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Repeat Gamma Knife Surgery for Incompletely Obliterated Cerebral Arteriovenous Malformations

Yen, Chun-Po MD; Jain, Surbhi MD; Haq, Iftikhar-ul MD; Jagannathan, Jay MD; Schlesinger, David PhD; Sheehan, Jason MD, PhD; Steiner, Ladislau MD, PhD

doi: 10.1227/01.NEU.0000370204.68711.AC
Clinical Studies: Editor's Choice

OBJECTIVE: The causes of failure after an initial Gamma procedure were studied, along with imaging and clinical outcomes, in a series of 140 patients with cerebral arteriovenous malformations (AVMs) treated with repeat Gamma Knife surgery (GKS).

METHODS: Causes of initial treatment failure included inaccurate nidus definition in 14 patients, failure to fill part of the nidus as a result of hemodynamic factors in 16, recanalization of embolized AVM compartments in 6, and suboptimal dose (< 20 Gy) in 23. Nineteen patients had repeat GKS for subtotal obliteration of AVMs. In 62 patients, the AVM failed to obliterate despite correct target definition and adequate dose. At the time of retreatment, the nidus volume ranged from 0.1 to 6.9 cm3 (mean, 1.4 cm3), and the mean prescription dose was 20.3 Gy.

RESULTS: Repeat GKS yielded a total angiographic obliteration in 77 patients (55%) and subtotal obliteration in 9 (6.4%). In 38 patients (27.1%), the AVMs remained patent, and in 16 patients (11.4%), no flow voids were observed on magnetic resonance imaging. Clinically, 126 patients improved or remained stable, and 14 experienced deterioration (8 resulting from a rebleed, 2 caused by persistent arteriovenous shunting, and 4 related to radiation-induced changes).

CONCLUSION: By using repeat GKS, we achieved a 55% angiographic cure rate. Although radiation-induced changes as visualized on magnetic resonance imaging occurred in 48 patients (39%), only 4 patients (3.6%) developed permanent neurological deficits. These findings may be useful in deciding the management of AVMs in whom total obliteration after initial GKS was not achieved.

OBJECTIVE: To determine the cause of treatment failure, clinical and imaging results after initial Gamma Knife Radiosurgery (GKRS) for patients with cerebral arteriovenous malformations who required repeat GKRS. METHODS: Causes of initial treatment failure included inaccurate nidus definition in 14 patients, failure to fill part of the nidus as a result of hemodynamic factors in 16, recanalization of embolized AVM compartments in 6,and suboptimal dose (<20 Gy) in 23. Nineteen patients had repeat GKS for subtotal obliteration of AVMs. In 62 patients, the AVM failed to obliterate despite correct target definition and adequate dose. At the time of retreatment, the nidus volume ranged from 0.1 to 6.9 cm 3 (mean, 1.4 cm 3), and the mean prescription dose was 20.3 Gy. RESULTS: Repeat GKS yielded a total angiographic obliteration in 77 patients (55%) and subtotal obliteration in 9 (6.4%). In 38 patients (27.1%), the AVMs remained patent, and in 16 patients (11.4%), no flow voids were observed on magnetic resonance imaging. Clinically, 126 patients improved or remained stable, and 14 experienced deterioration (8 resulting from a rebleed, 2 caused by persistent arteriovenous shunting, and 4 related to radiation-induced changes). CONCLUSION: By using repeat GKS, we achieved a 55% angiographic cure rate. Although radiation-induced changes as visualized on magnetic resonance imaging occurred in 48 patients (39%), only 4 patients (3.6%) developed permanent neurological deficits. These findings may be useful in deciding the management of AVMs in whom total obliteration after initial GKS was not achieved.

Lars Leksell Center for Gamma Surgery, Department of Neurological Surgery, University of Virginia Health Sciences System, Charlottesville, Virginia

Reprint requests: Ladislau Steiner, MD, PhD, Lars Leksell Center for Gamma Surgery, Department of Neurological Surgery, University of Virginia, 1215 Lee St, Room G-512, Charlottesville, VA 22908. E-mail: ls9e@virginia.edu

Received, March 13, 2009.

Accepted, August 29, 2009.

Copyright © by the Congress of Neurological Surgeons