A noninvasive spinal stimulation device safely improves upper-extremity function in people with a cervical spinal cord injury (SCI), results of a prospective nonsignificant risk trial suggest.
The study showed that the device (ARC-EX; ONWARD Medical) improved at least one measure of hand and arm strength and at least one measure of hand and arm function in 72% of people with chronic cervical SCI.
In addition, 90% of study participants had improvement in either strength or function in their upper extremities.
The intervention also boosted sensory scores, improved quality of life and sleep, decreased the frequency and severity of muscle spasms, and reduced pain.
“This therapy really has important implications for improving real life function and quality of life in people who have tetraplegia,” study author Edelle C. Field-Fote, PhD, Shepherd Center, Crawford Research Institute and Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, said at a press briefing.
“Simple things like using an ATM card or putting a key in a lock or unwrapping a piece of candy are things we take for granted, and even little improvements in those functions can make a really big difference to someone’s ability to be independent and to their quality of life,” Field-Fote continued.
The findings were published online on May 20 in Nature Medicine.
Every year, about 18,000 people in the US experience an SCI. Of these, about 60% have tetraplegia (also called quadriplegia), a condition that results in no or very limited hand, arm, and leg function, said Field-Fote.
The single-arm, open-label trial (Up-LIFT) enrolled 64 mostly male adults at 14 sites in the US, Canada, the UK, and the Netherlands aged 22-75 years (mean age, about 47 years). Participants had had a traumatic, nonprogressive cervical (C2-C8) SCI more than 12 months before their enrollment, but in some cases, the injury had occurred more than 30 years prior to the study.
Study participants had to have an American Spinal Injury Association Impairment Scale classification of B, C, or D, a Graded Redefined Assessment of Strength, Sensibility and Prehension (GRASSP) prehension (reaching and grasping) score ≥ 10, or a GRASSP strength score ≥ 30.
They must also have been referred by a treating physician or therapist for upper-extremity training.
Participants who had been prescribed and still required antispasticity medications had to reduce their total dose to
Intensive Rehab
Study participants underwent an intensive rehabilitation program over 2 months, then continued that rehab program, with the addition of stimulation during each rehab session, for 2 more months. Participants completed a minimum of 12 and maximum of 20 in-clinic rehabilitation sessions per month.
This trial design enabled participants to serve as their own controls, which the authors said is the most appropriate method to control for the large variation in impairment among participants, potential for responsiveness, and optimal stimulation dose.
The stimulation device includes two surface electrodes placed above and below the injury (generally one vertebral segment rostral and one vertebral segment caudal). Two large return electrodes are positioned over the iliac crests or clavicles.
The device delivers a “very high frequency waveform” — 10 kilohertz (kHz), or 10,000 times per second — which is oscillated during each stimulus pulse, lead study author Chet Moritz, PhD, professor of electrical and computer engineering and rehabilitation medicine at the University of Washington, Seattle, said during the briefing.
“We believe this effectively numbs or anesthetizes the skin under the electrodes,” which “allows access to sensory nerves that enervate the spinal cord that can lead to enhanced function and enhanced neuro recovery and plasticity,” Moritz said.
There was some expected recovery of function during the rehabilitation-alone period, but most of those improvements plateaued during the 2 months of rehab, Moritz added.
The primary effectiveness endpoint tested the hypothesis that more than 50% of participants would experience significant improvements in both strength and function from the end of the rehabilitation-alone period to the end of the stimulation period.
Participants were considered responders if they met the minimally important difference (MID), calculated as the change in score between the beginning and the end of the stimulation period, for at least one of the strength measures — International Standards for Neurological Classification of Spinal Cord Injury–Upper Extremity Measurement Scale (ISNCSCI-UEMS) score (MID=2-point improvement), GRASSP strength score (MID=4-point improvement), or grasp force or pinch force (MID=≥ 6-N improvement) — and at least one of the functional measures, consisting of Capabilities of the Upper Extremity Test (CUE-T) score (MID=4-point improvement) and GRASSP prehension performance score (MID=2-point improvement).
