Figure 5:

Evaluation of example and human data sets. A. Reich et al.³ report that short pulse widths increase therapeutic window and better focus the stimulation effect within small, nearby axons. In our simulations of their therapeutic and side effect thresholds, activation spread did not vary significantly across pulse widths. Pulse-width tuning therefore did not impact therapeutic window from a biophysical perspective. B. Woods et al.⁶ associated long pulse widths with cognitive decline in thalamic DBS. Simulations with their parameters yielded larger VTAs in those with decline than in those without, supporting that VTA size (cf. pulse width per se) may be predictive of cognitive decline. C. Choe et al.⁴ found that, when balanced for energy use, short pulses reduce side effects, but directional stimulation does not. From our simulations of their parameters, overall spread reduced with pulse width for both fiber sizes (5.7 μm shown on left). Maintaining amplitude with one contact increased spread in the intended direction, but also largely in the opposite direction. Using our equivalence equation from supplemental appendix C, we match the intended spread for 2.0 μm fibers with more directionality and reduced 5.7 μm spread.