in the productive years of human life, and the socio-economic ramifications on society bearing on human resources in the development and progress of society.

What is a cerebral aneurysm?

A cerebral aneurysm (also known as brain, intracranial or intracerebral aneurysm) is a weak or thin spot on a blood vessel in the brain that balloons out and fills with blood.  The bulging aneurysm can put pressure on a nerve or surrounding brain.  It may also leak or rupture, spilling blood into the surrounding tissue (called a hemorrhage).  Cerebral aneurysms can occur anywhere in the vascular tree of the brain, but most are located along a loop of arteries that run between the underside of the brain and the base of the skull.

What causes a Brain Aneurysm?

Cerebral aneurysm can be congenital, resulting from inborn abnormality in an artery wall.  They are also more common in people with certain genetic diseases, such as connective tissue disorders (Marfan’s syndrome and Ehlers-Danlos syndrome) and polycystic kidney disease, and certain disorders, such as arteriovenous malformations (snarled tangle of arteries and veins in the brain that disrupt blood flow.

Other causes include trauma or injury, high blood pressure, certain infections, tumors, atherosclerosis (a blood vessel disease in which fat builds up on the inside of artery walls) other vascular diseases, cigarette smoking, and drug use (particularly Cocaine).  There is speculation that oral contraceptive may increase the risk of developing aneurysms.

Who is at risk?

Brain aneurysms can occur in anyone, at any age.  They are more common in adults than in children and slightly more common in women than in men.  People with certain inherited disorders are also at higher risk.

All cerebral aneurysms have a potential to rupture and cause bleeding within the brain.  The incident of reported aneurysm is about 10 in every 100,000 persons per year, most commonly in people ages 30 and 60 years.  Possible risk factors for rupture include hypertension, alcohol abuse, drug abuse (particularly cocaine), and smoking.  In addition, the condition and size of the aneurysm affect the risk of rupture.

What are the dangers?

Aneurysms may burst and bleed into the brain, causing serious complications, including hemorrhagic stroke, permanent nerve damage, or death.  Once it has bust, the aneurysm may burst again (rebleed) at any time but usually the peak incidence of rebleed is between 7 to 14 days.  More commonly, the bleed is in the subarachnoid space (the space between the skull and the brain).  Some may bleed into the brain, the subdural space, or into the ventricle.  Serious complications of aneurysmal bleed include hydrocephalus (plugging of the CSF flow in the subarachnoid space with buildup of fluid in the ventricles with resulting swelling and pressure on the brain tissue),   Another post rupture complication is vasospasm, in which other blood vessels in the brain contract and limit blood flow to vital areas of the brain resulting in stroke of tissue damage.

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