I often get asked about this study, as every few months it will pop on social media with a catchy headline like “Fibromyalgia Mystery Solved!” I have seen it recycled so many times since the study was first published in 2013, always presented as a “new” finding.
While it sadly does not solve the mystery, it definitely gives us an important clue.
So let’s break down what this study really shows. They compared skin samples taken from the palms of people with fibromyalgia to those taken from healthy controls. They counted how many and what types of nerves were in each sample. Anyone who has burned their hand on hot stove or had a case of sweaty palms can tell you that everyone has both pain-sensing nerves and nerves that make us sweat in our hands. And that is exactly what the researchers found.
The samples from both groups contained both pain-sensing nerves (called sensory nerves) and nerves that regulate blood flow and sweating (called sympathetic nerves) clustered together near the small blood vessels in the skin. This is all normal and to be expected in any samples taken from skin in the hand.
So what’s the big deal? Well, they found that the fibromyalgia samples contained more of both types of nerves, but especially more of pain-sensing nerves. The researchers theorized that the excessive amount of pain-sensing nerves might be the cause of fibromyalgia pain. And certainly it does make some sense that “more pain-sensing nerves = more pain.”
However, other studies have found conflicting results and reported less than normal amounts of pain-sensing nerves in skin samples from the legs of fibromyalgia patients. So the jury is still out how much the actual amount of pain-sensing nerves contributes to pain.
No matter the amount of pain-sensing nerves, it is how they are functioning that matters for pain. And we know that in fibromyalgia, the pain-sensing nerves are not functioning correctly, because they are sending excessively high signals. The piece of the fibromyalgia mystery we have not figured out is what has triggered the pain-sensing nerves to go haywire. But the clue may be another finding in the skin samples: There were slightly more sympathetic nerves in the fibromyalgia patients.
And remember that sympathetic nerves are all tangled up with the pain-sensing nerves and these two types of nerves send signals back and forth to each other that affect how they work.
This is the most important piece to remember; that we already know that the fundamental problem in fibromyalgia is that the sympathetic nervous system—all the way from the brain to those tiny nerves in the hand—is malfunctioning and overactive. The sympathetic nervous system is also called the fight-or-flight system, and it is triggered in times of danger. But in fibromyalgia, this response has gone haywire and is active all the time, even when there is no danger, like a smoke alarm going off even though there is no smoke. You can find more detail on this in my book The FibroManual.
When sympathetic nerves are hyperactive, they leak chemicals that irritate pain-sensing nerves into sending louder signal, and this is what likely triggers the exceptionally loud pain signals of fibromyalgia. So it may not be the amount of pain-sensing nerves that matters as much as whether they are being sprinkled with irritating “lemon juice” from the sympathetic nerves around them.
For me the take-away from this study is that we need to focus more on the interplay between sensory and sympathetic nerves in fibromyalgia. While this study does not solve the fibromyalgia mystery, it is a clue to point us in the right direction to focus more on the sympathetic nerves and their effects on pain.