In their study, the team developed a device which delivered regular pulses of electricity to damaged peripheral nerves in rats after a surgical repair process. The result was accelerated regrowth of nerves in their legs and enhanced recovery of muscle strength and control.
The size of a dime and the thickness of a sheet of paper, the wireless device operates for about two weeks and is designed to wrap around an injured nerve and deliver electrical pulses at selected time points for days, before naturally absorbing into the body. The device is powered and controlled wirelessly by a transmitter outside the body that acts much like a cellphone-charging mat.
While the device has not been tested in humans, the scientists believe their findings offer promise as a future therapeutic option for nerve injury patients. For cases requiring surgery, standard practice is to administer some electrical stimulation during the surgery to aid recovery. Until now however, doctors have lacked a means to continuously provide that added boost at various time points throughout the recovery and healing process.
"We know that electrical stimulation during surgery helps, but once the surgery is over, the window for intervening is closed," said co-senior author Dr. Wilson Ray, an Associate Professor of neurosurgery at Washington University. "With this device, we've shown that electrical stimulation given on a scheduled basis can further enhance nerve recovery."
In their work, the researchers used the device to provide one hour per day of electrical stimulation to the rats for one, three or six days or no electrical stimulation at all, and then monitored their recovery for 10 weeks.
They found that any electrical stimulation was better than none at all at helping the rats recover muscle mass and muscle strength. In addition, the more days of electrical stimulation the rats received, the more quickly and thoroughly they recovered nerve signalling and muscle strength. No adverse biological effects from the device and its reabsorption were found.
The researchers are now investigating whether delivering electrical stimulation for double the amount of days (12 instead of 6) would be more therapeutic beneficial.
By varying the composition and thickness of the materials in the device, the team say they can control the precise number of days it remains functional before being absorbed into the body. New versions can provide electrical pulses for weeks before degrading.
The ability of the device to degrade in the body takes the place of a second surgery to remove a non-biodegradable device, which the team says will eliminate additional risk to the patient.
The research study also showed the device can work as a temporary pacemaker and as an interface to the spinal cord and other stimulation sites across the body. These findings suggest broad utility, beyond just the peripheral nervous system.