TY - JOUR
T1 - Effect of TMS coil orientation on the spatial distribution of motor evoked potentials in an intrinsic hand muscle
AU - Souza, Victor Hugo
AU - Vieira, Taian Martins
AU - Peres, André Salles Cunha
AU - Garcia, Marco Antonio Cavalcanti
AU - Vargas, Claudia Domingues
AU - Baffa, Oswaldo
PY - 2018/12/1
Y1 - 2018/12/1
N2 - Previous reports on the relationship between coil orientation and amplitude of motor evoked potential (MEP) in transcranial magnetic stimulation (TMS) did not consider the effect of electrode arrangement. Here we explore this open issue by investigating whether TMS coil orientation affects the amplitude distribution of MEPs recorded from the abductor pollicis brevis (APB) muscle with a bi-dimensional grid of 61 electrodes. Moreover, we test whether conventional mono- and bipolar montages provide representative MEPs compared to those from the grid of electrodes. Our results show that MEPs with the greatest amplitudes were elicited for 45° and 90° coil orientations, i.e. perpendicular to the central sulcus, for all electrode montages. Stimulation with the coil oriented at 135° and 315°, i.e. parallel to the central sulcus, elicited the smallest MEP amplitudes. Additionally, changes in coil orientation did not affect the spatial distribution of MEPs over the muscle extent. It has been shown that conventional electrodes with detection volume encompassing the APB belly may detect representative MEPs for optimal coil orientations. In turn, non-optimal orientations were identified only with the grid of electrodes. High-density electromyography may therefore provide new insights into the effect of coil orientation on MEPs from the APB muscle.
AB - Previous reports on the relationship between coil orientation and amplitude of motor evoked potential (MEP) in transcranial magnetic stimulation (TMS) did not consider the effect of electrode arrangement. Here we explore this open issue by investigating whether TMS coil orientation affects the amplitude distribution of MEPs recorded from the abductor pollicis brevis (APB) muscle with a bi-dimensional grid of 61 electrodes. Moreover, we test whether conventional mono- and bipolar montages provide representative MEPs compared to those from the grid of electrodes. Our results show that MEPs with the greatest amplitudes were elicited for 45° and 90° coil orientations, i.e. perpendicular to the central sulcus, for all electrode montages. Stimulation with the coil oriented at 135° and 315°, i.e. parallel to the central sulcus, elicited the smallest MEP amplitudes. Additionally, changes in coil orientation did not affect the spatial distribution of MEPs over the muscle extent. It has been shown that conventional electrodes with detection volume encompassing the APB belly may detect representative MEPs for optimal coil orientations. In turn, non-optimal orientations were identified only with the grid of electrodes. High-density electromyography may therefore provide new insights into the effect of coil orientation on MEPs from the APB muscle.
KW - brain stimulation
KW - conventional electrodes
KW - electric field direction
KW - high-density electromyography
KW - muscle imaging
KW - transcranial magnetic stimulation
UR - http://www.scopus.com/inward/record.url?scp=85037627267&partnerID=8YFLogxK
U2 - 10.1515/bmt-2016-0240
DO - 10.1515/bmt-2016-0240
M3 - Article
C2 - 28796636
AN - SCOPUS:85037627267
SN - 0013-5585
VL - 63
SP - 635
EP - 645
JO - Biomedizinische Technik
JF - Biomedizinische Technik
IS - 6
ER -