Intratemporal facial nerve neuromas and their mimics; CT and MR findings

ABSTRACT

CT and MR findings of nine cases with intratemporal facial nerve nouromas were described and compared with CT findings of 3 cases with facial nerve palsy and facial nerve canal erosion which may mimic facial nerve neuroma. The tympanic segment of the facial nerve was involved in 8 cases, mastoid segment in 7 cases and labyrinthine segment in 5 cases. The lesions were easily diagnosed with high resolution CT with bone algorythms by showing the expansion of bony structures along the course of the facial nerves. In 4 cases with large vertical segment tumors. Extensive destruction of mastoid air cells and external auditory canals posed difficulty in making a diagnosis. Two out of 5 cases with labyrinthine segment imvolvement were presented as middle cranial fossa masses. MRI with enhancement was performed in 4 cases and was useful in characterizing the lesion as a tumor with its superior sensitivity to enhancement. Three cases of facial neuroma-mimicking lesion including post-inflammatory perineural thickening. Perineural extension from parotid adenoidcystic carcinoma, and congenita cholesteatoma showed irrgular erosion or mild expansion of the facial nerve canal which may be helpful for differential diagnosis from neuromas.