Weekend Reads | Promising New Developments in Treating Spinal Cord Injuries

by Kevin Schofield

This weekend's read is a research paper published in the journal Nature Medicine on what could end up being an enormous medical breakthrough: a therapy to improve hand and arm function in people with spinal cord injuries.

For the past few months, ONWARD Medical, a health care company that was spun out of the highly respected Swiss Federal Institute of Technology, has been talking up the results of a safety and efficacy trial it recently completed on its new treatment for some spinal cord injuries — specifically those to the cervical discs in the neck area. Cervical spinal injuries can cause permanent impairment of the arms and hands. The "holy grail" for medical researchers who work on spinal injuries has been to find a way to regrow nerves to repair or reconnect damaged ones; unlike other parts of the body, spinal nerve tissue typically doesn't regenerate to heal itself when damaged. But the folks at ONWARD Medical may have found a way to stimulate the spinal cord to grow new tissue and heal. To be clear, it's still early days: They are not claiming that they can reconnect a severed spinal cord. But they do believe that where a neck injury has damaged some spinal cord nerves, they can grow new nerve tissue to take its place and restore some feeling and function.

In the absence of any proven method to stimulate regrowth and healing, the standard therapy for spinal cord injuries has been rehabilitation through physical exercises. In most cases, rehabilitation produces some limited improvement in sensation and function over the first 1 to 2 months, but then reaches a plateau.

ONWARD Medical's new therapy, called ARC^EX, involves placing electrodes on the back of the neck above and below the damaged area and applying electrical stimulation through a series of pulses. According to its studies, the stimulation encourages the growth of new nerve tissue. It believes that, combined with ongoing rehabilitation therapy, can lead to restoring sensation and function in the arms and hands.

The researchers conducted a study with 60 patients with cervical spinal cord injuries to assess both the safety of the treatment and its effectiveness. Patients had, on average, 25 ACR^EX sessions over a two-month period while also doing rehab therapy. The new treatment was found to be safe; to the extent that there were adverse effects of the treatment, they were minor. But the amazing news is that 90% of patients saw meaningful improvement in at least one area of functional performance in their arms and hands, and 72% of them had improvement in both strength and functional performance. Moreover, the improvements didn't seem to plateau, suggesting that if the electrical stimulation treatment were applied over a longer period of time, the patients might see even more improvement. Many of the patients also experienced improved sensation, which rehab therapy alone generally doesn't lead to.

One of the advantages of this new therapy is that it's not invasive. The electrodes are applied to the skin, but nothing is injected into the body (other than the electrical pulses, which travel through the skin). That makes the therapy both safer and easier to deliver.

This is very promising, but there's a lot of work ahead for the researchers to move it forward into a mainstream therapy. They need to further explore which types of injuries it works best for, and which it doesn't work well (or at all) for. That includes understanding whether there is any hope for restoration for partially or fully severed spinal cords.

There are also many questions of timing and coordination. Earlier studies have shown that spinal nerve tissue seems to be more open to reorganizing itself to circumvent damaged tissue in the first year after an injury. Does that suggest that ARC^EX therapy should be a priority immediately after the injury, or that the longer the time period after an injury, the less effective it will be? In the researchers' initial study, the patients' average time since their injury was about six years and 72% of them saw improvement. But 60 patients in a study isn't enough to fully understand how time affects the amount of improvement seen; they will need to do a larger follow-up study to understand that. They will also need to look at variations in the electrical stimulation itself — the strength and length of the pulses, the frequency used, and how often the treatment is given — to understand whether it should be modified from patient to patient based on the type or location of their injury, the patient's age or size, and how much time has passed since the injury occurred.

Also, what is the relationship between rehab therapy and the effectiveness of the ARC^EX therapy? Does first spending a couple of months doing rehab "prime" the body to respond better to electrical stimulation, or would it be better to start the stimulation treatment right away? Similarly, how important is it to continue to do rehab therapy simultaneously with the ARC^EX therapy; does actively using the nerves push the body harder to regenerate nerve connections and help "train" the new tissue to do the right thing?

And, of course, researchers need to study how injuries to other parts of the spinal cord might respond to this kind of treatment — and how it might best be delivered. They are focused on hand and arm function, but could this work for leg and foot function as well?

The medical community will probably be a bit skeptical about this apparent breakthrough for a while. First, the researchers admit themselves that there are some reasons they couldn't conduct the study the way it would ideally be done. For instance, it wasn't a "blind" study where the patients (and the doctors) don't know whether a specific patient is getting the real treatment or a placebo, because the patients can feel the electrical stimulation. The researchers also didn't do a "control" where another set of patients received the rehab therapy but not the electrical stimulation to be able to measure how much improvement came from which. So before there is broad buy-in, this will need to be replicated several times and in different forms.

All that said, this is an incredibly exciting development. For all of recorded human history, a spinal cord injury has led to permanent loss of strength, function, and sensation, and there have been no effective treatments to help patients regain them. But now a simple, bare-bones experiment has led to meaningful results. And equally important, to hope that as this technique is better understood and fine-tuned in the months and years to come, it will give back to those who have suffered from debilitating spinal cord injuries some or all of what they have lost.

Non-invasive spinal cord electrical stimulation for arm and hand function in chronic tetraplegia: a safety and efficacy trial

Featured image via Viacheslav Nikolaenko/Shutterstock.com.