Cerebellar and Spinal Direct Current Stimulation in Children: Computational Modeling of the Induced Electric Field

Abstract

Recent studies have shown that the specific application of transcranial direct current stimulation (tDCS) over the cerebellum can modulate cerebellar activity. In parallel, transcutaneous spinal DC stimulation (tsDCS) was found to be able to modulate conduction along the spinal cord and spinal cord functions. Of particular interest is the possible use of these techniques in pediatric age, since many pathologies and injuries, which affect the cerebellar cortex as well as spinal cord circuits, are diffuse in adults as well as in children. Up to now, experimental studies of cerebellar and spinal DC stimulation on children are completely missing and therefore there is a lack of information about the safety of this technique as well as the appropriate dose to be used during the treatment. Therefore, the knowledge of electric quantities induced into the cerebellum and over the spinal cord during cerebellar tDCS and tsDCS, respectively, is required. This work attempts to address this issue by estimating through computational techniques, the electric field distributions induced in the target tissues during the two stimulation techniques applied to different models of children of various ages and gender. In detail, we used four voxel child models, aged between 5- and 8-years. Results revealed that, despite inter-individual differences, the cerebellum is the structure mainly involved by cerebellar tDCS, whereas the electric field generated by tsDCS can reach the spinal cord also in children. Moreover, it was found that there is a considerable spread toward the anterior area of the cerebellum and the brainstem region for cerebellar tDCS and in the spinal nerve for spinal direct current stimulation. Our study therefore predicts that the electric field spreads in complex patterns that strongly depend on individual anatomy, thus giving further insight into safety issues and informing data for pediatric investigations of these stimulation techniques.

Transcutaneous spinal direct current stimulation improves locomotor learning in healthy humans

“…provided mechanistic foundation to these empirical findings (29)(30)(31)(32). It is then possible that tsDCS could also influence locomotor learning.…”

Realistic Anatomically Detailed Open-Source Spinal Cord Stimulation (RADO-SCS) Model

“…Models of SCS have been continuously refined and applied from the early 80's through recent efforts 1,2,5,10,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] (see Table 1). Development of models of increasing complexity offered mirrored general enhancements in numerical modeling techniques (finite element analysis), with proprietary efforts by numerous groups, each subject to multiple version iterations.…”

“…Parazzini and colleagues in 2014 and Fiocchi and colleagues in 2016 developed an MRIderived SCS model for non-invasive SCS with enhanced anatomical precision in vertebrae, CSF, and spinal cord; however, other major spinal canal tissue compartments, such as epidural space, dura mater, and roots were not modelled. Moreover, it was unclear whether epidural fat was included in the FEM model 20 . In 2013, Laird and colleagues developed a limited precision SCS model while modeling spinal root fiber as an electrical cable model 43 .…”

A computational pipeline to determine lobular electric field distribution during cerebellar transcranial direct current stimulation

“…Here, computational modeling studies have shown that the ctDCS electric field distribution reaches the human cerebellum where the posterior and the inferior parts of the cerebellum (i.e., lobules VI-VIII) are particularly susceptible (Grimaldi et al, 2016). However, a lobular atlas-based analysis of subject-specific electric field distribution during ctDCS was not found in the literature , , (Fiocchi et al, 2016). Therefore, the main objective of this technology report is to present a freely available computational pipeline that allows visualization of the lobular electric field distribution during ctDCS.…”

“…Here, the goal is an optimal electrode placement, e.g., with more focal high-definition (HD) ctDCS montages (Fiocchi et al, 2017), that can in principle direct the electric field towards deeper targets by taking advantage of the high conductivity of the CSF and the interhemispheric fissure. Moreover, computational modeling , , (Fiocchi et al, 2016) is important to address the inter-subject variability in the ctDCS effects for its clinical translation (Ferrucci et al, 2016). This is crucial since ctDCS effects were recently said to be mediated by mechanisms other than cerebellar excitability changes (Grimaldi et al, 2016) since non-focal electric field with two-electrode montages may affect brain areas other than cerebellum.…”