Vestibular schwannoma management. Part II. Failed radiosurgery and the role of delayed microsurgery

Object. The indications, operative findings, and outcomes of vestibular sch wannoma microsurgery are controversial when it is performed after stereotac tic radiosurgery. To address these issues, the authors reviewed the experie nce at mio academic medical centers. Methods. During a 10-year interval, 452 patients with unilateral vestibular schwannomas underwent gamma knife radiosurgery. Thirteen patients (2.9%) u nderwent delayed microsurgery at a median of 27 months (range 7-72 months) after they had undergone radiosurgery. Six of the 13 patients had undergone one or more microsurgical procedures before they underwent radiosurgery. T he indications for surgery were tumor enlargement with stable symptoms in f ive patients, tumor enlargement with new or increased symptoms in five pati ents, and increased symptoms without evidence of tumor growth in three pati ents. Gross-total resection was achieved in seven patients and near-gross-t otal resection in four patients. The surgery was described as more difficul t than that typically performed for schwannoma in eight patients, no differ ent in four patients, and easier in one patient. At the last follow-up eval uation, three patients had normal or near-normal facial function, three pat ients had moderate facial dysfunction, and seven had facial palsies. Three patients were incapable of caring for themselves, and one patient died of p rogression of a malignant triton tumor. Conclusions. Failed radiosurgery in cases of vestibular schwannoma was rare . No clear relationship was demonstrated between the use of radiosurgery an d the subsequent ease or difficulty of delayed microsurgery. Because some p atients have temporary enlargement of their tumor after radiosurgery, the n eed for surgical resection after radiosurgery should be reviewed with the n eurosurgeon who performed the radiosurgery and should be delayed until sust ained tumor growth is confirmed. A subtotal tumor resection should be consi dered for patients who require surgical resection of their tumor after vest ibular schwannoma radiosurgery.