Radiosurgery for Cerebellar Arteriovenous Malformations: Does Infratentorial Location Affect Outcome? Dale Ding, Robert M. Starke, Chun-Po Yen, Jason P. Sheehan
Key words Cerebellum - Gamma knife - Intracranial arteriovenous malformation - Radiosurgery - Stroke - Vascular malformations -
The cerebellum is an uncommon location for arteriovenous malformations (AVM) with unique angioarchitecture compared to the cerebrum. We evaluate the outcomes of radiosurgery in a cohort of cerebellar AVMs and assess the effect of infratentorial location by comparing them to a matched cohort of supratentorial AVMs.
Abbreviations and Acronyms AVM: Arteriovenous malformation DSA: Digital subtraction angiography MRI: Magnetic resonance imaging RAS: Radiosurgery AVM scale RBAS: Radiosurgery-based AVM score RIC: Radiation-induced changes Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia, USA To whom correspondence should be addressed: Jason P. Sheehan, M.D., Ph.D. [E-mail: [email protected]
] Citation: World Neurosurg. (2014). http://dx.doi.org/10.1016/j.wneu.2014.02.007 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2014 Elsevier Inc. All rights reserved.
INTRODUCTION The vast majority of intracranial arteriovenous malformations (AVM) are located in the supratentorial compartment (1). Of the 10% to 15% of AVMs that occupy the posterior fossa, the majority reside in the cerebellum (3, 4, 7). Cerebellar AVMs have a very high rate of hemorrhagic presentation comprising approximately 70% to 90% (4, 7, 23, 28, 38). Ruptured AVMs possess a signiﬁcantly higher prospective risk of hemorrhage than unruptured ones (10, 24, 33). Because of the relatively restricted nature of the posterior fossa, mass effect and edema from cerebellar AVM rupture are more likely to result in clinical manifestations than equivalently sized supratentorial hematomas. Although brainstem AVMs pose signiﬁcant hurdles to safe microsurgical resection, cerebellar AVMs are more superﬁcial and therefore more amenable to surgical extirpation. Furthermore, because violation of the cerebellar cortex is generally well
From a prospective AVM radiosurgery database of 1400 patients, we identified 60 cerebellar AVM patients with at least 2 years of radiologic follow-up or obliteration. The median volume and prescription dose were 2.3 mL and 22 Gy, respectively. The median radiologic follow-up was 39 months. The cerebellar AVM patients were matched (3:1) to a cohort of supratentorial, lobar AVM patients based on AVM size and patient age. Univariate and multivariate Cox proportional hazards regression analyses were used to identify factors associated with obliteration and favorable outcome.
Cerebellar and supratentorial AVMs were similar in baseline characteristics except for an increased incidence of ruptured lesions in the cerebellar AVM cohort (P < .001). Obliteration was achieved in 72% of cerebellar AVMs. Younger age (P [ .019), no preradiosurgery embolization (P < .001), and decreased volume (P [ .034) were independent predictors of obliteration. The annual risk of postradiosurgery hemorrhage in cerebellar AVMs was 1.3%. The rates of symptomatic and permanent radiation-induced changes were 7% and 3%, respectively. Compared with the matched supratentorial AVM cohort, there was no difference in the rates of obliteration, postradiosurgery hemorrhage, or symptomatic radiationinduced changes.
Radiosurgery is an effective treatment modality for cerebellar AVMs with relatively limited adverse events. Infratentorial location did not affect radiosurgery outcomes.
tolerated, many cerebellar AVMs are referred for surgical management. Despite the immediate elimination of microsurgical risk by complete AVM resection, the morbidity and mortality associated with this treatment modality are not inconsequential (28). Radiosurgery has been well established as a therapeutic alternative to microsurgery for AVMs, but the obliteration and complication rates afforded by radiosurgery for cerebellar AVMs are poorly deﬁned. We present our radiosurgery experience with the management of cerebellar AVMs. Additionally, we examine the effect of infratentorial location on radiosurgical outcomes and radiosurgery-related complications by comparing our cerebellar
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AVM cohort to a matched cohort of supratentorial, lobar AVMs.
METHODS Patient Population We reviewed a prospectively collected, institutional review boardeapproved database of 1400 patients with AVMs who were treated with Gamma Knife radiosurgery at our institution over a 21-year span, from 1989 to 2010, and identiﬁed all patients harboring cerebellar AVMs. Patients with