Epidural stimulation restores muscle synergies by modulating neural drives in participants with sensorimotor complete spinal cord injuries.
Rajat Emanuel Singh, Aliya Ahmadi, Ann M Parr and 4 others
PMID 37138361WHAT IT FOUND
Epidural stimulation in six people with complete spinal cord injury reduced the number of muscle synergies to match healthy controls, indicating restored coordination.
However, the left and right sides remained uncoordinated, and movement was less precise than in able-bodied individuals.
Key findings
01Stimulation significantly reduced the complexity of muscle activation, bringing it closer to that of healthy controls.
02The number of muscle synergies needed to explain movement decreased from ten to four, matching the count in healthy participants.
03Despite matching the number of synergies, the structure remained asymmetric, with left and right leg muscles activated in separate patterns unlike the coordinated bilateral pattern in controls.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study included only six participants, which limits the generalizability of the findings. Hip extensor muscles (hamstrings and gluteus maximus) were not recorded, so coordination patterns for hip extension could not be analyzed. Electromyography data could not be normalized to maximum voluntary contraction because the participants could not perform these movements, potentially affecting the comparison of signal amplitudes. The analysis relies on estimated spinal activity derived from muscle signals, not direct neural recording.
Declared interests
Funded by the MN State SCI/TBI grant from the Minnesota Office of Higher Education. No other conflicts of interest are explicitly stated in the provided text.
The easy way to misread this
Do not assume that matching the number of muscle synergies means normal movement function has been restored. The study shows that while the quantity of coordination patterns improved to match controls, the quality remained impaired, with significant asymmetry and involuntary muscle activation persisting.