Why is neck pain so common? Spatial summation of cryptic insults

If five bees stung you all at once, in one small area on the back of your neck, you would probably think you had been stung by one super-bee. Or maybe that you’d been poked with a cattle prod.

Two sources of pain close together are often felt as one larger painful spot, a neurological effect called “spatial summation.” Pain perception is low resolution and fuzzy, and the brain can merge pains that are up to about 20cm apart. There are two ways that this might explain why some areas of the body, like the neck and back, are such common places for people to hurt:

1. Maybe the brain can “sum” more widely spaced sources of pain in some places than others.
2. And/or some areas simply have more to sum up, more potential sources of pain.

The first possibility was probably eliminated just recently (see Holbert). This makes it even more likely that there’s probably just more sources of pain in the neck to add up. Spines are super complex anatomically; there are many potential sources of tissue irritation that can be perceptually glued together.

For example, if you have one cranky facet joint on the left side of your third cervical vertebra, and another on the right side of your fourth, you might not be able to tell them apart. All you know is that the middle of your neck hurts — and hurts worse than you’d expect from any one minor problem. Because there actually is more than one minor problem.

This may also explain the chronicity of spinal pain: if you have “one” neck pain problem that’s actually coming from two nearby sources, you’re going to think you have same neck pain problem until both sources back off.

And if you have 4-6 minor sources of discomfort? All constantly easing and flaring up randomly, at least a couple of them active to some degree at any one time? That will probably just feel like one endless pain in the neck with erratic changes in intensity, and an epicentre that drifts around a bit.

And that’s going to sound familiar to a lot of neck pain patients.

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This is an abridged excerpt from a recent update to my neck pain book (paywalled content). The book continues with a discussion of “cryptic insults,” which sounds like something from a Monty Python sketch.? But I mean threats to tissues that we can’t see or understand from context. And “when in doubt, the pain system is fine tuned by hundreds of millions of years of animal evolution to err on the side of louder, longer alarms.”