Adventures in Podiatry and Neurology

WARNING: THIS ONE IS GRAPHIC EVEN BY MY STANDARDS.  NEEDLES, PAIN, AND TOENAILS.

Recently I learned toenails aren’t supposed to be under the skin of your foot and hurt constantly; this is an ingrown toenail and it’s a solvable problem.  By “recently” I mean a year and a half ago, but a little pain when I flexed my toes in a shoe did not seem as important as the pain in my mouth or my inability to digest food, so I only got around to seeing a podiatrist now.  If you develop an ingrown toenail there are home treatments to coax it better, but if you’ve always had it the cure is a little more drastic: they cut off the bit of the nail that has grown under the skin and cauterize the nail bed so it never grows back. If you are curious, here’s a video of the actual medical procedure:

The worst part is the lidocaine injection. There’s a topical anesthetic, but they root the extremely thin nail around under your skin in order to find the nerves and inject directly over them. The podiatrist will describe it as slightly painful, but they are lying, and it will make you doubt them when they promise the rest of the procedure is painless. That part turned out to be true: with enough lidocaine you genuinely can’t feel them slip the scissors/pliers under the nail bed, or the burny stuff*, unless you are a freak who processes -cain very quickly, in which case they will give you more and it will stop hurting.  But the anesthetic injection was pretty brutal.

That is not actually the interesting part. In between the lidocaine and the scissors/pliers, they test your numbness with what looked like a large blunt toothpick. My podiatrist, which more flourish then was strictly necessary, brought it down from a great height onto my toe.

I screamed.

Then I realized it didn’t hurt at all. My brain had combined the memory of the painful needles and the visual information about incoming sensation and preemptively sent a scream response before it noticed I couldn’t feel anything. I never had quite that strong a reaction again, but there was an extremely weird dissonance as I watched something I knew should hurt, yet got only vague reports of pressure from the area.

This works in reverse too.  Phantom limb syndrome is a condition in which people missing a limb (even one they never had) experience excruciating pain where their brain thinks that limb should be.  One of the only effective treatments is mirror therapy, where a mirror is used to simulate the appearance of the missing limb, and somehow the brain goes “oh, I guess it’s fine.”  This clip from House is not quite as accurate as the matrixectomy one (mirror therapy rarely involves kidnapping), but the science is sound.

The lesson here is that even something that feels incredibly simple and real, like pain, is in fact an artifact of post-processing on several different inputs.

*Dr. Internet says phenol but I could have sworn it started with an M. In my defense, he gave me the proper name after the needles bit and I was fuzzy.