Effect of aging on sensory nerve conduction study parameters.

Research evaluating the changes in nerve conduction with time has been limited to cross-sectional studies. We present a cohort study estimating how sensory nerve conduction study (NCS) parameters change with time when subjects are measured at two time-points. We evaluated 440 working adults by performing median and ulnar antidromic sensory NCS of both hands on two occasions, about 5.4 years (range, 4.3-7.0 years) apart. The rate of change in the NCS parameters was estimated using a mixed-models analysis controlling for each hand, gender, age, and body mass index (BMI). After controlling for gender, age, height, and BMI, the amplitudes of the median sensory nerve action potentials (SNAP) decreased by about 2.3 microV, peak latencies increased by 0.11 ms, onset latencies increased by 0.07 ms, and conduction velocities decreased by 1.1 m/s over 5 years. Corresponding values for the ulnar nerve were 1.75 microV, 0.06 ms, 0.04 ms, and 0.71 m/s, respectively. The findings are consistent with the findings of previous cross-sectional studies. The rate of change over time was not affected by hand (dominant versus nondominant hand), gender, age, or BMI at baseline. The rate of change seen with some of the median nerve parameters was significantly greater than that with the ulnar nerve.