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Neuro rehab technology

New major advancement in recovering limb movement after stroke

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Neurotechnology that can provide stimulation for the spinal cord has shown to instantly improve arm and hand mobility, which allows patients affected by moderate to severe stroke to be able to conduct everyday activities.

The pair of spaghetti-like thin metal electrodes are implanted along the neck to engage intact neural circuits, this allowed stroke patients to be able to fully open and close their fist, lift their arm above their head or use a fork and knife to cut a piece of steak for the first time in years.

Corresponding and co-author, Marco Capogrosso, says: “We discovered that electrical stimulation of specific spinal cord regions enables patients to move their arm in ways that they are not able to do without the stimulation. Perhaps even more interesting, we found that after a few weeks of use, some of these improvements endure when the stimulation is switched off, indicating exciting avenues for the future of stroke therapies.

“Thanks to years of preclinical research building up to this point, we have developed a practical, easy-to-use stimulation protocol adapting existing FDA-approved clinical technologies that could be easily translated to the hospital and quickly moved from the lab to the clinic.”

Stroke experts believe that more and more adults over the age of 25 will become more likely to have a stroke in their lifetime, with a prediction that every fourth adult over 25 will have a stroke, with 75 per cent of those having lasting deficits in motor control of their arm and hand.

As things stand, no treatments are effective for treating paralysis in what is known as the chronic stage of stroke, which starts around the six months after the stroke incident. According to researchers, this new technology has the potential to offer hope for people living with impairments that would have otherwise been considered permanent.

Senior co-author, Elvira Pirondini, says: “Creating effective neurorehabilitation solutions for people affected by movement impairment after stroke is becoming ever more urgent.

“Even mild deficits resulting from a stroke can isolate people from social and professional lives and become very debilitating, with motor impairments in the arm and hand being especially taxing and impeding simple daily activities, such as writing, eating and getting dressed.”

This method of spinal cord simulation technology uses a set of electrodes placed on the surface of the spinal cord to deliver pulses of electricity that activate nerve cells inside the spinal cord. This technology has already been used to treat high-grade, persistent pain. In addition, multiple research groups around the would gave shown that spinal cord stimulation can be used to restore movement to the legs after spinal cord injury.

However, due to the unique dexterity of the human hand, combined with the wide range of motion of the arm at the shoulder and the complexity of the neural signals controlling the arm and hand, a significantly higher set of challenges is added.

After years of extensive preclinical studies involving computer modelling and animal testing in macaque monkeys with partial arm paralysis, researchers were cleared to test this optimised therapy in humans.

Co-senior author, Douglas Weber, says: “The sensory nerves from the arm and hand send signals to motor neurons in the spinal cord that control the muscles of the limb.

“By stimulating these sensory nerves, we can amplify the activity of muscles that have been weakened by stroke. Importantly, the patient retains full control of their movements: The stimulation is assistive and strengthens muscle activation only when patients are trying to move.”

Tests were tailored to individual patients, stimulation enabled the patients to perform tasks of different complexity, from moving a hollow metal cylinder to grasping common household objects, such as a can of soup, and opening a lock. Clinical assessments displayed that stimulation targeting cervical nerve roots immediately improves strength, range of movement and function of the arm and hand.

The researchers were left in awe as the effects of stimulation seemed to last longer than they had originally expected, not only that, but the effects persisted even after the device was removed, which suggests that it could be used both as an assistive and a restorative method for upper limb recovery.

The immediate effects of the stimulation enable administration of intense physical training that, in turn could lead to even stronger long-term improvements in the absence of stimulation.

In order to make further advancements, researchers will continue to enrol additional trial participants to gain a better understanding which stroke patients can benefit most from this therapy and how to optimise stimulation protocols for different severity levels.

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