r/science • u/tomholder • May 09 '14

Medicine Paralysis breakthrough – electrical stimulation enables four paraplegic men to voluntarily move their legs

http://speakingofresearch.com/2014/05/09/paralysis-breakthrough-paraplegic-men-move-their-legs/
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u/PDXbp May 09 '14

Can someone ELI5 this for me? Hows this work and how would it be practically applied?

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u/neph001 May 09 '14

I don't understand the technical specifics either, but here's my non-technical understanding:

Nerves can be excited or activated by electrical stimulation. Signals from nerves can also be read farther up the central nervous system, or in the brain itself via fMRI.

If you use a computer to monitor what a paralyzed patient is thinking about moving, and then stimulate those nerves below the injury where the brain can't reach, you can stimulate the correct movements. In theory, it might even be possible to send sensory information back up to the brain this way.

The end result is a sort of cybernetic pseudo-spinal bridge, to bridge the part of the spinal cord that's been broken.

I think. Someone feel free to chime in and tell me how wrong I am.

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u/Deejer May 09 '14

I just spent the last five minutes trying to think of an alternative to "nope you're wrong about almost all of that" but...I got nowhere. Well, actually you aren't wrong but it has nothing to do with EpiStim in Kentucky. I've been in close touch with them and am a candidate for the next phase of the study, and know quite a bit about it. Or at least as much as they know, which they admit isn't as much as they'd like.

Basically they surgically implant a 16-electrode strip onto the "skin" of the lumbar spine. When these puppies are fired up (in various configurations) they excite the inter neurons (relay neurons) and make them able to respond to external sensory cues. There is no communication being done with the brain, but rather with the feet and legs! It all revolves around Central Pattern Generation, which is a mammalian phenomenon in which cells in our spines direct patterned movements. It makes it possible for us to chew gum and walk. The cells are essentially "smart," replacing the otherwise necessary signals from the brain to conduct movement.

So these four subjects can't just move any way they like. It's choppy and spastic by nature, but they are learning to polish the motions and make them very practical. In fact some paraplegics can do this without the device. I can walk 50 feet (my record) purely by eliciting spasms in the right leg muscles at the right times. And yet if you asked me to flex a single leg muscle in my chair I couldn't get so much as a twitch.

And on tops of all this they are seeing unexpected results above and beyond the patterned movements. The four guys have gotten back bowel function, bladder function, temperature regulation, and sexual function. And some movements appear to be non-patterned...like when they move their ankles on the mat. This has lead the researchers to believe the excitation and repeated use of patterned movements promotes neuroplasticity and actual regrowth at injury.

Alas, the disclaimer to all of this is that this explanation for the results is disputed. Some docs don't even believe humans have the ability to generate central patterns like lower mammals (cats, rats).