Deep brain stimulation (DBS) may provide immediate improvements in arm and hand strength for individuals with traumatic brain injuries or strokes, according to researchers from the University of Pittsburgh School of Medicine, as reported in Nature Communications.
The encouraging results from extensive testing in monkeys and humans pave the way for a new clinical application of this widely used brain stimulation technology and offer insights into the neural mechanisms underlying movement deficits caused by brain injuries.
Arm and hand paralysis significantly impacts the quality of life for millions worldwide. Currently, effective solutions are lacking for patients who have suffered strokes or traumatic brain injuries, but there is a growing interest in using neurotechnologies to stimulate the brain to enhance upper limb motor functions.
Dr. Elvira Pirondini, the lead and corresponding author, an assistant professor of physical medicine and rehabilitation at Pitt, stated, "Deep brain stimulation has changed the lives of many patients. Now, thanks to ongoing advances in the safety and precision of these devices, DBS is being explored as a promising option to help stroke survivors regain their motor functions."
Brain injuries caused by severe trauma or strokes can disrupt neural connections between the motor cortex—a key brain region essential for voluntary movement—and the muscles, leading to movement deficits, including partial or complete paralysis of arms and hands.
To boost the activation of existing but weakened connections, researchers proposed using DBS, a surgical procedure that involves placing small electrodes in specific areas of the brain to deliver electrical impulses that regulate abnormal brain activity. Over the past few decades, DBS has revolutionized the treatment of neurological conditions like Parkinson's disease by providing a means to control symptoms that were once difficult to manage with medication alone.
Following the success of another Pitt project that used spinal cord electrical stimulation to restore arm function in stroke-affected individuals, scientists hypothesized that stimulating the motor thalamus—a structure deep in the brain that acts as a key relay center for movement control—using DBS could help restore movements essential for daily activities, such as grasping objects. However, since this theory had not been tested before, they first had to verify it in monkeys, whose neural connections between the motor cortex and muscles are similar to those of humans.
To understand how DBS of the motor thalamus enhances voluntary arm movement and to refine the specific implant location and optimal stimulation frequency, researchers implanted an FDA-approved stimulation device in monkeys with brain injuries affecting their hand usage.
As soon as the stimulation was activated, significant improvements in muscle activation and grip strength were observed, with no involuntary movements noted.
To verify that the procedure could benefit humans, the same stimulation parameters were applied to a patient scheduled for DBS implantation in the motor thalamus to alleviate arm tremors caused by severe brain injury from a car accident, which resulted in significant paralysis in both arms.
Upon reactivation of the stimulation, the amplitude and strength of the arm movement improved immediately: the participant was able to lift a moderately heavy weight and reach, grasp, and lift a glass more efficiently and smoothly than without stimulation.
To help bring this technology to more patients clinically, researchers are now working to test the long-term effects of DBS and determine if chronic stimulation could further enhance arm and hand function in individuals affected by traumatic brain injuries or strokes.
Other contributors to this research include Jonathan Ho, BS, Erinn Grigsby, Ph.D., Arianna Damiani, MS, Lucy Liang, MS, Josep-Maria Balaguer, MS, Sridula Kallakuri, Lilly Tang, BS, Jessica Barrios-Martinez, MD, Vahagn Karapetyan, MD, Ph.D., Daryl Fields, MD, Ph.D., Peter Gerszten, MD, T. Kevin Hitchens, Ph.D., MBA, Theodora Constantine, PA-C, Gregory Adams, BS, Donald Crammond, Ph.D., and Marco Capogrosso, Ph.D., all from Pitt.
This research was supported by internal funding from the Departments of Physical Medicine and Rehabilitation and Neurological Surgery at Pitt. The Walter L. Copeland Foundation, Hamot Health Foundation, and National Institutes of Health provided additional funding (R01NS122927-01A1).