Of the 60 participants completing the study, 43 (71.7%) met or exceeded the MID criteria for at least one outcome of the strength domains and at least one outcome of the functional performance domains.
Compared with rehab alone, there were significant improvements with stimulation in terms of pinch force (mean difference, 4.8; P=.002), GRASSP prehension score (mean difference, 1.6; P <.001 grassp strength score difference p and isncsci-uems>
About 90% of participants met the MID criteria for at least one strength or functional outcome.
Increased Sensation
In addition to improved strength and function, there was a significant increase in ISNCSCI total sensory score (mean difference, 9.6; P <.001 in response to the stimulation therapy compared with rehabilitation alone.>
Participants with some movement in their hands “pretty much without exception made improvements in their strength, their function, and their sensation,” Field-Fote said. “For individuals who really didn’t have movement, about half of them also had improvement in the measures we captured.”
Field-Fote added that she is keen to explore indicators for which patients are likely to be responders. “That can help us identify what needs to be changed to help people who didn’t meet the responder category to get them to become responders.”
The study also indicated improved quality of life, as measured by self-reported EuroQol five-dimensional five-level scores (mean difference, 1.7; P <.028 in response to stimulation compared with rehabilitation alone.>
In addition, there was a significant decrease in the frequency of muscle spasms following stimulation (P=.009), improvements in sleep quality (P=.025), and reduced pain (P=.04).
A total of 238 adverse events occurred throughout the study, which included constipation and urinary tract infections. Forty-four adverse events were related to the device, but none were serious. The incidence and nature of the adverse events were consistent with published reports of people living with chronic cervical SCI, said the authors.
Researchers decided against performing a standard randomized controlled trial of the device in part because they felt that subjecting people with tetraplegia, for which there are no available treatments, to the potential risks and discomfort of a sham stimulation without any expected benefit was inappropriate, investigators said.
The team saw changes in physiology in a preliminary study “that can in no way be attributed to a placebo effect,” Moritz said. These included sweating and low heart rates and blood pressures that returned to normal several days into the stimulation.
Working Hands
The press briefing featured two study participants who elaborated on how the intervention changed their lives. One participant — a woman who experienced an SCI 14 years ago when she fell off a horse — said she experienced “very positive results” from the intervention, including a “much stronger left hand with improved grip” that she can now use to release a seat belt or put her hair in a ponytail.
“Everyone thinks with spinal cord injury all you want to do is be able to walk again, but if you’re a tetraplegic or quadriplegic, what matters most is working hands,” she said.
Another participants whose injury occurred in a 2014 wrestling accident said the stimulation improved his typing speed by about 30%, and he can now help in the kitchen and tie balloons for his kids’ birthday parties.
Moritz said the stimulation amplitude can be individualized for such people and adjusted for different exercises. The device “integrates really seamlessly with physical therapy and occupational therapy that’s already offered in the clinic, but yet gives people much more strength and much more function,” he added.
The device may be used to recover other neurologic functions — for example, after a stroke — another study author, Grégoire Courtine, PhD, NeuroX Institute and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Geneva, and ONWARD Medical co-founder, told the briefing.
On its website, the company said it has received Breakthrough Device Designation status from the US Food and Drug Administration (FDA) for the use of its ARC-EX platform for bladder control, alleviation of spasticity, and blood pressure regulation in people with SCI.
Courtine said the company has submitted a De Novo application to the FDA for regulatory clearance of the device and plans to follow this with an application for regulatory approval in Europe.
The company is also investigating an implanted neurostimulator, which involves implanting a pulse generator and lead placed near the spinal cord, with the system potentially activating nerves more directly than the external device. Courtine said the company expects to start a pivotal trial with its implantable platform in the US at the beginning of next year.
The trial was sponsored by ONWARD Medical, which provided the devices and field support for study investigators. Study investigators hold various patents in relation with the present work, act as consultants to ONWARD Medical and may be minority shareholders of ONWARD Medical.
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