Fourteen years ago, Melanie Reid, a journalist, experienced a life-changing accident when she fell off a horse and broke her neck. This severe injury to her spinal cord resulted in tetraplegia, a condition that left her paralyzed, limiting the function of her four limbs and torso. For over a decade, Reid’s left hand was incapable of either sensation or motion. Today, however, Reid can not only move that hand but also perform tasks like putting her hair in a ponytail, thanks to a remarkable—if incomplete—recovery that required neither surgery nor medication, but rather, exercise and electricity.
The breakthrough: arcEX stimulation
Reid was one of 60 patients participating in a groundbreaking trial across three countries, involving a novel form of non-invasive spinal cord stimulation known as arcEX. This method was pioneered by Grégoire Courtine of the École Polytechnique Fédérale de Lausanne and his colleagues. Published in Nature Medicine on May 20th, the results of the trial suggest a promising future for this innovative treatment.
Understanding spinal cord function and paralysis
Muscles in the human body move when electrical signals are transmitted from the brain via the spinal cord. Reflexive movements can occur directly from the spinal cord, bypassing the brain altogether. When the nerves in the spinal cord are damaged, this electrical circuit is disrupted, leading to paralysis.
It is well established that applying electricity to the remaining nerves can enhance the signal from the brain sufficiently to cause paralyzed limbs to move. Historically, the best results were achieved through surgical implants placed directly on the spinal cord. Recent studies, however, have demonstrated that non-invasive techniques can be equally effective. By pulsing electricity through electrodes placed on the skin’s surface, some muscle function can be restored without the need for invasive procedures.
The study and its findings
Dr. Courtine’s study is the largest and most robust to date, focusing on restoring function in the muscles of the arms and hands. According to a 2004 survey of people with tetraplegia, the recovery of these muscles is most desired by patients.
Traditionally, physical rehabilitation has been the primary treatment for tetraplegia, aimed at strengthening and maintaining existing function. For those with severe impairments in handling objects and experiencing sensation, this often involves passive stretching of muscles. Those with some movement and feeling undergo targeted weight and resistance training exercises. While these exercises help patients perform basic tasks, they only marginally improve sensation and muscle control.
In Dr. Courtine’s trial, all participants first underwent two months of physical rehabilitation. This was followed by an additional two months of rehabilitation supplemented with arcEX electrical stimulation. Researchers placed two stimulating electrodes on the back of the patient’s neck—above and below the injury site—and two electrodes by the collarbone or hipbone to close the circuit. A current was applied at a frequency of 30Hz, perceived by patients as an internal buzzing noise. Patients continued their existing exercise regimen, completing tasks to improve movement and grip strength.
Results showed that during the initial two months of rehabilitation alone, functional abilities increased but then plateaued. With electrical stimulation, 72% of participants significantly improved their performance on neurological assessments measuring strength and function. Ninety per cent of participants experienced improvements in at least one area, even after the stimulation was turned off. Importantly, no serious adverse effects were reported.
Additional benefits and mechanisms
Beyond improved muscle function, other physiological benefits were recorded. Some participants experienced heart rate and blood pressure improvements to near-normal levels, while others had fewer muscle spasms, leading to better sleep. According to Damiano Barone at the University of Cambridge, this study suggests that electrical stimulation may play a positive role in rehabilitating incomplete spinal cord injuries.
The reasons behind the long-lasting effects of electrical stimulation are not entirely clear. Previous research indicates that such stimulation can strengthen existing connections between nerve cells that link the brain to the muscles and encourage the growth of new connections. This might explain why the effects of stimulation persist even after the treatment stops.
Prospects and considerations
While the stimulation shows promise, it cannot achieve results alone. The degree of recovery depends significantly on the intensity of the patient’s exercises and the extent to which they use their limbs. The severity of the initial injury also plays a crucial role in recovery outcomes.
Successful studies like Dr. Courtine’s increase the likelihood of these devices being approved for clinical use. Dr Courtine is currently in discussion with America’s Food and Drug Administration for the approval of arcEX and hopes to commercialize it by the end of the year. While it remains uncertain whether patients with the most severe spinal cord injuries will benefit, any advancement is positive news for patients. “There are no miracles” in recovery from spinal cord injury, says Melanie Reid, “But tiny gains can be life-changing.”
The arcEX system represents a significant step forward in the treatment of spinal cord injuries. By combining non-invasive electrical stimulation with traditional rehabilitation exercises, many patients with tetraplegia can achieve improved muscle function and sensation. As research continues and technology advances, there is hope for even greater recovery possibilities in the future.
