What is Detachable Coil Embolization?

Detachable coil embolization offers a new approach to treating aneurysms and other blood vessel malformations in the brain. A brain aneurysm, or weakness in the arterial wall, is a serious medical condition. If an aneurysm ruptures, internal bleeding may cause a stroke or loss of life. In less severe cases, a bulging aneurysm may compress surrounding nerves and brain tissue resulting in nerve paralysis, headache, neck and upper back pain as well as nausea and vomiting. Cerebral angiography, computed tomography (CT) or magnetic resonance (MR) imaging can detect aneurysms prior to rupturing.

Interventional neuroradiologists perform detachable coil embolization to alleviate much of the danger presented by aneurysms. The interventional neuroradiologist inserts a tube, called a catheter, into an artery in the leg. This catheter is then manoeuvred through the body to the aneurysm's position. Once in position, the radiologist places one or more small coils through the catheter into the aneurysm. The body responds by forming a blood clot around the coil that strengthens the weak spot in the artery.

Detachable coils may also be used to treat a rare intracranial congenital vascular condition called arteriovenous malformation. In this instance, the brain's arteries and veins are not connected by capillaries but are linked instead by abnormal connections called arteriovenous fistulas. These fistulas may empty the arteries of blood before cerebral circulation is completed. This abnormal blood exchange between cerebral arteries and veins may cause headaches, haemorrhage, seizures and strokes, as well as neurological symptoms impacting memory, movement, speech and vision.
 
Coils can be used to either block blood flow to the affected area or to fill the aneurysm or fistula, thus preventing a rupture. Occasionally, additional coils may be inserted during a subsequent procedure to complete treatment.

Using detachable coils to close off the aneurysm or fistula is effective in prolonging life and relieving symptoms. Unsuccessful attempts were originally made to fill aneurysms with detachable balloons without rupturing the aneurysm. To minimize the risk of rupture, researchers developed soft, detachable coils. Coil embolization currently is used to treat approximately 30 percent of cerebral aneurysms and 20 percent of arteriovenous malformations.

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What are some common uses of the procedure?

Coil embolization is most frequently used to treat aneurysms and fistulas in the brain where open surgery is risky. The coils prevent rupture and further growth by creating a blood clot to close off blood flow to the affected area.

A variety of clinical and biological factors come into play when identifying a candidate for detachable coil embolization. Physicians consider the patient's age and health status as well as the position and form or structure of the aneurysm and its relationship to surrounding normal circulatory system structures. Young, healthy patients respond well to this procedure. However, there are benefits for older people as well. Coil embolization is especially useful for patients who are unsuitable for brain surgery. This procedure is also ideal for those seeking to avoid blood transfusion or general anaesthesia.

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How should I prepare for the procedure?

When CT or MR imaging detects a brain aneurysm or arteriovenous malformation, a cerebral angiogram may be necessary for diagnosis and treatment. During this minimally invasive procedure, contrast material is injected into the problem artery to allow x-ray visualization. Some procedures allow the brain's vascular system to be displayed in three dimensions, which makes diagnosis much easier.

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What do the coils look like?

There are three types of detachable coils—bare platinum coils, coated platinum coils and biologically active coils. All three types are made of soft platinum wire of less than a hair's width. All detachable coils are scientifically proven to be safe and effective and approved by the Food and Drug Administration (FDA).

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How does the procedure work?

Plugging the weak, bulging section of the artery or fistula stops blood flow to the affected area and eliminates the risk for rupture. The coils are designed to remain anchored within the aneurysm or fistula and do not require eventual removal. Depending upon the size of the aneurysm, coils of different diameters and lengths may be selected.

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How is the procedure performed?

Detachable coil embolization is performed in the neuro-interventional angiography unit by an interventional neuroradiologist. An anaesthesiologist is present, along with surgical staff, which closely monitors blood pressure, heart rate and rhythm and blood oxygenation during the embolization procedure. The interventional neuroradiologist delivers a catheter through a leg artery to the aneurysm. The detachable coils are then inserted to fill the sac of the aneurysm and/or block the arteriovenous fistula.

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What will I experience during the procedure?

The procedure may take between 30 minutes and four hours depending upon complexity. Either local or general anaesthesia can be used to for this procedure. Your radiologist will help you decide which is best for you.

Patients undergoing local anaesthesia will feel relaxed and sleepy after the intravenous (IV) sedative is started. You may feel slight pressure when the catheter is inserted, but no serious discomfort. Patients who receive general anaesthesia will have no memory of the procedure.

The severity of symptoms varies widely between ruptured and unruptured aneurysms. Patients who had a stroke will have a more difficult recovery and only 25 percent may be symptom-free after the procedure. Recovery depends upon the brain damage from the bleeding. Very sick patients with narrowed cerebral arteries following a ruptured aneurysm may benefit from surgical brain manipulation.

Following endovascular treatment, bed rest will be required. Patients who did not have a ruptured aneurysm prior to treatment may be able to leave the hospital the day after the procedure. Stroke patients should expect a post-procedure recovery in the neurosurgical intensive care unit followed by a seven to 10 day recovery on the neurosurgery floor and may require sedation.

Following the procedure, patients may experience mild nausea and low-grade fever. Headaches may last from seven days to six months. However, headaches are often not a major issue for those with unruptured aneurysms or fistulas. Following the procedure, follow-up reviews of coil positioning may be completed using x-ray, MRI or cerebral angiography. Aspirin or blood thinners may be prescribed.

Recovery time varies by patient. Most people are able to care for themselves within 10 days to six months. Many patients return to work after one month and begin driving at three months. Those with unruptured aneurysms and fistulas typically recover within 24 hours.

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Who interprets the results and how do I get them?

The interventional neuroradiologist will evaluate your procedure and results and coordinate appropriate follow-up care with your primary care physician.

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What are the benefits vs. risks?

Benefits

• Minimally invasive: Detachable coil embolization allows treatment of cerebral aneurysms that previously were considered inoperable. This procedure is less invasive and requires significantly less recovery time than open surgery for aneurysm repair. Additional benefits include minimal blood loss and the option of local anaesthesia.
• Durable effect: Recurrence depends on the coils' success or failure in controlling the neck of the aneurysm or fistula. If the coil completely prevents blood flow into the aneurysm, then the patient need not be concerned about recurrence. The durability of coil embolization varies depending on the size and shape of the aneurysm. Coil embolization of small aneurysms with small necks has better results than embolization of large or giant aneurysms with wide necks. Long-term follow-up has shown permanent success in more than 80 percent of aneurysms treated with coil embolization.

Risks

• Catheter-related risks: Intra-arterial catheterization involves a risk of bleeding, infection and arterial damage. Experience on the part of the interventional neuroradiologist coupled with good infection control can help minimize these risks.
• Surgical risks: As with any invasive procedure, there is a slight risk of death and illness; however, coil embolization of unruptured aneurysms and fistulas carries less risk than embolization following a stroke. Approximately seven percent of cases require additional treatment or surgery.

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What are the limitations of Detachable Coil Embolization?

Aneurysms are being treated with coil embolization more frequently due to the incorporation of other medical technologies such as balloon assistance and micro-stenting. Unfortunately, large aneurysms with wide necks remain a challenge. Most neurosurgeons are knowledgeable about this widely available procedure as are an increasing number of neurologists.

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