Effect of Fixed Distance Recording and Foot Length on Sensory Nerve Action Potential of Dorsal Sural Nerve in Normal Adults.

Background and objectives: Due to its distal location in the lower limb, the dorsal sural sensory nerve is pivotal in diagnosing early and subclinical peripheral neuropathy. This study aimed to establish reference data for latency, amplitude, and conduction velocity at fixed varying distances (80, 100, and 120 mm) between active and stimulating electrodes, while examining the impact of foot length on sensory nerve action potential.

Methods: A prospective nerve conduction study (NCS) included 48 healthy participants aged 19-54 years.

Results: The upper and lower limits for latency, amplitude, and conduction velocities at 80 mm distance from the stimulating electrode were 3.1 and 1.01 ms, 36.8 and 1.45 μV, and 58.87 and 20.32 m/s, respectively. Similarly, the upper and lower limits for latency, amplitude, and conduction velocities at 100 mm distance from the stimulating electrode were 3.33 and 1.63 ms, 32.81 and 1.355 μV, and 55.24 and 24.75 m/s, respectively. The upper and lower limits for latencies and conduction velocities at 120 mm distance from the stimulating electrode were 4.25 and 1.76 ms and 59.43 and 21.77 m/s, respectively. The highest and lowest recorded amplitudes at 120 mm distance were 34.47 and 2.2 μV, respectively. Notably, univariate analysis findings were significant for latency (t = 2.86, P = 0.006) and conduction velocity (t = -2.13, P = 0.03) in relation to foot length when the distance between electrodes was 80 mm.

Conclusion: This study provides reference normative data for the East Indian population, augmenting the understanding of NCS in diagnosing peripheral neuropathy.