by James Cavuoto, editor
May 2014 issue
May 31, 2014 | While research teams in the U.S. have made considerable progress recently using spinal cord stimulation for neuroprosthetic and neurorehabilitation applications [NBR Apr14 p2], an independent effort at several European institutions is gaining momentum. Recently, investigators from the Fraunhofer Institute in Germany reported progress in fabricating flexible microelectrodes that will be used to restore function in individuals with spinal cord injury.
Much of the impetus for this new work has come from the European Union’s NEUWalk research program, which was launched in 2010 and funded with €9 million. Gregoire Courtine from EPFL in Switzerland serves as the scientific co-manager of NEUWalk. His research team has shown that a severed section of the spinal cord can make a comeback when its own innate intelligence and regenerative capacity is awakened. They injected a chemical solution of monoamine agonists into the rat spinal cord in order to prime it for plasticity. This cocktail replaces neurotransmitters released by brainstem pathways in healthy subjects and acts to excite neurons and ready them to coordinate lower body movement when the time is right. Five to 10 minutes after the injection, the team electrically stimulated the spinal cord with electrodes implanted in the epidural space. “After a couple of weeks of neurorehabilitation with a combination of a robotic harness and electrical-chemical stimulation, our rats are not only voluntarily initiating a walking gait, but they are soon sprinting, climbing up stairs and avoiding obstacles when stimulated,” said Courtine.
Peter Detemple, department head at the Fraunhofer Institute for Chemical Technology’s Mainz branch and NEUWalk project coordinator, has developed flexible, wafer-thin microelectrodes that are implanted within the spinal canal on the spinal cord. These multichannel electrode arrays stimulate the nerve pathways with electric impulses that are generated by the accompanying 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,” said Detemple.
Researchers intend to try out their system on two human subjects with incomplete SCI this summer. “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,” said Detemple.
Other goals of the NEUWalk program are to alleviate severe Parkinsonian symptoms in rodents, to develop multisite stimulation strategies to engage the spinal networks, and to enhance methods of cortical signal recording and neural decoding. The program seeks to devise dedicated neuroprosthetic interfaces suited for chronic implantation using microelectronics, real time data processing, and wireless signal transmission, Ultimately, NEUWalk is expected to open the doors for future therapy of severe SCI enabling partial restoration of voluntary control of paralyzed limbs and for establishing a novel, efficient clinical strategy for symptomatic treatment of Parkinson’s disease.
Other institutions involved with NEUWalk include ETH in Switzerland, University College London in the U.K. Scuola Superiore Sant’ Anna in Italy, and Universite Victor Segalan in Bordeaux, France. Commercial firms participating in NEUWalk include Mega Electronics in Finland, Inomed Medizintechnik in Germany, and Finetech Medical in the U.K.
