Leksell Gamma Knife for pediatric and adolescent cerebral arteriovenous malformations: results of 100 cases followed up for at least 36 months.
OBJECTIVE
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 also confirmed on multivariate analysis) significantly influenced OR. Lower S-M grades and single-session planned treatments correlated with shorter treatment obliteration interval on univariate analysis. This statistical analysis suggests that a staged radiosurgical treatment should be planned when nidus volume > 10 ml and/or when the recommended PD is ≤ 16 Gy.
Istituto di Neurochirurgia, DAI di Neuroscienze;
Antonio
A
Nicolato
Istituto di Neurochirurgia, DAI di Neuroscienze;
Michele
M
Longhi
Centro Interdipartimentale di Documentazione Economica (C.I.D.E.), University of Verona;
Nicola
N
Tommasi
Neuroradiologia - d.O. and.
Giuseppe Kenneth
GK
Ricciardi
Istituto di Neurochirurgia, DAI di Neuroscienze;
Roberto
R
Spinelli
Servizio Fisica Ospedaliera, DAI Patologia e Diagnostica; and.
Roberto Israel
RI
Foroni
Servizio Fisica Ospedaliera, DAI Patologia e Diagnostica; and.
Emanuele
E
Zivelonghi
Istituto di Neurochirurgia, DAI di Neuroscienze;
Simone
S
Zironi
Radioterapia Ospedaliera, DAI di Chirurgia ed Oncologia, Verona, Italy.
Stefano
S
Dall'Oglio
Neuroradiologia - d.O. and.
Alberto
A
Beltramello
Istituto di Neurochirurgia, DAI di Neuroscienze;
Mario
M
Meglio
D000293:Adolescent; D000465:Algorithms; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D007558:Italy; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D011379:Prognosis; D016634:Radiosurgery / Q000295:instrumentation*; D013238:Stereotaxic Techniques; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
ARE = adverse radiation effects; EE = endovascular embolization; GK = Gamma Knife; Gamma Knife; LINAC = linear accelerator; MD = maximal dose; OR = obliteration rate; PD = prescription dose; RS = radiosurgery; S-M = Spetzler-Martin; TOI = treatment obliteration interval; cAVM = cerebral arteriovenous malformation; cerebral arteriovenous malformation; pediatric patients; stereotactic radiosurgery