[EN] Objective: Using computer simulation, we investigated the effect of electrode polarity on neural activation in spinal cord
stimulation and propose a new strategy to maximize the activating area in the dorsal column (DC) and, thus, paresthesia
coverage in clinical practice.
Materials and Methods: A new three-dimensional spinal cord model at the T10 vertebral level was developed to simulate
neural activation induced by the electric field distribution produced by different typical four-contact electrode polarities in
single- and dual-lead stimulation. Our approach consisted of the combination of a finite element model of the spinal cord
developed in COMSOL Multiphysics and a nerve fiber model implemented in MATLAB. Five evaluation parameters were
evaluated, namely, the recruitment ratio, the perception and discomfort thresholds, and the activating area and depth. The
results were compared quantitatively.
Results: The dual-guarded cathode presents the maximum activating area and depth in single- and dual-lead stimulation.
However, the lowest value of the ratio between the perception threshold in DC and the perception threshold in the dorsal
root (DR) is achieved when the guarded cathode is programmed. Although the two versions of bipolar polarity (namely bipolar
1 and bipolar 2) produce higher activating area and depth than the guarded cathode, they are suitable for producing DR
stimulation. Similarly, dual-lead stimulation is likely to activate DR fibers because the electrodes are closer to these fibers.
Conclusions: The results suggest that the activating area in the DC is maximized by using the dual-guarded cathode both in
single- and dual-lead stimulation modes. However, DC nerve fibers are preferentially stimulated when the guarded cathode is
used. According to these results, the new electrode programming strategy that we propose for clinical practice first uses the
dual-guarded cathode, but, if the DR nerve fibers are activated, it then uses guarded cathode polarity.The authors thank Virginie Callot for providing us with all the
spinal cord measurements from her research group’s study. The
authors would like also to thank Surgicen S.L. for providing
financial assistanceDurá, JL.; Solanes, C.; De Andrés, J.; Saiz Rodríguez, FJ. (2019). Computational Study of the Effect of Electrode Polarity on Neural Activation Related to Paresthesia Coverage in Spinal Cord Stimulation Therapy. Neuromodulation: Technology at the Neural Interface. 22(3):269-279. https://doi.org/10.1111/ner.1290926927922