A real electro-magnetic placebo (REMP) device for sham transcranial magnetic stimulation (TMS).

摘要

Objective: There is growing interest in neuropsychiatry for repetitive transcranial magnetic stimulation (rTMS) as a neuromodulatorytreatment. However, there are limitations in interpreting rTMS effects as a real consequence of physiological brain changes or as placebo-mediated unspecific effects, which may be particularly strong in psychiatric patients. This is due to the fact that existing sham rTMSprocedures are less than optimal. A new placebo tool is introduced here, called real electro-magnetic placebo (REMP) device, which cansimulate the scalp sensation induced by the real TMS, while leaving both the visual impact and acoustic sensation of real TMS unaltered.Methods: Physical, neurophysiological and behavioural variables of monophasic and biphasic single-pulse TMS and biphasic 1 Hz and20 Hz rTMS procedures (at different intensities) were tested in subjects who were expert or naı¨ve of TMS. Results of the real TMS werecompared with those induced by the REMP device and with two other currently used sham procedures, namely the commercially availableMagstim sham coil and tilting the real coil by 90.Results: The REMP device, besides producing scalp sensations similar to the real TMS, attenuated the TMS-induced electric field (asmeasured by a dipole probe) to a biologically inactive level. Behaviourally, neither expert nor naı¨ve TMS subjects identified the ‘‘coilat 90’’ or the ‘‘Magstim sham coil’’ as a real TMS intervention, whilst naı¨ve subjects were significantly more likely to identify theREMP-attenuated TMS as real.Conclusions: The ‘‘goodness of sham’’ of the REMP device is demonstrated by physical, neurophysiological, and behavioural results.Significance: Such placebo TMS is superior to the available sham procedures when applied on subjects naı¨ve to TMS, as in case ofpatients undergoing a clinical rTMS trial.