Non-invasive spinal cord neuromodulation enables volitional anti-gravity leg movements after motor-complete spinal cord injury: responders vs. non-responders
Bibliographic record
Abstract
Abstract Background and Objectives Transcutaneous spinal cord stimulation (tSCS) is an emerging treatment for motor recovery following spinal cord injury (SCI). However, the extent of motor recovery with tSCS and the reasons why some individuals with motor-complete SCI respond less effectively, despite having the same injury classification, remain unclear. Here, we demonstrate that lumbosacral tSCS can enable anti-gravity voluntary movement following motor-complete SCI, and identify markers that distinguish responders from non-responders. Methods Ten individuals with chronic motor-complete SCI received 30Hz lumbosacral tSCS for 60 min, 2-5 times per week, for a minimum of 6 weeks. Post-intervention, volitional movement was measured using surface electromyography (EMG) over the quadriceps and tibialis anterior (TA), and knee and ankle joint range of motion. To identify markers of responsiveness, we assessed the integrity of the corticospinal tract (motor evoked potentials; MEPs), ascending sensory pathways (somatosensory evoked potentials; SEPs), spinal cord reflexes (H-reflex), and motor neurons (compound muscle action potential, CMAP), along with muscle morphology using ultrasound echo-intensity. Results Five of 10 individuals demonstrated voluntary anti-gravity knee extension and ankle dorsiflexion strength in the presence of tSCS. TA MEPs were observed in one responder only and tibial nerve SEPs were not observed in any participants. All participants showed poor TA muscle morphology. Four responders had a soleus H-reflex (compared to 2/5 non-responders) and a normal amplitude fibular CMAPs (compared to 2/5 non-responders). Discussion These results show that tSCS can enable volitional motor activity against gravity in people with motor-complete SCI, but there is variability in responsiveness. Using conventional neurophysiological techniques, we were unable to consistently demonstrate the pathways facilitating voluntary control or the factors differentiating responders versus non-responders, but trends were observed. Spinal cord reflex and peripheral motor nerve integrity may be important for responding to tSCS but may not distinguish responders from non-responders. Additional assessments are needed to develop biomarkers for stratifying motor responders to tSCS.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".