Various aspects of F-wave values in a healthy population

Objective: To characterize various aspects of F-wave in a healthy population and establish normative data for future clinical use. Methods: A total of 100 healthy volunteers underwent sensory and motor nerve conduction studies of the ulnar and tibial nerves, including F waves elicited by 32 stimuli. Results: The F-wave measurements (mean±SD for ulnar vs tibial nerve) consisted of persistence (83±19 vs 97±5%), minimum, mean and maximum latencies (26.5±2.1, 28.1±2.2, and 30.4±2.3 vs 47.0±4.1, 49.6±4.4, and 52.5±4.4 ms), minimum, mean and maximum F-wave conduction velocities (FWCV) (55.0±2.7, 60.0±2.3, and 64.0±3.0 vs 49.0±2.9, 52.2±3.1, and 55.5±3.4 m/s), chronodispersion (3.9±0.9 vs 5.5±1.4 ms), mean amplitude (347±152 vs 384±148 μV) and mean duration (8.6±2.9 vs 13.0±4.5 ms). Additional measures, registered by electronic averaging, included latency (27.4±2.3 vs 48.6±4.7 ms), duration (9.6±2.2 vs 16.4±4.2 ms), and amplitude (299±156 vs 208±116 μV). Conclusions: The use of a height nomogram serves well as an acceptable means to adjust F latencies for the limb length. In addition to the commonly used minimal latency, maximal FWCV, and persistence, clinically relevant measures with a narrow variability includes mean and maximal latencies, chronodispersion, and mean duration. In particular, mean latency obtained with 10 stimuli gave accurate results either for group or individual analysis. Significance: The data help establish an adequate manner of recording F-wave latencies in clinical evaluation.