Stereotactic spine radiosurgery for intradural and intramedullary metastasis

Object: Stereotactic radiosurgery (SRS) has become an important treatment alternative to surgery for a variety of spinal lesions. However, the use of SRS in the management of intradural intramedullary (IDIM) metastasis remains controversial. The aim of this study was to determine the clinical efficacy and safety of SRS for treatment of IDIM metastasis. Methods. Nine patients with 11 IDIM metastases treated with SRS at Henry Ford Hospital were retrospectively reviewed. The mean age at presentation was 50 years, with a range of 14-71 years. There were 4 intradural extramedullary and 7 intramedullary lesions. The radiosurgery procedure used techniques of image-guided and intensity-modulated radiation. The mean treatment dose was 13.8 Gy, with a range of 10-16 Gy. All patients had clinical follow-up (except in 1 lesion), with an emphasis on initial symptoms and ambulatory status, and 8 patients (9 lesions) had imaging studies. The median follow-up duration was 10 months. Results. The presenting symptoms were improved in 8 (80%) of 10 evaluable lesions, unchanged in 1 case, and worsened in 1 case. Radiographic responses were seen as follows: complete response in 2 (22%) of 9; partial response in 3 (33%) of 9; stable disease in 3 (33%) of 9; and progressive disease in 1 (11%) of 9. After radiosurgery, 7 patients (78%) remained ambulatory until the last follow-up visit. The overall median survival time after SRS was 8 months, with a range of 2-19 months. No radiation toxicity was detected clinically during the follow-up period. Conclusions. Despite the fact that this was a small series of patients with IDIM metastasis who had limited treatment options, SRS appears to be an effective and safe method of treating patients with these lesions.