WASHINGTON – In a groundbreaking development, three individuals grappling with spinal muscular atrophy (SMA), a debilitating disease that progressively hampers muscle function, experienced an improvement in their mobility through the use of an implanted spinal cord stimulator. This device, which previously was under investigation for its effectiveness in aiding individuals suffering from paralysis, has shown promising preliminary results in enhancing muscle function temporarily in those with neurodegenerative conditions.
Researchers revealed these findings on Wednesday, highlighting what they regard as the initial evidence that the spinal-stimulating implant may offer relief not only for paralysis but also for diseases like SMA. Marco Capogrosso, an assistant professor affiliated with the University of Pittsburgh and principal investigator of the study, noted that participants did not anticipate any positive change. However, throughout the month-long pilot trial, gradual enhancements in their physical capabilities were observed.
SMA is characterized by a genetic defect that leads to the degeneration of motor neurons—nerve cells within the spinal cord responsible for muscle control. The condition causes muscles, particularly in the legs, hips, shoulders, and even those related to respiratory and swallowing functions, to atrophy gradually. Currently, there is no definitive cure for SMA; however, gene therapies exist that can save the lives of infants suffering from the severe forms of the disease, and certain medications can help slow disease progression in older patients.
The application of low-level electrical stimulation to the spinal cord has been a mainstream practice for chronic pain management for years. Capogrosso and his team tested this stimulation technique for those paralyzed due to strokes or spinal injuries, intending to activate dormant nerve circuits below the site of injury to promote movement. This led Capogrosso to hypothesize that the same approach could potentially revitalize the sensory nerves linked to SMA, thereby enabling impaired muscle cells to engage and move to prevent further wasting.
In the study, electrodes were implanted in the lower spinal cord of three adults diagnosed with SMA. Researchers monitored their muscle strength, fatigue levels, mobility range, and walking patterns during periods when the device was active versus deactivated. Although normal movement was not reinstated, significant enhancements were reported after just a few hours of stimulation weekly, as documented in the journal Nature Medicine.
Doug McCullough, a 57-year-old participant from Franklin Park, New Jersey, expressed that within a progressive disorder, improvement is often unheard of. He stated, “You’re either stable or deteriorating, so any enhancement is both surreal and incredibly thrilling.” By the conclusion of the study, all three subjects were able to walk farther in six minutes compared to before, with one participant who had previously been unable to rise from a kneeling position achieving that feat by the study’s end. McCullough’s gait also improved dramatically, increasing the length of each step significantly.
Capogrosso remarked on the findings, noting that participants demonstrated reduced fatigue, enabling them to maintain their ability to walk for extended durations, which is notable even for those who have lived with the disease for many years. Intriguingly, the benefits observed did not vanish immediately upon deactivation of the stimulator; some positive effects lingered during follow-up assessments despite a gradual decline over time. McCullough revealed that even in the absence of stimulation, he sometimes felt as if his legs were energized.
While he recognized the necessity of removing the device at the conclusion of the research, McCullough expressed a sense of disappointment. At his six-week follow-up, he reported some residual benefits, yet these had diminished by the six-month mark.
Susan Harkema, a neuroscientist known for her pioneering research in spinal cord stimulation in the context of spinal injuries, urged caution about interpreting the findings since the study’s scale and duration are limited. Nevertheless, she affirmed its value as a significant proof of concept, advocating for further investigations into this approach for various muscle-degenerating conditions. Harkema, now associated with the Kessler Foundation, remarked on the complexity of human spinal circuits, emphasizing its sophisticated nature beyond mere reflex actions governed by the brain.
Capogrosso indicated that additional, longer-duration studies are forthcoming at the University of Pittsburgh, potentially paving the way for broader applications of this innovative technique.
