Amplitudes of Sural and Radial Sensory Nerve Action Potentials in Orthodromic and Antridromic Studeis in Children

Several previous studies of adults have reported that the amplitudes of the sural and superficial radial nerve (SN and SRN) action potentials are larger with antidromic than with Orthodromic recordings. However, this difference has not been documented in children. This study evaluated the amplitudes of SN and SRN sensory nerve action potentials (SNAPs), obtained with antidromic and orthodromic recordings in children with and without neuropathy, and compared these data with similar findings in adults. The SNAPs of SN or SRN or both of 10 neurologically normal children, 6 children with neuropathy and 7 healthy adults were studied with surface stimulation and recording. The position of the stimulating and recording electrodes for the orthodromic recordings were the reverse of that for the antidromic recordings. Peak to peak SNAP amplitudes were measured and analyzed. The mean of the SRN SNAP amplitude was significantly higher with the antidromic than the Orthodromic technique for the first and third groups (P<0.05). The mean SN SNAP amplitude was higher in the three groups, but the difference was not statistically significant because of the small number of subjects. This difference became significant when the data for the children and normal adult groups were combined and reanalyzed (P<0.05). Consistent responses were obtained with both techniques. However, the antidromic technique was superior to the orthodromic technique because of the greater amplitude of responses. We recommend the use of the antidromic technique for its greater amplitudes, ease of use and potential reduction of discomfort to the patient. Acta Medica Iranica, 42(5): 359-362; 2004