Modeling Electric Fields in Transcutaneous Spinal Direct Current Stimulation: A Clinical Perspective
Matteo Guidetti,
Stefano Giannoni-Luza,
Tommaso Bocci,
Kevin Pacheco-Barrios,
Anna Maria Bianchi,
Marta Parazzini,
Silvio Ionta,
Roberta Ferrucci,
Natale Vincenzo Maiorana,
Federico Verde,
Nicola Ticozzi,
Vincenzo Silani,
Alberto Priori
Affiliations
Matteo Guidetti
Aldo Ravelli Research Center for Neurotechnology and Experimental Neurotherapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
Stefano Giannoni-Luza
Sensory-Motor Lab (SeMoLa), Department of Ophthalmology—University of Lausanne, Jules Gonin Eye Hospital/Fondation Asile des Aveugles, 1015 Lausanne, Switzerland
Tommaso Bocci
Aldo Ravelli Research Center for Neurotechnology and Experimental Neurotherapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
Kevin Pacheco-Barrios
Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Boston, MA 02129, USA
Anna Maria Bianchi
Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy
Marta Parazzini
Istituto di Elettronica e di Ingegneria Dell’Informazione e delle Telecomunicazioni (IEIIT), Consiglio Nazionale delle Ricerche (CNR), 10129 Milan, Italy
Silvio Ionta
Sensory-Motor Lab (SeMoLa), Department of Ophthalmology—University of Lausanne, Jules Gonin Eye Hospital/Fondation Asile des Aveugles, 1015 Lausanne, Switzerland
Roberta Ferrucci
III Neurology Clinic, ASST-Santi Paolo e Carlo University Hospital, 20142 Milan, Italy
Natale Vincenzo Maiorana
Aldo Ravelli Research Center for Neurotechnology and Experimental Neurotherapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
Federico Verde
Department of Neurology, Istituto Auxologico Italiano IRCCS, 20149 Milan, Italy
Nicola Ticozzi
Department of Neurology, Istituto Auxologico Italiano IRCCS, 20149 Milan, Italy
Vincenzo Silani
Department of Neurology, Istituto Auxologico Italiano IRCCS, 20149 Milan, Italy
Alberto Priori
Aldo Ravelli Research Center for Neurotechnology and Experimental Neurotherapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
Clinical findings suggest that transcutaneous spinal direct current stimulation (tsDCS) can modulate ascending sensitive, descending corticospinal, and segmental pathways in the spinal cord (SC). However, several aspects of the stimulation have not been completely understood, and realistic computational models based on MRI are the gold standard to predict the interaction between tsDCS-induced electric fields and anatomy. Here, we review the electric fields distribution in the SC during tsDCS as predicted by MRI-based realistic models, compare such knowledge with clinical findings, and define the role of computational knowledge in optimizing tsDCS protocols. tsDCS-induced electric fields are predicted to be safe and induce both transient and neuroplastic changes. This could support the possibility to explore new clinical applications, such as spinal cord injury. For the most applied protocol (2–3 mA for 20–30 min, active electrode over T10–T12 and the reference on the right shoulder), similar electric field intensities are generated in both ventral and dorsal horns of the SC at the same height. This was confirmed by human studies, in which both motor and sensitive effects were found. Lastly, electric fields are strongly dependent on anatomy and electrodes’ placement. Regardless of the montage, inter-individual hotspots of higher values of electric fields were predicted, which could change when the subjects move from a position to another (e.g., from the supine to the lateral position). These characteristics underlines the need for individualized and patient-tailored MRI-based computational models to optimize the stimulation protocol. A detailed modeling approach of the electric field distribution might contribute to optimizing stimulation protocols, tailoring electrodes’ configuration, intensities, and duration to the clinical outcome.
