Facial Nerve Function Recovery after Removal of Cerebellopontine Angle Tumor

Introduction: Paralysis of the seventh nerve early after operation of cerebellopontine angle tumor is still common. Later in the postoperative course, when anatomical continuity of the nerve is preserved, function of the nerve frequently improves. We encountered improvement to House-Brackmann grade I even when grade V function was present shortly after surgery. In some centers patients with H-B grade V or VI are qualified for reconstructive surgery, regardless of a relatively short time from surgery. In our material we observed the possibility of facial nerve function improvement even after more than 12 months of severe paresis.

Material and Methods: We analyzed a group of 224 patients operated via the retrosigmoid approach. There were 146 vestibular schwannomas, 27 meningiomas, 22 epidermoid cysts, and 29 other tumors. Facial nerve according to the House-Brackmann scale was assessed immediately after operation, at discharge from the hospital, and up to 18 months after surgery. During this time, follow-up assessments were conducted every second month in most cases. When direct assessment was impossible, patients responded to a questionnaire regarding facial function.

Results: In most cases with different grades of seventh nerve paresis just after surgery, improvement in a later period was observed. In the final assessment in the group of vestibular schwannoma, facial nerve status was grade I in 42 (29%) cases, grade II in 22 (15%) cases, III in 21 (14%) cases, IV in 12 (8%) cases, V in 21 (14%) cases, and VI in 15 (10%) cases. In a group of meningiomas, epidermal cysts, and other CPA tumors, the number of patients in corresponding grades was: grade I—36 (46%); grade II—11 (14%); grade III—4 (5%); grade IV—11 (14%); grade V—2 (3%); grade VI—4 (5%). Time and dynamic of facial nerve improvement after operation was analyzed, and dependence on age, sex, tumor size, and histological classification of tumor was checked. The group with vestibular schwannoma was divided into different histopathological subtypes in WHO 2000 classification.

Conclusions: Facial nerve function improvement in cases of minor structural damages and low postoperative H-B grading was quite fast (1 to 3 months). In cases of severe damage, (axonothmesis type) axonal regeneration is required, and this lengthens the time to noticeable recovery beyond even 12 months after operation.