Paralyzed patients regain some feeling and movement using brain-machine rehabilitation

Investigators reported that patients with severe paralysis regained partial sensation and motor control in their legs after a year of gait neurorehabilitation. In this first-of-its-kind study, patients used brain-responsive robotics—termed brain-machine interfaces—that helped stimulate neurological recovery during training.

“As far as we can tell, this is the first clinical study to report the occurrence of consistent, reproducible, and significant partial neurological recovery in multiple chronic spinal cord injury (SCI) patients,” the authors wrote in an article published online August 11, 2016 in Scientific Reports.

The brain-machine interface used in this study consisted of a cap embedded with multiple EEG recording electrodes situated over the areas of the brain that control movement. Patients wore the EEG cap to interface with several components of rehabilitation, such as immersive virtual reality training, enriched visual-tactile feedback, and walking with two EEG-controlled robotic actuators (including a custom-designed lower limb exoskeleton also capable of delivering tactile feedback to patients).

“Originally, our central goal was to explore how much such a long-term BMI-based protocol could help SCI patients regain their ability to walk autonomously using our brain-controlled exoskeleton,” the authors explained.

Unexpectedly, after 12 months of training, all 8 patients in the study showed neurological improvements in somatic sensation—pain localization, fine/crude touch, and proprioceptive sensing—in multiple dermatomes. Patients also regained voluntary motor control in muscles below their level of SCI, which resulted in pronounced improvements in walking.

“Our hypothesis is that this training triggered a combination of cortical and spinal plasticity because of the combined use of the brain-machine interface with virtual reality, physical leg movement, and tactile feedback,” said lead author and neuroscientist Miguel Nicolelis, MD, PhD, Co-Director of the Duke University Center for Neuroengineering, in Durham, NC.

“When the patients are moving their legs and walking upright again, they are exciting the proprioceptors in their muscles, tendons, and joints. And those proprioceptors are sending signals back to the spinal cord,” added Dr. Nicolelis, who is principal investigator of the Walk Again Project, a consortium of more than 100 scientists from 25 countries. It was they who launched this neurorehabilitation study, based in São Paulo, Brazil.

“One previous study has shown that a large percentage of patients who are diagnosed as having complete paraplegia may still have some spinal nerves left intact,” Dr. Nicolelis explained. “These nerves may go quiet for many years because there is no signal from the cortex to the muscles. Over time, training with the brain-machine interface could have rekindled these nerves. It may be a small number of fibers that remain, but this may be enough to convey signals from the motor cortical area of the brain to the spinal cord.”

In the current study, all 8 patients showed the beginnings of sensory and motor recovery after 7 months of training. Most patients also saw improvements in their bladder control and bowel function. After a year, four patients’ sensation and muscle control changed significantly enough that doctors upgraded their diagnoses from complete paralysis to partial paralysis.

One participant—a 32-year-old woman who had been paralyzed for 13 years at the time of the trial—showed the most impressive improvements. At the start of training, she was unable to stand using braces; but over the course of the study, she was able to walk using a walker, braces and the help of a therapist. By 13 months, she was able to move her legs voluntarily while her body weight was supported in a harness.

Now, after more than two years of training, nearly all of the patients in the study are continuing with rehabilitation, Dr. Nicolelis said. He and his fellow investigators plan to publish additional data on the patients’ continued progress. They also intend to begin a new trial with patients who suffered more recent spinal cord injuries to see whether earlier treatment can lead to faster or better results.