Transcutaneous spinal stimulation in people with and without spinal cord injury: Effect of electrode placement and trains of stimulation on threshold intensity

Physiological Reports, 2023 · DOI: 10.14814/phy2.15692 · Published: May 3, 2023

Simple Explanation

This study investigates how different electrode placements affect the amount of electrical stimulation needed to activate muscles in the legs using transcutaneous spinal cord stimulation (TSS). The study also compares the amount of stimulation needed when using single pulses versus repeated pulses (trains) of stimulation. The findings help optimize TSS techniques for improving motor function in people with and without spinal cord injuries.

Study Duration

Not specified

Participants

9 non-SCI participants and 9 participants with SCI

Evidence Level

Not specified

Key Findings

1
In non-SCI participants, the L1-midline electrode configuration required lower stimulation intensities compared to T11-midline and L1-ASIS configurations.
2
There was no significant difference in stimulation intensity required between the T11-midline and L1-midline configurations for participants with SCI.
3
Threshold intensities were generally lower with trains of stimulation compared to single pulses in non-SCI participants, but not in participants with SCI.

Research Summary

This study investigated the impact of electrode configuration and stimulation type (single pulses vs. trains) on spinally evoked motor response (sEMR) thresholds in lower limb muscles of non-SCI and SCI participants. The L1-midline electrode configuration generally resulted in lower stimulation thresholds, particularly in non-SCI participants. Trains of stimulation resulted in lower thresholds compared to single pulses in non-SCI participants, but not in SCI participants. The findings suggest that electrode placement and stimulation type can influence the effectiveness of transcutaneous spinal cord stimulation (TSS) for activating lower limb muscles.

Practical Implications

Optimized Electrode Placement

The L1-midline configuration may be preferred for TSS due to lower stimulation thresholds, potentially increasing comfort and effectiveness.

Stimulation Type Considerations

Single-pulse threshold intensities may overestimate threshold intensities for therapeutic TSS, but tolerance to trains of stimulation is often the limiting factor.

Personalized TSS

Individual factors and muscle-specific thresholds should be considered when determining stimulation parameters for TSS.

Study Limitations

1
The position of participants was not identical between the non-SCI and SCI groups.
2
Threshold intensities were determined at a resolution of 10 mA.
3
The sample size was relatively small.

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