Notice: Users may be experiencing issues with displaying some pages on stanfordhealthcare.org. We are working closely with our technical teams to resolve the issue as quickly as possible. Thank you for your patience.
An aneurysm is an abnormal ballooning out of an artery. This occurs when there is a weakening in the wall of the artery and this puts a patient at risk of rupturing or bleeding from the aneurysm. Bleeding from an aneurysm represents a serious medical problem that can cause subarachnoid hemorrhage and is a frequent cause of hemorrhagic stroke.
Aneurysms usually form over time. The average age when a person has symptoms from an aneurysm is usually 40-60 years old, although this can be quite variable. It may be associated with other medical conditions like hypertension and with a history of smoking. Aneurysms occur slightly more frequently in women. About 20% of patients with aneurysms will have multiple (two or more) aneurysms at the same time. There may be an increased incidence in family members related directly to a person with aneurysms.
Many patients have no symptoms until the aneurysm ruptures. In some cases, aneurysms can cause headaches or neurologic symptoms before bleeding. Some aneurysms are found prior to breaking or bleeding using CT (computed tomography) or MRI (magnetic resonance imaging). While CT and MRI can show many aneurysms, most people with aneurysms need a cerebral angiogram for definitive diagnosis and to determine the best treatment.
The treatment goal with aneurysms is to close off the aneurysm, thereby eliminating the chance of bleeding. This can be done with a surgical procedure to "clip" the aneurysm or an endovascular procedure to "coil" the aneurysm. Clipping an aneurysm is done by opening the skull and placing a clip over the aneurysm.
Coiling of the aneurysm is done by placing a catheter (a hollow plastic tube) through the arteries to the aneurysm. The procedure is monitored by interventional neuroradiologists using a low-level X-ray (fluoroscopy) so they can see the exact location of the catheter at all times. Once positioned, tiny detachable platinum micro coils are placed into the aneurysm, in a similar way to filling a pothole in a road. Multiple images (controlled angiography) are done during the procedure to monitor the filling (occlusion) of the aneurysm. Once there is no blood flow into the aneurysm, the risk of bleeding is eliminated.
Aneurysm coiling pre-treatment
Angiogram from a patient who has an aneurysm which has bled. (Blue arrow points to aneurysm.)
Aneurysm coiling post-treatment
Angiogram completed after fine coils made of platinum were used to fill up the aneurysm and prevent it from bleeding again.
Larger aneurysms with wider necks or openings are sometimes treated with other endovascular techniques using a balloon to help keep the coils in position inside the aneurysm, or a small stent, which is a small mesh tube that can keep the coils in place. When aneurysms are even larger, a different kind of mesh tube can be placed into the artery without coils to block the opening of the aneurysm and prevent blood flow into the aneurysm.
Aneurysm flow diverter pre-treatment
Angiogram from a patient with a large aneurysm (between blue arrows). This aneurysm was enlarging and pressing on the nerves going to the eye and causing double vision.
Aneurysm flow diverter placed
The flow diverter (outlined by arrows), which has been placed across the opening of the aneurysm in the artery the aneurysm arises from.
Aneurysm flow diverter post-treatment
Angiogram from the same patient three months later showing the aneurysm has been completely occluded and there is normal blood flow through the artery.
These minimally invasive techniques allow the hospital stay to be shortened following treatment. If the aneurysm has not ruptured prior to endovascualr treatement, the patient may spend only one night in the hospital prior to going home. If the patient has already suffered from bleeding, the recovery in the hospital will be determined by the extent of the initial bleed and any complications that it caused.
Sometimes after an aneurysm bleeds, there is a reaction of the blood vessels around the area called vasospasm (narrowing of the blood vessel). This after-effect can be life-threatening and must be treated aggressively to prevent further neurologic deficits.
Treatment of vasospasm may include IV fluids, or elevating the patient's blood pressure with medications. Interventional neuroradiologists treat patients for this problem of vasospasm that have had either clipping or coiling of the aneurysm. They may place catheters into the narrowed blood vessels in the brain and infuse medication directly into the artery or perform an angioplasty. Angioplasty consists of placing a special balloon-tipped catheter into the blood vessels in the brain that are narrowed. The balloon is then blown up, which pushes the walls of the blood vessel open, and blood flow is restored to the brain.