Early versus late arteriovenous malformation responders after stereotactic radiosurgery: an international multicenter study.
OBJECTIVE The goal of stereotactic radiosurgery (SRS) for arteriovenous malformation (AVM) is complete nidus obliteration, thereby eliminating the risk of future hemorrhage. This outcome can be observed within the first 18 months, although documentation of AVM obliteration can extend to as much as 5 years after SRS is performed. A shorter time to obliteration may impact the frequency and effect of post-SRS complications and latency hemorrhage. The authors' goal in the present study was to determine predictors of early obliteration (18 months or less) following SRS for cerebral AVM. METHODS Eight centers participating in the International Gamma Knife Research Foundation (IGKRF) obtained institutional review board approval to supply de-identified patient data. From a cohort of 2231 patients, a total of 1398 patients had confirmed AVM obliteration. Patients were sorted into early responders (198 patients), defined as those with confirmed nidus obliteration at or prior to 18 months after SRS, and late responders (1200 patients), defined as those with confirmed nidus obliteration more than 18 months after SRS. The median clinical follow-up time was 63.7 months (range 7-324.7 months). RESULTS Outcome parameters including latency interval hemorrhage, mortality, and favorable outcome were not significantly different between the 2 groups. Radiologically demonstrated radiation-induced changes were noted more often in the late responder group (376 patients [31.3%] vs 39 patients [19.7%] for early responders, p = 0.005). Multivariate independent predictors of early obliteration included a margin dose > 24 Gy (p = 0.031), prior surgery (p = 0.002), no prior radiotherapy (p = 0.025), smaller AVM nidus (p = 0.002), deep venous drainage (p = 0.039), and nidus location (p < 0.0001). Basal ganglia, cerebellum, and frontal lobe nidus locations favored early obliteration (p = 0.009). The Virginia Radiosurgery AVM Scale (VRAS) score was significantly different between the 2 responder groups (p = 0.039). The VRAS score was also shown to be predictive of early obliteration on univariate analysis (p = 0.009). For early obliteration, such prognostic ability was not shown for other SRS- and AVM-related grading systems. CONCLUSIONS Early obliteration (≤ 18 months post-SRS) was more common in patients whose AVMs were smaller, located in the frontal lobe, basal ganglia, or cerebellum, had deep venous drainage, and had received a margin dose > 24 Gy.
Department of Neurosurgery and Gamma Knife Center, University of Virginia, Charlottesville, Virginia.
Or
O
Cohen-Inbar
Department of Neurosurgery and Gamma Knife Center, University of Virginia, Charlottesville, Virginia.|Department of Neurological Surgery and Radiology, University of Miami, Florida.
Robert M
RM
Starke
Department of Neurosurgery and Gamma Knife Center, University of Virginia, Charlottesville, Virginia.
Gabriella
G
Paisan
Department of Neurosurgery, University of Pittsburgh, Pennsylvania.
Hideyuki
H
Kano
Department of Neurosurgery, New York University Langone Medical Center, New York, New York.
Paul P
PP
Huang
Department of Neurosurgery, University of Puerto Rico, San Juan, Puerto Rico.
Rafael
R
Rodriguez-Mercado
Department of Neurosurgery, University of Puerto Rico, San Juan, Puerto Rico.
Luis
L
Almodovar
Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan.
Inga S
IS
Grills
Department of Neurosurgery, University of Sherbrooke, Centre de Recherche Clinique Étienne-LeBel, Sherbrooke, Quebec, Canada.
David
D
Mathieu
Rose-Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic, Cleveland, Ohio.
Danilo
D
Silva
Rose-Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic, Cleveland, Ohio.
Mahmoud
M
Abbassy
Rose-Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic, Cleveland, Ohio.
Symeon
S
Missios
Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania; and.
John Y K
JYK
Lee
Rose-Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic, Cleveland, Ohio.
Gene H
GH
Barnett
Department of Neurosurgery, New York University Langone Medical Center, New York, New York.
Douglas
D
Kondziolka
Department of Neurosurgery, University of Pittsburgh, Pennsylvania.
L Dade
LD
Lunsford
Department of Neurosurgery and Gamma Knife Center, University of Virginia, Charlottesville, Virginia.
Jason P
JP
Sheehan
D000328:Adult; D001164:Arteriovenous Fistula / Q000150:complications / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D038622:Internationality; D002538:Intracranial Arteriovenous Malformations / Q000150:complications / Q000532:radiotherapy*; D008297:Male; D016634:Radiosurgery; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
AVM = arteriovenous malformation; GKRS = Gamma Knife radiosurgery; Gamma Knife; IGKRF = International Gamma Knife Research Foundation; MRA = MR angiography; RBAS = Radiosurgery-Based AVM score; RIC = radiation-induced change; SM = Spetzler-Martin; SRS = stereotactic radiosurgery; VRAS = Virginia Radiosurgery AVM Scale; arteriovenous malformation; early obliteration; embolization; radiosurgery; stereotactic radiosurgery; vascular disorders