EEG onset of a seizure during TMS from a focus independent of the stimulation site

Abstract

The risk of a seizure in temporal association with a TMS session in a patient with epilepsy is less than 2%, both for single and paired-pulse TMS (Schrader et al., 2004) and for repetitive TMS (rTMS) (Bae et al., 2007). With rare exceptions (Dhuna et al., 1991), TMS-associated seizures in epilepsy patients have been clinically similar to the patients’ typical spontaneous seizures, leaving uncertainty as to whether they are causally related to stimulation. Here we describe a patient with an epileptic brain malformation who, while undergoing paired-pulse TMS over a cortical region distant from his seizure focus, had a spontaneous seizure of his usual semiology, with demonstrated ictal EEG onset from his expected epileptogenic focus.