A man suffering complete paralysis in both legs has regained theability to walk again using electrical signals generated by his own brain.Unlike similar efforts that have seen paralyzed subjects walk again by usingtheir own brainwaves to manually control robotic limbs, the researchers saythis is the first time a person with complete paralysis in both legs due tospinal cord injury was able to walk again under their own power anddemonstrates the potential for noninvasive therapies to restore control overparalyzed limbs.
The subject of the research, carried out by scientists at theUniversity of California, Irvine, had been paralyzed for five years. The workbegan with a stint of mental training designed to reengage the brain's walkingability, which saw the subject don an electroencephalogram (EEG) cap (a pieceof headwear fitted with electrodes that monitor the brain's electricalimpulses). The man was first made to control an avatar in a virtualenvironment, which was then followed with physical training to build up thestrength of his leg muscles.
With a system that delivers the electrical signals from hisbrain to electrodes placed around his knees to initiate movement, he beganpractising walking in the air, suspended around 5 cm (2 in) above the ground.This allowed him to become accustomed to the walking motion without his legsactually needing to support the weight of his body. On his 20th visit, equippedwith a support system to avoid falls and take some of his body weight, hemanaged to put one foot after the other along a 3.66 m (12 ft) walking course.The researchers report that across a 19 week testing period, he developedbetter control of his limbs.
This work builds on previous research carried out at UCLA whereelectrode arrays have been used to stimulate motion in sufferers of paralysis.In 2011, its researchers managed to restorevoluntary leg movement ina paralyzed man by applying electrical signals to the spinal cord's own neuralnetwork, tapping into the sensory input from the legs rather than the brain totrigger muscle and joint movement.
And earlier this year, UCLA researchers were able to get theparalyzed legs of five men moving again by placing electrodes on the skin ofthe lower back to stimulate the nerves. Then earlier this month its scientistsadapted this technique to allow a completely paralyzed man to control a bionicexoskeleton and takethousands of steps.
But the UC Irvine scientists say this is the first time a personwith complete paralysis in both legs has been able to walk without manuallycontrolled robotic limbs.
"Even after years of paralysis the brain can still generaterobust brain waves that can be harnessed to enable basic walking," saysDr. An Do, one of the lead researchers. "We showed that you can restoreintuitive, brain-controlled walking after a complete spinal cord injury. Thisnon-invasive system for leg muscle stimulation is a promising method and is anadvance of our current brain-controlled systems that use virtual reality or arobotic exoskeleton."
Though optimistic, the scientists are urging caution, notingthat the study only involved a single patient and further work must be donebefore they can conclude whether the promising results will translate to otherswith paraplegia. They also anticipate that implants could improve user controland provide sensation.
"Once we've confirmed the usability of this noninvasivesystem, we can look into invasive means, such as brain implants," sayssenior lead researcher Dr. Zoran Nenadic. "We hope that an implant couldachieve an even greater level of prosthesis control because brain waves arerecorded with higher quality. In addition, such an implant could deliversensation back to the brain, enabling the user to feel their legs."
The team's research was published in the Journal of Neuroengineering andRehabilitation.
Source: BioMed Central
