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October 2, 2009
Hope for spinal cord injuries
Israeli robotic technology helps patients relearn how to walk.
JEANIE KEOGH
Spinal cord injury patients are now able to relearn how to walk, thanks to Dr. Arahon Lev-Tov, his research team and a $250,000 robotic machine. Attendees at the Stretch Your Mind series, offered Sept. 12 and 13 at the Beth Israel Synagogue by Canadian Friends of Hebrew University (CFHU), were treated to lectures on scientific developments in diverse fields.
Professor of neurobiology and chair of the Hebrew University Medical School, Lev-Tov admitted that, "Ten to 15 years ago [spinal cord] patients would end up in a kind of miserable state. After this technique and similar techniques have been introduced, these patients can regain some mobility. They're not going to run the marathon but they can take 10 to 15 steps – they can support their own body weight."
He explained that when the spinal cord is injured, the brain cannot send a message to the motor nerve cells through the spinal central pattern generator (CPG), a neural nerve network that translates information between the brain and the spinal cord that allows movement in the human body.
By way of explanation, Lev-Tov said, "Whenever you want to start to walk, all you have to do is command yourself to start walking.... You do not think 'Well now, I have to flex the muscles on my right leg or on my left leg.' Everything is done automatically ... automatically controlled by the brain."
Lev-Tov and his research team figured that if a patient with a spinal cord injury can still receive sensory information from the skin, joint or muscle receptors, this alone could make the spinal cord work independently of the brain.
"Normally, we have a kind of sensory feedback from the ground.... The information is transmitted all the time to the spinal cord in order to adjust the pace, in order to make changes in cases where we hit an obstacle or step on a stone," he said.
Lev-Tov was able to isolate the spinal cord from the body and keep it alive by immersing it in artificial cerebral spinal fluid enriched with glucose and supplied with oxygen. It responded when activated with neural active compounds.
In another experiment, pinching the skin on the hind leg of a rat when the brain was disconnected allowed the spinal CPG to function through the input of sensory, or afferent, nerves.
Further analysis revealed that if the spinal cord was split vertically in two, as long as it was connected at the very least at one location then information could be exchanged between the left and right sides of the brain, which is necessary for inter-limb coordination.
"Under normal conditions everything is activated by the brain. The job of the brain is just to get the system started. The coordination, the generation of the rhythm is performed in the spinal cord in this 'magic' spinal generator [CPG]."
Lev-Tov tested the discovery using a machine manufactured in Switzerland, called the Lokomat, which simulates the body's internal spinal CPG.
The patient is supported by a harness and lowered onto a treadmill where robotic leg braces simulate the movement of walking. Electrodes attached to the shin and calf record the sensory data when the weight-bearing foot touches down.
Lev-Tov explained that patients aren't able to feel anything when they move however, because walking is controlled by the external CPG and so the information doesn't reach their consciousness.
The success rate, Lev-Tov said, is 100 percent but it can depend on the extent of the damage to the spinal cord.
According to Lev-Tov, another benefit of the machine is that the incidence of muscle spasticity, a common condition in patients where muscles receive constant messages from the active neurons to tighten and contract, decreases during the training. This means less stiffness in the legs and less reliance on anti-spastic drugs, which have been known to cause serious adverse effects, including psychological problems.
Lev-Tov stressed the significance of this new development for his patients saying, "You think, 'Oh, what's the big deal, so you support his body weight and he can move a step or two,' [but] this is just fantastic to them."
He described a high-spirited, optimistic young Israeli soldier who was a quadriplegic as a result of a motor vehicle accident.
"The first time I put him on a treadmill he said, 'Well Arahony, I can stand'; this was the first time after about four or five months in bed. Then he said, 'Now I can walk,' once we started the operating system."
Plans for a Lokomat at Vancouver's General Hospital are in development.
Jeanie Keogh is a freelance writer living in Vancouver.
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