Performance of transverse tripoles vs. longitudinal tripoles with anode intensification (AI) in spinal cord stimulation: computational modeling study.

Objective: In spinal cord stimulation, anodes tend to have a strong effect over the area of dorsal column (DC) activation, when configured as both longitudinal guarded cathodes (LGCs) and transverse tripoles (TTs). Inclusion of a small spacing step (LGC+) in the center-center (C-C) spacing of the LGC can be an efficient method to study the local effects around the electrode. The primary aim of this computer modeling study is to investigate if enhanced DC recruitment is achieved when anodal currents in TT and LGC combinations (both LGC and LGC+) are increased up to 30% with respect to the cathodal current. Secondly, the merits of anodal intensification (AI) are evaluated by comparing the DC recruitment areas (S(RA)) and energy consumption (EDT ) of LGC+ with AI, against stimulation using an LGC without AI.

Materials And Methods: The commercially available LGC and LGC+, with 4.0 and 4.5 mm C-C, respectively, were modeled on a single percutaneous lead at the low-thoracic vertebral region (T10-T12). Transverse tripolar stimulation (TTS) was modeled on triple percutaneous leads.

Results: TTS with 10% AI recruited a smaller S(RA) as compared with TTS with no AI. AI of LGC and LGC+ resulted in increasing SRAs respectively to that of LGC and LGC+ without AI. Also, AI of LGC+ recruited a larger S(RA) and usage range (UR) at lower E(DT) compared with that of LGC without AI.

Conclusions: AI of TTS is not advantageous. LGC and LGC+ with AI allow additional DC stimulation, which may increase the likelihood of activating fibers inaccessible with conventional programming. LGC+ with AI can be more efficient than LGCs without AI, as a larger SRA and UR is achieved at lower EDT .