Stimulating the spinal cord improves arm mobility after stroke

People who suffer from cerebrovascular accident moderate or severe They may lose mobility in their extremities and have difficulty walking or carrying out their daily activities. One in four people over the age of 25 will experience a stroke at some point and an estimated 75% of these patients will experience impairment, weakness, or paralysis in the arms and handswhich will significantly limit its autonomy.

The motor deficits in arm and hand motor control experienced by these individuals currently have no effective treatment, but now scientists at the University of Pittsburgh and Carnegie Mellon University have developed neurotechnology capable of immediately improve the mobility of the arms and hands after a stroke by means of the spinal cord stimulation.

This technology consists of two thin metal electrodes shaped similar to spaghetti that are implanted in the neck and connected to intact neural circuitry, and has been tested on two volunteers suffering from a chronic partial paralysis of the arm and hand on one side of the body (hemiparesis) to increase the functionality of motor neurons in the arm and hand. The result was that they were able to fully open and close their fist, raise their arm above their head, or cut a piece of meat with a fork and knife for the first time in years.

“The stroke patient retains full control of their movements: stimulation is assistive and strengthens muscle activation only when patients attempt to move”

“We found that electrical stimulation of specific regions of the spinal cord allows patients to move their arm in ways that would be impossible without stimulation. Perhaps even more interesting is that we found that after a few weeks of use, some of these improvements persist when stimulation is stopped, pointing to exciting avenues for future stroke therapies.” Mark Capogrossoassistant professor of neurological surgery at Pitt and co-senior author.

This expert adds that after years of preclinical research they have managed to develop a “practical and easy-to-use stimulation protocol that adapts existing FDA-approved clinical technologies that could be easily transferred to the hospital and quickly moved from the laboratory to the clinic.” The clinical trial is still ongoing and these first results have been published in Nature Medicine.

Combat the sequelae of strokes

“Even mild deficits resulting from stroke can isolate people from social and professional life and become very debilitating, and motor impairments in the arm and hand are especially demanding, preventing simple daily activities such as writing, eating and getting dressed,” said co-senior author Elvira Pirondini, an assistant professor of physical medicine and rehabilitation at Pitt. Therefore, she considers it urgent to create “neurorehabilitation solutions Effective for people affected by movement impairment after stroke.

Spinal cord stimulation has already been successfully investigated to restore leg movement after leg injury. This technology uses an array of electrodes that are placed on the surface of the spinal cord and send electrical signals that activate nerve cells within the spinal cord, a technique already used to treat persistent severe pain.

In the case of the human hand, the challenge is greater, since this extremity is characterized by its great dexterity, which is combined with the wide range of movement of the arm and the complexity of the neural signals that control the arm and hand. The authors of the new work spent years conducting preclinical studies in which they used computer models and carried out tests on macaque monkeys with partial paralysis of the armafter which they were authorized to test the therapy in humans.

“Sensory nerves in the arm and hand send signals to motor neurons in the spinal cord that control muscles in the limb,” explained co-senior author Douglas Weber, a professor of mechanical engineering at Carnegie Mellon University’s Institute for Neuroscience. . “By stimulating these sensory nerves, we can amplify the activity of muscles that have been weakened by a stroke. It is important to highlight that the patient retains full control of their movements: the stimulation is assistive and strengthens muscle activation only when the patients try to move.”

In the tests carried out with patients, the stimulation allowed the participants to perform various tasks: from moving a hollow metal cylinder, to grasping household objects or opening a lock. Clinical evaluations revealed that targeted stimulation to the cervical nerve roots immediately improves arm and hand strength, range of motion, and function.

The effects of the stimulation appear to last longer than scientists had thought, and even persisted after removal of the device, suggesting that it could be used as an assistive and restorative method for upper extremity recovery. In addition, the fact that the stimulation has immediate effects would allow the patient to carry out intense physical training that could further improve their mobility in the long term without the need to continue the stimulation.


Leave a Reply