Herpes simplex virus type I reactivation as a cause of a unilateral temporary paralysis of the vagus nerve.

Infection by neurotropic viruses, as exemplified by the herpes family, is universally accepted as a cause of palsies of the cochleo-vestibular and facial nerve. Palsies of the vagus nerve with a possible viral etiology have been described, although viruses have been identified in only a few selected cases. We report a 52-year-old man with unilateral otalgia, hoarseness and dysphagia. Examination revealed unilateral (left-sided) pharyngeal dysfunction, and paralysis of the left vocal cord fixed in the paramedian position. A barium swallow documented dysfunction of the left pharyngeal constrictor muscles. These findings suggested the lesion to be located either at the inferior ganglion of the vagus nerve or cranially. At direct laryngoscopy a smear was obtained from a 4-mm mucosal ulcer at the region of the left arytenoid cartilage. This smear demonstrated antibodies to herpes simplex virus (HSV) type I by immunofluorescence. On follow-up 19 months after the initial infection there was complete remission of the paralysis of the left vocal cord and normal pharyngeal function. The demonstration of HSV type 1 antibodies from a mucosal lesion in the distribution of the superior laryngeal nerve suggests that reactivation of HSV type I was the most likely explanation for the temporary nerve palsy seen.