What is a brain aneurysm?
An aneurysm is a weak area in the wall of an artery which leads to a balloon or pouch formation. The wall of the pouch is thinner than the rest of the artery wall and is at risk of breaking. This type of aneurysm is known as a berry aneurysm, or saccular aneurysm, based on the way it appears. If the aneurysm breaks, then there can be bleeding in the brain. Other types of aneurysms include lateral aneurysm, where a bulge appears along one wall of the artery, or fusiform aneurysm, when the entire artery is enlarged.
The specific cause why aneurysms form is unknown. Aneurysms can be hereditary (run in families), or occur due to an abnormality which occurred during gestation. Some diseases can lead to weakness in artery walls and formation of aneurysms; these include polycystic kidney disease, some of the connective tissue disorders, or vascular malformations. Trauma, high blood pressure, or drug use may also increase the risk of developing aneurysm. In rare cases, infection within the wall of the artery can cause an aneurysm to form.
What is endovascular coiling?
Endovascular coiling is a way to treat aneurysms without opening the skull or performing brain surgery. The coil refers to a thin wire which is bunched up (coiled) within the aneurysm. The coil prevents further blood flow into the aneurysm by causing a clot to form, while the rest of the artery remains open to transport blood to the brain. The wire is inserted through a catheter which is fed through the large arteries of the body and into the arteries of the brain. This procedure is done as an alternative to aneurysm clipping (surgically isolating the aneurysm by placing a clip at the base of the aneurysm to keep blood from entering), which requires brain surgery. to isolate the area of the aneurysm.
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Differences between surgical clipping and endovascular coiling procedures
Treatment for a symptomatic aneurysm is to repair the blood vessels. Clipping and coiling are two treatment options.
- Clipping: A neurosurgeon can operate on the brain by cutting open the skull, identifying the damaged blood vessel and putting a clip across the aneurysm. This prevents blood from entering the aneurysm and causing further growth or blood leakage.
- Coiling: An interventional neurologist, neurosurgeon, or interventional radiologist can thread a tube through the arteries, as with an angiogram, identify the aneurysm, and fill it with coils of platinum wire or with latex. This prevents further blood from entering the aneurysm and resolves the problem.
Who needs endovascular coiling?
Many different patients can go through endovascular coiling. This procedure can be done whether the aneurysm is intact or has ruptured. Younger patients and elderly individuals may be candidates. The ultimate determination of whether a patient can undergo endovascular coiling or requires open surgery is based on the size and shape of the aneurysm, where the aneurysm is located, and the age and associated illnesses of the patient. This procedure may be chosen over open surgery for patients who may not be healthy enough for major brain surgery.
What happens during an endovascular coiling procedure?
Patients are admitted to a hospital on the day of their procedure. Patients are not allowed to eat or drink on the day of the procedure. An IV is started to supply fluids. At the time of the procedure, the patient is taken to a special room in the radiology department; some anesthesia or sedation is used to help the patient relax. A catheter, or long tube, is inserted into the femoral artery and carefully fed through the aorta (the main artery of the body) into one of the arteries which goes into the brain. Dye is used to identify the aneurysm; once the aneurysm is located, small wires (typically made of platinum) are inserted into the aneurysm and coil into place. Additional wires are implanted in this way until the aneurysm is full. After the wires are completely inserted and the associated artery is checked with dye to confirm there is no injury, the catheter is removed. The area where the catheter had been inserted in the femoral artery is held firmly for several minutes to prevent bleeding.
After the procedure is completed, patients are observed for several hours. Following the procedure, patients may be allowed to go home the same day. However, if the procedure had been performed to treat an aneurysm that had leaked or ruptured, patients may be hospitalized for several days or weeks.
There are typically some limitations of activity for several days following an endovascular coiling procedure, including no driving or working and some weight-lifting restrictions. Patients need to be seen for follow-up about a month after the procedure to confirm there are no complications.
Endovascular coiling vs. surgical clipping
Surgical clipping has been around for longer than endovascular coiling, and there is some data that suggests that the clipping procedure is less likely to require a repeat procedure over time. However, a study performed in 2002 looking at open surgical clipping vs. endovascular coiling as treatment for ruptured aneurysms (the International Subarachnoid Aneurysm Trial, or ISAT) was stopped early as the rates of associated disability or death after 1 year were much less in the group which was selected to receive endovascular coiling.
However, since that time, surgical approaches have changed; surgeons now make very small incisions to access the aneurysm, which decreases disability and length of hospitalization even for the surgical clipping. Additionally, there have been no studies comparing the two types of procedures for unruptured aneurysms. Evaluation of the data collected for both types of procedures suggests that patients who undergo endovascular coiling have shorter hospital stays, fewer complications, and faster recovery times.
What is the recovery time after endovascular coiling?
Recovery times vary per patient, location of the aneurysm, and whether the aneurysm ruptured. For patients with unruptured aneurysms who undergo endovascular coiling, recovery times may be as short as a month; other individuals find that they're back to baseline after about 3 to 6 months. If an aneurysm ruptures, recovery can take weeks to months; depending on the area of the brain where the aneurysm was located, permanent damage to the brain may occur.
What are the potential risks and complications of endovascular coiling?
There are some possible risks associated with endovascular coiling. These can include injury or damage to the artery or aneurysm being treated; in rare cases, the aneurysm can rupture. Vasospasm, or a sudden narrowing of the artery, can occur and lead to decreased blood flow to the brain which is fed by that artery. A blood clot can form on the catheter, the coils as they are injected, or in the artery where the catheter is fed. If this occurs, the clot can cause blockage of blood flow or a stroke. The coils may not stay in place or may not completely occlude the aneurysm; if this occurs, the aneurysm might regrow or get larger. Patients may have an allergic reaction to the dye used during the procedure. With any procedure, there is a risk of infection.
How much does endovascular coiling cost?
The specific costs of endovascular coiling are not available. Many factors play a role in determining the cost of the procedure, including whether the aneurysm has already ruptured, the age of the patient, the presence of associated illnesses, whether hospitalization is needed following the procedure, and the number of aneurysms that need to be addressed.
Molyneux, A., et al. “International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2,143 patients with ruptured intracranial aneurysms: a randomised trial.” Lancet 11.6 (2002): 304-314.
National Institute of Neurological Disorders and Stroke. “Cerebral Aneurysms Fact Sheet.” 23 Feb. 2015.