For decades, paralysis after spinal cord injury was largely treated as permanent.
Patients might regain limited function through rehabilitation, adaptive devices or physical therapy, but once movement was lost, surgeons had few options to restore it.
Justin Brown, MD, believes that assumption is beginning to change.
“We can redistribute function,” he said.
Dr. Brown, a neurosurgeon at Boston-based Massachusetts General Hospital and director of the hospital’s Paralysis Center, has spent much of his career focused on restoring movement after spinal cord, brain and peripheral nerve injuries. Through emerging nerve transfer procedures, electrical stimulation strategies and regenerative therapies, he and other researchers are challenging long-standing beliefs about what recovery after paralysis can look like.
For some patients, that includes the possibility of restoring arm and hand movement years after injury.
Rethinking paralysis
Dr. Brown’s path into spinal cord injury reconstruction began in peripheral nerve surgery, where surgeons learned that directly repairing damaged nerves was not always the best option. Instead, surgeons increasingly began rerouting healthy nerves with redundant functions to reanimate more critical muscles.
The brain, he said, can adapt remarkably well to new movement patterns.
“Even though the brain has to learn a different way of activating the muscle, you can get just as good a result,” he said.
In many cases, patients gradually relearn how to associate an existing movement with an entirely new function after the nerve is rerouted.
That realization raised a larger question: Could the same principles be applied to paralysis caused by spinal cord injury?
For many cervical spinal cord injury patients, the answer appears to be yes.
Patients with injuries around the C5 level often retain shoulder and elbow movement while losing hand function. Because several upper-extremity movements rely on overlapping muscle groups, surgeons can sometimes redirect functioning nerves toward more valuable targets.
“There’s a nerve in there that we can steal, and they probably wouldn’t miss it,” Dr. Brown said.
One commonly used example involves rerouting a nerve responsible for forearm rotation to the nerve controlling finger extension, allowing patients to potentially regain hand-opening function.
The process is painstakingly slow. After nerves are surgically connected, microscopic fibers regenerate roughly 1 millimeter per day as they grow toward their new muscle targets.
“But the brain figures that out,” he said.
Why timing matters
Not every spinal cord injury patient is a candidate for functional restoration surgery. According to Dr. Brown, success depends heavily on both injury level and the type of spinal cord damage present on imaging. “The more you have, the more we can do,” he said.
Patients with preserved shoulder, elbow or wrist function provide surgeons with more nerves that can potentially be reassigned to restore other movement. The timing of surgery also varies depending on the nature of the spinal cord injury itself.
Some patients sustain relatively focal injuries, where a small but critical area of the cord is damaged while surrounding pathways remain intact. In those cases, Dr. Brown said nerve transfer procedures may still be successful even years later.
More extensive injuries are different. When long segments of the spinal cord are stretched, hemorrhaged or severely damaged, the muscles connected to those nerves begin to deteriorate over time.
“If you wait beyond two years, I cannot recover the muscles,” he said. “It would be really aggressive.”
For those patients, surgeons often aim to intervene within six to 12 months before irreversible muscle loss occurs.
The growing role of electrical stimulation
To expand those treatment windows, Dr. Brown and other researchers are increasingly combining surgery with electrical stimulation therapies.
One approach involves stimulating denervated muscles directly to keep them alive longer after injury.
“If you provide enough energy, you can maintain the muscle itself,” he said.
Current FDA-approved stimulators in the U.S., he noted, often do not deliver sufficient energy for that purpose, forcing some research groups to develop custom devices or use systems from overseas.
Another strategy focuses on stimulating donor nerves before surgery to accelerate nerve regeneration after transfer procedures.
“If you apply a current to that nerve ideally a week before the operation, it will grow faster,” Dr. Brown said. Researchers are also exploring whether electrical stimulation of the spinal cord itself can help patients recover partial walking ability or improve muscle tone and spasticity.
Recent studies from institutions, including the University of Louisville and University of California Los Angeles have suggested that some patients with incomplete spinal cord injuries may regain previously undetected voluntary movement through spinal cord stimulation.
“I think that there is promise in a subset of patients,” Dr. Brown said.
Dr. Brown also believes the future of spinal cord injury care may increasingly involve combining acute spine surgery with early restorative interventions designed to preserve vulnerable neural pathways before further degeneration occurs.
That could include more aggressive decompression strategies, interventions aimed at reducing secondary spinal cord injury from swelling or hemorrhage and earlier use of stimulation therapies to preserve residual neural function.
“I think there are a lot of low-hanging fruit in that acute intervention time,” he said.
Why stem cells remain complicated
As regenerative medicine advances, stem cell therapy has become one of the most heavily discussed, and heavily debated, areas of spinal cord injury research.
Dr. Brown believes much of the public conversation around stem cells oversimplifies what the technology can realistically accomplish.
“People have treated stem cells like they are magic pixie dust,” he said. In his view, the problem is not stem cells themselves, but the complexity of what researchers are asking them to do.
Reconstructing the spinal cord, he said, is far more complicated than many people realize.
“The spinal cord is essentially a tubular brain,” he said. Rebuilding those pathways requires recreating extraordinarily intricate neural networks capable of receiving, processing and transmitting signals across long distances.
Still, he believes stem cells may hold real promise in more targeted applications.
One strategy being studied involves injecting engineered motor neuron cells into peripheral nerves to preserve muscle viability while surgeons prepare for reconstruction procedures later.
In those situations, he said, the cells are being asked to perform a much more specific biological role, one that may prove far more achievable than rebuilding entire spinal cord pathways.
A rapidly changing field
Beyond restoring movement in completely paralyzed muscles, Dr. Brown said surgeons are also increasingly treating patients whose recovery leaves them with disabling spasticity and stiffness.
In some cases, selective nerve procedures can reduce overactive muscle tone while preserving useful movement.
The field, he said, is evolving rapidly.
“There’s lots of new interventions that we’re applying right now,” he said. For patients living with paralysis, he hopes the message is increasingly shifting away from permanence and toward possibility.
“Give them hope,” he said. “There are things that can be done to restore function.”
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