Subperineural 'onion-peeling' dissection for maximizing extent of resection and facial nerve preservation for onco-functional balance in vestibular schwannoma surgery.
In a single-surgeon retrospective cohort of 146 vestibular schwannoma resections, subperineural “onion-peeling” dissection was associated with ≥95% resection in 97.3% of patients, House-Brackmann grade I–II facial function in 95.2%, and 3.4% tumor recurrence over a mean 89.8-month follow-up.
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In a single-surgeon retrospective cohort of 146 vestibular schwannoma resections, subperineural “onion-peeling” dissection was associated with ≥95% resection in 97.3% of patients, House-Brackmann grade I–II facial function in 95.2%, and 3.4% tumor recurrence over a mean 89.8-month follow-up.
Research significance
The reported outcomes support the clinical hypothesis that retaining a thin perineurial layer as a buffer over the facial nerve may permit maximal vestibular schwannoma resection while preserving facial function; superiority to planned subtotal resection plus radiosurgery remains an inference because the supplied record provides only historical, not randomized or contemporaneous, comparison.
Source abstract
INTRODUCTION: Planned subtotal resection (STR) of vestibular schwannomas (VS) followed by stereotactic radiosurgery (SRS) has gained popularity for minimizing facial nerve injury. However, recurrence risk correlates with residual tumor volume, and long-term outcomes remain unknown. The authors report their facial nerve outcomes with planned maximal safe resection using a facial nerve-sparing subperineural "onion-peeling" technique, and compare their outcomes to those of the hybrid STR-SRS approach. METHODS: A retrospective study was performed on 146 patients who underwent VS resection by a single surgeon using a subperineural "onion-peeling" technique, leaving a thin layer of perineurium as an anatomic buffer overlying the facial nerve. Tumor size, operative approach, extent of resection (EOR: GTR 100%, NTR 95-99%, STR < 95%), facial nerve outcomes by House-Brackmann (HB) grade, recovery time, recurrence, and postoperative SRS usage were analyzed. RESULTS: Most tumors were Koos grade III-IV (69.9%), followed by grade I-II (30.2%), removed via retrosigmoid (86.3%) or translabyrinthine (13.7%) approaches. At last follow-up (mean follow-up = 89.8 months), 95.2% of patients achieved HB I-II scores while obtaining an EOR ≥ 95% (GTR/NTR) in 97.3% of patients. There was no significant difference in rates of HB I-II outcomes whether EOR was GTR or NTR (97.8% vs. 92.5%, p = 0.196). HB I-II outcomes were achieved in 100% of Koos I-II and 93.1% of Koos III-IV tumors. There was a trend of decreased GTR and increased NTR with increasing Koos grade I to IV (GTR: 93.75%, 86.2%, 76.9%, 39.5%; NTR: 6.25%, 13.8%, 23.1%, 55.3%, respectively). Postoperative CSF leak rate was 2.7%. Tumor recurrence (3.4%) was lower with GTR than NTR (1.1% vs. 7.5%, p = 0.0646). CONCLUSION: The subperineural "onion-peeling" dissection technique provides a safe, nerve-sparing approach for maximal VS resection while preserving facial nerve function thus achieving excellent onco-functional outcomes. Compared to historical hybrid STR-SRS data, our approach demonstrated favorable facial nerve outcomes with higher EOR, lower tumor recurrence, and less radiation usage.