Radiosurgery for venous angiomas.

Radiosurgical treatment with the gamma knife for venous angiomas was used as an alternative to microsurgical removal in order to avoid abrupt cessation of venous drainage, which may be shared by the venous angioma and important parts of the brain. Thirteen cases of venous angioma were treated between 1977 and 1991. In two cases cavernous angiomas were also present and in one case a distant arteriovenous malformation (AVM) was also found. In two cases the angioma shared the venous drainage with an adjoining AVM; this is the first description of such pathology. For venous angiomas irradiation was prescribed to cover at least the convergence of the medullary veins. For AVM's close to a venous angioma the treatment was exclusively prescribed to the AVM nidus. After treatment, complete obliteration of the venous angioma was observed in one case, partial obliteration was observed in three cases, and five venous angiomas were unaffected by the treatment. Undue effects of radiation occurred in four cases: one focal edema and three radionecroses. Extirpation of the radionecrotic tissue 6 months after radiosurgery was necessary in one case. In the other three cases, the venous angioma was observed to be completely or partially obliterated, or unaffected by the treatment (one case each). In two cases of combined AVM and venous angioma, complete obliteration of the treatment AVM nidus was obtained. It is concluded that radiosurgery for venous angioma, although conceptually attractive, still does not fulfill the rigid criteria of minimal risk which must be set for the treatment of a lesion with a benign natural history.