Acoustic Neuroma Grading System: An Evidence-Based Surgical Grading System for Large-to-Giant Vestibular Schwannoma

Objective: Treatment strategy for large to giant vestibular has progressively shifted from tumor excision to nerve preservation; however, there is a lack of reporting standardization for vestibular schwannoma (VS) outcomes. The objective of this study was to determine the facial nerve function and extent of resection as an outcome in the surgical management of large VS surgery (VSs = ≥2.5-cm maximal).

Methods: We conducted a systematic review of the electronic databases using different MeSH terms from 1990 to 2021. Pooled and subgroup analysis were performed using random effect model, and multivariate logistic regression analysis was conducted to determine the factors affecting outcomes.

Results: A total of 5,623 patients from 56 studies were included. Surgical approach was reported in 5,144 patients, including translabyrinthine approach (TL) in 43.3% (n = 2,225), retrosigmoid (RS) approach in 56.3% (n = 2,899), retrolabyrinthine (RL) approach in 0.3% (n = 16), and extended translabyrinthine (EX) approach in 0.1% (n = 4). Patients with subtotal resection (STR) had higher likelihood of better clinical outcomes (House–Brackmann [HB] grades I and II) compared with near total resection (NTR; OR = 4.13, 95% CI: 3.71–7.25, p < 0.0001) and gross-total resection (GTR; OR = 3.22, 95% CI: 3.12–7.6, p < 0.0001), and NTR had better clinical outcome with respect to GTR (OR = 1.5, 95% CI: 1.14–4.6, p < 0.0001). According to our acoustic neuroma grading system, patients with GTR, NTR, and STR with good facial nerve (HB I and II) falls under category A, B, and C, respectively, while those with poor facial nerve outcome (HB III–VI) are graded into D, E, and F, respectively. Furthermore, there exists a significant association of TL (p < 0.001), RS (p < 0.001), and RL (p = 0.03) with grade A, TL (p < 0.001) and RL (p = 0.03) with grade B, EX (p = 0.01) with grade C, TL (p = 0.001), RS (p < 0.001), and RL (p = 0.006) with grade D, TL (p = 0.001) and RL (p < 0.001) with grade E, and TL (p = 0.05) and EX (p = 0.001) with grade F.

Conclusion: This evidence-based review corroborates a new grading system which would reduce the consistency in reporting outcomes.

Publication History

Article published online:
15 February 2022