ManageMent options for arteriovenous malformations (AVMs) have expanded and evolved over time. However, the underlying goal of intervention remains complete obliteration of the AVM and maintenance of neurological function. 16,40,41 The rates of AVM occlusion after a single Gamma Knife surgery generally range from 70% to 80% over a 5-year observation period. 6,11,19,25 In addition, stereotactic radiosurgery (SRS) has a relatively low risk profile for adverse radiation effects (AREs).
23The lateral geniculate nucleus gives rise to the sublenticular and retrolenticular segments of the optic radiation that travel through the temporal and parietal lobes, respectively, on a path that terminates in the striate cortex. Because the distance and fragility of these pathways create the opportunity for disruption by an AVM, associabbreviatioNs ARE = adverse radiation effect; AVM = arteriovenous malformation; SRS = stereotactic radiosurgery. submitted January 8, 2014. accepted October 14, 2014. iNclude wheN citiNg Published online November 28, 2014; DOI: 10.3171/2014.10.JNS1453. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Dr. Lunsford is a consultant and stockholder for AB Elekta. , and 19 Gy (range 14-25 Gy) was the median margin dose. Obliteration of the AVM was confirmed in 80 patients after a single SRS procedure at a median follow-up of 74 months (range 5-297 months). The actuarial rate of total obliteration was 67% at 4 years. Arteriovenous malformations with a volume < 5 cm 3 had obliteration rates of 60% at 3 years and 79% at 4 years. The delivered margin dose proved significant given that 82% of patients receiving ≥ 22 Gy had complete obliteration. The AVM was completely obliterated in an additional 18 patients after they underwent repeat SRS. At a median of 25 months (range 11-107 months) after SRS, 9 patients developed new or worsened visual field deficits. One patient developed a complete homonymous hemianopia, and 8 patients developed quadrantanopias. The actuarial risk of sustaining a new visual deficit was 3% at 3 years, 5% at 5 years, and 8% at 10 years. Fifteen patients had hemorrhage during the latency period, resulting in death in 9 of the patients. The annual hemorrhage rate during the latency interval was 2%, and no hemorrhages occurred after confirmed obliteration. coNclusioNs Despite an overall treatment mortality of 5%, related to latency interval hemorrhage, SRS was associated with only a 5.6% risk of new visual deficit and a final obliteration rate close to 80% in patients with AVMs of the postgeniculate visual pathway.