Gamma knife surgery in acoustic tumours.

Presentation of the experiences with 254 acoustic neurinomas, treated at the Karolinska Gamma Knife Center from 1969 to 1991, with a minimum follow-up of 12 months. Early loss of contrast enhancement on CT or MRI was seen in 70%. Unilateral tumours showed size decrease in 55%, no change in 33%, and increase in 12%. NF 2 tumours had decrease in 33%, no change in 43%, and increase in 24%. Some degree of facial weakness was seen after 17% of treatments, but always with later improvement of function. The incidence of trigeminal neuropathy was 19%. Preservation of hearing was 77%. Gamma knife treatment is as efficient as microsurgery, but without risk of infection, bleeding or CSF leak. It requires no hospitalisation. The patient can go back to work after a few days. It therefore should be offered as an alternative to every acoustic neurinoma patient.