Reliability of transcranial magnetic stimulation-related measurements of tibialis anterior muscle in healthy subjects.

OBJECTIVE: The main purpose of this study was to determine the reliability of transcranial magnetic stimulation (TMS)-related measurements linked to the corticospinal control of the tibialis anterior (TA) muscle in healthy subjects. METHODS: Inter-investigator and intra-investigator (within-session with a 1.5-h interval; between-session with a 4-week interval) reliability of the motor threshold, recruitment curve with its slope and MEP area at the plateau, MEP latency, maximum MEP (MEPmax) area, and duration of the maximum and minimum silent period (SPmax and SPmin) were assessed in 50 (29 men and 21 women) healthy subjects (mean age 44.8 years, range 22-74 years) using intraclass correlation coefficients (ICC), standard error of measurement (SEM) and smallest real difference (SRD). RESULTS: The high ICC values and lower SEM and SRD values indicate a good intra- and inter-investigator reliability for motor threshold (ICC range 0.94-0.98), MEP latency (ICC range 0.79-0.93), SPmax (ICC range 0.89-0.95) and SPmin (ICC range 0.79-0.81) in healthy subjects. CONCLUSIONS: These results suggest that the TMS-related measurements investigated are reliable in healthy subjects. SIGNIFICANCE: These data could be useful in further studies on cortical excitability changes, such as those induced by therapeutic interventions (e.g. rehabilitative treatment).