Ephaptic and Ectopic Transmissions

[jensequitur]

Ess asked about ephaptic transmissions, and I thought it deserved its own post - it's an interesting side effect of demyelinated nerves, and it really affects all of us.

Here's where I first learned about it:

http://www.unitedspinal.org/msscene/2008/11/18/paroxysmal-symptoms-of-multiple-sclerosis-they-come-and-they-go/

Essentially, the article says that as nerves lose their myelin coating, they start shorting out and the transmissions don't get to their destination.  If you have a new symptom, it's because of a new focal area of demyelination.

as an aside: Personally I believe that axons are actually breaking before the myelin is lost... but that's just a theory.

Paroxysmal symptoms of MS are temporary neurological disturbances.  They're like MS attacks, but they're short lived - anywhere from a few seconds to a few minutes.  However, they can occur several times a day - like my myoclonic jerks of my back.  They're caused by the signals from the axons shorting out and not getting to their destination.  So where do they go?

Ectopic transmission:  Demyelinated axons can become overexcitable at the MS lesion.  They get crazy and start sending out stuff that has nothing to do with what the brain is telling it.  That nerve impulse goes out in both directions to the neuron, which sends stuff back to the axons and tells them to fire - and WHAM!  I have a myoclonic jerk.  (Definitely read the article on this one - I've condensed it for comprehension, but it's very interesting.)

Ephaptic transmission: Active axons that are near the demyelinated region are enough to trigger the nerve to fire - like the electricity from one nerve is jumping and going to the other.  This is why when I drink a cold liquid, the center of my right shoulder gets cold.

The reason I'm interested in it is because I've been prescribed Keppra for the myoclonic jerks.  Dr. C callled it ephaptic transmission, although I think the ectopic describes my situation better.  She thinks that the Keppra will help keep the ion channels (the means by which the nerves transmit information) not be quite so excitable, and perhaps not fire off inappropriate signals all the time.

[jensequitur]

Don't worry - I know you're going through a lot right now!

I've created a health page on this topic:

http://www.medhelp.org/health_pages/Multiple-Sclerosis/Ephaptic-and-Ectopic-Transmissions/show/1208?cid=36

[essdipity]

Thanks for this, Jen. I'm too weary to look into this tonight, but will soon.

ess