Staged radiosurgery for extra-large cerebral arteriovenous malformations: method, implementation, and results

J Neurosurg. 2008 Dec;109 Suppl:65-72. doi: 10.3171/JNS/2008/109/12/S11.

Abstract

Object: The effectiveness and safety of radiosurgery for small- to medium-sized cerebral arteriovenous malformations (AVMs) have been well established. However, the management for large cerebral AVMs remains a great challenge to neurosurgeons. In the past 5 years the authors performed preplanned staged radiosurgery to treat extra-large cerebral AVMs.

Methods: An extra-large cerebral AVM is defined as one with nidus volume > 40 ml. The nidus volume of cerebral AVM is measured from the dose plan-that is, as being the volume contained within the best-fit prescription isodose. From January 2003 to December 2007, the authors treated 6 patients with extra-large AVMs by preplanned staged GKS. Staged radiosurgery is implemented by rigid transformation with translation and rotation of coordinates between 2 stages. The average radiation-targeted volume was 60 ml (range 47-72 ml). The presenting symptoms were seizure in 4 patients and a bleeding episode in 2. One patient had undergone a previous craniotomy and evacuation of hematoma. The mean interval between the 2 radiosurgical sessions was 6.9 months (range 4.5-9.1 months). The prescribed marginal dose given to the nidus volume in each stage ranged from 16 to 18.6 Gy. The expected marginal dose of total nidus was 17-19 Gy. Regular follow-up MR imaging was performed every 6 months. The mean follow-up period was 28 months (range 12-54 months).

Results: Most of the patients exhibited clinical improvement: relief of headache and reduced frequency of seizure attack. All patients had significant regression of nidus observed on MR imaging follow-up. Two patients had angiogram-confirmed complete obliteration of the nidus 45 and 60 months after the second-stage radiosurgical session. One patient experienced minor bleeding 8 months after the second-stage radiosurgery with mild headache. She had satisfactory recovery without clinical neurological deficit after conservative treatment.

Conclusions: These preliminary results indicate that staged radiosurgery is a practical strategy to treat patients with extra-large cerebral AVMs. It takes longer to obliterate the AVMs. The observed high signal T2 changes after the radiosurgery appeared clinically insignificant in 6 patients followed up for an average of 28 months. Longer follow-up is necessary to confirm its long-term safety.

MeSH terms

  • Adult
  • Cerebral Angiography
  • Cohort Studies
  • Female
  • Humans
  • Intracranial Arteriovenous Malformations / diagnostic imaging
  • Intracranial Arteriovenous Malformations / pathology
  • Intracranial Arteriovenous Malformations / surgery*
  • Magnetic Resonance Imaging
  • Male
  • Radiosurgery / adverse effects
  • Radiosurgery / methods*
  • Radiotherapy Dosage
  • Retrospective Studies
  • Risk Assessment
  • Treatment Outcome
  • Young Adult