Acute peripheral facial palsy simulating Bell's palsy in a case of probable multiple sclerosis with a clinically correlated transient pontine lesion on magnetic resonance imaging.

A transient pontine lesion was demonstrated in a young adult male who had a complete acute peripheral facial nerve palsy due probably to multiple sclerosis. In the acute stage of the palsy. T2-weighted magnetic resonance imaging (MRI) revealed a high signal intensity in the ipsilateral pons in the region of the nucleus and pontine part of the facial nerve. The patient recovered completely 5 weeks after the onset of the palsy, and at this stage, the lesion in the brainstem was no longer demonstrable on MRI. The onset and course of the disease resembled the idiopathic form of facial palsy (Bell's palsy): the present findings along with recent MRI and topodiagnostic studies may indicate that in some cases of Bell's palsy the primary lesion is located centrally. By improved MRI techniques and intravenous contrast agents it may be possible to visualize and follow the disease process and ascertain more of the pathogenesis of Bell's palsy.