How does epidural stimulation work?

Authors: Dominik Zbogar and Sharon Jang | Reviewer: Susan Harkema | Published: 14 February 2022 | Updated: ~

Normally, input from your senses travels in the form of electrical signals through the nerves, up the spinal cord, and reaches the brain. The brain then tells the muscles or organs what to do by sending electrical signals back down the spinal cord. After a spinal cord injury, this pathway is disrupted, preventing electrical signals from traveling below the level of injury to reach where they need to go. However, the nerves, muscles, and organs can still respond below the injury to electrical signals.

Epidural stimulation works by helping the network of nerves in the spinal cord below the injury function better and take advantage of any leftover signals from the spinal cord. To do so, the stimulation must be fine-tuned to make sure the amount of stimulation is optimal for each person and a specific function, such as moving the legs.

Recent studies of the role of epidural stimulation on standing and walking have noted unexpected beneficial changes in some participants’ bowel, bladder, sexual, and temperature regulation function. This highlights both the potential for epidural stimulation to improve quality of life in multiple ways and that much research remains to be done to understand how epidural stimulation affects the body.

There may still be spared connections in the spinal cord with a complete injury.

Being assessed with a complete injury implies that there is no spared function below the injury. However, scientists are finding that this may not be the case. Studies have found that even with a complete loss of sensory and motor function, there may be some inactive connections that are still intact across the injury site. These remaining pathways may be important for regaining movement or other functions. Another hypothesis is that epidural stimulation in combination with training may encourage stronger connections across the level of injury. Although these pathways may provide some substitution for the injured ones, they are not as effective as non-injured pathways across the injury level.