Initial Results of Flexible ECAP-Based Closed-Loop Spinal Cord Stimulation

Overview

This single-arm study evaluated a flexible closed-loop spinal cord stimulation (CL-SCS) system using evoked compound action potentials (ECAPs) to adjust stimulation amplitude. Results showed significant reduction in overstimulation compared to open-loop SCS and substantial pain relief in patients with chronic neuropathic pain at 1 and 3 months.

Background

Spinal cord stimulation (SCS) is an established therapy for chronic neuropathic pain refractory to conservative treatments. Traditional open-loop (OL) SCS systems deliver fixed-amplitude stimulation, which can lead to inconsistent dosing due to changes in lead-to-cord distance with patient movement, causing discomfort or inadequate pain relief. Closed-loop (CL) SCS systems that adjust stimulation amplitude based on biosignals such as ECAPs can provide more consistent dosing and improve patient comfort. This study evaluates a flexible ECAP-based CL-SCS system capable of delivering multiple waveforms with automatic amplitude adjustment up to 50 times per second.

Data Highlights

Key Findings

• 89.3% of subjects reported reduced overstimulation with CL-SCS versus OL-SCS at 1 month (statistically significant).
• At 3 months, 86% of subjects with low-back/leg pain and all subjects with upper limb pain achieved ≥50% pain reduction from baseline.
• 60% of subjects preferred below-perception stimulation waveforms during at-home use.
• The flexible CL-SCS system automatically adjusted stimulation amplitude up to 50 times per second based on ECAP feedback.
• CL-SCS improved consistency of therapy delivery by compensating for postural and movement-related changes in lead-to-cord distance.

Clinical Implications

The ECAP-based closed-loop SCS system offers a promising approach to optimize spinal cord stimulation by automatically adjusting stimulation amplitude to maintain patient comfort and effective dosing. This technology may reduce the need for manual adjustments, decrease overstimulation-related discomfort, and improve pain relief consistency, potentially enhancing patient adherence and satisfaction with SCS therapy.

Conclusion

This study demonstrates that a flexible ECAP-based closed-loop SCS system can significantly reduce overstimulation and provide substantial pain relief in patients with chronic neuropathic pain. The system’s ability to deliver multiple waveforms with rapid automatic amplitude adjustment supports its clinical utility in improving therapy consistency and patient comfort.

References

1. ClinicalTrials.gov NCT05177354 -- Closed-Loop Spinal Cord Stimulation Study