Prospects for clinical applications of transcranial magnetic stimulation and real-time EEG in epilepsy.

Recent advances in methods for transcranial magnetic stimulation (TMS) enable its coupling to real-time EEG (TMS-EEG). Although TMS-EEG is applied largely in neurophysiology research, there are prospects for its use in clinical TMS practice, particularly in epilepsy where EEG is already in wide use, and where TMS is emerging as a diagnostic and therapeutic tool. In diagnostic applications, TMS-EEG may provide a useful measure of cortical excitability at baseline or after antiepileptic treatment. For therapeutic purposes, TMS-EEG may be of use in selection of appropriate TMS strength outside of the motor cortex where the threshold for cortical activation is more apparent with the aid of EEG. In other realistic clinical applications, TMS-EEG may be of use in real-time monitoring for epileptiform activity in vulnerable populations where TMS may trigger seizures, or as a component of a responsive neurostimulation setup in which TMS timing is determined by underlying EEG activity. Future trials and evolution of TMS-EEG methods are likely to provide answers as to the actual clinical value of TMS-EEG.