Intra cranial Aneurysm Embolization
A cerebral or intracranial aneurysm is an abnormal focal dilation of a blood vessel (artery) in the brain which is a result of weakening of the blood vessel wall. The vessel develops a "blister-like" dilation that can become thin and rupture without warning. The bleeding that results into the space around the brain is called a subarachnoid hemorrhage (SAH). This hemorrhage can lead to stroke, coma or even death.
Coil embolization is a minimally invasive procedure to treat an aneurysm by filling it with material that closes off the sac and prevents the risk of bleeding or re-bleed (if it has ruptured and lead to SAH). It is performed from "within" the artery (endovascular) through a steerable catheter inserted into the blood stream at the groin (similar to a cardiac angiography) and guided uptil the brain vessels. Tiny coils or mesh stents are used to promote clotting and close off the aneurysm or isolate it from the circulation. Coiling is performed by a neuroradiologist or some neurosurgeons who have specialized training in endovascular surgery.
The choice of aneurysm treatment (observation vs surgical clipping vs endovascular coiling) must be weighed against the risk of rupture and overall health of the patient.
Coiling may be an effective treatment for the following:
- Ruptured aneurysms with resultant subarachnoid hemorrhage (SAH). The risk of repeated bleeding is very high within the first 2 weeks of the first bleed. So ideally, treatment should usually be executed within 72 hours of the first bleed.
- Unruptured aneurysms may not cause symptoms and are typically detected incidentally during routine testing for another condition. The risk of aneurysm rupture may be high or low depending on the size and location of the aneurysm.
The goal of endovascular coiling is to isolate an aneurysm from the normal circulation without blocking off any small arteries nearby or narrowing the main vessel. Endovascular describes the minimally invasive technique of accessing the aneurysm from within the bloodstream, specifically during angiography. The bloodstream is entered through the femoral artery in the upper thigh. A flexible catheter is advanced from the femoral artery to one of four arteries in the neck that lead to the brain. The doctor steers the catheter through the blood vessels while injecting a special dye that makes them visible on the monitor. The result is a kind of roadmap of the arteries.
Once the catheter reaches the aneurysm, a very thin platinum wire is inserted. The wire coils up as it enters the aneurysm and is then detached. Multiple coils are packed inside the dome to block normal blood flow from entering. Over time, a clot forms inside the aneurysm, effectively removing the risk of aneurysm rupture. Coils remain inside the aneurysm permanently. Coils are made of platinum and other materials, and come in a variety of shapes, sizes, and coatings that promote clotting. Coils accomplish from the inside what a surgical clip would accomplish from the outside: they stop blood from flowing into the aneurysm but allow blood to flow freely through the normal arteries.
However, simple coil packing is not the only tool in the armamentarium of the neuro-interventionist. Depending on the aneurysm configuration and neck, other ancillary assisting hardware or flow diverters can be used.
The treatment decision for observation, surgical clipping or endovascular coiling or flow diversion largely depends on the aneurysm’s size, location, and neck geometry. The less invasive nature of coiling was traditionally believed to be favored in patients who were older, in poor health, having serious medical conditions, or having aneurysms in certain locations. However, with advanced and evolving endovascular hardware and techniques, there are very few cases which would be offered surgical option as solitary first choice. Rather it would be factors of local expertise available and cost that will decide one choice over the other.
Most patients treated with coils for an unruptured aneurysm can expect to live normal and productive lives. They typically can work and enjoy activities, including exercise, as before. Part of their healthcare regimen is to return for follow-up angiograms as prescribed.
