Atypical clinical manifestations of herpes zoster oticus: diagnostic usefulness of magnetic resonance imaging.

Typical symptoms of Ramsay Hunt syndrome (RHS) consist of painful vesicular eruptions in the external ear, unilateral facial palsy, and/or vestibulocochlear deficit. When RHS patients show atypical clinical manifestations, correct diagnosis can be delayed, and ideal treatment timing for antiviral therapy may be missed. The aim of this study is to describe RHS patients with atypical clinical manifestations and evaluate the usefulness of magnetic resonance imaging (MRI) for early differential diagnosis. We retrospectively reviewed the clinical data and investigated the findings of internal auditory canal (IAC) MRI of seven patients diagnosed with RHS presenting "atypical" clinical manifestations between January 2013 and December 2016. "Typical" symptoms of RHS consist of herpetic vesicular eruption and facial palsy with or without vestibulocochlear deficit. Regardless of symptomatic presentations, IAC MRI demonstrated post-contrast enhancement of cranial nerve (CN) VII, CN VIII, and IAC dura in patients with atypical clinical manifestations. In cases with multiple lower CN palsy, enhancement along the involved nerve was observed on IAC MRI. When RHS was complicated by acute parotiditis, diffuse enhancement of the parotid gland was demonstrated. The present study shows that in IAC MRI of RHS patients with atypical clinical manifestations, post-contrast enhancement was not confined to the facial nerve but also observed in CN VIII and IAC dura regardless of the symptoms, which may facilitate early diagnosis of RHS.