Arteriovenous malformations of the medial cerebral hemisphere and the limbic system.

In a series of 164 resected arteriovenous malformations (AVM's), 25 were located on the medial aspect of the cerebral hemispheres. These AVM's require special attention because of the following characteristics: 1) their obscure location, making resection more difficult than the usual AVM; 2) a high incidence of intraventricular hemorrhage; 3) their frequent involvement of the choroid plexus of the ventricles and the arteries and veins related to the choroid plexus; and 4) the configuration of their venous drainage, which is often to superficial veins as well as to the deep venous systems. The results achieved with excision of these difficult AVM's were good. There was no mortality and the morbidity rate was under 4%. The surgical exposures, which were tailored to the location of these malformations, are described in detail.