Radiosurgery for low-grade intracranial arteriovenous malformations

J Neurosurg. 2014 Aug;121(2):457-67. doi: 10.3171/2014.1.JNS131713. Epub 2014 Mar 7.


Object: Low-grade, or Spetzler-Martin (SM) Grades I and II, arteriovenous malformations (AVMs) are associated with lower surgical morbidity rates than higher-grade lesions. While radiosurgery is now widely accepted as an effective treatment approach for AVMs, the risks and benefits of the procedure for low-grade AVMs, as compared with microsurgery, remain poorly understood. The authors of this study present the outcomes for a large cohort of low-grade AVMs treated with radiosurgery.

Methods: From an institutional radiosurgery database comprising approximately 1450 AVM cases, all patients with SM Grade I and II lesions were identified. Patients with less than 2 years of radiological follow-up, except those with complete AVM obliteration, were excluded from analysis. Univariate and multivariate Cox proportional-hazards and logistic regression analyses were used to determine factors associated with obliteration, radiation-induced changes (RICs), and hemorrhage following radiosurgery.

Results: Five hundred two patients harboring low-grade AVMs were eligible for analysis. The median age was 35 years, 50% of patients were male, and the most common presentation was hemorrhage (47%). The median AVM volume and prescription dose were 2.4 cm(3) and 23 Gy, respectively. The median radiological and clinical follow-up intervals were 48 and 62 months, respectively. The cumulative obliteration rate was 76%. The median time to obliteration was 40 months, and the actuarial obliteration rates were 66% and 80% at 5 and 10 years, respectively. Independent predictors of obliteration were no preradiosurgery embolization (p < 0.001), decreased AVM volume (p = 0.005), single draining vein (p = 0.013), lower radiosurgery-based AVM scale score (p = 0.016), and lower Virginia Radiosurgery AVM Scale (Virginia RAS) score (p = 0.001). The annual postradiosurgery hemorrhage rate was 1.4% with increased AVM volume (p = 0.034) and lower prescription dose (p = 0.006) as independent predictors. Symptomatic and permanent RICs were observed in 8.2% and 1.4% of patients, respectively. No preradiosurgery hemorrhage (p = 0.011), a decreased prescription dose (p = 0.038), and a higher Virginia RAS score (p = 0.001) were independently associated with postradiosurgery RICs.

Conclusions: Spetzler-Martin Grade I and II AVMs are very amenable to successful treatment with stereotactic radiosurgery. While patient, physician, and institutional preferences frequently dictate the final course of treatment, radiosurgery offers a favorable risk-to-benefit profile for the management of low-grade AVMs.

Keywords: AVM = arteriovenous malformation; DSA = digital subtraction angiography; Gamma Knife; RBAS = radiosurgery-based AVM scale; RIC = radiation-induced change; SM = Spetzler-Martin; Virginia RAS = Virginia Radiosurgery AVM Scale; intracranial arteriovenous malformation; low Spetzler-Martin grade; stereotactic radiosurgery; stroke; vascular disorders; vascular malformation.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Embolization, Therapeutic / adverse effects
  • Embolization, Therapeutic / methods
  • Female
  • Follow-Up Studies
  • Humans
  • Intracranial Arteriovenous Malformations / pathology
  • Intracranial Arteriovenous Malformations / surgery*
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Neurosurgical Procedures / adverse effects
  • Neurosurgical Procedures / methods*
  • Postoperative Hemorrhage / epidemiology
  • Radiosurgery / adverse effects
  • Radiosurgery / methods*
  • Reoperation / statistics & numerical data
  • Retrospective Studies
  • Risk Assessment
  • Treatment Outcome
  • Young Adult