Long-term follow up data on difficult to treat intracranial arteriovenous malformations treated with the CyberKnife

Abstract

IntroductionThe CyberKnife, a frameless, robotic, stereotactic device, has been developed to radiosurgically treat arteriovenous malformations (AVMs). While most AVMs are obliterated within two-to-three years, a subset remain recalcitrant; long-term data on these difficult to treat AVMs are limited in the neurosurgical literature. Materials and methodsA retrospective analysis of all patients who underwent CyberKnife treatment for intracranial AVMs at a single U.S. institution between 2002 and 2012, whose AVMs had failed to obliterate within 48 months or longer from the treatment start date, were eligible for inclusion. ResultsEleven patients (9 AVMs; 7 males, 2 females) were followed for an average of 85.2 months (range 56.2–119.4). The median lesion size was 3.5 cm (range: 2.8–8.0 cm) and median Spetzler-Martin grade was 3 (range: 2–5). All AVMs were treated with one radiation dose (median prescribed dose was 18.0 Gy; median Dmax: 23.7 Gy). Six (66.7%) were obliterated in a median time of 84 months (range: 52–94 months), while 3 (33.3%) remained active after a median of 90.8 months (range 69.7–119.4). Transient, post-radiosurgery adverse radiation effects occurred in 5 (55.6%) cases. One (11.1%) patient had an acute hemorrhage from the AVM after radiosurgery. Four (44.4%) patients underwent repeat radiosurgery and/or embolization. Three of these lesions eventually obliterated, while 1 did not. ConclusionThe median time to obliteration was 84 months. Two-thirds of AVMs which persisted for over 4 years following initial radiosurgery treatment eventually obliterated. Transient post-radiosurgery adverse effects were common; delayed hemorrhages were rare in our case series.