Correlation between the size of the compound muscle and sensory nerve action potentials recorded from the foot in distal axonopathy.Electromyogr Clin Neurophysiol. 2005 Apr-May; 45(3):135-8.EC
Nerve conduction study was performed on 71 diabetic patients with distal sensorimotor axonopathy. Of 76 lower limbs studied, 46.1% showed no recordable sural compound sensory nerve action potential (CSNAP), and 55.3% no superficial peroneal CSNAP. Only 2.6% revealed no recordable compound muscle action potential (CMAP) from the abductor hallucis (AH) muscle, and 9.2% showed no obtainable CMAP from the extensor digitorum brevis (EDB) muscle. There were fairly good positive correlations between the amplitudes of the sural CSNAPs and AH CMAPs (r = 0.66), and between the superficial peroneal CSNAP and EDB CMAP amplitudes (r = 0.63). There were no instances in which a CSNAP could be obtained from the sural or superficial peroneal sensory nerve, but a CMAP could not be recorded from the AH or EDB muscle. If the CMAP amplitudes of the AH and EDB muscles were reduced to less than 0.3 mV, usually a CSNAP could longer be recorded from the sural and superficial peroneal sensory nerves. The size of the CSNAP is a more sensitive measure compared to the CMAP in revealing the presence of distal sensorimotor axonopathy.