Leksell Gamma Knife for pediatric and adolescent cerebral arteriovenous malformations: results of 100 cases followed up for at least 36 months

Abstract

J neurosurg Pediatr 16:736-747, 2015 abbreviations ARE = adverse radiation effects; cAVM = cerebral arteriovenous malformation; EE = endovascular embolization; GK = Gamma Knife; LINAC = linear accelerator; MD = maximal dose; OR = obliteration rate; PD = prescription dose; RS = radiosurgery; S-M = Spetzler-Martin; TOI = treatment obliteration interval. obJect The goal of this study was to evaluate advantages, risks, and failures of Gamma Knife radiosurgery (GKRS) in a large series of pediatric and adolescent patients with cerebral arteriovenous malformations (cAVMs) who were followed up for at least 36 months. methods Since February 1993, 100 pediatric and adolescent patients (≤ 18 years of age) with cAVMs have undergone GKRS at the authors' institution and were followed up for at least 36 months. Forty-six patients were boys and 54 were girls; the mean age was 12.8 years (range 3-18 years). Hemorrhage, either alone or combined with seizure, was the clinical onset in 70% of cases. The mean pre-GK cAVM volume was 2.8 ml; 92% of cAVMs were Spetzler-Martin (S-M) Grades I-III. Most lesions (94%) were in eloquent or deep-seated brain regions, according to S-M classification. The parameters for mean and range in treatment planning were prescription isodose 53.8% (40%-90%); prescription dose (PD) 20.2 Gy (9.0-26.4 Gy); maximal dose (MD) 37.8 Gy (18-50 Gy); and number of shots 4.7 (1-17). On the day of GKRS, stereotactic CT or stereotactic MRI and digital subtraction angiography were used. results Obliteration rate (OR) was angiographically documented in 75 of 84 cases (89.3%) after single-session GKRS, with actuarial ORs at 3 and 5 years of 68.0% and 88.1%, respectively. A repeat treatment was performed in 7 patients (6 with obliteration), and 16 patients with cAVMs underwent staged treatment (9 of them were angiographically cured). Thus, the overall OR was 90%, with actuarial ORs at 3, 5, and 8 years of 59.0%, 76.0%, and 85.0%, respectively. Permanent symptomatic GK-related complications were observed in 11% of cases, with surgical removal of enlarged mass seen on post-RS imaging needed in 5 cases. Hemorrhage during the latency period occurred in 9% of patients, but surgical evacuation of the hematoma was required in only 1 patient. One patient died due to rebleeding of a brainstem cAVM. Radiosurgery outcomes varied according to cAVM sizes and doses: volumes ≤ 10 ml and PDs > 16 Gy were significantly associated with higher ORs and lower rates of permanent complication and bleeding during the latency period. conclusions The data from this study reinforce the conclusion that GKRS is a safe and effective treatment for pediatric and adolescent cAVMs, yielding a high OR with minimal permanent severe morbidity and no mortality. The very low frequency of severe hemorrhages during the latency period further encourages a widespread application of RS in such patients. Univariate analysis found that modified RS-based cAVM score, nidus volume, PD, integral dose, S-M grade, and preplanned treatment (the last 2 parameters were al...

Comparison of the Long-term Efficacy and Safety of Gamma Knife Radiosurgery for Arteriovenous Malformations in Pediatric and Adult Patients

“…First, its retrospective nature might have introduced selection biases in terms of participants and treatments. Nevertheless, our results are consistent with those of recent studies of pediatric patients, 19 , 25 , 86 – 92) which suggests that they are robust and applicable to clinical practice. Second, there was a sample size imbalance between the pediatric and adult cohorts.…”

International multicenter cohort study of pediatric brain arteriovenous malformations. Part 2: Outcomes after stereotactic radiosurgery

“…71 In contrast, Nicolato et al reported an overall obliteration rate of 90%, when the use of repeat radiosurgery was included, in a cohort of 100 pediatric patients with at least 36 months of post-radiosurgery followup. 58 We found higher radiosurgical margin dose to be an independent predictor of obliteration (p < 0.001) and favorable outcome (p < 0.001). An optimum dose cutoff of 22 Gy was identified, and those AVM patients who were treated with a dose ≥ 22 Gy had a significantly higher rate of favorable outcome (78% vs 47%, p < 0.001).…”

“…66 Nicolato et al found that AVM volume < 10 cm 3 and margin dose > 16 Gy were associated with significantly higher rates of obliteration and lower rates of posttreatment adverse events. 58 Dinca et al reported similar obliteration rates for pediatric AVMs treated with margin doses of 20 (83%) and 25 Gy (86%), therefore suggesting that the benefit of employing a margin dose > 20 Gy may be, at most, incremental. 16 In the current study, the absence of prior embolization was an independent predictor of favorable outcome (p = 0.001).…”

“…These outcomes are generally consistent with prior pediatric AVM radiosurgery series, and the post-radiosurgery hemorrhage rate compares favorably with the natural history of untreated AVMs. 47,48,58,62,66,71 Likely due, in part, to the smaller sizes of pediatric AVM cohorts, their outcomes after radiosurgery display greater variability than studies including adult patients. Sheth et al reported a 3-year obliteration rate of 30% after radiosurgery in a cohort of 42 pediatric AVMs.…”

“…A higher margin dose has been found to be predictive of AVM obliteration in prior pediatric AVM radiosurgery studies. 29,47,58,71,81 Potts et al reported an obliteration of 52% for pediatric AVMs treated with a margin dose of 18-20 Gy, compared with only 16% for those treated with a margin dose < 18 Gy. 66 Nicolato et al found that AVM volume < 10 cm 3 and margin dose > 16 Gy were associated with significantly higher rates of obliteration and lower rates of posttreatment adverse events.…”