Electrical stimulation is one of the most promising spinal cord injury treatments available.
It involves using electric currents to stimulate movement, reduce pain, or stabilize autonomic functions at and below you level of injury.
To help you understand what electrical stimulation is, this article will explore various types of electrical stimulation and weigh out their pros and cons.
How Electrical Stimulation for Spinal Cord Injury Works
The spinal cord relays messages between the brain and body.
After a spinal cord injury, messages may be unable to get past the site of injury, which can cause paralysis.
The nerves below the level of injury are not damaged. They just can’t receive messages from the brain and become inactive.
Electrical stimulation mimics brain signals to re-activate the nerves below one’s level of injury.
This can be done by stimulating: 1) the spinal cord below the injury site, or 2) the peripheral nerves that branch off the spinal cord.
Now that you understand how electrical stimulation works, let’s go over the various ways it can be applied.
5 Types of Electrical Stimulation for Spinal Cord Injury
Several treatment interventions involve electrical stimulation.
Some are more developed than others, but they all show significant potential to improve one’s quality of life after spinal cord injury.
In the following sections, we’ll go over 5 different ways spinal cord injury patients can utilize electrical stimulation.
1. Epidural Stimulation
Epidural stimulation is an invasive type of electrical stimulation that can significantly improve mobility after spinal cord injury.
By implanting a stimulator and 16-electrode array to the spinal column, electrical currents can excite motor neurons below the level of injury to promote movement.
Clincial trials have demonstrated that even individuals with complete spinal cord injuries may be able to recover over-ground walking by using a combination of epidural stimulation and intensive gait training.
Additionally, epidural stimulation can help activate spinal cord circuits that can improve bowel and bladder control and stabilize blood pressure.
2. Functional Electrical Stimulation (FES)
Functional electrical stimulation is a non-invasive treatment option. Individuals simply place the electrodes on the surface of the skin and control the electric emissions on a device.
While epidural stimulation applies electric currents directly to the spinal cord, FES applies them to the peripheral nerves that stimulate muscle contractions.
During FES, the patient must also perform a task using the stimulated muscles.
By directly activating muscle contractions, FES can help improve circulation, range of motion, and muscle strength.
3. Transcutaneous Electrical Nerve Stimulation (TENS)
Another non-invasive form of electrical stimulation for spinal cord injury patients is transcutaneous electrical nerve stimulation.
It involves placing electrodes on the skin to stimulate sensory nerves.
TENS focuses on relieving pain after spinal cord injury, not movement.
It works by blocking pain signals and stimulating the production of endorphins.
4. Intraspinal Microstimulation (ISMS)
Another electrical stimulation treatment for SCI is intraspinal microstimulation.
Intraspinal microstimulation involves implanting thin, flexible electrode wires into the lumbar region of the spinal cord. This allows for more selective muscle activation.
The hair-like wires have to be placed inside the gray matter of the spinal cord, which sends electric currents directly to the motor pools responsible for controlling movement.
Because of the increased precision in stimulating the spinal circuits, ISMS should hypothetically lead to more stable functional outcomes.
5. Brain-Computer Interface
The last treatment that uses electrical stimulation for spinal cord injury is brain-computer interface.
This process goes by many different names including brain-machine interface, brain-controlled interface, neural-control interface, and mind-machine interface; however, they all refer to the same process.
Brain-computer interface involves placing electrodes near the primary motor cortex of the brain to monitor the intent to move.
The electrodes then stimulate electrical currents to restore functional activity in paralyzed limbs.
Just by thinking about walking, people can control the electrical stimulation that enables movement of the legs.
Although the idea is still in earlier stages of research and needs further development, brain-computer interface appears to be a promising treatment for SCI patients with lower-body paralysis (paraplegia).
The video below shows a patient with paraplegia achieving over-ground walking during a non-invasive brain-controlled interface trial.
Pros and Cons of Electrical Stimulation for Spinal Cord Injury
Now that you understand what types of electrical stimulation can help promote recovery after spinal cord injury, let’s recap the risks and benefits of electrical stimulation.
Potential benefits of electrical stimulation for spinal cord injury include:
- Reduced pain (While electrical stimulation won’t get rid of the source of pain, it can change the way your brain reacts to pain.)
- Improved bowel and bladder control
- Stabilized blood pressure
- Enhanced movement patterns
- Reversibility (implants can be removed and treatment can be stopped at any time)
- Availability of non-invasive options (i.e. FES and TENS)
In contrast, some weaknesses of electrical stimulation include:
- High costs (The average cost of treatment per patient ranges from $19,246-$47,190.)
- Device complications (Lead migration and breakage appear to be the most common device-related issues.)
- Invasiveness (Patients should assume the general risks involved with any surgical procedure like infections or bleeding.)
- Discomfort (from the stimulator itself or the electric currents it emits)
- Lack of guarantees (Although promising, the mechanisms behind electrical stimulation have yet to be fully understood. Not everyone will experience the same results.)
Depending on each individual’s needs after spinal cord injury, some electrical stimulation options may be more ideal than others.
Understanding Electrical Stimulation for Spinal Cord Injury
It’s clear that electrical stimulation can play a significant role in the future of spinal cord injury recovery.
However, spinal cord injury rehabilitation requires more than electrical stimulation. The only way to relearn how to move is to physically train the body to recognize movement patterns.
The more an individual practices a movement, the better the spinal cord will get at recognizing a demand for that function.
Through the spinal cord’s ability to rewire itself (neuroplasticity), weakened functions can be strengthened and improved.
Repetition is key, but epidural stimulation can provide the extra boost necessary to jumpstart movement.
Photos from top to bottom: iStock/microgen/javi_indy/