Long-Term Outcome of Gamma Knife Radiosurgery for Symptomatic Brainstem Cavernous Malformation

OBJECTIVE: We sought to analyze the long-term outcome of Gamma Knife radiosurgery (GKS) for symptomatic brainstem cavernous malformation (s-BSCM). METHODS: Forty-five patients (14 males, 31 females) were treated with GKS for s-BSCM from January 1998 to December 2011. All patients were followed up for >5 years, and their clinical data were analyzed retrospectively. All patients had a history of symptomatic bleeding once or more before GKS. These hemorrhages caused neurologic deficits including cranial nerve deficits, hemiparesis, hemisensory deficits, spasticity, or chorea. The mean target volume of s-BSCM was 1.82 cm(3), and the median prescribed marginal dose of radiation was 13 Gy. The mean clinical and imaging follow-up period was 9.31 years (range 5.1-19.4 years). RESULTS: The 45 patients had 69 hemorrhagic events before GKS. During the follow-up period after GKS, 35 patients had no hemorrhagic event, 6 patients had 1 episode of symptomatic hemorrhage, and 4 patients had 2 episodes. The calculated annual hemorrhage rate was 40.06% at pre-GKS, 3.3% at 2 years after GKS, 1.48% at 5 years after GKS, and 4.64% at >5 years after GKS. In this study of 45 patients, symptomatic radiation-induced complications developed in only 1 patient (2.2%). No patients had died at the last follow-up. CONCLUSIONS: GKS for s-BSCM is a safe and effective alternative to surgical resection for reducing the rate of recurrent hemorrhage. Because the annual hemorrhage rate increases >5 years after GKS, clinicians should monitor patients closely to determine their subsequent treatment.