Endovascualr surgery (or coiling aneurysms) involves the insertion of metallic coils into the aneurysm from the inside of the artery. Via an angiogram a tube (known as a catheter) is threaded within the arteries of the body and neck into the inside of the aneurysm. These coils are packed into the aneurysm preventing blood entering the aneurysm. They also promote clotting of the blood around them. The most favourable aneurysms to coil are small aneurysms that are rounded with a small entry from the normal artery into the aneurysm. This is in order to hold the aneurysm coils within the aneurysm. Some more difficult aneurysms can be treated by this technique with additional endovascular procedures (such as the temporary placing of a balloon in the artery to help pack the coils into the aneurysm, placing a permanent scaffolding stent within the artery to support the coils, and newer aneurysm coils that promote bonding within the aneurysm.
The risks, expectations and alternatives of this technique need to be fully understood. The risks include rupturing the aneurysm during the procedure (the very complication that the procedure aims to treat and prevent producing the problems indicated above), unexpected blood clotting within an artery of the brain (causing a stroke), and re-opening of the aneurysm at a later date causing a subarachnoid haemorrhage.
Endovascular surgery (or coiling) is the preferred treatment option for some aneurysms but aneurysms come in many locations, shapes and sizes and the best treatment requires an expert to evaluate whether the aneurysm is best treated by this technique, surgery or just maintained surveillance. In some cases the aneurysm can be treated with either microsurgical or endovascular technique and the recommendation as to the preferred technique for a individual needs to take into account many factors including the age of the patient (for the durability of the procedure), the skills of the proceduralists (and their track record of similar aneurysms), the need for progress surveillance angiography, and many other considerations.
A recent development with aneurysm repair is flow diverters. This is very promising and may prove to be very useful in the management of some very difficult to treat aneurysms. It works by inserting a stent (a loose woven tube) within the artery and this becomes adherent to the artery wall. Although this looks to be very effective, not enough time has passed for us to know how good this is as an aneurysm treatment. With reports by some of late rebleeding and strokes (in a small number of cases) its use needs to be carefully considered against the choice of long established techniques that have been well studied over many years.
Progress surveillance digital subtraction angiography is usually performed at 6 months, 12 months and 24 months following initial treatment. Further, follow-up studies may also be needed depending on the result of ongoing assessment of this treatment. If re-opening of the aneurysm occurs on these studies there is a risk of haemorrhage and treatment may need to be repeated or surgery performed.
Microsurgery aims to repair the aneurysm from the outside of the artery placing a strong spring clip across where the aneurysm arises from the artery – like pinching off the neck of a balloon. This prevents blood entering the aneurysm from the artery. At surgery a small window of bone is removed from the skull and with the use of the microscope the valleys of the brain are traversed without the need for cutting into the brain. This gains access to the artery with the aneurysm allowing the clip to be placed permanently across the neck of the aneurysm. At the end of the surgery the bone is replaced and secured.
The risks, expectations and alternatives of this technique need to be fully understood. The risks include rupturing the aneurysm during the procedure (the very complication that the procedure aims to treat and prevent producing the problems indicated above) and inadvertently blocking an artery of the brain.
This is the preferred treatment option for some aneurysms but aneurysms come in many locations, shapes and sizes and the best treatment requires an expert to evaluate whether the aneurysm is best treated by this technique, endovascular coil placement or just maintained surveillance. In some cases the aneurysm can be treated with either technique and the recommendation as to the preferred technique for a individual needs to take into account many things including the age of the patient (for the durability of the procedure), the skills of the proceduralists and their track record of similar aneurysms, the need for progress surveillance angiography, and many other considerations.
It is unusual to develop another aneurysm at the site of aneurysm repair by microsurgery. Therefore, progress surveillance is not usually recommended for the treated aneurysm but because new aneurysms can occur (in as many as 20% of cases) at other sites ongoing monitoring may be necessary. This may be done by CTA, MRA or digital subtraction angiography (although the latter is not always thought necessary).
Treatment by brain bypass
For very complex aneurysms it is occasionally necessary to perform a bypass surgery to remove the aneurysmal section of artery from the circulation. This surgery may involve removing a segment of vein in the leg and substituting this vein into the brain circulation.
In some cases, no treatment is warranted either because the risk of aneurysm rupture is so small that the risks of treatment become too great to consider. In other cases, no safe treatment is possible. In such people it may be appropriate to monitor the aneurysm for changes either by MRI, CTA or digital subtraction angiography at intervals. In the case of small aneurysms that are thought to be at low risk for bleeding, such monitoring will lead to a change to treatment by surgery or coiling if the aneurysm changes in size or shape. The need for and method of monitoring vary from person to person. Although aneurysms can rupture without any underlying precipitating factors it may well be that very good blood pressure management and stopping smoking are helpful.