Electrophysiological features of patients with POEMS syndrome

Objective Polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes (POEMS) syndrome is a rare cause of polyneuropathy. Although the polyneuropathy component is essential for the diagnosis of the disease, the pattern of associated electrodiagnostic abnormalities has not been characterized in detail. The purpose of this study was to elucidate the features of nerve conduction abnormalities in POEMS syndrome. Methods We reviewed the medical records and nerve conduction studies (NCS) of 12 consecutive patients with POEMS. Results A total of 68 motor and 46 sensory nerves were examined. Compound muscle action potentials (CMAPs) and sensory nerve action potentials (SNAPs) were not elicited in lower limbs more frequently compared with in upper limbs (P<0.05, in both motor and sensory nerves), and the CMAP amplitude was more attenuated in lower limbs than in upper limbs (P<0.05). Abnormal conduction slowing was frequently observed in motor (95%) and sensory (76%) nerves. Distal motor latencies were abnormally prolonged in 75% of the motor nerves, and terminal latency indices were significantly higher in patients than in normal controls (P<0.05). Conclusions NCS in POEMS syndrome showed characteristic patterns, in which conduction abnormalities were more frequently and severely affected in the lower limbs, and more predominantly in the intermediate nerve segments than in the distal portions. Significance The recognition of these characteristic patterns may be helpful for the early diagnosis of polyneuropathy in POEMS syndrome.