Shocks helping stroke victims
BRITAIN: Tens of thousands of stroke patients could recover the use of their hands with a device that triggers their nerves through a series of clicks and electric shocks.
About half of the people who survive a stroke are left with a disability, which often takes the form of a persistently clenched fist.
Scientists from the University of Newcastle in England believe they can teach patients how to loosen their hands, by changing the wiring through which the brain sends messages to the limbs.
Their invention, an iPod-sized device connected to an earpiece at one end and sticky electrodes on the forearm at the other, has already been demonstrated to have a significant effect on the reflexes of healthy people, and will now be tested in a 150-patient clinical trial in Calcutta.
Stuart Baker, professor of movement neuroscience at Newcastle, said the idea was to strengthen the brain’s lines of communication with the hand.
Normally, when people waggle their fingers or grasp things, the commands come from a region called the cortex, which evolved relatively recently and tends to handle much of our conscious and voluntary thinking. When this machinery is snarled up by a stroke, however, the task reverts to a more ancient backup channel known as the reticulospinal tract, running from the primeval base of the brain to the rest of the body though the spinal cord.
‘‘Most animals have a paw rather than a hand that can move its different fingers in an independent way,’’ Baker said. ‘‘What happens if somebody has a stroke is they have to go back to this more primitive system that’s like manipulating a paw. You can regain the ability to do only half of want you want.’’
Several years ago, Baker and his colleagues discovered by accident that they could give primates much better control over their hands if they played them sharp bursts of sound a few thousandths of a second after stimulating their nerves with bursts of electricity.
In a new paper, published in the Journal of Neuroscience, the researchers describe how they boosted the strength of a stretch reflex by about 50 per cent in the biceps of 74 adults who used the device for a day.
Their theory is that the mild electric shock starts a cascade of electrical signals that is somehow boosted by the sound of the click one hundredth of a second later, possibly because the noise activates balance processing centres linked to the reticulospinal tract. Every shock-click sequence strengthens the brain’s control over the muscle.
- The Times