[A case of CIDP with horizontal gaze-evoked nystagmus and ataxia].

A 46-year-old man developed mild to moderate weakness in the distal muscles of lower limbs and then had gradually progressive weakness and sensory loss in four limbs. He subsequently developed difficulty in walking over a few months. Examination showed severe distal muscle weakness and atrophy, but mild proximal weakness in four limbs. Superficial sensation was decreased in both distal limbs and his vibratory sense was mildly decreased in bilateral feet. All tendon reflexes were absent. Furthermore, he showed four-limb and truncal ataxia with bilateral horizontal gaze-evoked nystagmus in both directions. Nerve conduction study revealed sensorimotor neuropathy, and sural nerve biopsy showed mixed axonal damage and demyelination. Cerebrospinal fluid protein levels were raised 212 mg/dl. Lumbar spine MRI showed marked cauda equina enhancement with gadolinium. Anti-ganglioside antibodies were negative but serum antineuronal antibodies without known antigen specificity were found. Neurootological findings indicated bilateral horizontal gaze-evoked nystagmus was caused by spinocerebellar damage. We diagnosed this case was CIDP with cerebellar ataxia. After administration of high dose steroid therapy, intravenous methylprednisolone 1000 mg/day, his symptoms including ataxia and polyneuropathy were apparently improved.