[A case of ipsilateral ageusia, sensorineural hearing loss and facial sensorimotor disturbance due to pontine lesion].

We report a 58-year-old woman with pontine lesion presented with subacute onset of unilateral gustatory disturbance accompanied by facial numbness, and hearing loss. Neurologic examination revealed superficial hypesthesia and paresthesia on the right side of the face, right peripheral type facial paresis, ageusia on the right half of the tongue and right sensorineural deafness. No other neurologic signs were observed, and laboratory data were all normal. Brain MRI revealed a small lesion in the right dorsolateral tegmentum of the middle pons. Electrogustometry showed marked reduction in the sense of taste on the right half of the tongue. ABR showed diminished amplitude in the IV-V wave of the right side, while SEP and VEP were normal. The clinical diagnosis was demyelinating lesion and intravenous methylprednisolone (1 g/day) was administered for 3 consecutive days, resulting in prompt improvement in the symptoms. The lesion was suspected of affecting ipsilateral side of the spinal trigeminal nerve tract and the nucleus, the intraaxial infranuclear facial nerve fiber, the lateral lemniscus adjacent to the superior olivary nucleus and the central gustatory tract. Our case suggests that the central gustatory pathway projecting from the nucleus of the solitary tract to the parabrachial nucleus, presumed to be pontine taste area, ascends ipsilaterally and is located laterally from the medial lemniscus.