Two stroke patients have been able to move their hands again after an experimental procedure that appears to "tickle" temporarily restored the weakened connections between their upper limbs and the brain and spinal cord.
Heather Rendlick was one of those women. For one month, as part of a groundbreaking study led by researchers at the University of Pittsburgh, she was able to maneuver her handicapped arm more easily when electrical impulses were firing at the top of her spinal cord.
Rendlick had suffered a stroke in her early 20s that left the left side of her body paralyzed. Like many stroke survivors, she regained some balanced movement but this soon stalled, and many daily tasks such as tying shoes or chopping vegetables were out of her reach.
For many years, Rendlick has been "living one-handed in a two-handed world" - but now, spinal cord stimulation is proven to be safe and effective.
"When the stimulation is on, it feels like I now have control of my arms and hands again, which I haven't had in over nine years," says Rendlick. "The stimulation feels kind of ticklish, and it's never painful, but it takes some getting used to."
While only two cases were reported in the study, Rendlick and the co-author showed clear improvements in grip strength, arm movement and manual dexterity immediately after the device was turned on.
The device consists of a pair of thin metal electrical implants - as flexible as strands of spaghetti - that are inserted into the upper part of the spinal cord where they join sensory inputs from the arm and hand.
When the electrodes were turned on, they delivered electrical impulses to spinal circuits that had been weakened by the stroke but remained intact. Instead of forcing the muscles to move, the impulsive current amplifies messages in the nerve circuits of the spine to aid movement.
"We wanted to capture these weak signals and essentially convert them into functional outputs so that a person can voluntarily control their hand," Marco Capogroso, a biomedical engineer at the University of Pittsburgh, told NPR.
The two women in this study suffered from different types of strokes, but they showed improvement in hand and arm movements to varying degrees. They received the experimental form of stimulation four hours a day, five days a week, over a month-long trial period.
In a series of tests captured on video and using wireless sensors that detect muscle contraction, Rendlick can be seen raising her arm, picking up a can of soup, picking up food with a fork, opening a lock and drawing basic shapes.
The researchers say that these skillful movements, along with the wide range of arm and shoulder motion, posed a greater challenge than stimulating leg movement.
And just last year, researchers reported that nine people were able to walk again with assistance after five months of spinal cord stimulation and rehabilitation.
Prior to this, a 2016 study showed that electrical stimulation may also improve upper limb movement after a spinal cord injury. With more animal testing and computer modeling, the researchers behind this latest study are encouraged to believe that stroke survivors may also benefit.
To the researchers' surprise, some improvements in mobility persisted for up to four weeks after the implants were removed — but those gains have since dissipated, says Rendlick.
"However, small patient numbers and findings need to be validated in a larger study," tweeted Ewan McCaughey, a biomedical engineer who studies electrical stimulation for spinal cord injuries.
These studies may take years to bear fruit, but the results will be key to understanding which types of stroke patients might benefit from the treatment, at what stage of recovery, and whether there are any safety issues or limitations to its effectiveness.
"This is for research purposes, it's very early," Ilan Sivanesan, director of neuromodulation at Johns Hopkins University, told STAT News. "There is promising hope. It's good to have hope, but I don't want to mislead patients by claiming that this is something that will be available to them tomorrow." .
Rendlick also hopes that her participation in the study has helped the researchers, and that someday in the future she can get a permanent stimulus to tickle her nerves again.
The research has been published in the journal Nature Medicine.
Source: ScienceAlert
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