Recurrent hypogeusia in a patient with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

Hypogeusia, a condition with diminished sense of taste, is caused by several conditions, including zinc deficiency and as a side-effect of drugs, but is not common in neurological disorders. A 55-year-old Japanese man with a 30-year history of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) presented with hypogeusia during hospitalization for a recurrence of CIDP. The hypogeusia improved after treatment with high-dose intravenous methylprednisolone (HIMP). Two years later, hypogeusia developed again. A complete taste deficit was revealed by a filter paper test. Brain MRI showed enhancement of the bilateral facial nerve ganglia. Hypogeusia was partially ameliorated after extensive immunosuppressive therapy with repeated HIMP and plasma exchange. Improvement was more prominent in the area innervated by the chorda tympani nerve than that innervated by the glossopharyngeal nerve. To our knowledge, this is the first report of recurrent hypogeusia, which might be caused by cranial nerve injury associated with CIDP.