[Measurement of central motor conduction time (CMCT) in healthy Chinese subjects]

Transcutaneous electrical stimulation of the central nervous system was used to measure CMCT between the human cerebral cortex and spinal cord. 64 normal volunteers (46 healthy adult males and 18 females, age of 20-67 years, body height of 156-185 cm) were recruited as experimental subjects. Action potentials of muscles were recorded from upper limb (Thenar) and lower limb (Muscle tibialis anterior) following cortical and spinal stimulation. The cortical and spinal latent periods (Lcor., Lsp.) were measured and CMCT was obtained by subtracting Lsp. from Lcor. for each muscle. The CMCT between the cerebral cortex and the first thoracic (Th1) cord was 6.69 +/- 1.48 ms, while that between the cerebral cortex and the first lumber (L1) cord was 12.90 +/- 1.59 ms. Statistical analysis indicated that CMCT was not related to sex, age, body height and left or right side of the body as well. The motor conduction velocity in spinal cord (MCVsp) between Th1 and L1, [distance (Th1 to L1)/CMCT (Muscle tibialis anterior)-CMCT (Thenar)] was found to be 71.34 +/- 10.89 m/s, which corresponds to the conduction velocity of the large fibers in the pyramidal tract. The results of the present study are valuable in diagnosis and prognosis of motor system diseases in CNS.