P088 Different modulation effects of TBS produced by different repetitive TMS machines

Abstract

Introduction The Rapid2 from Magstim and MagPro X100 from MagVenture are 2 major TMS machines on the market. It is generally considered that both machines can produce similar stimulation and their effect are usually considered similar. However, a head-to-head comparison of the two machines has never been done. Thinking of the different inner designs of the 2 machines, it deserves a careful study to compare the effects of a single protocol produced by the two machines. Objectives To evaluate and compare the effects of theta burst stimulation (TBS) generated by Magstim Rapid2 and MagVenture MagPro X100 in the same subjects. Patients & Methods Healthy subjects have participated 2 sessions that were one week apart from each other in a randomized order. In each session, the effect of continuous TBS at 70% rest motor threshold followed by 1-min subtle voluntary contraction (cTBSc0) on the size of MEP was assessed. 30 baseline MEPs at approximately 1 mV were recorded. Then cTBSc0 was applied to the motor hot-spot. After contraction, 12 MEPs evoked by the stimulus intensity identical to that for baseline MEPs were recorded every minutes for 5 min then every 2 min until 21 min after cTBS. The only different between the two sessions is that cTBS was given by Magstim Rapid2 in one session and by MagVenture MagPro X100 in the other. Result Our data suggested that the effect of cTBSc0 generated by Magstim Rapid2 and by MagVenture MagPro X100 was different. The cTBSc0 by Magstim Rapid2 induced a significant excitatory effect as previously reported, while cTBSc0 by MagVenture Magpro X100 tended to generate an inhibitory effect. Conclusion Although the effects of all the TMS machines are generally considered the same, the present study suggests that such assumption may not be true. We suggest the further head-to-head comparison of different TMS machines in different protocols.