Plenary Oral Presentations - Macquarie University Hospital

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16 th International Meeting of the Leksell Gamma Knife ® SocietyMarch 2012, Sydney, AustraliaVA-39Hypertension may not convey excess risk ofradiation-induced change in Gamma Knife radiosurgery ofcerebral arteriovenous malformation1Mark Quigg, 2 Chun-Po Yen, 1 Micaela Chatman, 1 Anders Quigg, 2 Jason Sheehan1University of Virginia, Dept of Neurology2University of Virginia, Dept of NeurosurgeryObjective: No studies exist to determine the excess risk of radiation toxicity in patients with diabetesmellitus or hypertension who undergo Gamma Knife radiosurgery (RS) of cerebral arteriovenousmalformation (AVM). Limited studies suggest DM and HTN are associated with excessive complicationsfollowing fractionated radiotherapy of lesions outside the central nervous system.Methods: This single-center, retrospective, consecutive case series determined the associations betweenradiation-induced changes (RIC) visible on MRI following RS for AVM. Patients with incompletefollow-up and children ≤ 17 years were excluded. History or medication use for DM or HTN, tobaccouse, age, sex, AVM volume, Spetzler-Martin severity grade (1-2 vs 3-5), pre-RS surgery, embolization,or hemorrhage were compared between RIC(+) and RIC(–) groups by univariate and logistic regressionmultivariate analyses.Results: RIC occurred in 38% of 539 adults within 12±10 months (mean±standard deviation) of RSin a median follow-up of 55 months. 34% of those with RIC had symptoms of headache, neurologicaldeficits, or new-onset seizures, with larger RIC associated with greater symptomatology. DM (3% ofsample) was significantly higher with RIC (RIC(+) 5%, RIC(–) 1%, P=0.02 Fisher’s exact test), butHTN (20%) was not. Larger AVM volume and Spetzler-Martin grades 3-5 had significant associationswith RIC. The proportion of patients with pre-RS surgery and pre-RS hemorrhage were significantlydecreased in the RIC(+) group. Older age had borderline associations with RIC. Sex, tobacco use, orpre-RS AVM embolization had no associations with RIC. The factors significantly associated withRIC in multivariate analysis were larger AVM volumes, Spetzler-Martin grades 3-5, and absence ofpre-RS surgery.Conclusions: HTN, traditionally considered to increase the risk of RS in the CNS, did not carrysignificant risks in development of RIC. The number of patients with DM was too low to determinerisk accurately.70
16 th International Meeting of the Leksell Gamma Knife ® SocietyMarch 2012, Sydney, AustraliaVA-50Treatment results of radiosurgery for cerebralarteriovenous malformations in the modern APS eraShunsuke Kawamoto, Fumi Higuchi, Phyo KimDepartment of Neurosurgery, Dokkyo University School of MedicineObjective: The authors sought to assess the efficacy and safety of gamma knife radiosurgery (GKRS)with meticulously-planned conformal coverage using multiple small isocenters in 47 patients withcerebral arteriovenous malformations (AVMs) treated by GammaKnife Type C between 2005 and2008.Methods: The mean volume of AVMs was 4.3 ml (range, 0.04-27.4). Eight patients had AVM niduslarger than 10ml. Dose planning was primarily based on MR angiography and was confirmed ondigital subtraction angiography (DSA). The mean marginal dose was 21.3 Gy (range, 16.7-25). Totalnumber of isocenters used in irradiation ranged from 2 to 76 (mean 27, median 27). In the follow-upperiod, MR images were taken every six months, and DSA was performed to confirm nidus obliterationat 3 years or earlier after GKRS. Outcomes such as the rates of obliteration, hemorrhage after treatment,and adverse radiation effects were analysed.Results: All the 46 patients were followed up for longer than 3 years. Thirty-seven of them underwentDSA and thirty-five (94.6%) showed complete obliteration. In Kaplan-Meier analysis, the completeobliteration rate at 36 months was 97.8% for AVMs with a volume of less than 10 ml. The margindose was the single factor associated with higher obliteration rate (p=0.022). Moderate to extensiveradiation-induced edema was revealed on MR images in 21.3% (10 of 47). The number of totalisocenters was the single significant factor associated with development of radiation-induced edema(p=0.03). Ten of 47 (21.3%) developed new or worsened neurologic symptom and three (6.4%)persisted. Six patients (12.8%) suffered hemorrhage from their AVMs after GKRS; two died of thehemorrhage and one became severely disabled. Among the eight patients with AVMs larger than 10ml, five (62.5%) suffered hemorrhage.Conclusions: Meticulous conformal coverage using multiple small isocenters contributed to higherobliteration rates at earlier stage after GKRS than previously reported, but does not lead to decreasein complication, and might be associated with higher bleeding rate with larger AVMs during thelatency period.71
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Plenary Oral Presentations - Macquarie University Hospital

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