How are epidural stimulation electrodes implanted?

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

When it is decided that an individual will receive epidural stimulation, a health professional, such as a neurosurgeon, will perform an assessment of the spinal cord using magnetic resonance imaging (MRI) to determine the best place to implant the electrodes.

In most of the studies mentioned in this article, the electrodes were placed between the T9-L1 levels, though researchers are investigating the impact of epidural stimulation on hand function.

Xray image of wires connecting power and signal to electrodes (red circle) placed on a spinal cord.

There are two possible procedures. One approach is to have two surgeries. During the initial surgery, a hollow needle is inserted through the skin into the epidural space, guided using fluoroscopy, a type of X-ray that allows the surgeon to see where the needle is in real time. Potential spots on the spinal cord are tested using a stimulator. A clinician will look to see if stimulation over those areas of the spinal cord leads to a desired response. Once found, the electrode array is properly positioned over the dura and the surgery is completed. This begins a trial period where the response to epidural stimulation is monitored. During this time the electrode array is attached to an electrical generator and power supply, which is worn on a belt outside of the body. When it is shown that things are working as desired, the generator is implanted underneath the skin in the abdomen or buttocks. The generator can be rechargeable or non-rechargeable. A remote control allows one to turn the generator on or off and control the frequency and intensity of stimulation.

The second method is to only have one surgery and no trial period. This is possible due to increased knowledge in how to stimulate the spinal cord. Soon after surgery, the individual will be taught how and when to use the epidural stimulation system at home. If needed, the frequency (how often) and intensity (how strong) of the stimulation will be adjusted at follow-up appointments with the physician. In other cases, many practice sessions of learning the right way to stimulate may be needed before a person can stimulate at home.

If the epidural stimulation is used for leg control, movement training, standing, and stepping will be required to learn how to coordinate and control movement during stimulation. This is required for the recovery of voluntary movements, standing and/or walking.