Alternate Names: Aneurysm - cerebral

Causes and Risks:

Aneurysms in the brain occur when there is a weakened area in the wall of a blood vessel. They may occur as a congenital defect or may develop later in life.

A saccular aneurysm (berry aneurysm) can vary in size from a few millimeters to over a centimeter. Giant berry aneurysms can reach well over 2 cm. The aneurysm resembles a sack of blood attached to one side of the blood vessel by a narrow neck. These are more common in adults.

Multiple berry aneurysms are not unusual. About 25% of patients have more than one aneurysm. They can occur in any blood vessel which supplies the brain, but they are most often seen in the large arteries at the base of the brain. Berry aneurysms are associated with polycystic kidney disease and coarctation of the aorta. Rarely, berry aneurysm can run in families.

Other types of cerebral aneurysm may involve widening (dilatation) of the entire circumference of the blood vessel in an area, or may appear as a ballooning out of part of a blood vessel.

These types of aneurysms can occur in any blood vessel which supplies the brain. Trauma and infection, causes for injury to the blood vessel wall, are two reasons which lead to the development of these types of aneurysm.

Symptoms usually do not appear until complications develop. Bleeding is the most common cause of symptoms, with subarachnoid hemorrhage being the usual type of bleed. Weakness, numbness, or other loss of nerve function (neurologic deficits) may occur because of pressure from the aneurysm on adjacent brain tissue or because of reduced blood flow caused by a spasm of other blood vessels near a ruptured aneurysm.

It is estimated that 5% of the population has some type of aneurysm. However, the incidence of ruptured aneurysm is approximately 10 out of 100,000 people per year.

Prevention: There is no known way to prevent formation of a cerebral aneurysm. If discovered in time, unruptured aneurysms can be treated before causing problems. The decision to repair an unruptured cerebral aneurysm is based on the size and location of the aneurysm; and the patient's age and general state of medical health.

Symptoms: Symptoms of a bleed may include:

• Sudden occurrence of a headache (severe or described as "the worst in patient’s experience")
• Headaches with nausea or vomiting
• Stiff neck (occasionally)
• Muscle weakness, difficulty moving any part of the body
• Numbness or decreased sensation in any part of the body
• Vision changes (double vision, loss of vision)
• Eye lid drooping
• Changes in mental status, the person may be confused, lethargic, sleepy, or stuporous
• Seizures
• Slow, sluggish, lethargic movement
• Speech impairment
• Irritability, impulsivity or poor temper control

Signs and Tests: There may be signs of increased pressure within the brain (raised intracranial pressure) including swelling of the optic nerve (papilledema) or tiny hemorrhages into the retina of the eye that are evident on careful eye examination.

Cerebral aneurysm is usually diagnosed by tests to determine the cause of bleeding within the brain.

• A CT scan of the head indicates bleeding and occasionally locates the aneurysm.
• A CSF (cerebrospinal fluid) examination (spinal tap) may confirm bleeding when CT scan is non-diagnostic.
• An MRI of the head may be an alternative to a CT scan, but is not as sensitive to bleeding within the brain (subarachnoid bleeding). MRI scans can demonstrate the actual aneurysm if it is greater than 3 mm in size.
• Cerebral angiography is the most sensitive tool and pinpoints the location and size of the aneurysm(s).
• EEG (electroencephalogram) may be performed if seizures occur.

Treatment:

Because symptoms often do not appear until bleeding occurs, a ruptured cerebral aneurysm is an emergency condition when it is discovered. The goal of treatment is to control symptoms and prevent further bleeding.

Neurosurgery is the primary treatment for cerebral aneurysm. The base of the aneurysm is closed off with clamps, sutures, or other methods that prevent blood flow through the aneurysm. Interventional neuroradiologists can also treat some aneurysms using special coils to obliterate the aneurysm. This is considered a less invasive approach than brain surgery, and in the appropriate circumstances, it is regarded as the best form of treatment.

If surgery is not feasible because of the location or size of the aneurysm or the condition of the person, medical treatment is similar to treatment for subarachnoid hemorrhage.

This may include restricting activity (often complete bedrest is advised), treating symptoms such as headache, controlling blood pressure, and prescribing preventive (prophylactic) use of antiseizure medications.

Prognosis: The outcome varies. A cerebral aneurysm that does not rupture may not cause any symptoms. However, about 25% of ruptured cerebral aneurysms are fatal within 24 hours. Approximately another 25% are fatal within about 3 months. Of the remaining people with ruptured cerebral aneurysm, more than one-half will have some sort of permanent disability.

Complications:

• Subarachnoid hemorrhage
• Stroke
• Epilepsy
• Paralysis of any part of the body
• Permanent loss of sensation of any part of the face or body
• Other neurologic deficits (such as vision changes, loss of speech ability, cognitive decline)
• Communicating hydrocephalus

Go to the emergency room or call the local emergency number (such as 911) if sudden or severe headache occurs, particularly if accompanied by nausea, vomiting, seizures, or any other neurologic symptom.