Novel Neuromodulation Restores Movement After Paralysis

In a first-in-human case study, researchers used a double neural bypass neuroprosthesis to restore hand movement and sensation in a man with complete tetraplegia following spinal cord injury (SCI).Over 3 years, the system combined a brain-computer interface (BCI), AI, and targeted stimulation of the spinal cord and brain to enable functional improvements, including self-feeding and grasping objects.Slowly but surely, the patient, Keith Thomas, who was paralyzed in a diving accident, regained the ability to feed himself, drink from a cup, and perceive touch.The near doubling of his strength and almost 10-fold improvement in touch sensitivity years after the original injury surprised principal investigator Chad Bouton because recovery after SCI typically plateaus within the first year.The investigators also reported that the technology appears to promote neuroplasticity, with improvements that persisted even when the neural bypass was turned off.“In this study, we implanted additional chips in the sensory area of the brain and combined precision stimulation of these areas with spinal cord stimulation using a novel ‘double neural bypass’ approach,” Bouton, PhD, founder of Neuvotion and professor in the Institute of Bioelectronic Medicine at the Feinstein Institutes for Medical Research in Manhasset, New York, told Medscape Medical News.“With this approach, we could not only restore immediate tactile sensations but [also] promote lasting improvements in sensation, even when the bypass was turned off,” he added.The study was published online on July 16 in Nature Medicine.A Novel ApproachIn the US, up to 390,000 people are living with SCI. Studies have shown that those with tetraplegia rank the restoration of upper-limb function as one of their highest priorities.In 2023, the Feinstein researchers completed the world’s first double neural bypass that links implants in the brain to the spinal cord and body with the help of AI.The patient was implanted with five microelectrode arrays in the brain and 128 recording channels in the motor cortex and 96 in the sensory cortex.When the patient imagines moving his hand, AI decodes movement intentions from neural activity that triggers muscle stimulation to move the hand. The algorithms decoded these signals with up to 85% accuracy.To restore the sense of touch, sensors in a 3D-printed orthotic device measured pressure during grasping that activated stimulation in the sensory cortex.The investigators used cortical mirroring to restore tactile sensation, relying on brain signals typically activated during touch to drive stimulation of the sensory cortex along with synchronized skin and spinal cord stimulation.“This approach is a new way to treat severe paralysis — we’re not just bypassing the injury; we’re actually rewiring the nervous system. Our team of engineers, neurosurgeons, and clinical research staff accomplished something that’s never been done before,” Bouton said in a news release.‘Rewiring the Nervous System’Prior to the trial, the patient needed total assistance with activities of daily living because he could not grasp objects or feel sensation in his hands.Over 8 months, the technology produced statistically significant improvements of 86% in right arm strength and 62% in left arm strength compared with baseline. These gains lasted several months and enabled the patient to touch his face with both hands.The patient was able to pick up objects with fine motor control and grasp eggshells without damaging them in 87% of attempts. He also performed these reaching tasks while maintaining conversations, suggesting this technology places a lower cognitive burden than earlier BCI systems and has a greater potential for real-world use, the investigators noted.Tactile sensitivity in the right wrist also improved significantly during the transcutaneous spinal cord stimulation and cortical mirroring intervention.Improvements in sensation and strength were still evident more than 2 years after the intervention, the investigators reported in a recent follow-up.“Being able to feel my sister’s hand, to pet my dog and feel her fur — these experiences that the injury took away have been restored,” Thomas said in a news release. “But beyond the study sessions, I can now scratch my face, wipe my eyes independently. The technology has given me back both connection and a sense of self,” he added.A limitation of the study was that only a single task requiring a specific level of force was evaluated — grasping eggshells without breaking them.The researchers are now evaluating the technology in additional participants with SCI and exploring its potential application in other neurologic conditions, including stroke.“The FDA has approved an increase in our trial size, and we have already launched a study to test some of the underlying technologies in stroke. We are extremely excited about the expanded use and future possibilities for patients needing this technology worldwide,” Bouton told Medscape Medical News.Bouton disclosed having financial interests in Neuvotion, Inc., and Sanguistat, LLC, as well as having multiple patents in the field of neuroprosthetics and related fields. This study was funded by the New York State Department of Health Spinal Cord Injury Research Board and the Feinstein Institutes for Medical Research at Northwell Health, with additional support from Blackrock Neurotech and Good Shepherd Rehabilitation Network.