The rhythm of throbbing pain

Is your pain a throbbing pain? Pain often has a pulsating quality, especially when it’s severe and acute. If you’ve ever thought about why it pulses, you probably assumed that it’s pulsating with your pulse. Heck, “pulsatile pain” is actually a clinical term used to describe throbbing pain that is assumed to be surging in time with the arterial pulse.

I have always particularly noticed the throbbing of little infections — like a hangnail that’s gotten out of hand — and I always thought that I was feeling the blood pushing through the ultra-sensitized tissue.

But Mirza et al just checked that assumption… and got a fun science surprise. They checked in a bunch of patients with jack-hammering dental pain, getting them to tap out the rhythm of their throbbing with a button… and discovered that their throbs were actually much slower than their heart rates, almost half the pace, just not in sync. They were clearly different rhythms! Not so pulsatile after all.

That’s a fascinating upset to conventional wisdom.

The authors cannot definitively explain what does set the rhythm of the throb, but they did take a crack at it: “an emergent property, or perception, whose “pacemaker” lies within the CNS." (Which is a bit of a hand wave. Perception and the brain can explain anything. Try it sometime!)

Reality is always more complicated than the conventional wisdom or a slam-dunk of a debunk. The safe bet is that there are several kinds of throbbing pain. I doubt anyone will be checking them all anytime soon, so we can just enjoy the uncertainty indefinitely. But I definitely suspect that some of our throbbing pains actually are pulsatile. Like that infected hangnail, maybe. Ow, ow, ow, ow, ow…