06/05/2025
A nerve is like a wire. It carries electrical impulses. When a nerve is injured, it conducts fewer electrical impulses. Skin goes numb, muscles go weak. Just like a snipped wire makes a TV go dead.
But that doesn’t explain neuropathic pain. Unlike a snipped wire, an injured nerve also conducts more impulses. Pain, pins and needles…
That sounds like a paradox.
If you shift your perspective to think of the nerve as a living thing, it makes more sense.
Nerve cells are busy. They’re constantly building ion channels and shuttling them to the cell's membrane, where the ion channels can spark and carry electrical impulses.
Now imagine that nerve cell is injured.
The ion channels at the site of injury won’t be able to spark and carry those electrical impulses any more. Skin goes numb, muscles go weak - as expected.
And here’s what doesn’t happen in a wire: the injured nerve cell makes more ion channels. The whole cell becomes super-excitable. In fact, many of these ion channels bunch up at the site of the injury, creating an electrical ‘hot spot’, where rogue impulses can spark.
Why does this happen? Probably, it’s accidental: the nerve cell, when injured, can’t regulate how many ion channels it produces, so they just keep churning out. Or, it might be deliberate: the nerve cell senses danger and the extra ion channels help it to keep the lights on.
In any case, the paradox - that the nerve works less and works more - only looks like a paradox if you’re thinking like an electrician. Think like a biologist, and it makes sense.
Tom Jesson
