Radiologic Findings of Facial Nerve Schwannoma

ABSTRACT

PURPOSE: To analyze the radiologic findings of facial nerve schwannoma. MATERIALS AND METHODS: The authors retrospectively reviewed CT and/or MR images and clinical history of eight patients with histologically provenfacial nerve schwannoma. After classifying this extratemporal and intratemporal types, clinical and radiologic findings were analysed. RESULTS: The most common clinical findings of facial nerve schwannoma were facial nervepalsy and hearing impairment in an intratemporal schwannoma(4/5), and a palpable parotid mass in an extratemporal schwannoma(3/3). On CT, each involved segment of intratemporal schwannomas(five cases) showed characteristic radiologic findings, while extratemporal schwannomas(three cases) showed masses of various types. On MRI, all tumors(two cases) showed hypointensity on T1WI, hyperintensity on T2WI, and strong enhancement on Gd-DTPA enhanced T1WI. CONCLUSION: Intratemporal facial nerve schwannomas can be easily diagnosed by characteristic clinical and radiologic findings. Extratemporal facial nerve schwannomas show nonspecific findings. However, if the tumor islocated between the superficial and the deep lobe of the parotid gland and extends to the posterior portion of thestyloid process, then facial nerve schwannoma is strongly suspected.