Spine Implant Opens New Avenues for Paralysis Research
Research showing how a paraplegic man could stand up and regain some movement in his legs through a spinal implant opens up exciting paths for tackling paralysis, doctors said.
In a study published by The Lancet, US surgeons implanted a cluster of electrodes in the lower spine of a 25-year-old man paralysed below the chest from a hit-and-run car accident in 2006.
After 26 months of retraining of the leg muscles, followed by the pioneering surgery, the patient can now reach a standing position and support his own weight for up to four minutes at a time.
With a harness support and some help from a therapist, he can make repeated stepping motions on a treadmill and voluntarily move his toes, ankles, knees and hips on command.
The surgeons voiced delight which they leavened with caution, a response shared by other neurologists.
“This is a breakthrough,” said Susan Harkema, a professor at the Spinal Cord Research Center at the University of Louisville, Kentucky, who led the 11-member team.
“It opens up a huge opportunity to improve the daily functioning of these individuals… but we have a long road ahead.”
Assessing the work, Gregoire Courtine and Rubia van den Brand from Zurich University and Pavel Musienko of the Pavlov Institute of Physiology in St Petersburg said the level of recovery was “unprecedented” for spinal injury.
The biggest advance could be conceptual, for it opened up a field of electrically enabled motor control.
“We are entering a new era when the time has come for spinal-cord injured people to move,” they wrote in The Lancet.
The patient, Rob Summers, said he was ecstatic.
“To be able to pick up my foot and step down again was unbelievable, but beyond all of that, my sense of wellbeing has changed,” Summers said. “My physique and muscle tone has improved greatly, so much that most people don’t even believe I am paralysed.”
Paralysis comes from damage to the spinal cord down which the brain sends electrical signals along nerve fibres to instruct limb movement.
Decades of experimental effort have been devoted to reconnecting severed fibres through surgery or regrowing them through drugs or stem cells.
The new research takes a different route, exploring the idea that there are ways paralysed people can move without reconnecting the nerve link between the brain and lower extremities.
It focuses on nerve networks in the lower spine that are relatively autonomous – they can follow through the commands for weight-bearing and coordinated stepping without input from the brain.
This mechanism works thanks to feedback from nerves in the muscles of the legs and feet that is sent to the spinal cord, helping the individual to adjust his balance, movement and weight-bearing in response to surfaces and inclines.
Summers underwent 26 months of locomotor training to get his leg muscles used again to the sensation of movement, thus reviving the feedback system.
Surgeons implanted 16 electrodes in the lumbosacral spinal cord, connecting them to thick nerve bundles that largely control movement of the ankles, hips, knees and toes.
The unit then sent down electrical signals to mimic those sent down the spine by the brain in order to initiate movement.
The hope is that, using a portable stimulation unit, at least some individuals could stand up and bear weight and, with a walker, maintain balance and do some steps.
The Christopher and Dana Reeve Foundation – founded by “Superman” actor Christopher Reeve who was left paralysed by a riding accident – said it was excited by the research, to which it contributed financially.
“Today’s announcement clearly demonstrates proof of concept,” its executive vice president for research, Susan Howley, said. “Where it leads to from here is fundamentally a matter of time and money.”
First among the caveats is that this is not a cure, only an improvement – albeit significant – in the patient’s motor control.
It only involves a case study. Just one person has so far had the treatment, out of five authorised by the US Food and Drug Administration.
Summers was rated a “B” on the US classification of spinal injury, as he did retain some feeling below the spot where the damage occurred.
It is unknown whether the procedure will work on “A” patients, who have no sensation below the injury. In addition, Summers is young and was extremely fit before his accident.Filed under: Health