Introduction
Embolisation is the process of intentionally blocking off blood vessels to prevent further flow and encouraging clotting. It is used to treat a number of neurovascular conditions, such as brain aneurysms, arteriovenous malformations (AVM), dural arteriovenous fistula (DAVF) and carotid-cavernous fistulas (CCF), as well as for tumours by reducing blood supply and potentially shrinking them.
Much like brain aneurysm coiling and stents, it is a minimally invasive endovascular procedure with no large incisions are required. A thin tube (catheter) is introduced via an artery (normally in the groin) while a real time x-ray, called digital subtraction angiography (DSA), is conducted to ensure the catheter is accurately positioned.
Indications
Embolisation is a procedure used to treat the following conditions…
- Brain Arteriovenous Malformation (AVM)
- Dural Arteriovenous Fistula (DAVF).
- Carotid-Cavernous Fistula (CCF).
Preoperative Instructions
Before all neurosurgical procedures, including this procedure, you should…
- Be “Nil by mouth” (Nothing to eat or drink) from midnight the night before the procedure. Continue to take medications with small sips of water.
- Let our office know if you take blood thinners – Some types of blood thinners are allowable, so please consult your doctor ahead of the procedure about whether blood thinners should be ceased.
- If other dental treatment (within three weeks) or any other form of surgery (within three months) of the planned procedure can be rescheduled to a later date, this would be advisable.
- To reduce risks of peri-operative infection, please notify our office if you develop any symptoms of infection, e.g. a cold or flu, before surgery, or if you are receiving treatment for an infection.
Procedure
The patient may remain awake with sedation during this procedure, although in general, most procedures are carried out under general anaesthesia.
The catheter is introduced via an entry point in the groin (via either an artery and/or vein) and is carefully manouvered into position near the malformation/fistula. The angiography gives the surgeon a real time image of the structure of the blood vessels and the appropriate 'agent' is selected for embolisation. These agents may be…
- Coils.
- Liquid embolic agents (Onyx / PHIL).
- Glue (cyano-acrylate).
- Microbeads / Particles (PVA).
- Microvascular Plugs.
One of these agents is then introduced via the catheter to the blood vessel where the embolisation needs to occur. Under constant X-Ray vision, the embolic material is delivered precisely to the desired area to block off the intended blood vessels. While most AVMs are treated through the arterial system, DAVF or CCF can be treated through either the arteries or the veins. The choice of approach and embolic agents are determined by the neuro-interventional surgeon based on the features of the vascular condition.
In general, the goal of AVM and tumour embolisation is to decrease blood flow, so to assist open microsurgical removal of AVMs or tumours by reducing blood loss. AVMs cannot typically be cured by embolisation, unlike DAVF and CCF, in which complete cure can be obtained by endovascular methods alone.
In some AVM or DAVF cases, multiple sites may need to be embolised on separate occasions, and so a series of staged procedures may need to be conducted over a period of weeks to months, allowing approximately 2-3 weeks between procedures.
Postoperative Instructions
Patients are generally kept overnight for observation in intensive care, and then can return home the following day, and can often return to normal day-to-day activities within a few days.
Risks
In addition to the standard risks of surgery and anaesthesia generally, the following are potential risks associated with this procedure…
- Stroke (resulting in weakness, numbness, vision and speech disturbance).
- Bleeding in the brain.
- Damage to artery at groin insertion point.
- Infection (usually at the groin).
- Failure of embolic agent; or placement of embolic agents in unintended locations.