Segmental conduction times in the motor nervous system.

The study was performed in 30 normal subjects (24 females and 6 males) with an age range between 18 and 55 years and a height range between 154 and 188 cm. Electrical stimulation was applied to the peroneal nerve with simultaneous recording of the orthodromic response (MEP-M) and F-wave (MEP-F) from the tibialis anterior (TA) and extensor digitorum brevis muscles (EDB). Magnetic stimulation of the L5 level and cerebral cortex was applied using different coils with simultaneous recording of responses from the right and left TA and EDB muscles. Mean normative values and formulae of linear regression were established within the observed correlations with height for the parameters measured (latencies) and derived parameters (segmental conduction times). A software system was developed which allows the readout of the selected parameter values from the Mystro device, calculation of the derived parameters, and classification of the results according to 95% confidence intervals for the parameters obtained in the group of normal subjects included in the study. This fast and painless investigation, which carries no risk to the patient, should prove useful in the electrophysiological diagnosis of motor pathway function including the entire length.