Silent period following transcranial magnetic stimulation: a study of intra- and inter-examiner reliability.
Transcranial magnetic stimulation-evoked silent period (SP) has been attributed largely to the activity of intracortical inhibitory systems and recent reports provided evidence that it is a useful indicator of central motor disturbances. We studied the intra- and inter-examiner reliability of SP measurements in 28 healthy subjects. In 15 subjects SP measurements were performed by one single examiner and repeated by the same examiner 3 days and 7 days later, showing a high degree of intra-examiner reliability over time. In another subgroup consisting of 13 volunteers SP measurements were performed on the same subject by three different examiners, demonstrating a higher level of variability. In both subgroups we found a high interindividual variability ranging from 44-258 ms and a considerably lower side-to-side difference within subjects. Our results suggest that longitudinal assessments of the SP in patients with central motor involvement should optimally be performed by a single examiner. Regarding the wide range of possible SP durations in healthy subjects the intraindividual side-to-side symmetry seems to be the most valuable parameter.
Fritz
C
C
Department of Neurology, Philipps-University Marburg, Germany.
Braune
H J
HJ
Pylatiuk
C
C
Pohl
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002540:Cerebral Cortex / Q000502:physiology*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D050781:Transcranial Magnetic Stimulation