Background: Since navigated transcranial magnetic stimulation (nTMS) is increasingly used in neurosurgical research, interpretation of its results is of utmost importance.
Objective: To evaluate test-retest-reliability of nTMS.
Methods: 12 healthy participants underwent nTMS at two different sessions, separated by 10.3 +/- 9.6 days. Investigated parameters comprised resting motor thresholds (RMT), hotspots (HS) and centers of gravity (CoG), being calculated for the first dorsal interosseous, abductor pollicis brevis, extensor digitorum, tibial anterior and abductor hallucis muscles.
Results: Excellent reliability of RMTs was observed. HS and CoGs showed moderate to excellent repeatability along the anteroposterior axis (ICC = 0.54 – 0.89), whereas the X-coordinate presented mainly poor to moderate stability (ICC = 0.11 – 0.89). Movement of CoGs over sessions was 0.57 +/- 0.32 cm and HS laid 0.79 +/- 0.47 cm apart. Calculation of coefficient of variation (CV) revealed high reliability of investigated parameters in upper extremities; in lower extremity muscles high variation across sessions was observed.
Conclusion: nTMS can be considered as a reliable tool, thus opening new fields of non-invasive investigations in neurosurgery. Presented results should be considered when interpreting individual nTMS results.
From: Test-Retest-Reliability of Navigated Transcranial Magnetic Stimulation of the Motor Cortex by Forster et al.