Neurofibromatosis type 2:: Preliminary results of gamma knife radiosurgery of vestibular schwannomas

Between 1992 and 1997, 27 patients (12 females and 15 males, mean age = 27, from 14 to 65 year old) affected of neurofibromatosis type 2 underwent a Gamma knife radiosurgical procedure for 35 vestibular schwannomas. This group of patients represented 8,2% of the total group of vestibular schwannomas radiosurgically treated by our team. The mean tumor volume was 4 cubic centimeters (0.4 to 14,4 cc). Twenty six (74%) of the treated tumors were controled by the treatment (15 stabilisation and 11 regression of the tumor volume) with a mean follow-up of 32 months (6 to 70 months). One microsurgical removal was required in a growing large tumor. Three post-radiosurgical facial nerve deficits (9%) were observed, 2 of them were transient. Usefull hearing was preserved in 57% of cases. Our experience confirms that tolerance of Gamma knife radiosurgery compares favorably with microsurgery of bilateral vestibular schwannomas. This treatment should be restricted to small and medium growing tumors.