Toward more rational nerve conduction interpreations: The effect of height

One hundred four normal subjects ranging in age from 17 to 77 years and in height from 115 to 203 cm underwent nerve conduction studies of sural, peroneal, tibial, and median nerves. Foot temperature was measured in each patient. A strong inverse correlation was found between height and sural (r = −0.7104), peroneal (r = −0.6842), and tibial (r = −0.5044) conduction velocities. These correlations were significant at the P< 0.001 level. Median conduction velocity was not correlated with height. Height was correlated with the distal latencies of all nerves studied (sural r = 0.6518), peroneal r = 0.4583, tibial r = 0.7217, median (r = 0.5440). These correlations were significant at the P < 0.001 level. Age was inversely correlated with both tibial (r = −0.4071) and median (r = −0.3464) nerve conduction velocities but not with sural and peroneal conductions. There were no correlations between distal latencies and age. If the variation in conduction velocity accounted for by the linear relationship with height was removed, then age would be inversely correlated to all conduction velocity measurements with the exception of the sural. Temperature is inversely correlated with the sural (r = −0.2233), peroneal (r = −0.2102), and tibial (r = −0.2710) distal latencies. In all instances, the effects of age and temperature were minor determinants when compared with the effects of height. Diagnostic conclusions made from nerve conduction data without correcting for height may be invalid in patients taller and shorter than normal. We believe that using normal values for nerve conductions that do not take height into account can no longer be considered an acceptable standard of practice.