Nasser Institute

Arteriovenous Malformations

These are formed before birth. The name is shortened for convenience to AVM. They are congenital, meaning they are due to a defect of develop­ment. They are however not hereditary. This means they are not inherited.








These AVMs may make their presence known with epilepsy. The patient has one or more epileptic attacks and this leads to investigation and diagnosis.


When a bleed occurs the patient may either have severe headache and vomit­ing starting suddenly. Another thing that may happen is the patient be­comes unconscious for a period. On waking up the patient may or may not have some degree of paralysis.

Aims of Treatment

If the problem is epilepsy then medi­cine is given to help with that. This may or may not be enough. If the problem is bleeding then any damage left by the bleed is treated with physiotherapy and rehabilitation. Damaged brain cannot be replaced or repaired.

It is important to understand that the treatment is aimed at preventing an­other bleed or in bringing the epilepsy under control. Moreover, patients with epilepsy may bleed later so again the aim of treatment is to prevent that happening.Thus the purpose of the Gamma Knife is to destroy the AVM so that it may not bleed again. One of the useful side effects is that this will usually improve or even stop the epilepsy.


AVMs may be treated by observation, though that is rarer today. Mostly in­terventions are tried. The commonest forms of intervention are surgery, em­bolization and radiosurgery (Gamma Knife).

Not all AVMs may be treated. Some are simply to big and complex. How­ever, once a decision is made to treat the lesion then a further decision must be taken as to which treatment method is best. In many instances a combination of treatments may be required.

Gamma Knife

The Gamma Knife cannot improve any symptoms due to damage done during a bleed. The image to the right shows the destruction rate of AVMs at the

Gamma Knife Center. This chart illus­trates also how the successful treat­ments increase with time. These early results are amongst the best reported.

One of the nicest things about treating this condition is that the patient may in principle return to work and forget the illness. The Gamma Knife also has the advantage that it can treat AVMs which are not possible to treat in any other way.


Normal Circulation

In the normal situation, red blood (with oxygen)

passes through capillaries. The oxygen leaves the

blood which without oxygen is blue in colour.

The capillaries are very narrow and the pressure

driving the blood round falls as the blood passes

through them. Thus the pressure in the veins is


AVM Circulation

There are no capillaries so that the red blood

(with oxygen) loses very little of its oxygen and

remains much more red in colour in the veins.

There are no capillaries to reduce the pressure in

the blood. Thus the pressure in the veins is

higher than normal. Veins are not made to resist

high pressures. Thus bleeding may occur.