Adolescent idiopathic scoliosis may be caused by a disease of the central nervous system, recent studies suggest. Based on this theory, scientists from Fraunhofer Institute for Photonic Microsystems have developed a prototype implant that provides electrostimulation to replace nerve signals either weakened or disabled by disease.

Out of every 100 children and teens, two will suffer from a curvature of the spine known as adolescent scoliosis. While this growth disorder causes lasting deformation, the exact cause of the spinal curvature is unknown (or ‘idiopathic’) in 90 percent of cases. The central nervous system theory of this disease asserts that connections between nerves and muscles are impaired on only one side of the back, explained Dr. Andreas Heinig of the Dresden-based institute. So when the muscles on the healthy side contract, the muscles on the unhealthy side fail to balance the contraction out and this causes the entire spinal column to twist and buckle.

Working with partners in Spain and France, Heinig developed a new method for treating adolescent idiopathic scoliosis based on this well-known theory. Essentially, the research team decided to use electrostimulation to replace nerve signals that have become either lost or too weak to function due to disease. The impulses generated by their device would stimulate deep muscles along the spinal column creating counter-contractions that in turn spur symmetrical growth.

Their prototype device is implanted in the groin region, with specially-designed precision surgical instruments. From the device, eight electrical cables will lead to select spots along the spinal cord where electrodes will stimulate the slack muscles on the neglected side of the body. Several additional electrodes will lead to the healthy side of the body as well to record natural muscle activity and adjust electrostimulation accordingly.

Heinig explained that it takes 50 pulses per second to stimulate the rotator muscles of the spine and, in order to be corrective, these pulses must be delivered over a long period of time. A typical training program, then, would involve six to eight hours of treatment every day with several waves of muscle stimulation separated by at least ten minutes of rest. However, compared to operations that fuse the spine or corsets worn for years, electrostimulation would be preferable to many sufferers since it is both minimally invasive and could offer a lasting correction.

Initial proof-of-concept testing has shown the technology to be sound, with the device seamlessly sending data in both directions and muscle activation working as theorized.

"We have clearly shown that this form of therapy is technically feasible,” Heinig said in a company report. “Now it's up to future clinical studies to demonstrate that the therapy is medically effective and can cure or at least alleviate scoliosis.”