BACKGROUND: Microsurgery and gamma knife are the mainly ways to treat arteriovenous malformation of brain in grade Spetzler-Martin Ⅰ Ⅲ; however, therapeutic effects of them need to be further studied.OBJECTIVE: To compare the therapeutic effects between microsurgery and gamma knife on the treatment of arteriovenous malformation of brain in grade Spetzler-Martin Ⅰ-Ⅲ.DESIGN: Retrospective analysis.SETTING: Department of Neurosurgery, the Third Hospital Affiliated to Sun Yat-sen University;Guangdong Microinvasion Center.PARTICIPANTS: A total of 86 patients with arteriovenous malformation of the brain were selected from the Department of Neurosurgery, the Third Hospital Affiliated to Sun Yat-sen University and Guangdong Microinvasion Center from January 1997 to February 2007. After DSA, CT and/or MRI examinations,patients were evaluated in grade Spetzler-Martin Ⅰ - Ⅲ. All patients were divided into microsurgery group (n = 34) and gamma knife group (n =52). There were 22 males and 12 females in the microsurgery group and their mean age was 26 years, while there were 34 males and 18 females in the gamma knife group and their mean age was 28 years. The grade of Spetzler-Martin was comparable in the two groups. All their relatives provided the confirmed consent and the study was allowed by ethics committee of our hospital.METHODS: Under complete anesthesia, patients were given microsurgery and the operative approach was chosen based on diseased regions. Firstly, feeding artery was blocked; secondly, it was separated along band of gliosis between malformation vessel mass and brain tissue; finally, draining vein was cut off and malformation vessel mass was resected. On the other hand, patients in the gamma knife group received Leksell-2300B gamma knife treatment. Leksell-G stereotaxis headframe was installed; GE1.5TMR scanning device was used for localization; r-Plan5.2 workstation was used for target design and dosage program;Leksell B gamma knife was used during the whole operative procedure. The target was 1 - 4 and peripheral dosage was 12 - 28 Gy. At 0.5, 1 and 2 years after operation, angiography was used to detect vascular occlusion in the two groups. Meanwhile, focal hemorrhage and new neurological function defect (including hemiplegic paralysis, language disorder, cerebellar function disorder, increasing frequency of epilepsy, etc.)were also observed.MAIN OUTCOME MEASURES: Rate of vascular occlusion, focal hemorrhage and neurological function defect at different time points after operation.RESULTS: All 86 patients were involved in the final analysis. Vascular nest of patients in the microsurgery group disappeared completely; while, two patients (6%, 2/34) had new neurological function defect but did not have rehaemorrhagia and death after operation. On the other hand, vascular nest of 43 patients (83%,43/52) in the gamma knife group disappeared completely, and 8 (15%, 8/52) had new neurological function defect. There was significant difference between the two groups (χ2=2.63, P ＜ 0.05). Six patients (12%,6/52) in the gamma knife group had rehaemorrhagia after operation, and one (2%, 1/52) died.CONCLUSION: Both microsurgery and gamma knife have great effects on the treatment of arteriovenous malformation of brain in grade Spetzler-Martin Ⅰ - Ⅲ; however, the therapeutic effects of microsurgery are superior to those of gamma knife.