Facial nerve outcomes after surgery for large vestibular schwannomas: do surgical approach and extent of resection matter?

OBJECT: The object of this study was to evaluate facial nerve outcomes in the surgical treatment of large vestibular schwannomas (VSs; ≥ 2.5 cm maximal or extrameatal cerebellopontine angle diameter) based on both the operative approach and extent of tumor resection.
METHODS: A PubMed search was conducted of English language studies on the treatment of large VSs published from 1985 to 2011. Studies were then evaluated and included if they contained data regarding the size of the tumor, surgical approach, extent of resection, and postoperative facial nerve function.
RESULTS: Of the 536 studies initially screened, 59 full-text articles were assessed for eligibility, and 30 studies were included for analysis. A total of 1688 tumor resections were reported. Surgical approach was reported in 1390 patients and was significantly associated with facial nerve outcome (ϕ= 0.29, p < 0.0001). Good facial nerve outcomes (House-Brackmann Grade I or II) were produced in 62.5% of the 555 translabyrinthine approaches, 65.2% of the 601 retrosigmoid approaches, and 27.4% of the 234 extended translabyrinthine approaches. Facial nerve outcomes from translabyrinthine and retrosigmoid approaches were not significantly different from each other, but both showed significantly more good facial nerve outcomes, compared with the extended translabyrinthine approach (OR for translabyrinthine vs extended translabyrinthine = 4.43, 95% CI 3.17-6.19, p < 0.0001; OR for retrosigmoid vs extended translabyrinthine = 4.98, 95% CI 3.57-6.95, p < 0.0001). There were 471 patients for whom extent of resection was reported. There was a strong and significant association between degree of resection and outcome (ϕ= 0.38, p < 0.0001). Of the 80 patients receiving subtotal resections, 92.5% had good facial nerve outcomes, compared with 74.6% (n = 55) and 47.3% (n = 336) of those who received near-total resections and gross-total resections, respectively. In the 2-way comparison of good versus suboptimal/poor outcomes (House-Brackmann Grade III-VI), subtotal resection was significantly better than near-total resection (OR = 4.21, 95% CI 1.50-11.79; p = 0.004), and near-total resection was significantly better than gross-total resection (OR = 3.26, 95% CI 1.71-6.20; p = 0.0002) in producing better facial nerve outcomes.
CONCLUSIONS: In a pooled patient population from studies evaluating the treatment of large VSs, subtotal and near-total resections were shown to produce better facial nerve outcomes when compared with gross-total resections. The translabyrinthine and retrosigmoid surgical approaches are likely to result in similar rates of good facial nerve outcomes. Both of these approaches show better facial nerve outcomes when compared with the extended translabyrinthine approach, which is typically reserved for especially large tumors. The reported literature on treatment of large VSs is extremely heterogeneous and minimal consistency in reporting outcomes was observed.