Abstract
Objective To investigate the variation in the course of the facial nerve (FN) in patients undergoing
acoustic neuroma (AN) surgery, its adhesion to tumors, and the relationship between
such adhesions and postoperative facial palsy.
Methods The subjects were 356 patients who underwent AN surgery in whom the course of the
FN could be confirmed. Patients were classified into six groups: ventro-central surface
of the tumor (VCe), ventro-rostral (VR), ventro-caudal (VCa), rostral (R), caudal
(C), and dorsal (D).
Results The FN course was VCe in 185 cases, VR in 137, VCa in 19, R in 10, C in 4, and D
in one. For tumors < 1.5 cm, VCe was most common. For tumors ≥ 1.5 cm, the proportion
of VR increased. No significant difference was observed between the course patterns
of the FN in terms of postoperative FN function, but for tumors > 3.0 cm, there was
an increasing tendency for the FN to adhere strongly to the tumor capsule, and postoperative
facial palsy was more severe in patients with stronger adhesions.
Conclusions The VCe pattern was most common for small tumors. Strong or less strong adhesion
to the tumor capsule was most strongly associated with postoperative FN palsy.
Keywords
acoustic neuromas - facial nerve - retrosigmoid approach - adhesion