A case of Charcot-Marie-Tooth disease (CMT) type 1 complicated by diabetes mellitus (DM) showing bilateral phrenic nerve palsy

We here report a 44-year-old woman with Charcot-Marie-Tooth disease (CMT) type 1 who showed severe bilateral phrenic nerve palsy (PNP). She had chronic progressive distal dominant muscle weakness and atrophy since early in her second decade and had been unable to walk by herself due to weakness of the legs since she was 40-years old. At that time, she was diagnosed with diabetes mellitus (DM). She also had difficulty breathing when she was in a supine position. On admission, sural nerve biopsy showed a marked decrease of large and small myelinated fibers and numerous onion bulb formations, which are compatible with CMT type 1. Chest X-ray showed bilateral elevation of the diaphragm, which was more marked on the right side, indicating bilateral PNP. Since it is reported that CMT patients show demyelination of the phrenic nerve subclinically, and DM itself may facilitate the development of PNP, periodic evaluations of respiratory function may thus be useful for preventing respiratory failure in patients with CMT, especially when it is complicated with DM.