Abnormal connections between arteries and veins are called Arteriovenous malformations of the brain or spine. Difficult or dangerous to treat, AVM might cause bleeding into or around the brain, most commonly in young adults. Even though AVMs are responsible for causing headaches or other symptoms, very often they are discovered on CT or MRI scans that were performed for other reasons. And if they are left untreated, there are chances that they might start bleeding, therefore causing neurologic damage that might be severe or might even lead to death. Safe, surgical removal of AVMs or treatment with radiation require either partial or complete closure of the AVM by embolization (blocking) techniques. This improves the safety, effectiveness and outcome of surgery.
AVMs are natural as people are born with it, even though they do not appear to be inherited from their parents, neither are they given to the children. It is as if AVMs might be caused by a rupture or clotting of a blood vessel that started to develop during development before the person was born. It is generally not associated with other maldevelopments or with other AVMs.
The most generalized symptoms of AVMs are Seizures and headaches, but no particular type of seizure or headache pattern can be identified. Seizures might be partial or total, and would involve a loss of control over movement, convulsions or a change in the person’s level of consciousness. Headaches might be different greatly in frequency, in their duration and their intensity, at times might even become as severe as migraines. There are times when a headache continuously affecting one side of the head might be linked closely to the site of an AVM. Even more frequently, however, the location of the pain might not specific to the lesion and might encompass most of the head.
AVMs are also responsible for causing a wide range of more specific neurological symptoms that would vary from person to person, and that would depend primarily upon the AVMs’ location. These symptoms might include muscle weakness or paralysis in one part of the body; there would be a loss of coordination that can lead to problems like gait disturbances; apraxia, or difficulties in carrying out tasks that require planning; dizziness might be very common; visual disturbances like loss of part of the visual field; inability in being able to control eye movement; swelling of a part of the optic nerve known as the optic disk can happen; there would be a great deal of problems in using or understanding language this is known as aphasia; abnormal sensations like numbness, tingling or spontaneous pain which are known as paresthesia or dysesthesia are very common as well; memory deficits; and mental confusion, hallucinations or dementia; these are some very commonly occurring symptoms of AVM.
Embolization is a method that helps in plugging the blood vessels of the AVM. With the help of an X-ray guidance, a small tube known as a catheter has to be guided from the femoral artery in the leg up into the area that has to be treated.
Before and after a small amount of medicine is injected a neurological exam is performed. This helps in figuring out if the vessel that has been feeding the AVM is also able to feed normal and important portions of the brain. Following this, into the AVM a permanent agent is injected and the catheter has to be removed. For each vessel that feeds the AVM this is repeated. The patient is awake during the embolization but is made comfortable with the help of the anesthesia team that monitors them and gives them medicines by an intravenous line. The patients usually spend the night in the Neurological Intensive Care Unit after the embolization where they would be monitored closely. Generally patients are hospitalized for three nights for each embolization and two or three embolizations are required at intervals of two to six weeks. Patients might be able to resume their normal full activity soon after discharge. There are chances that there might be some kind of mild headache after the embolization and it is related to the blood vessels of the AVM clotting, or some nausea might also be there that would be related to some of the medicines that are given.
On its own embolization is rarely curative. Surgery or radiations which are needed to completely cure the AVM are not replaced by it. When performed before surgery or radiation the embolization procedure is very helpful. For example, embolization is useful before surgery because it is able to block the shunts, so that it doesn’t lead to much bleeding during surgery. Following the radiation, by blocking the shunts, the size of the AVM can be reduced and therefore the area that has to be radiated would be smaller. The smaller the area radiated is the less chance there is that the radiation would damage the brain tissue around the AVM.