Introduction: Facial nerve palsy results in the loss of facial expression and is most commonly caused by a benign self-limiting inflammatory condition, known as Bell's palsy. However, there are other conditions which may result in injury of the seventh cranial nerve and the radiologist should be familiar with their imaging appearances.
Materials and methods: The relevant anatomy of the facial nerve and pathology which may affect the intratemporal portion of the nerve is described. The role of imaging and choice of imaging modality is also reviewed.
Results: High-resolution computer tomography(HRCT) images of the temporal bone and magnetic resonance(MR) images of the facial nerve from 11 patients who presented with facial nerve palsy were used to illustrate how intratemporal facial nerve injury of other aetiologies can mimic Bell's palsy. The typical imaging appearance of Bell's palsy was also presented.
Conclusions: Most patients with suspected Bell's palsy do not require radiologic imaging. However, when symptoms progress, persist or when there is multiple cranial nerve involvement, recurrent symptoms or subacute onset of facial nerve palsy, causes other than Bell's palsy should be considered.