TMS to Play a Key Role in the Future of Spinal Cord Injury Recovery
November 6, 2020
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Medical experts are exploring many different applications for Transcranial Magnetic Stimulation (TMS), the latest of which is treating partial paralysis after a spinal cord injury. Researchers at Helsinki University have had some majorly promising results with a particular patient regaining the ability to walk after TMS was paired with electronic limb stimulation.
Common types of spinal cord injuries
The most basic way to think about spinal cord injuries is to divide them into “complete” and “incomplete.” Complete spinal cord injuries generally mean that sensation and movement are gone from the area of the body below the injury. Incomplete means that some or even most sensory and/or movement is retained below the injury. Doctors use methods such as CT scans, X-Rays, and MRIs to determine the severity and extent of the injury.
The American Spinal Injury Association (ASIA) has a grading system to rank the severity of the injury, much like your schoolwork was back in the day. It ranges from A-- the most complete and severe-- to E-- normal. In both complete and incomplete spinal cord injuries, the spinal cord itself may or may not be totally severed.
Generally speaking, incomplete spinal cord injuries stand a better chance of recovery than complete injuries.
Current treatments for both include occupational and physical therapies, counseling, and psychotherapy. There may or may not be pain medication involved, as some spinal cord injury patients experience pain after the trauma.
Spinal cord injury patients suffer from a multitude of issues related to their physical trauma, including uncontrollable muscle contractions (spasticity), high blood pressure (even if none existed prior to the trauma), and neurogenic pain. Spinal cord injury patients also tend to become depressed and anxious, partially due to the injury and partially due to their new limited capacity for movement and independence.
Current areas of research into healing spinal cord injuries include: neuroprotection, regeneration, cell replacement, and retraining the body’s and brain’s circuitry and plasticity.
Neuroprotection is aimed at saving any surviving nerve cells from the trauma area and preventing any further damage to them. It involves ways to reduce or prevent inflammation, cell death, and preventing other cells from becoming overactive. Steroids and antibiotics have shown promise, as has lowering body temperature (interestingly termed “therapeutic hypothermia”) and certain types of hormone therapy.
Nerve cells die if they don’t when they don’t make enough synapses (chemical interactions with adjacent cells), so when a physical trauma kills off a whole bunch of them suddenly, others die as a consequence. It’s a domino effect that regeneration aims to stop. Antibodies, anti-inflammatory drugs, and certain proteins are currently being investigated as regenerative therapies.
Cell replacement therapy is rife with debate and controversy. Stem cells are the most familiar to the everyday person, but several other kinds of cells are being examined. The key is to look for effectiveness and safety when restoring the connectivity and function following such a physically traumatic event as a spinal cord injury.
The last area of experimentation is retraining the mind’s and body’s circuitry to restore connectivity between cells and function to the limbs. It essentially involves stimulating the paralyzed areas of the body with electricity, sometimes with the help of a robot or exercise therapy. There are some cases of patients regaining the ability to walk with or without assistance after electrodes were applied to specific areas of trauma, and combined with physical therapy.
Here is where Transcranial Magnetic Stimulation (TMS) may play a key role in spinal cord injury treatments, which is explained in the next section.
TMS and Paired Associative Stimulation
TMS has major potential for restoring connectivity in the body’s circuitry, because it helps the brain rewire itself when certain areas are targeted. Since spinal cord injuries disrupt the relationship between the brain and the body, TMS may help the brain rewire itself to help restore functionality to limbs damaged by incomplete spinal cord injuries.
But it can’t do it alone. TMS rewires the brain, not the whole body. To rewire the body, electricity must stimulate the nerve endings in the limbs. Combining the two is called Paired Associative Stimulation, and it has helped at least one incomplete spinal injury patient regain the ability to walk.
The University of Helsinki partnered with the Helsinki University Hospital and Aalto University at the BioMag Laboratory and had already proven that synchronized brain and body stimulation could potentially restore mobility to a patient. What made the difference, though, in this particular case was the incomplete paraplegia and the use of Paired Associative Stimulation combined with walking therapy.
Incomplete paraplegia is a type of incomplete spinal cord injury where the spinal cord is not completely severed, so some neural circuitry exists. This is what allows the Paired Associative Stimulation to work.
The remaining mind-body connection is strengthened by TMS, which helps the brain rewire how to use that surviving connection. When the limbs’ nerve endings are stimulated at the same time with electricity, it fires up that connection even more. Thus, the brain and body are able to retrain their circuitry.
When combined with walking therapy, the brain and body relearn how to walk. We already know that repetition is a great way to learn, especially concerning the concept of muscle memory. Putting all three therapies together was ingenious, and has massive potential to explore.
In the case of the patient mentioned above, he was 47 years old and could not bear his own weight, so originally, walking therapy was not introduced. He received Paired Associative Stimulation for two years after the trauma, with walking therapy introduced after three months when he began to be able to support his own weight for very short periods of time.
As time went on, he was able to bear more of his weight for longer periods of time. This is particularly remarkable when you consider that under normal circumstances, recovery begins to slow down after two year from the trauma. It’s now two years out, and he’s still improving!
What else could TMS do in the future?
This is why TMS is so important to the future of spinal cord injury treatments. When combined with other therapies, it extends recovery time and improves the overall results of the recovery. Further research is needed to see if it could potentially shorten recovery time.
There is a great variety in the severity and type of incomplete spinal cord injuries, but TMS is able to be finely tuned to the needs of the patient. Therefore the number of patients for whom this could be life-changing increases, because TMS is both universal and able to be tailored at the same time.
Consider also that TMS is already approved to treat depression, which we’ve previously mentioned is widespread in patients who suffer from any type of spinal cord injury. Plus, it has little to no known side effects (with exceptions to folks with bipolar disorder or seizures).
As of right now, current spinal cord injury treatments are limited and not as effective as doctors would like them to be. We need new methods, preferably less invasive than surgery, considering the trauma the body has already undergone and is still attempting to repair.
Pair Associative Stimulation isn’t just applicable to the lower limbs. Patients who have lost all, most or part of their upper limb mobility can also be treated with this method, with great outcomes.
It is important to note that at this time, it is not an appropriate method to treat complete spinal cord injuries. This makes unfortunate sense, because in this type of injury, the spinal cord has been completely severed. There is no longer a mind-body link with which to work. Perhaps if a way to re-establish the link-- or to re-attach the spinal cord-- were to be found, Paired Associative Stimulation might be effective. Unfortunately, that is currently not the case.
That does not mean to say that TMS couldn’t be used by itself to treat any depression or anxiety-- or perhaps phantom nerve pain-- that result from the paralysis and injury of a complete spinal cord injury.
Current treatments for patients who have completely severed their spinal cords include immobilization and surgery, in order to prevent further injury and damage from bone fragments, spasms, or movement.
Complications from spinal cord injuries and the full to partial paralysis that can result from them include bowel and bladder issues, skin ulcers, blood clots, respiratory infections, muscle contractions and deconditioning, and kidney issues. These are also because of the lack of movement, which heavily affects the circulatory system.
Imagine all of the good better treatments could do!
It appears that TMS has a bright future ahead of it, and perhaps patients who suffer from incomplete spinal cord injuries might have some hope because of it. More research is currently being conducted, and more data is being gathered. The results are mixed at this point, because the application of this technology in this manner is so new. However, we see reason for hope.
And hope is worth everything.