Stereotactic radiosurgery for cavernous malformations: Kjellberg's experience with proton beam therapy in 98 cases at the Harvard Cyclotron.

Abstract

The lack of treatment options for surgically inaccessible cavernous malformations has made radiosurgery a possible alternative to conservative management. The few previous reports of radiosurgical efficacy have been limited by small numbers, short follow-up, or lack of attention to the full spectrum of end points, including neurological disability. In an attempt to elucidate the risk-to-benefit ratio of radiosurgery for cavernous malformations, we undertook a retrospective analysis of of 95 patients with 98 lesions treated by the late Raymond N. Kjellberg. Patients were followed for an average of 5.4 years (range, 0.3-12.3 yr), and data regarding hemorrhage, seizure, neurological disability, and incidence of radiation-induced complications were gathered. The analysis revealed a drop in annual hemorrhage rates from 17.3% per lesion per year before treatment to 4.5% per lesion per year after a latency period of 2 years. Improvement in seizure control was evident. However, a 16% incidence of permanent neurological deficit and a 3% mortality rate were attributable to radiographically confirmed radiation-induced complications. Neurological disability scores, measured by the modified Rankin disability scale, indicated a significant decline in neurological functioning during the follow-up interval, a result of the combined effects of radiation-related injury, hemorrhage, and clinical progression of the lesion. We conclude that although radiosurgery does seem to reduce hemorrhage, there is potential for complications and continued lesion progression after radiosurgery. These risks and benefits must be carefully balanced against the natural history of untreated lesions if the use of radiosurgery is considered.