In past research, electrical stimulation of the lower spinal cord, combined with motor training, allowed patients who were paralyzed below the chest because of spinal cord injuries to regain some voluntary movement of their legs.
A team led by Dr. Daniel Lu at the University of California, Los Angeles (UCLA), set out to test whether epidural stimulation could restore some hand strength and control in people with tetraplegia, also known as quadriplegia (the loss of use of all 4 limbs). The study was funded in part by NIH’s National Institute of Biomedical Imaging and Bioengineering (NIBIB) and other NIH components. Results appeared online on May 18, 2016, in Neurorehabilitation and Neural Repair.
The study included 2 people with severe injuries to their cervical spines—the spinal cord at the level of the neck. Both had been paralyzed for more than 18 months. They were implanted with an array of 16 electrodes that spanned their injury sites. The participants practiced grasping and moving a handgrip while receiving varying levels of electrical pulses from the devices. One person was tested daily over 7 days while the other had weekly sessions for 8 weeks.
The participants’ hand strength improved over the course of a single session. With additional sessions, the force they could generate gradually increased. Hand control, including hand opening and closing, improved as well. These effects were maintained even in the absence of stimulation.
Both individuals made large gains in feeding, dressing, bathing, and grooming. Their mobility in bed and ability to get themselves in and out of bed improved as well. One participant regained the ability to pick up and drink from a cup.
This is the first time that this approach has been used to improve function in the upper limbs of people with severe spinal cord injuries. The researchers believe that stimulation affects the spinal cord’s underlying circuitry, reawakening networks that have been silent since the injury. The circuitry starts to relearn and reorganize to become more functional.
“In this study we demonstrate that through cervical epidural stimulation, hand and upper extremity function can be substantially improved, imparting the ability to participate in activities of daily living, self-care and transfer, and to live independently,”Lu says.
“Even relatively minor gains in function of the upper limb can make huge differences in the quality of life for a person who can’t grasp anything,” adds co-author Dr. V. Reggie Edgerton of UCLA.
The team is planning future studies in more patients to further evaluate the long-term safety and optimal conditions for using the approach. The group reported last year on a noninvasive technique that goes through the skin, called transcutaneous stimulation. That approach allowed 5 men with complete lower-limb paralysis to make step-like movements. The team is currently investigating the approach in the upper body as well.