[Gamma knife radiosurgery for hemangioblastomas: clinical results and pathological findings]

To retrospectively evaluate the effects of Gamma knife in the treatment of cerebral hemangioblastomas.

From 1993 to 1996, seventeen patients with 29 hemangioblastomas were treated with Gamma knife. The patients mean age was 35 years (range: 16 - 61 years). The mean tumor diameter was 16 mm (range: 6 - 55 mm). Thirteen patients had recurrent or residual hemangioblastomas. Four with primary hemangioblastomas were diagnosed using CT, MRI and DSA. The maximum dose to the tumors was 21.0 - 50.0 Gy, with mean dose of 33.7 Gy. The radiation dose to the periphery of tumors was 12.0 - 24.0 Gy, with mean dose of 17.6 Gy.

All the patients had been followed up for 18 to 62 months, with mean 46 months. Five patients experienced clinical improvement and reduction in tumor volume, and 5 remained stable and tumor unchanged in volume during the follow-up period. Three patients died of tumor progression, surgery and cancer after treatment 18, 22, 25 months respectively. Four patients underwent surgery respectively at 3, 4, 29 and 48 months after gamma knife operation. The local control rate of the tumors at 1 year was 92%, 2 years 88%, 3 years 80% and 4 years 75%. Pathological findings in these patients showed varying degrees of small vessel thickening and occlusion together with degeneration, necrosis in the center of tumor and loss of tumor cells at periphery.

Gamma knife is not adequately reliable for the control of hemangioblastoma cysts, it is an effective treatment of small or medium-size solid tumors, but long-term follow-up is needed. The recommended dose is 16 to 20 Gy.