Vestibular Schwannoma: Microsurgery after Partial Removal and Stereoradiosurgery.

Introduction: The aim of this work is to compare the results of vestibular schwannomas (VS) that were primarily radically microsurgically removed to those removed after previous partial resection and stereoradiosurgery after recurrence.

Material and Methods: Between 1997 and 2004, 100 patients were treated. The majority (90%) had large VS of grade III to IV that compressed the brainstem. All tumors were microsurgically radically removed by the retrosigmoid approach using intraoperative nerve monitoring. Eight patients (8%) were operated on for a growth of VS after previous partial resection and stereoradiosurgery by Leksell Gamma-knife in another department.

Results: In the primary operated group of patients, small VS were removed without any injury to the facial nerve and with subsequent serviceable hearing. Large VS were removed with fairly good facial nerve function or with a temporary functional lesion. Less than 5% of operated large VS necessitated a facial nerve reconstruction in the cerebellopontine angle. In all the cases we achieved good reinnervation.

Cross anastomosis between nerves was never used. No serviceable hearing was maintained after surgery of large VS. One patient died due to the surgery because of cerebellar hemorrhage. The majority have returned to their previous activities. With the group of patients who were operated after previous partial removal and stereoradiosurgery, the radical removal was much more difficult. This was because of the adhesion of tumor with structures of the PCA. Histology showed recurrence activity in only partially necrotic tumors. The nerves were incorporated into a capsula. We were unable preserve n. VIII in any of the patients. In no patient was the normal function of n. VII preserved. In 4 cases (50%), n. VII had to be anatomically interrupted and the proximal stump was damaged. These patients had to be treated by cross anastomosis or plastic surgery. (An auditory brainstem implant presented a new chance of maintaining hearing in 6 patients with neurofibromatosis 2 and bilateral VS.)

Conclusion: Our study supports the opinion that growing VS should be primarily microsurgically radically treated in the earliest stage. Secondary resection after previous partial removal and stereoradiosurgery is much more difficult and brings much poorer results, harming the patient.