Research efforts are focusing on a novel, pharma-free strategies to deal with SCI-related neuropathic pain.
Proprioception allows us to map, in 3D and real time, the location, movements, and actions of various parts of our bodies.
Body awareness is your ability to innately sense where your extremities are—even when you can’t see them, and even when they’re in motion. Central to body awareness is proprioception. This feedback loop in our central nervous system allows us to map, in 3D and real time, the location, movements, and actions of various parts of our bodies. The most obvious example of proprioception is being able to touch your nose with your finger while your eyes are closed. SCI often leads to loss of proprioception and, as a result, body awareness, in our paralyzed extremities.
And this loss of awareness seems to be linked to neuropathic pain, says Dr. Ann Van de Winckel, a Belgian physical therapist and assistant professor in the Department of Rehabilitation Medicine at the University of Minnesota.
Loss of proprioception seems to be linked to neuropathic pain
She explains that, after SCI, some parts of the body, such as the pelvis, buttock, thighs, legs, and feet, gradually become unrepresented in the body map. “But those parts of the body,” says Van de Winckel, “are still receiving inputs from the environment—contact sensation, pressure, and weight—because they’re in contact with the wheelchair or bed. This causes a conflict between the sensory messages that are being sent from the lower parts of the body and the brain, which can’t interpret this information correctly because those parts of the body are not represented anymore in the body map. This conflict gives rise to neuropathic pain.”
The harder the brain tries to locate or make sense of the signals, the worse it becomes. “So it’s like a radio channel that isn’t working properly—a lot of noise comes through, with only a little bit of music. So the brain cranks up the volume to listen better, and that is the neuropathic pain. Another way of explaining what probably happens is that when the brain cannot identify the information—because it is different from the normal sensation it is expecting to receive—then it labels it as pain.”
Restoring the brains ability to proprioceive paralyzed limbs with cognitive multisensory rehabilitation (CMR)
So what would happen if you could somehow restore the ability of the brain to proprioceive paralyzed limbs? Would this somehow turn the neuropathic pain amplification down? Van de Winckel believes this is the case, and is in the process of testing her hypothesis.
For many years, she studied the potential of a treatment called cognitive multisensory rehabilitation (CMR), in people who had experienced a stroke, as a means of improving movement and sensation. Her research demonstrates that a CMR regimen improved proprioception and allowed people to “remap” their sense of body awareness, which led to significant improvements.
Using MRI scans, Van de Winckel determined that CMR treatment in these stroke patients resulted in partial restoration of two parts of the brain that are vital to body awareness—the parietal operculum and the insula. “The brain is plastic,” she explains. “The changes seen in the brain occurred alongside sensorimotor improvement in all participants, and alongside pain reduction—we had one person who had a 10 out of 10 intensity level of pain at the beginning of the study; this went down to three out of 10 after three sessions, and remained this low with only peaks to a maximum of five out of 10 for up to one year after the intervention stopped.”
Designing a study
She knew that these parts of the brain are also vital to both body awareness and pain perception, and it occurred to her that using CMR to improve body awareness might lead to restoration of the pain processing network and reduce neuropathic pain brought by SCI. So she collaborated with Dr. Leslie Morse, professor and head of the University of Minnesota’s Department of Rehabilitation Medicine, to design a study to test her hypothesis.
The project, which got underway earlier this year, is seeking to evaluate approximately 26 adults with paraplegia and SCI neuropathic pain.
They are being randomized into two groups: one receives six weeks of CMR followed by six weeks of observation; the order is reversed for the second group. In addition to measuring changes in their pain levels, all participants will undergo three brain MRIs to see if and how the function of their brains changes. Additionally, their brain function will be measured against a similar-size cohort of able-bodied recruits.
How does Cognitive Multisensory Rehabilitation CMR work?
At this point, you’re probably wondering what CMR involves. It can be described as “thinking” rehabilitation—in other words, it’s exercises for your brain, rather than physical exercise. The purpose is to help people with SCI recreate their 3D map of their lower body, despite a lack of sensation and movement.
A session typically begins with participants sitting with their lower body concealed from their vision with a barrier. They can only see their upper thighs, the barrier, and a CMR-trained therapist kneeling in front of them. The therapist then asks them a variety of questions. For example, the therapist might ask, “If I reach out with my hand, do you think I can touch your leg, and, if so, where on your leg?” “To answer the question, participants have to reconstruct an image based on what they see of the upper part of their legs,” explains Van de Winckel.
“They must envision and understand the relationship between the arm of the therapist and their own leg. They must also understand how much space their legs occupy. When this awareness is restored, the therapist will also use exercises to increase sensation and even, in some situations, help the participant regain some movement.”
When repeated over time, the exercises improve the participant’s ability to proprioceive their legs, stimulating the brain to rewire itself in the process so that benefits are lasting, if not permanent. “Restoring the awareness of the body and thus the body map through CMR actually helps the brain interpret those sensations correctly,” says Van de Winckel. “Instead of labelling the sensation as ‘pain’ the brain will now correctly identify the sensation as pressure, texture, etcetera, in the correct body part.”
Initial observations encouraging
So far, eight people with SCI have already completed the research project. The data gathered from their experiences cannot be published until the entire study is finished, but Van de Winckel offers some cautious observations to date. “Even though we have only collected preliminary data, and data collection is ongoing, we have consistently seen in all participants so far during the CMR intervention that, when they start to regain awareness of their body and use the sensory experiences to create a correct body map, the pain goes down,” she says, adding that some have also reported some degree of recovery of sensory and motor function. For fulsome results and conclusions, we will have to wait for the project’s completion until late in 2022.
This article was originally published in the Fall 2021 issue of The Spin and featured two other studies on neuropathic pain relief. Read more here:
- The Power of Illusion: Using virtual reality technology (VR) for neuropathic pain relief
- Low concentration topical capsaicin to relieve neuropathic pain: Hot sauce relief for neuropathic pain