A new treatment which stimulates the spinal cord with electric impulses offers some hope to those with severe spinal cord injuries. Currently they have little prospect of recovery, remaining confined to a wheelchair.

Researchers from Fraunhofer-Gesellschaft developed the implantable microelectrode sensors for the EU’s NEUWalk project. A group of European research institutions and companies are working on a new method of treatment intended to restore motor function in paraplegic patients. The technique involves electrically stimulating the nerve pathways in the spinal cord.

Damaged Nerve Cells

“In the injured area, the nerve cells have been damaged to such an extent that they no longer receive usable information from the brain, so the stimulation needs to be delivered beneath that,” said Dr. Peter Detemple, NEUWalk project coordinator.

Detemple and his team are currently developing flexible, superthin microelectrodes that will be implanted in the spinal canal of the spinal cord. These multichannel electrode arrays stimulate the nerve pathways with electric impulses that are generated by the accompanying by microprocessor-controlled neurostimulator.

“The various electrodes of the array are located around the nerve roots responsible for locomotion. By delivering a series of pulses, we can trigger those nerve roots in the correct order to provoke motion sequences of movements and support the motor function,” says Detemple.

Restoring Independence

Tests have already been successfully done by the project on rats in which the spinal cord had not been completely severed. In addition to stimulating the spinal cord, the rats were given a combination of medicine and rehabilitation training. Following this, the animals were able not only to walk but also to run, climb stairs and get around obstacles.

“We were able to trigger specific movements by delivering certain sequences of pulses to the various electrodes implanted on the spinal cord,” said Detemple. “We hope that we will be able to transfer the results of our animal testing to people. Of course, people who have suffered injuries to their spinal cord will still be limited when it comes to sport or walking long distances. The first priority is to give them a certain level of independence so that they can move around their apartment and look after themselves, for instance, or walk for short distances without requiring assistance."

Parkinson’s Disease

Parkinson’s disease patients may also be able to benefit from the neural implant. The most familiar symptoms of this disease are trembling, extreme muscle tremors and a short, stooped gait that has a profound effect on patients’ mobility. This neurodegenerative disorder has until now mostly been treated with dopamine agonists. These are drugs which chemically imitate the effects of dopamine. Unfortunately they often lead to serious side effects when taken over a longer period of time.

Once Parkinson’s has reached an advanced stage, doctors frequently turn to deep brain stimulation treatment. This requires a complex operation to implant electrodes in specific parts of the brain so that the nerve cells in the region can be stimulated or suppressed as required.

In the NEUWalk project, researchers are working on electric spinal cord simulation – an altogether less dangerous intervention that should however ease the symptoms of Parkinson’s disease just as effectively.

NEUWalk researchers plan on trying out their system on two patients this summer. The patients are not completely paraplegic, as they retain some limited communication between the brain and the legs. The scientists are currently working on tailored implants for the intervention.

“However, even if both trials are a success, it will still be a few years before the system is ready for the general market. First, the method has to undergo clinical studies and demonstrate its effectiveness among a wider group of patients,” says Detemple.

_ Image © Fraunhofer IMM_

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