A case of motor and sensory polyneuropathy with retinitis pigmentosa and diffuse idiopathic skeletal hyperostosis

We here report a 53-year-old man who presented with motor and sensory polyneuropathy, retinitis pigmentosa and diffuse idiopathic skeletal hyperostosis (DISH). He had a 15-year history of diabetes mellitus (DM). Visual impairment appeared at 17 years of age. Since age 47, he showed a slowly progressive sensory impairment and muscle weakness of the extremities. On neurological examination, retinitis pigmentosa and severe muscle atrophy, muscle weakness and sensory disturbance of all modalities in the distal portions of all four extremities were observed. Deep tendon reflexes were absent. A plain X-P showed diffuse ossification of the spinal and extraspinal ligaments. The motor nerve conduction velocities were severely reduced and no sensory nerve action potentials were evoked. The CSF examination revealed an increased protein level without pleocytosis. The sural nerve biopsy showed a marked onion bulb formation and a loss of the myelinated nerve fibers, which could not be solely explained by DM. As the phytanic acids levels, β- lipoprotein, lactate and pyruvate in the sera were within the normal ranges, Refsum disease, Bassen-Kornzweig syndrome and mitochondrial diseases were unlikely in this patient. The presence of demyelinating and axonal polyneuropathy in this patient may have been caused by a common metabolic disturbance which produced both retinitis pigmentosa and DISH.