Leksell Gamma Knife Radiosurgery of Cerebral Arteriovenous Malformations: Long-Term Clinical and Radiological Outcome in Iran Gamma Knife Center

Abstract

Background: Intracranial arteriovenous malformations (AVMs) are congenital vascular lesions affecting 0.01-0.5% of the general population. Radiosurgical treatment has a slow and progressive thrombotic effect on fragile vessels of AVMs. The aim of this study was to evaluate the long-term clinical and the radiological outcome of the patients on treated AVMs with Leksell Gamma knife radiosurgery.

Materials and Methods: We reviewed the outcomes of 388 patients who underwent Gamma Knife radiosurgery for AVMs in 8 years starting from 2002. These results are compared to other contemporary radiosurgical series. Patient follow up was performed by MRI, MR angiography or Angiography.

Results: The patients were followed up for a mean period of 61.6 months (range, 12 to 93 months) after the initial GKS. 95% of patients with AVMs had follow-up imaging. Complete obliteration in angiographic studies was observed in 45% of the patients in the first year of follow up and 64% in mean 5 years follow up and also reduction in lesion volume was noted in MRI studies in 65% of cases after mean 5 years. A significant relation was found between obliteration rate and risk of hemorrhage (p<0.001).  Complications such as transient hemi-paresis, VA and VF defect, cranial nerves palsy and very low rate of re-bleeding mostly in first year & in subtotal obliteration was observed.

Conclusion: GKS for cerebral AVM offers an effective and relatively safe treatment modalities, with low complication rate. AVMs are well-suited for radiosurgery, since radiation can be focused on a well circumscribed region, while adjacent neural structures are spared. Cortically located AVMs with a nidus volume less than 10 ml could be operated, with or without pre-surgical embolization,   unless there is a single feeder that can easily be catheterized and embellished for obliteration, or other obvious target for embolization such as pseudoaneurysms or large fistulae. Centrally located AVMs with a nidus volume less than 10 ml should be treated by radiosurgery, unless suitable for embolization as indicated above.