LATE RESPONSES AFTER TRANSCRANIAL MAGNETIC STIMULATION IN STROKE

In addition to early responses after transcranial magnetic stimulation , usually designated as Motor Evoked Potentials (MEP), several late re sponses have been reported in intervals up to 500 ms following stimulu s. Our attention in this work was focused on the response in interval 150-300 ms after stimulus output, which is also designated as S > 150 response. We monitored longitudinally late S > 150 response in group o f 19 stroke patient with verified hemispherical ischemic lesion. Our r esults have shown that the presence of late S > 150 response on the fi rst day after stroke predicts an excellent improvement of clinical def icit ana that late S > 150 response is more sensitive to hemispheric l esion than early MEPs. From this point of view, recording of late resp onses can supplement early MEP recording. Our study demonstrated that supratentorial structures are involved in the origin of the S > 150 re sponse. According to the observation that in some patients a normal ea rly response was present and an S > 150 response was absent on the hem iparetic side, and both responses were present on the unaffected side, we hypothesize that cortical structures play an important role in S > 150 response.