Future spine surgery to implant nerve stimulators may treat spinal cord injury

Oct 19 2011
Research on micro-electric nerve stimulators, implanted through spine surgery, may lead to a new treatment to help patients with spinal cord injury recover functions lost in paralysis.

The developing therapy from the New Jersey Institute of Technology (NJIT) is currently in the third year of its four-year grant from the National Institutes of Health. In September, the investigators published the results of trials conducted in rats.

Each day, about 30 people in the U.S. endure some paralysis as a result of a spinal cord injury. This totals to nearly 11,000 Americans every year, according to the ThinkFirst National Injury Prevention Foundation. The leading causes of these injuries are car accidents, violent acts, falls and sports.

In these kinds of mishaps, the spinal cord or its nerve roots are damaged, and the brain has difficulty communicating with the parts of the body, particularly if they are below the site of the injury. In addition to the initial physical damage, injury to the spinal cord may be aggravated by inflammation or poor blood flow.

The average lifetime cost of living with a spinal cord injury can range from $500,000 to more than $3 million, depending on its severity, according to the Centers for Disease Control and Prevention (CDC).

The scope of the effects of a spinal cord injury depends on where it occurs. The higher the injury, the greater the potential loss of function, movement and sensation in the body. Paralysis, which may be permanent or temporary, is a common complication of an injury. Other symptoms, which can differ between individual cases, may include difficulty breathing, incontinence, loss of sexual function or exaggerated movements.

Less than 1 percent of patients with a spinal cord injury fully recovery, according to ThinkFirst. Most available treatments focus on adapting to new challenges posed by one's condition, such as maintaining physical fitness and independence in everyday life.

There have been several experimental technologies designed to restore function to damaged nerves through electrical stimulation from a device. However, researchers from NJIT have developed the floating light activated micro-electrical stimulators (FLAMES) device as a wireless system.

FLAMES includes a semiconductor surgically implanted into the spinal cord to activate nerves below the site of injury; an optical fiber attached to a low power near-infrared laser; and an external unit, controlled by the patient, to activate the laser and power the semiconductor.

The recently reported trial in rats demonstrated that the wireless connection between the laser and the semiconductor does not diminish the activation of the device, regardless of how they move relative to each other in the spine.

"The unique aspect of the project is that the implanted stimulators are very small, in the sub-millimeter range," said engineer Mesut Sahin, Ph.D. "A key benefit is that since our device is wireless, the connections can't deteriorate over time plus, the implant causes minimal reaction in the tissue which is a common problem with similar wired devices."

Ultimately, the researchers intend to move into clinical trials on humans, where they hope their device can restore functions that were lost because of spinal cord injuries.