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Updated: Apr 23, 2026
Assessing Primary Motor Cortex Excitability and Excitability Modulation by Pairing Transcranial Magnetic Stimulation with Electromyography
Published on: October 7, 2025
How reproducible are transcranial magnetic stimulation-induced MEPs in subacute stroke?
Maurits H W J Hoonhorst1, Boudewijn J Kollen, Peter S P van den Berg
1*Department of NeuroRehabilitation, Vogellanden Center for Rehabilitation, Zwolle, the Netherlands; †Department of General Practice, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; Departments of ‡Neurology and §Rehabilitation Medicine, Isala Klinieken, Zwolle, the Netherlands; and ‖Department of Rehabilitation Medicine, MOVE Research Institute Amsterdam, VU University Medical Center, Amsterdam, the Netherlands.
Purpose:
Motor evoked potentials (MEPs) and total motor conduction time (TMCT) induced by transcranial magnetic stimulation (TMS) are used to make assumptions about the prognosis of motor outcome after stroke. Understanding the different sources of variability is fundamental to the concept of reliability. Reliability testing of TMS-MEPs and TMCTs within and between two independent examiners in healthy and stroke subjects is still an unexplored field in the clinical neurophysiology. Assessing the reproducibility of TMS measurements requires studies to investigate the test-retest reliability of TMS-induced MEPs and TMCT. The authors set out to test the reliability of these TMS measurements.
Methods:
Eighteen patients with stroke and 8 healthy volunteers were tested twice within a 1-week period by 2 examiners using TMS to determine MEPs and TMCT for the abductor pollicis brevis muscle of their affected and unaffected hands.
Results:
The authors found moderate to perfect reliability of TMS-induced MEPs in healthy volunteers, noninfarcted hemispheres (perfect agreement), and infarcted hemispheres (Kappa's = 0.45-0.87). Reliability of TMCT was good to excellent in the volunteers (intraclass correlation coefficients = 0.77-0.97), excellent in the noninfarcted hemispheres (intraclass correlation coefficients = 0.97-1.00), and poor to excellent in the infarcted hemispheres (intraclass correlation coefficients = 0.44-0.90).
Conclusions:
The reliability of TMS-induced MEPs and TMCT measurements in healthy volunteers and the noninfarcted hemisphere of patients with stroke with an upper paretic limb was good to excellent. In contrast, TMS measurements in the infarcted hemisphere were less consistent. Based on the lower reproducibility of TMCT measurements in the infarcted hemisphere, we recommend to repeat the TMCT measurements to improve the reliability of tests.
Insights
Transcranial magnetic stimulation (TMS) measurements of motor evoked potentials (MEPs) and total motor conduction time (TMCT) show good reliability in healthy individuals and stroke patients' non-affected sides. However, reliability is lower in the stroke-affected hemisphere, suggesting repeated TMCT measurements may be needed.
Area of Science:
- Neuroscience
- Clinical Neurophysiology
- Rehabilitation Medicine
Background:
- Transcranial magnetic stimulation (TMS) is utilized to assess motor function prognosis post-stroke.
- Reliability of TMS-derived motor evoked potentials (MEPs) and total motor conduction time (TMCT) is crucial for clinical application.
- Limited research exists on the reliability of TMS measurements within and between examiners in both healthy and stroke populations.
Purpose of the Study:
- To evaluate the test-retest reliability of TMS-induced MEPs and TMCT.
- To assess the reproducibility of these measurements in healthy volunteers and stroke patients.
- To investigate inter-examiner reliability for TMS assessments.
Main Methods:
- Eighteen stroke patients and 8 healthy volunteers participated.
- Two examiners conducted TMS assessments twice within a week.
- MEPs and TMCT were measured for the abductor pollicis brevis muscle in affected and unaffected hands.
Main Results:
- Moderate to perfect reliability for TMS-induced MEPs was observed in healthy volunteers and stroke patients' non-infarcted hemispheres.
- Good to excellent reliability for TMCT was found in volunteers and the non-infarcted hemispheres.
- Reliability for TMCT in the infarcted hemispheres showed a wide range from poor to excellent.
Conclusions:
- TMS-induced MEPs and TMCT measurements demonstrate good to excellent reliability in healthy individuals and the non-infarcted hemisphere of stroke patients.
- Measurements in the infarcted hemisphere were less consistent, particularly TMCT.
- Repeated TMCT measurements are recommended for the infarcted hemisphere to enhance test reliability.
