Friday, June 1, 2012

New therapy can help paraplegics walk again

A paralysis is one of the most severe impediments of life. Paraplegics lose control over, mostly, limb functions because their muscles are no longer working. This is caused by malfunctions in the nervous system, which ultimately controls muscle movement by sending signals coming from the brain. Sadly, a paralysis is also one of the hardest things to cure, as we are currently unable to assert much influence over the nervous system. The body lacks internal repair systems, and attempts to artificially regenerate the required neural networks have been troublesome. A group of scientists from the Swiss Federal Institute of Technology have developed a way to 'rewire' the nervous system in order to find a cure for paralysis.

So far, they have seen quite some success by using rats. The rodents, with artificially induced paralysis, received an implant featuring several electrodes that tapped into the dysfunctional nervous system. Additionally, they were given a cocktail of chemicals that function in neural communication. Receptors of these neurotransmitters, called dopamine, serotonin and adrenalin, were injected into the spine, where they 'nested' on the dysfunctional cells. This 'primed' them for receiving stimulatory signals. Receptors are needed to accept an incoming signal and relay it into the cell, where it leads to behavioural changes. In the case of neural cells, it leads to an electrical pulse that can then be propagated, eventually leading to action of some sort, such as muscle movement.
One of the paralysed rats learning to walk again.
After being implanted, the electrodes sent several electrical pulses into the newly aroused neural cells. This helped the neurons to regain their function and send out signals to muscles. Basically, by modifying the signalling system by administering neurotransmitter receptors and then inducing electrical stimulation, the neural network is getting rewired. Normally, the nervous system uses other signalling molecules, but the artificial receptor priming and electrical stimulation helped to rouse the dysfunctional neurons in a way that helps muscles regain their function.
An overview of the study. 1. Paralysis is induced. 2. Injection of the required receptors followed by electrical stimulation. 3. Rats are put on a robotic treadmill to encourage walking. 4. The nervous system is rewired. 5. It is a miracle.
While stimulating the muscles, the rats in the study had to be taught how to walk again. They were put on a robot-assisted treadmill that slowly helped them to regain control over muscle function. Of course, stimulation does not 'turn on' the nervous system overnight: it takes careful and long training programmes before such complex signalling systems are functioning properly again. Nevertheless, the scientists showed that after training the rats for a while, they fully regained their previously lost ability to walk. This is shown in a demonstration video found below.

Using electrical pulses to kick-start neurological functions is not something new. Scientists have been experimenting with it for years in order to treat previously untreatable neurological conditions. Examples include stimulation of new memory cells in alzheimer's or as a new treatment for parkinson's. Even patients with a depression can benefit from electrical stimulation.

By showing that their therapy made rats walk again, the electrochemical stimulation looks very promising for paraplegics. If this method makes it into the clinic, a paralysis would no longer have to be something untreatable and severely life-impeding. Walking again after paralysis could soon be a reality, but because a lot of research is required before scientists can make the step from animal to human, it may still take several years.

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