Magnetic resonance imaging of facial nerve schwannoma.
OBJECTIVE
This study characterizes the magnetic resonance (MR) appearances of facial nerve schwannoma (FNS). We hypothesize that the extent of FNS demonstrated on MR will be greater compared to prior computed tomography studies, that geniculate involvement will be most common, and that cerebellar pontine angle (CPA) and internal auditory canal (IAC) involvement will more frequently result in sensorineural hearing loss (SNHL).


METHODS
Retrospective study.


METHODS
Clinical, pathologic, and enhanced MR imaging records of 30 patients with FNS were analyzed. Morphologic characteristics and extent of segmental facial nerve involvement were documented.


RESULTS
Median age at initial imaging was 51 years (range, 28-76 years). Pathologic confirmation was obtained in 14 patients (47%), and the diagnosis reached in the remainder by identification of a mass, thickening, and enhancement along the course of the facial nerve. All 30 lesions involved two or more contiguous segments of the facial nerve, with 28 (93%) involving three or more segments. The median segments involved per lesion was 4, mean of 3.83. Geniculate involvement was most common, in 29 patients (97%). CPA (P = .001) and IAC (P = .02) involvement was significantly related to SNHL. Seventeen patients (57%) presented with facial nerve dysfunction, manifesting in 12 patients as facial nerve weakness or paralysis, and/or in eight with involuntary movements of the facial musculature.


CONCLUSIONS
This study highlights the morphologic heterogeneity and typical multisegment involvement of FNS. Enhanced MR is the imaging modality of choice for FNS. The neuroradiologist must accurately diagnose and characterize this lesion, and thus facilitate optimal preoperative planning and counseling.
Division of Neuroradiology, Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
Andrew L
AL
Thompson
Richard I
RI
Aviv
Joseph M
JM
Chen
Julian M
JM
Nedzelski
Heng-Wai
HW
Yuen
Allan J
AJ
Fox
Aditya
A
Bharatha
Eric S
ES
Bartlett
Sean P
SP
Symons
D000328:Adult; D000368:Aged; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005155:Facial Nerve Diseases / Q000175:diagnosis*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies