Reliability of the motor evoked potentials elicited through magnetic stimulation at three sites☆
Received 24 September 2002; received in revised form 13 November 2002
Abstract
Background
Motor evoked potentials (MEPs) obtained from magnetic stimulation allow the measurement of the excitability of motor nerve cells. Although this technique is becoming widely used, its reliability has yet to be established.
Objective
To determine the reliability of MEPs and evaluate their stability.
Design
Subjects received magnetic stimulation at 3 different sites: cranial, cervical, and peripheral. Three stimulations were given at each site. Stimulations were given under 4 conditions: eyes open or closed and with or without controlled mental activity.
Setting
The study was performed in a research laboratory setting.
Participants
Nine healthy subjects (mean age = 21 years ± 0.9), asymptomatic of any neural or musculoskeletal dysfunctions.
Main outcome measures
Normalized peak-to-peak amplitude of MEPs at the opponens pollicis muscle.
Results
Intraclass correlations were high for all conditions (R > 0.90). The amplitude of the MEPs elicited from the transcranial site during the controlled mental activity condition was increased by 26.6% (P = .017). No other significant differences (P > .05) were obtained among the other conditions.
Conclusion
Intraclass correlation results reveal that MEP measurements are highly reliable in a controlled environment. The increase of MEPs during the controlled mental activity condition could be attributed to an elevation of neural activity of different nonmotor areas of the brain increasing corticospinal excitability.
aDépartement de kinanthropologie, Université du Québec à Montréal, Montréal, Québec, Canada
b Département de la chiropratique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
Submit requests for reprints to: Jean P. Boucher, PhD, FACSM, Département de kinanthropologie, Université du Québec à Montréal (UQAM), C.P. 8888, Succursale centre-ville, Montréal, Québec H3C 3P8, Canada
☆ This study was fully supported by the Fondation Chiropratique du Québec. Cette étude fut supportée entièrement par la Fondation Chiropratique du Québec.
ABSTRACT