Objective: The reports on facial nerve functional preservation and serviceable hearing rates
in vestibular schwannoma (VS) surgery are not uniform in the literature, and reliable
clinical and radiologic predictors are still lacking. We report our 12-year experience
in surgical management of VS via three main surgical approaches, with a special focus
on analyzing the predictability of radiologic characteristics of the tumor on facial
nerve and hearing outcomes.
Methods: A total of 205 patients with VS who underwent surgical resection from July 2012 to
July 2023 were retrospectively reviewed. Patients with neurofibromatosis type 2 (NF2)
and nonprimary VS were excluded. Audiogram findings and postoperative early (during
admission), short-term (at 6 months), and long-term (>1 year) facial examination follow-up
data were assessed.
Results: A total of 187 patients with a median age of 52 years (range: 18–77) and female rate
of 55.1% were included. Serviceable hearing was confirmed in 58/92 patients (63%)
before surgery. The median tumor size and fundal CSF space (FCS) horizontal diameter
were 17.7 mm (range: 3–52) and 3.2 mm (range: 0–11.1), respectively, with VS Koos
grade III and IV were identified in 104 patients (55.6%). MRI revealed FSC presence
in 125 (67.6%), T2-weighted hyperintensity in 83 (44.4%), brainstem compression in
78 (41.7%), and moderate to severe (>50% of the tumor bulk) heterogeneous gadolinium
enhancement in 53 (28.8%) patients. The patients underwent surgery via translabyrinthine,
retrosigmoid, and middle fossa approaches in 84 (44.9%), 65 (34.8%), and 38 (20.3%)
cases, respectively. Intraoperative facial nerve stimulation showed favorable responses
in 138/179 patients (77.1%), while 20/59 patients (33.9%) maintained V-wave through
auditory evoked potential (BAER) monitoring. Gross total resection (GTR) was achieved
in 122 patients (65.2%), with facial and cochlear nerves being anatomically preserved
in 182 (97.3%) and 96/133 (72.2%) patients, respectively. The facial nerve was functionally
preserved in 137/187 (73.3%), 155/186 (83.3%), and 118/136 (86.8%) patients through
early, short-term, and long-term postoperative examinations, respectively. Early and
short-term facial nerve outcomes were worse in heterogeneous enhancing tumors, while
favorable intraoperative facial nerve stimulation responses were the only independent
predictor of higher functional preservation in logistic analysis (OR: 4.02, 95% CI:
1.76–9.14, p < 0.001, and OR: 3.63, 95% CI: 1.43–9.17, p = 0.006, respectively). Both the presence and larger diameter of FCS were independently
associated with higher “early” facial nerve preservation (OR: 2.38, 95% CI: 1.11–5.09,
p = 0.025). Long-term facial nerve outcome was better in patients with GTR (92.1% vs.
77.3% in GTR vs. non-GTR group, p = 0.025) and favorable stimulation responses (91.3% in favorable vs. 73.1% in unfavorable,
p = 0.02). A serviceable hearing was preserved in 15/36 patients (41.7%) when attempted,
with “insignificantly” higher rates in the presence of FCS and homogenous gadolinium
enhancement.
Conclusion: A multidisciplinary surgical team can achieve favorable facial nerve and hearing
outcomes in neuromonitoring-guided vestibular schwannoma surgery. Fundal CSF space
in T2-steady state sequences is a positive prognostic sign of “early” facial outcomes
and should be considered in patient consultations. Larger case volume studies are
warranted, though, to detect the radiologic prognostic factors of hearing outcomes.
