OBJECTIVE: The aim of this study is to determine the reliability of preoperative CT and contrast enhanced MRI in differentiating FNS and FNVM. INTRODUCTION: Facial nerve schwannomas (FNSs) and facial nerve venous malformations (FNVMs) are rare lesions that arise from the facial nerve. The clinical features, natural history and treatment strategies for both lesions differ and therefore accurate diagnosis at imaging is crucial to assist the otorhinolaryngologist in management and operative planning. FNSs are slow-growing lesions that can present with hearing loss, tinnitus, vertigo and...

METHODS AND MATERIALS The HRCT temporal bone and MRI studies of 11 patients with 7 FNSs and 4 patients with FNVMs were retrospectively reviewed by two radiologists blinded to the clinical history and histopathology data. Lesion location was documented by the conventional intratemporal FN segmental anatomy (canalicular, labyrinthine, geniculate ganglion, tympanic and mastoid segment). Specific note was made of whether more than one FN segments were involved or if there were skip lesions. Bony remodelling patterns as depicted by HRCT were classified as thinning, scalloping,...

RESULTS A total of 11 patients with 7 FNSs and 4 FNVMs were reviewed. The mean patient age at time of initial imaging evaluation of FNSs and FNVMs was 39 years (range 14–63) and 47 years (range 39–57 years) respectively. FNS commonly extended over more than one segments of the intratemporal FN (Figure 1) and had propensity to involve the geniculate ganglion (2/7, 29%) (Figure 2) and mastoid segment (3/7, 43%) (Figure 3 and 4). In contrast, FNVMs most commonly occurred at the geniculate ganglion...

CONCLUSION Knowledge of lesion location and characteristic imaging features on temporal bone HRCT and MRI improves the diagnostic confidence and plays a crucial role in differentiation between FNSs and FNVMs at pre-operative evaluation.

Corresponding Author Dr Charlie Chia-Tsong Hsu, MBBS Department of Medical Imaging, Princess Alexandra Hospital Brisbane, Australia [email protected] Dr Dalveer Singh, MBBS Department of Medical Imaging, Princess Alexandra Hospital Brisbane, Australia [email protected]

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