Analysis of Factors Affecting Facial Outcome in Surgery of Large or Giant Vestibular Schwannoma

Objective: Surgical results of larger tumor, especially cystic vestibular schwannoma are reported to be unfavorable comparing to those of small tumors. We analyzed retrospectively facial nerve outcome in larger tumors considering extent of removal, consistency, age, and size. Patients and Methods: From 2000 to 2013, 242 vestibular schwannomas were removed. Among them, the number of larger tumors having maximum diameter at CP angle (MaxCPA) of over 30 mm was 93 (38%). Complete removal was intended in all cases via retrosigmoid approach. Small piece was left, however, if severe adhesion to the facial nerve was found and monitoring showed poor response during dissection. Results: Max CPA ranged from 30 to 60 mm (mean 37.4). Total 42 tumors were cystic and 51 were solid. Complete tumor removal could be achieved in 49 (52.7%). Good facial nerve function (HB I or II) was obtained in 83 (89.2%). It reached to 93.8% for completely removed tumors and 86.4% for the others. Multiple logistic regression analysis revealed that neither age, side, consistency nor size was related to facial nerve functional outcome. Only the degree of removal was the significant prognostic factor (95%CI: 1.14261-6.80429, p = 0.024). Conclusion: Neither tumor consistency nor size were not significant factor for the facial outcome in large or giant tumors. Incomplete removal resulted in poorer facial function. This could be explained by the fact that that tumor removal was ended incomplete due to severe adhesion or fragility of the nerve.