Pins and Needles: When our Nerves Freak the Heck Out
A few days ago, I experienced (for the umpteenth time in my life) one of the most unusual and unpleasant sensations that we humans frequently have to endure.
Picture this: there I am, just sitting cross-legged on one of those little milk-crate stools outside my favourite local coffee shop. I’m just enjoying my double espresso, and a hilarious albeit convoluted conversation with my friend about official definitional difference between a pin and a needle. (If you were wondering: the jury is still out on the actual distinction).
Then suddenly, as though my left foot had gained sentience and known what we were talking about, I was assaulted by what felt like a swarm of fire ants; each armed with their own freshly sharpened blade. Yup, that’s right. I was rudely and abruptly hit with the sensation of pins and needles.
But what, if not a throng of armed fire ants attacking, was actually happening inside my foot!?
As it turns out, “Pins and Needles” is not actually the scientific term for it. Clinicians formally call this sensation “Paraesthesia”, and it refers to that horrible tingling sensation you get in your fingers or toes when you’ve been sitting down for too long in an awkward position. It can range anywhere from a gentle tingle, through to the extreme stabby stabby fire-ant style pain I felt the other day.
It essentially occurs when the blood supply to your peripheral nerves gets shut off for a period of time. More serious cases of this can be caused by something like a tumour, or multiple sclerosis. Most of the time, however, it simply arises from something silly like crossing your legs for too long.
So, what happens when you cut off blood supply to a cell? That cell can no longer get the oxygen or nutrients it needs to function properly. This is exactly what happened to the nerve cells in my foot. Presumably due to the strange way I like to sit cross-legged on stools, the blood vessels responsible for supplying blood to these nerves got compressed and could no longer deliver nutrient-rich goodness to my foot.
Nerve cells transmit sensations back to the brain as electrical signals: Picture by National Center for Advancing Translational Sciences via Flickr
Now, the job of these nerve cells is to send the signals for touch, pain, and temperature back to the brain. When they don’t get adequate blood supply, they begin to malfunction and can actually stop sending signals all together. This is why we sometimes feel our limbs start to go to sleep after sitting a certain way.
Sometimes we might notice this numbness and actively rearrange our position to fix it. Other times, like my unsuspecting self the other day, we might not even notice any numbness and just subconsciously shift ourselves into a less blood-restrictive position.
Either way; BAM! A sudden onslaught of prickly fire ants hits your appendage.
But why did this position rearrangement cause such a weird and even painful feeling? Well, remember that the blood flow that was previously blocked off? After I shifted position, the flood gates were opened, and blood was allowed to go flooding back down to those nerves in my foot.
So, all should be fine and dandy again now, right? Back to our regularly scheduled touch-signalling? Unfortunately, not. The problem is that when my poor unsuspecting nerve cells got hit with a sudden batch of blood after being deprived, they freaked out a little bit. They began to misfire, and over-fire. The resulting signal then arrived in my brain as a warped kind of touch and pain sensation. This is what is experienced as pins and needles!
Even though pins and needles normally don’t last for long, there is no denying that it is an unpleasant feeling. So, is there any way to make this feeling go away faster?
Apparently, the approach I took the other day of repeatedly stamping my foot on the ground in an attempt to kill all the fire ants in my foot is not as ridiculous as it sounds. Doing this is actually effective at making the sensation fade faster, because it gets the blood pumping regularly again much quicker. The unfortunate trade-off is that doing this will flood your nerve cells with much more blood initially, so the pain of the pins and needles will probably be worse. It’s up to you whether you think that is worth it or not!