Implanted neuroprosthesis doubles walking speed in 64-year-old stroke patient

A stroke patient with limited mobility more than doubled his walking speed, and nearly quadrupled his walking distance, after surgical implantation of a neuroprosthesis that electrically stimulates coordinated muscle movement, according to a report published May 31, 2016 in the American Journal of Physical Medicine & Rehabilitation.

The 64-year-old patient has a left hemiparesis as a result of a hemorrhagic stroke suffered 21 months prior. His gait was impaired due to decreased strength, limited independent joint movement, and moderate hypertonia. But with the neuroprosthesis and electrical stimulation, along with gait training, the patient not only increased his walking speed and distance, but developed more symmetrical and dynamic gait.

“Neuroprosthetic improvements suggest that daily use of an implanted system could have significant clinical relevance to a portion of the stroke population,” according to the authors of the study, which was led by Nathaniel S. Makowski, PhD, Research Scientist at the Louis Stokes Cleveland Veterans Affairs Medical Center, in Cleveland, OH.

Other investigations using surface stimulation and percutaneous electrodes have demonstrated improved movement in patients. But this is the first report of the benefits of a fully implanted 8-channel pulse generator for hip, knee, and ankle control to assist walking after stroke, the researchers noted.

In this single-patient pilot study, surgeons implanted the system’s electrodes into 8 muscles of the hip, knee and ankle while the patient was under general anesthesia. Six weeks after surgery, the researchers began testing the system. During the patient’s gait training sessions, the researchers established and modified the stimulation pattern for normal muscle activity.

The patient’s maximum walking distance at the start of gait training was only 76 meters. After training but without stimulation, he could walk about 300 meters (in 16 minutes). With electrical stimulation, his maximum walking distance increased to more than 1,400 meters (in 41 minutes).

“Thus his walking distances increased by 370% with stimulation while walking nearly twice as fast,” the authors wrote.

The patient didn’t use stimulation when walking outside of the gait lab, but his walking ability in daily life still improved significantly. He went from “household-only ambulation” to increased walking outside in his neighborhood.

“The therapeutic effect is likely a result of muscle conditioning during stimulated exercise and gait training,” according to the researchers. “Persistent use of the device during walking may provide ongoing training that maintains both muscle conditioning and cardiovascular health.”

This system will need further refinement for widespread use in the home and community, the researchers acknowledged. “But these data demonstrate that an implanted stimulation system for multi-joint control is a promising intervention to provide assistance to stroke survivors during daily walking,” they concluded.