Prediction of isometric forces from combined epidural spinal cord and neuromuscular electrical stimulation in the rat lower limb

Not specified, 2023 · DOI: https://doi.org/10.21203/rs.3.rs-3377679/v1 · Published: October 4, 2023

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

The study investigates whether combining spinal cord and muscle stimulation can restore movement after spinal cord injury more effectively than using either approach alone. The researchers tested if the combined stimulation responses could be predicted by simply adding the individual responses of each stimulation type. The results suggest that while the combined stimulation is generally similar to the sum of individual stimulations, the variability in spinal stimulation responses contributes to prediction errors.

Study Duration

Not specified

Participants

6 female Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Force prediction errors were significantly larger for spinal/muscle co-stimulation compared to muscle/muscle co-stimulation.
2
The larger prediction errors in spinal/muscle co-stimulation are likely due to the increased variability of spinal responses.
3
There was limited evidence for non-linear interactions between spinal and muscle stimulation responses.

Research Summary

This study examined whether the combined effects of spinal and muscle stimulation could be predicted by simply adding their individual effects. The researchers found that while spinal/muscle co-stimulation outputs were generally similar to the sum of individual stimulations, they were not as predictable as muscle co-stimulation alone. The findings suggest that spinal/muscle co-stimulation could be a useful approach for lower limb FES controllers in patients with SCI.

Practical Implications

FES Controller Development

Linear summation can be a reasonable estimate of co-stimulation outputs, simplifying controller design.

Improved Prediction Accuracies

Collecting multiple spinal stimulation trials and incorporating variability into models can improve prediction accuracies.

Clinical Translation Considerations

Future controllers must account for limb trajectories, musculoskeletal properties, and sensory feedback.

Study Limitations

1
The largest source of prediction error is the trial-to-trial variability in spinal stimulation responses.
2
Variability of evoked responses might be reduced after chronic SCI or increased in awake behaving animals.
3
Translating to practical use requires control of limb trajectories in addition to isometric forces.

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