Difference of segmental motor nerve conduction study between chronic inflammatory demyelinating polyradiculoneuropathy and Clarcot-Marie-Tooth type 1 / 中华神经科杂志

ABSTRACT

Objective to assess the utility of segmental motor nerve conduction study in differential diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy(CIDP)and Charcot-Marie-Tooth type 1(CMT1).Methods A segmental motor nerve conduction study was performed on 16 patients with CIDP and 13 patients with CMT1.Distal motor latency,motor nerve conduction velocity,the changes of amplitude,area and duration of compound motor action potential over conventional segment were compared between the groups.ResultsDistal motor latency was (5.6±3.4) ms in CIDP and (9.3±2.1) ms in CMT1(t=5.347 P=0.000),motor nerve conduction velocity was (31.1±14.3) m/s in CIDP and(22.2±5.8)m/s(t=6.369,P=0.000),M50 of the decrease in amplitude over conventional segment was 29.7% in CIDP and 4.9% in CMT1 (Z=7.141,P=0.000).Distal motor latency was normal in 40.3% (25/62) nerves and motor nerve conduction velocity was normal in 18.1% (26/44)of segments in CIDP,while distal motor latency and motor nerve conduction velocity were abnormal in all nerves in CMT1.Motor nerve conduction block or abnormal temporal dispersion was detected in 29.2% segments in CIDP and 3.0% in CMT1 (x2=20.829,P=0.000).Conclusions The segmental motor nerve conduction study can help separate CIDP and CMT1.When motor nerve conduction block or abnormal temporal dispersion is detected,the motor nerve conduction velocity is distinctly various in different segments,the diagnosis of CIDP but not CMT1 should be considered.