RADIOSURGERY FACILITATES RESECTION OF BRAIN ARTERIOVENOUS MALFORMATIONS AND REDUCES SURGICAL MORBIDITY

OBJECTIVE: Stereotactic radiosurgery makes brain arteriovenous malformations (AVM) more manageable during their microsurgical resection. To better characterize these effects, we compared results of microsurgical resection of radiated (RS+) and nonradiated (RS-) AVMs to demonstrate that previous radiosurgery facilitates surgery and decreases operative morbidity. METHODS: From our series of 344 patients who underwent AVM resections at the University of California, San Francisco (1997-2007), 21 RS+ patients were matched with 21 RS- patients based on pretreatment clinical and AVM characteristics. Matching was blinded to outcomes, which were assessed with the modified Rankin Scale. RESULTS: Mean AVM volume was reduced by 78% (P < 0.01), and Spetzler-Martin grades were reduced in 52% of RS+ patients (P < 0.001). Preoperative embolization was used less in RS+ than in RS- patients (P < 0.001). Mean operative time (P < 0.01), blood loss (P < 0.05), and length of hospital stay (P < 0.05) were lower in the RS+ group. Surgical morbidity was 14% higher in RS- patients, and they demonstrated Significant worsening in modified Rankin Scale scores after surgery, whereas RS+ patients did not (P < 0.01). RS+ patients deteriorated between AVM diagnosis and surgery owing to hemorrhages during the latency period (P < 0.05). CONCLUSION: Previous radiosurgery facilitates AVM microsurgery and decreases operative morbidity. Radiosurgery is recommended for unruptured AVMs that are not favorable for microsurgical resection. Microsurgical resection is recommended for radiated AVMs that are not completely obliterated after the 3-year latency period but are altered favorably for surgery, even in asymptomatic patients. Prompt resection of persistent AVMs should be considered to avoid the risk of postlatency hemorrhage and to optimize patient outcomes.