Neuronavigated vs. conventional repetitive transcranial magnetic stimulation method for virtual lesioning on the Broca's area.

OBJECTIVES: This study was undertaken to test the hypothesis that repetitive transcranial magnetic stimulation (rTMS) using a neuronavigational TMS system (nTMS) to the Broca's area would elicit greater virtual aphasia than rTMS using the conventional TMS method (cTMS).
MATERIALS AND METHODS: Eighteen healthy subjects underwent a randomized crossover experiment to induce virtual aphasia by targeting the Brodmann area 44 and 45 for nTMS, and F3 of international 10-20 system for cTMS. Reaction time for a picture naming task and the reaction duration for a six-digit number naming task were measured before and after each session of stimulation, and compared between the cTMS and nTMS. The stability of the coil positioning on the target was measured by depicting the variability of talairach coordinates (x, y, z) of the sampled stimulation localizations.
RESULTS: At baseline, outcome variables were comparable between cTMS and nTMS. nTMS induced significant delays in reaction time from 944.0 ± 203.4 msec to 1304.6 ± 215.7 msec (p < 0.001) and reaction duration from 1780.5 ± 286.8 msec to 1914.9 ± 295.6 msec (p < 0.001) compared with baseline, whereas cTMS showed no significant changes (p = 0.959 and p = 0.179, respectively). The mean talairach space coordinates of nTMS demonstrated greater consistency of localization of stimulation with the target, and the error range relative to the target was narrower for the nTMS compared with the cTMS (p < 0.001).
CONCLUSIONS: nTMS leads to more robust neuromodulation of Broca's area, resulting in delayed verbal reaction time as well as more accurate targeting of the intended stimulation location, demonstrating superiority of nTMS over cTMS for therapeutic use of rTMS in neurorehabilitation.