Infranuclear facial palsy: importance of imaging the geniculate fossa.

Abstract

To highlight the importance of imaging the geniculate fossa in patients with solitary infranuclear facial palsy.
Prospective.
Tertiary referral center. ELIGIBILITY CRITERIA: Patients with solitary infranuclear facial palsy sent for imaging.
Diagnostic.
Imaging specifics concerning high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) are described in detail for evaluation of the intratemporal part of the facial nerve with special focus on the geniculate fossa.
Normal appearances of the geniculate fossa on HRCT and MRI and its normal anatomic variant, that is, dehiscence of the overlying bone are described. Imaging findings in a range of pathologies involving the geniculate fossa in a clinical setting of infranuclear facial nerve palsy is demonstrated. These include infections (tuberculosis), trauma, schwannoma, hemangioma, meningioma, and perineural spread of parotid malignancy.
The geniculate fossa is a small bony hiatus in the temporal bone and is situated at the junction of the labyrinthine and the tympanic segments of the intratemporal facial nerve canal. It houses important neural structures and is best visualized by a combination of HRCT and high-resolution MRI examination of the temporal bone. It is therefore imperative for imaging specialists to be familiar with the normal appearance of this structure on HRCT and MRI examinations of the temporal bone as subtle imaging findings involving the geniculate fossa can be indicators of a variety of abnormalities.