Cerebral Aneurysm

What is Cerebral Aneurysm ?

Cerebral aneurysm is a localized dilation of a cerebral artery that results from a weakness in the arterial wall. The most common form is the saccular (berry) aneurysm, a saclike out pouching in a cerebral artery.

Cerebral aneurysms commonly rupture, causing subarachnoid hemorrhage. Sometimes bleeding also spills into the brain tissue and subsequently forms a clot. This may result in potentially fatal increased intracranial pressure (ICP) and brain tissue damage.

Most cerebral aneurysms occur at bifurcations of major arteries in the circle of Willis and its branches. An aneurysm can produce neurologic symptoms by exerting pressure on the surrounding structures such as the cranial nerves.

Cerebral aneurysms are much more common in adults than in children. Incidence is slightly higher in women than in men, especially women in their late 40s or early to middle 50s, but cerebral aneurysm may occur at any age. In about 20% of patients, multiple aneurysms occur.

Causes of Cerebral Aneurysm

Cerebral aneurysm results from a congenital defect of the vessel wall, head trauma, hypertensive vascular disease, advancing age, infection, or atherosclerosis, which can weaken the vessel wall.

Signs & Symptoms of Cerebral Aneurysm

The presence of a cerebral aneurysm may not be known until the time of rupture. However, occasionally there may be symptoms that occur prior to an actual rupture due to a small amount of blood that may leak, called "warning leaks," into the brain.

The symptoms of an unruptured cerebral aneurysm include, but are not limited to, the following:

• Complaining of "the worst headache of my life"
• Dizziness
• Eye pain
• Vision deficits (problems with seeing)
• Loss of consciousness
• Stiff neck

Diagnostic Tests

The following tests help establish a diagnosis, which usually follows aneurysmal rupture:

Angiography confirms the aneurysm's location and displays the vessels condition.

Lumbar puncture can be used to detect blood in the cerebrospinal fluid (CSF), but this procedure is contraindicated if the patient shows signs of increased ICP.

Treatment

If indicated, initial emergency treatment includes oxygenation and ventilation. Then, to reduce the risk of rebleeding, the doctor may attempt to repair the aneurysm. Usually, surgical repair (by clipping, ligating, or wrapping the aneurysm neck with muscle) takes place as soon as the patient's condition allows after the initial bleeding.

After surgical repair, the patient's condition depends on the extent of damage from the initial bleeding and the degree of success in treating the resulting complications. Surgery can't improve the patient's neurologic condition unless it removes a hematoma or reduces the compression effect.

When surgical correction poses too much risk (in very elderly patients and those with heart, lung, or other serious diseases), when the aneurysm is in a particularly dangerous location, or when vasospasm necessitates a delay in surgery, the patient may receive conservative treatment, including:

• bed rest in a quiet, darkened room (may last for 4 to 6 weeks) if immediate surgery isn't possible
• avoidance of coffee, other stimulants, and aspirin
• codeine or another analgesic as needed
• hydralazine or another antihypertensive if needed
• a vasoconstrictor to maintain blood pressure at the optimum level (20 to 40 mm Hg above normal) if needed
• corticosteroids to reduce meningeal irritation
• phenobarbital or another sedative to relax the patient
• nimodipine, a calcium channel blocker, to decrease cerebral vessel vasospasm
• albumin for volume expansion, to decrease vasospasm.

What is the prognosis?

The prognosis for a patient with a ruptured cerebral aneurysm depends on the extent and location of the aneurysm, the person's age, general health, and neurological condition.  Early diagnosis and treatment are important.

Prevention Tips

There are no known methods to prevent an aneurysm from forming. If an aneurysm is discovered before it ruptures, it may be surgically removed. CT or MRI angiography may be recommended for relatives of patients with familial cerebral aneurysms.