Summary: About half of a small group of patients with fibromyalgia — a common syndrome that causes chronic pain and other symptoms — was found to have damage to nerve fibers in their skin and other evidence of a disease called small-fiber polyneuropathy (SFPN). Unlike fibromyalgia, SFPN has a clear pathology and is known to be caused by specific medical conditions, some of which can be treated and sometimes cured.

About half of a small group of patients with fibromyalgia — a common syndrome that causes chronic pain and other symptoms — was found to have damage to nerve fibers in their skin and other evidence of a disease called small-fiber polyneuropathy (SFPN).

Unlike fibromyalgia, which has had no known causes and few effective treatments, SFPN has a clear pathology and is known to be caused by specific medical conditions, some of which can be treated and sometimes cured. The study from Massachusetts General Hospital (MGH) researchers will appear in the journal PAIN and has been released online.

“This provides some of the first objective evidence of a mechanism behind some cases of fibromyalgia, and identifying an underlying cause is the first step towards finding better treatments,” says Anne Louise Oaklander, MD, Ph.D., director of the Nerve Injury Unit in the MGH Department of Neurology and corresponding author of the Pain paper.

The term fibromyalgia describes a set of symptoms — including chronic widespread pain, increased sensitivity to pressure, and fatigue — that is believed to affect 1 to 5 percent of individuals in Western countries, more frequently women.

While a diagnosis of fibromyalgia has been recognized by the National Institutes of Health and the American College of Rheumatology, its biological basis has remained unknown. Fibromyalgia shares many symptoms with SFPN, a recognized cause of chronic widespread pain for which there are accepted, objective tests.

Designed to investigate possible connections between the two conditions, the current study enrolled 27 adult patients with fibromyalgia diagnoses and 30 healthy volunteers. Participants went through a battery of tests used to diagnose SFPN, including assessments of neuropathy based on a physical examination and responses to a questionnaire, skin biopsies to evaluate the number of nerve fibers in their lower legs, and tests of autonomic functions such as heart rate, blood pressure, and sweating.

The questionnaires, exam assessments, and skin biopsies all found significant levels of neuropathy in the fibromyalgia patients but not in the control group. Of the 27 fibromyalgia patients, 13 had a marked reduction in nerve fiber density, abnormal autonomic function tests, or both, indicating the presence of SFPN.

Participants who met criteria for SFPN also underwent blood tests for known causes of the disorder, and while none of them had results suggestive of diabetes, a common cause of SFPN, two were found to have hepatitis C virus infection, which can be successfully treated, and more than half had evidence of some type of immune system dysfunction.

“Until now, there has been no good idea about what causes fibromyalgia, but now we have evidence for some but not all patients. Fibromyalgia is too complex for a ‘one size fits all’ explanation,” says Oaklander, an associate professor of Neurology at Harvard Medical School.

“The next step of independent confirmation of our findings from other laboratories is already happening, and we also need to follow those patients who didn’t meet SFPN criteria to see if we can find other causes. Helping any of these people receive definitive diagnoses and better treatment would be a great accomplishment.”

The Connection Between Fibromyalgia and Leg Pain

If you’re reading this, it’s because you want to more about the F-word no one likes talking about – fibromyalgia, the mysterious chronic pain disorder that many people suffer from, silently. Because the list of symptoms varies so widely from person to person, doctors run the risk of misdiagnosing the problem or even overlooking it entirely.

As you’re probably aware, fibromyalgia can cause intense waves of numbing, throbbing, deep, sharp, or burning pain anywhere and everywhere. On top of more common symptoms such as fatigue, anxiety or depression, headaches, and memory problems, leg pain especially plagues fibromyalgia sufferers. [1]

Is It Normal to Get Leg Pain with Fibromyalgia?

Ask anyone with fibromyalgia to describe their pain and somewhere along the line, they will compare it to the inflammatory pain caused by tendinitis or osteoarthritis… That’s because fibromyalgia affects the body’s “tender points” which include tendons, muscles, and joints. [1]

According to Healthline, these points are spots on the body that are extremely painful, even if the slightest bit of pressure is applied. Doctors have identified nine pairs of tender points, for a total of 18, in order to help determine whether or not someone has fibromyalgia: [2]

Both sides of the back of the head
Both sides of the neck
Top of each shoulder
Shoulder blades
Both sides of the upper chest
Outside of each elbow
Both sides of the hips
Buttocks
Insides of the knees

Regardless of whether you’re laying down, sitting or standing up, leg pain persists and can worsen if you stay in the same position for too long. So, you can see how it can make things like working a sedentary job, sitting for dinner, or sleeping near impossible. You will often experience leg pain inside of each knee or on the hip, just behind the hip bone, and can travel to the surrounding area at least a few inches making the muscles feel weak.

What Contributes to or Causes Fibromyalgia Leg Pain?

Although researchers are still somewhat stumped on the root cause of fibromyalgia, there are some symptoms and conditions that may be able to shed some light…

Fibromyalgia and Restless Legs Syndrome

People with fibromyalgia have a higher chance of also having restless leg syndrome (RLS), according to a 2010 study published in the Journal of Clinical Sleep Medicine. [3] It’s a disorder that causes an unpleasant twitching sensation in the leg muscles that can only be remedied by fidgeting or moving your legs. [4]

Researchers gathered 172 fibromyalgia patients (93% of whom were women) and 63 people who reported being pain-and-fatigue-free. After looking at who had restless leg syndrome, they found that 33% of fibromyalgia patients had RLS. (Only 3% of the pain-and-fatigue-free group had the syndrome!) [3]

Fibromyalgia and Neuropathy

Painful tingling or burning sensations in the feet can occur in some fibromyalgia patients and it may be caused by something called neuropathy. In November 2013, a study published in the journal Pain explored the similarities between fibromyalgia and another disease called small-fiber polyneuropathy (SFPN), wherein small fibers in the skin become damaged. [5]

In the 57-person study, 27 of the participants had fibromyalgia. Researchers found that 46% of them had SFNP, “a recognized cause of chronic widespread pain for which there are accepted, objective tests.” [6]

“Until now, there has been no good idea about what causes fibromyalgia, but now we have evidence for some but not all patients,” said study author and associate professor of neurology at Harvard Medical School, Anne Louise Oaklander. [6] “Fibromyalgia is too complex for a ‘one size fits all’ explanation.”

Fibromyalgia and Tender Points

Also known as “trigger points,” the nine pairs mentioned above can result in excruciating leg pain. In addition to these tender points, existing arthritis might also trigger longer-lasting muscle and joint pain due to inflammation. Although arthritis pain doesn’t last as long as fibromyalgia pain, the two most common symptoms shared between the two are morning stiffness and dull achiness in the joints. [7]

Natural Remedies and Treatments for Fibromyalgia Leg Pain

Until researchers are able to narrow down the true cause of fibromyalgia, it may be a long time before effective natural treatments become known. However, there are smaller yet significant steps fibromyalgia sufferers can take in order to live fuller, less painful lives. Here are some of them…