One suprasellar, one mesencephalic, and nine cerebellar
hemangioblastomas were treated with the gamma knife in 10 patients (median age 48 years) in Stockholm between 1978 and 1993. Four patients had
von Hippel-Lindau disease, a dominant inherited trait predisposing to
multiple hemangioblastomas. Six
hemangioblastomas were treated with
radiotherapy at a median margin dose of 25 Gy (20-35 Gy) before 1990 and the next five with a median of 10 Gy (5-19 Gy). Computerized tomography or magnetic resonance images were available for 10 of the 11
hemangioblastomas at a median follow-up time of 26 months (4-68 months) after radiosurgery. The solid part of six
hemangioblastomas shrank in a median of 30 months, whereas four
hemangioblastomas were unchanged at a median of 14 months. Five
hemangioblastomas had an adjoining
cyst and three of these
cysts had to be evacuated after radiosurgery. One solitary
hemangioblastoma later developed a de novo
cyst that also needed evacuation. One patient with two cerebellar
hemangioblastomas (margin dose 25 Gy each) developed
edema at 6 months and required a shunt and prolonged
corticosteroid treatment. The combined follow-up data of the 23
hemangioblastomas in 15 patients from previous literature and the present series indicate that, first, a solitary small- or medium-sized
hemangioblastoma usually shrinks or stops growing after radiosurgery. The recommended margin dose is 10 to 15 Gy. Second, the adjoining
cyst often does not respond to radiosurgery but requires later, sometimes repeated evacuation.