Central motor conduction time: reproducibility and discomfort of different methods.
Central motor conduction time, a useful measure for studying central motor pathways, is calculated by determining the difference between the latency of motor-evoked potentials and peripheral conduction time. The intraindividual trial-to-trial variability of central motor conduction time and the discomfort associated with three methods of measuring peripheral motor conduction time (F-wave latency, cervical magnetic stimulation, and cervical needle stimulation) were studied in 5 healthy subjects with the use of transcranial magnetic stimulation to elicit motor-evoked potentials. Central motor conduction time was calculated by using measurements, made on 3 separate days, from the same three muscles on each hand. A visual analog pain scale was used to determine the level of discomfort for each method. Intraindividual trial-to-trial variability of central motor conduction time was similar for all methods, with coefficients of variation of 13% for the F-wave latency, 15% for cervical magnetic stimulation, and 11% for cervical needle stimulation. The last method was significantly more painful than the other two methods; there was no significant difference in discomfort between the F-wave method and cervical magnetic stimulation. To assess peripheral motor conduction time, when determining central motor conduction time, either the F-wave method or cervical magnetic stimulation is preferable to cervical needle stimulation.
Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA.
A
A
Samii
C A
CA
Luciano
J M
JM
Dambrosia
M
M
Hallett
D000328:Adult; D004558:Electric Stimulation; D004594:Electrophysiology; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D009339:Needles; D009431:Neural Conduction; D009482:Neurophysiology / Q000379:methods / Q000592:standards*; D010146:Pain / Q000517:prevention & control*; D010147:Pain Measurement; D017060:Patient Satisfaction; D015203:Reproducibility of Results