[A case of hereditary neuropathy with liability to pressure palsies (HNPP) with diabetes mellitus].

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant neuropathy recently reported to be associated with deletion of the peripheral myelin protein-22 (PMP-22) gene. We report a 39-year-old man with recurrent brachial plexopathy and foot drop complicated by uncontrolled diabetes mellitus (DM). Right foot drop occurred at 31 years of the age and the patient subsequently experienced difficulty in raising his right arm. Neurological examination revealed weakness of the right deltoid, biceps muscles and tibialis anterior muscles. Deep tendon reflexes were generally absent. Sensory nerve conduction velocities in th ulnar, median and sural nerves were prolonged. Serum glucose and HB Alc levels were elevated to 468 mg/dl and 12.5%, respectively. Initially, it was difficult to diagnose the neuropathy as HNPP because the patient had poorly controlled diabetes mellitus and was unaware of similar disease in his family. In addition, focal asymmetric motor neuropathy and good recovery can develop in diabetes mellitus, occasionally with recurrence. We were able to make a final diagnosis of HNPP by detecting deletion of the PMP-22 gene region. After the diagnosis was confirmed, we examined the patient's family and found that his father experienced recurrent episodes of bilateral foot drop. This case suggests that gene analysis is sometimes essential in the differential diagnosis of hereditary peripheral neuropathies.