GAMMA-KNIFE RADIOSURGERY

Abstract

Clinical research to refine and minimize surgical interventions has continued to be one of the most important features of the neurosurgical development during the last half of the XX century. Prof. Lars Leksell, the inventor of the Gamma-Knife radiosurgery (GKRS), was a leader in stereotactic surgery. In addition, he coined the concept of radiosurgery more than 60 years ago. Leksell and his coworkers have defined the indications for radiosurgery and introduced stereotactic techniques into radiosurgery. Today, GKRS is one of the three generally accepted treatment modalities in the treatment of cerebral AVMs together with microsurgery and endovascular techniques. The authors present their experience in treating 461 patients harbouring cerebral AVMs with a Leksell Gamma-Knife unit between 2005 and 2023. The follow-up schedule was a MR examination performed 6 and 12 months after the treatment in order to define if a radiation induced oedema had developed or not, as this represents the beginning and the end of the timer period in which the complications usually occur. If a radiation induced oedema was visible and the patient asymptomatic, the oedema was not treated. After that, a MRI and a MRA examination after two years to define the timing of the angiogram are of need. If the 2-year MR suggests complete AVM occlusion, we always perform an angiogram to verify the occlusion, as we know that a small remnant cannot be definitely excluded by using MR examinations. If the 2-year MR examination reveals a persistent AVM nidus, we postpone the angiogram to 3 years after the treatment. Naturally, as for all patients, a neuroradiological examination can be prompted by clinical symptoms. The outcome of our patients following a GKRS in relation to their age can be summarized as follows: - AVMs in children: cure rate 86% at 24 months, cure rate 100% at 36 months; - AVMs in young adults: cure rate 81% at 24 months, cure rate 86% at 36 months; - AVMs in adults: cure rate 41% at 24 months, cure rate 82% at 36 months. Predilect areas for oedema were the Parietal lobe and the basal ganglia, and 5 of the 6 patients which developed it had AVMs in excess of 11 cm3. The probability for AVM obliteration is dependent of the dose to the AVM periphery, the volume of the nidus and its localization, best results being recorded in children.

Keywords

• GAMMA-KNIFE RADIOSURGERY