Gamma Knife Treatment of Arteriovenous Malformations (AVM's)
Arteriovenous malformations(commonly referred to as AVM's) are a collection of thin walled blood vessels which are massed together like a tangle of spaghetti. They are literally birthmarks in the brain. They can occur anywhere on the surface or the depth of the brain. There is always a risk of these fragile vessels rupturing and causing a subarachnoid or intracerebral haemorrhage. They can also act as an irritant and produce fits.
Treatment for these malformations in the past was either surgery or a wait and see policy if the lesion was in an inaccessible position. Now embolisation (“glue treatment”) and Gamma Knife radiosurgery (GKRS) are also used, in fact GKRS is the treatment of choice for the majority of AVMs in the UK.
Your specialists will have considered all of these options, perhaps in combination. Ideally, you should have only one, which ever for you, is the most appropriate intervention.
Therefore a thorough multidisciplinary discussion, including radiosurgery experts, is important before any treatment.
Many studies indicate that GKRS has a high clinical efficacy and a significantly reduced morbidity rate (production of side effects) compared with microsurgery in the treatment of the difficult lesions. The chance of complete obliteration of the lesion is around 90% for small lesions and this percentage decreases as the size of the lesion increases. It is often the treatment of choice for patients not wanting to risk conventional surgery or not able to have surgery. Gamma Knife radiosurgery is also very useful in treating AVMs in or near critical structures, such as the brain stem.
In more recent years the larger lesions (dependant on their size and where in the brain they are situated) can sometimes be treated by using staged treatment.
The Sheffield Centre for Stereotactic Radiosurgery has treated over 6,400 patients with these lesions since 1985.