Motor nerve conduction block in patients with diabetic peripheral neuropathy

Objective:To observe the motor nerve conduction block (CB) in patients with diabetic peripheral neuropathy(DPN),and the relationship between CB and other electroneurophysiological indexes.Methods:The electroneurophysiological data of 346 patients with diabetes mellitus,including motor nerve conduction velocity(MCV),F-response,sensory nerve conduction velocity(SCV),were analyzed retrospectively,and the amplitude and wave area of the compound muscle action potential(CMAP) elicited by stimulating the proximal nerve were compared with those elicited by stimulating the distal nerve so as to determine whether the CB exist or not.Results:①The conduction block was observed in 57 patients out of 346 ones with diabetic peripheral neuropathy,at a rate of 16.5%,sixty-two nerves showed abnormality in 1345 nerves detected(4.6%).The abnormality rate was the highest in tibial nerve.②The abnormality rate of SCV,F-response and MCV was 52.9%,47.4% and 45.1% orderly.③67.9% of all nerves with conduction block were accompanied by the prolongation of F wave latency and/or the decrease of F wave conduction velocity, 32.1%of them showed an increase of F-chronodispersion.Conclusions:Motor nerve conduction block might be observed in some patients with diabetes mellitus.The detection rate of conduction block might be the highest in tibial nerve.The motor nerve conduction block might be mostly accompanied by the abnormality of the other indexes of MCV.