Optimizing transcutaneous spinal stimulation: excitability of evoked spinal reflexes is dependent on electrode montage

Journal of NeuroEngineering and Rehabilitation, 2025 · DOI: https://doi.org/10.1186/s12984-024-01524-5 · Published: December 4, 2025

Physiology Neurology Neurorehabilitation

Simple Explanation

Transcutaneous spinal stimulation (TSS) is a neurorehabilitation tool used to improve walking, reduce spasticity and improve postural control. The study compares different electrode placements to find the most effective montage for activating spinal circuits and assesses tolerability among montages. The goal of this study was to compare PRM reflexes of 6 commonly reported electrode montages in individuals with intact neurological systems.

Study Duration

Not specified

Participants

15 adults with intact neurological systems

Evidence Level

Level 2; Randomized crossover study

Key Findings

1
DV-U and DV-I montages were associated with significantly lower soleus RT in both dominant and nondominant lower extremities compared to other montages
2
DV-U and DV-I montages also had larger AUCs, with significant differences among montages observed only in the nondominant soleus muscle
3
There were no significant differences in tolerability rating among montages.

Research Summary

The study compared six electrode montages for transcutaneous spinal stimulation (TSS) to identify which montage most effectively activates spinal circuits, using posterior root-muscle reflexes (PRM reflexes) as a measure. The dorsal–ventral umbilicus (DV-U) and dorsal–ventral iliac crests (DV-I) montages were found to have lower reflex thresholds and larger recruitment curve areas compared to other montages. There were no significant differences in tolerability among the tested montages, suggesting that DV-U and DV-I montages could be more effective due to lower required stimulation intensities.

Practical Implications

Optimized Electrode Placement

DV-U and DV-I montages are recommended for clinical use to enhance Ia afferent recruitment during interventional TSS and PRM reflex assessments.

Personalized Anode Placement

Given the minimal differences between DV-U and DV-I montages, clinicians should consider participant sensory tolerance to determine anode placement over the umbilicus or iliac crests.

Potential for Lower Stimulation Intensities

The lower reflex thresholds associated with DV-U and DV-I montages suggest the potential for using lower and more tolerable stimulation intensities in interventional stimulation.

Study Limitations

1
The study focused on the soleus muscle; future studies should investigate other muscles.
2
The results cannot be applied to individuals whose reflex threshold falls above 100 mA.
3
The study included only individuals with intact neurological systems; results may not be fully generalizable to individuals with neurologic conditions.

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