Surgical removal of vestibular schwannoma after failed gamma knife radiosurgery.

One of the main criticisms of vestibular schwannoma (VS) radiosurgery is that the risk of surgical morbidity is increased for patients whose tumor progresses in cases of failed procedures. The authors reviewed the French neurosurgical experience of operated patients after failed Gamma Knife radiosurgery (GKR). From July 1992 to December 2000, 23 unilateral VS out of the 1,000 treated patients have undergone a microsurgical procedure after failed GKR. In order to analyze the difficulties observed during the surgery, a questionnaire was completed by the surgeons. The mean interval between radiosurgery and removal was 39 months (range: 10-92 months). The mean increasing volume was 389% (range: 37-1,600) and the median was 150%. Seven patients have been operated on for radiological tumor growth and 13 for clinicoradiological evolution. In 10 cases, the surgeon considered that he had to face unusual difficulties mainly because of adhesion of the tumor to neurovascular structures. Tumor removal was total in 15 cases, near total in 4 cases and subtotal in 4 cases. One case of venous infarction was noticed on the 2nd day following surgery and was responsible for hemiparesis and aphasia that gradually recovered. At the last follow-up examination, facial nerve was normal or near normal (House-Brackmann grades 1 and 2) in 12 cases (52%) while it was grade 3 in 9 cases and grades 4 and 5 in 2 cases. Our results show that the quality of removal and of facial nerve preservation might be impaired after GKR in half of cases. However, these results do not support a change in our policy of first intention radiosurgical treatment of small- to medium-sized VSs.