We try to give an easy not to scientific explanation of what trans spinal stimulation is about.
The basic concept behind trans spinal stimulation is retraining function below the lesion of the damaged spinal cord. That can be motory functions, sensory functions, or others like better bowel/bladder control or blood pressure management and so on.
If the Spinal cord is damaged from an accident or illness the signal flow from the brain to the peripheral nerves is limited, so there are less connections as well as less signal strength coming through.
To move an arm, a leg - the muscle needs a certain amount of signal strength through the neuromuscular pathway of the required muscle. In other words if the signal strength is too low, the body can not fulfill his task to do the movement as our brain (we) wants to. The necessary signal strength can also be called the necessary threshold.
The stimulation of the Spinal cord with a trans spinal stimulation device basically increases the signal strength and therefore helps the body to learn the intended movement/function again. It works like an amplifier which highers the signal strength and puts it over the necessary threshold again so the brain/body can build new connections more easily.
So now we know a bit better how trans spinal stimulation basically works but just to put the electrodes on the spine and turn the unit on is not enough to retrain the body any functionality - as the word retraining says there is training necessary. The stimulation just helps the body to learn faster.
When we do an exercise with the help of a therapist, say "Sit to Stand", while the stimulation is on, the signals are sent from the muscles needed, quads, glutes etc., via the neuromuscular pathways of the muscle (periphery) to the CNS = Central Nervous System (spine and brain), allowing the body to build new connections - the stimulation "amplifies" this signal, helping the nervous system to quickly form new and/or stronger connections in the spinal cord.
Here a bit more technical explanation:
Transcutaneous spinal stimulation (also called neurostimulation) is a non-invasive medical therapy that doctors are investigating to improve or restore motor function in patients who are experiencing limited function or paralysis due to a chronic spinal cord injury.
Neurostimulation works by modulating the spinal cord circuitries (central pattern generator, CPG). To do this, electrodes are externally placed on a patient’s back, and electrical stimulation is delivered via the electrodes by a portable pulse generator (PPG). This system is used to facilitate motor function recovery. [1]