Neurophysiology of epidurally evoked spinal cord reflexes in clinically motor‑complete posttraumatic spinal cord injury

This study investigates how the spinal cord responds to repetitive electrical stimulation in patients with spinal cord injury (SCI). The researchers looked at short- and long-latency EMG responses in lower limb muscles. The study found that single stimuli could evoke both short-latency (likely monosynaptic) and long-latency (likely polysynaptic) responses. The short-latency responses were enhanced at low frequencies but declined at higher rates. The effects of eSCS were more complex when polysynaptic activity was elicited, leading to suppression, tonic, or rhythmical activity. The presence of polysynaptic activity could be a potential predictor for appropriate stimulation conditions.

• 1
  Short-latency responses were enhanced at low frequencies but declined at higher stimulation rates.
• 2
  Polysynaptic activity threshold varies with different stimulation frequencies, indicating temporal dependency.
• 3
  Polysynaptic components can manifest as direct responses, neuromodulation of monosynaptic responses, or independent drivers of muscle activity, contingent on the frequency level.