Transcranial magnetic stimulation (TMS) is widely used to assess cortical excitability. To detect changes in excitability with longitudinal studies, it is important to validate the repeatability of excitability measures within a subject between different sessions. Repeatability studies on paired pulse TMS are limited and reported agreement ranges from poor to good. Therefore this study aims to evaluate the repeatability of paired pulse TMS in healthy subjects.
We studies thirty healthy subjects twice, approximately one week apart. Both motor cortices were stimulated at six different interstimulus intervals (ISIs) between 50 and 300 ms. Repeatability was assessed using the intraclass correlation coefficient (ICC).
We found a large variation in repeatability at the subject and ISI level, ranging from poor to good agreement. On a group level, we found a good repeatability for the averaged paired pulse TMS curves, which decreased when individual curves were correlated.
In conclusion, for a correct interpretation of the cortical excitability outcomes it is important to know the subject specific repeatability and to analyse each ISI individually.
Wednesday 5 October 2016, 16:30 - 17:30 h
Building Carré - room CR 1.333