Early outcomes with a flexible ECAP based closed loop using multiplexed spinal cord stimulation waveforms-single-arm...

Spinal cord stimulation (SCS) systems that deliver fixed amplitudes expose target tissue to varying electrical fields due to the changing lead-to-cord distance accompanying postural shifts and other body movements. Inconsistent stimulation results in periods of overstimulation or under-stimulation perceived by patients as discomfort or potentially inadequate pain relief. CL-SCS may be applied to provide a comfortable level of perception down to imperceptible stimulation, commonly preferred in higher frequency and multiplexed programming. Here we report outcomes from a study evaluating a closed-loop (CL) SCS system that uses spinal evoked compound action potentials to adjust stimulation.

This ongoing study combines the evaluation of pain-related outcomes (for ≤24 months) with in-clinic randomized, crossover testing of CL performance.

Sixty subjects have been implanted with the CL-SCS system, and 54 subjects have completed the 3-month visit. Sixty percent preferred below-perception waveforms for therapy during at-home use. The study successfully met its primary endpoint with 89.3% of subjects in the Primary Analysis Set (n = 28) reporting reduction in overstimulation with CL-SCS relative to OL-SCS at 1 month (P < .001; binomial exact test); at 3 months, 86% of subjects with low-back/leg pain (n = 51); and all 3 with upper limb pain reported ≥50% reduction in pain, relative to baseline.

The data presented here support the performance of a flexible CL-SCS system that can deliver a variety of waveforms, with amplitude programmed to patient comfort and automatically adjusted up to 50 times per second, to improve the consistency of therapy experience.

This study is registered on ClinicalTrials.gov number NCT05177354 https://clinicaltrials.gov/search? term=NCT05177354.