Therapeutic strategy for large vestibular schwannomas

Summary Management of large vestibular schwannoma (VS) remains a difficult problem for which the extent of tumor resection and the role of radiosurgery continue to be the subject of debate. To develop an optimal therapeutic strategy for large VS, various treatment options within the avenues of microsurgery and radiosurgery were evaluated and compared. The authors carefully reviewed the clinical data of 50 surgical cases of large VS, defined as tumors with an average diameter over 3 cm in magnetic resonance imaging (MRI). All patients underwent microsurgery as the primary treatment. Gross total removal (GTR) was achieved in nine patients (18%), near total removal (NTR) in 8 (16%), radical subtotal removal (R-STR) in 31 (62%), and subtotal removal (STR) in 2 (4%). Among the 33 patients with R-STR and STR, eight had undergone adjuvant radiosurgery for the residual mass. Average tumor volume and diameter were 26.8 cm³ (13.5–55.1) and 36.4 mm (30.0–47.2), respectively. The mean follow-up duration was 113 months (58–167). The tumor control rate and facial nerve function according to the extent of removal were analyzed. The overall tumor control rate was 82%. Perfect tumor control was achieved after NTR and R-STR with adjuvant radiosurgery. However, 11% (1 of 9) of GTR patients and 32% (8 of 25) of R-STR-only and STR patients showed recurrence or regrowth. Overall favorable outcome of facial nerve function (H-B grade 1 or 2) was achieved in 78% of the patients. The facial nerve preservation rate was inversely proportional to the extent of tumor removal. NTR or R-STR with adjuvant radiosurgery might be acceptable therapeutic options for large VS in terms of achieving good tumor control and functional preservation of facial nerve.