Microsurgery of Vestibular Schwannoma Post-radiosurgery

Objectives: Microsurgery of vestibular schwannoma (VS) after radiosurgery is not common. In this study, we analyze nerve functional outcomes and technical challenges associated with the microsurgery following radiosurgery of VS. Materials and Methods: Sixteen patients underwent microsurgery at an average of 37 months (range 3-96 months) after radiosurgery. Indications of surgery included tumour progression or clinical worsening. Twelve of them had never undergone microsurgery before radiosurgery, and three had partial excision before radiosurgery. Maximum tumour diameter of all patients ranged from 23 to 51 mm, of which four were giant tumours. Operative findings and post-microsurgery clinical course, imaging and outcome were analysed. Results: The tumours found at surgery were firmer, with an avascular core but increased vascularity near the surface. There were thickened arachnoid and often adhesions with surrounding structures making total excision difficult. Near total excision was employed in such cases. Eleven patients underwent gross total/near total resection. No major morbidity or death was reported. Post-surgery, eight patients had grade I/II HB facial function, four had grades III and three had grades IV/V. Of the last three, two had the same deficit preoperatively. At the last follow-up (average 50 months), all patients had a stable facial function. None of the patients have undergone any further radiosurgery/microsurgery since the last intervention. Conclusion: For the few patients who require microsurgery after radiosurgery, excellent tumour resection with an acceptable outcome can be achieved with proper techniques and neuromonitoring. Leaving tiny residue attached to critical structures is the key to an optimal outcome.