Fibromyalgia is a complex chronic pain condition that affects millions of people worldwide. It is characterized by widespread muscle pain, fatigue, sleep disturbances, and cognitive difficulties. While the exact causes are still unknown, some researchers believe fibromyalgia may be related to abnormalities in how the body processes pain, rather than a problem with the muscles and connective tissues themselves. However, there is an ongoing debate about whether fibromyalgia should be classified as a connective tissue disorder. Here is a closer look at the evidence surrounding this question.
Symptoms of Fibromyalgia
The primary symptoms of fibromyalgia include:
- Widespread muscle pain and tenderness to touch
- Fatigue
- Sleep disturbances
- Cognitive dysfunction (brain fog)
- Headaches
- Numbness or tingling
- Irritable bowel syndrome
- Painful menstrual cramps
- Anxiety or depression
The pain associated with fibromyalgia often waxes and wanes in intensity. It typically occurs above and below the waist and on both sides of the body. People with fibromyalgia are extra sensitive to pressure in certain “tender points” throughout the body. Fatigue from fibromyalgia can range from mild to debilitating.
Criteria for Diagnosis
There are no lab tests that can definitively diagnose fibromyalgia. Instead, doctors diagnose it based on the patient’s symptoms and a physical exam.
The American College of Rheumatology has established diagnostic criteria that include:
- Widespread pain occurring on both sides of the body, above and below the waist, that persists for at least 3 months.
- Pain or tenderness at least 11 of 18 specific tender point sites when firm pressure is applied.
Other common symptoms like fatigue, sleep problems, and cognitive dysfunction may support the diagnosis but are not part of the official diagnostic criteria.
Who Develops Fibromyalgia?
An estimated 2-8% of the population has fibromyalgia, with a higher prevalence in women. While it can occur at any age, symptoms most commonly begin between the ages of 30-50.
There are some factors believed to increase the risk:
- Genetics – Fibromyalgia seems to run in families, although no specific genes have been identified.
- Sex – It occurs about 7 times more often in women than men.
- Rheumatic disease – People with lupus, rheumatoid arthritis or ankylosing spondylitis have an increased risk.
- Trauma or infection – Physical trauma, psychological stress, or a viral illness may trigger the development.
Possible Causes
While the exact cause is still unknown, most experts believe fibromyalgia results from abnormalities in how pain signals are processed in the central nervous system. Possible factors include:
- Chemical imbalances – Altered levels of certain chemicals that transmit pain signals, like serotonin, norepinephrine, and substance P, have been found.
- Inflammation – Some believe low levels of inflammation in the brain and spinal cord may sensitize nerves and amplify pain signaling.
- Sleep disturbances – Disruptions to deep restorative sleep negatively affect pain perception.
- Genetics – Susceptibility genes could make people more prone to developing fibromyalgia.
- Stress response – High levels of stress hormones may alter the pain threshold.
In contrast, there is little evidence that fibromyalgia is caused by actual damage to muscles, joints or soft tissues. Many people with fibromyalgia have tender points, but these areas appear normal when imaged.
Why Some Categorize Fibromyalgia as a Connective Tissue Disorder
Connective tissue consists of fibrous bands or fibers that provide structure and support to other tissues and organs. Examples include tendons, ligaments, cartilage, bone, and fascia.
Some doctors consider fibromyalgia a disorder of the connective tissues for the following reasons:
- Many patients experience tenderness at connective tissue sites when palpated.
- Fibromyalgia can co-occur with rheumatic diseases like lupus that are classified as connective tissue disorders.
- There may be some overlap or interactions between the autonomic nervous system and connective tissues involved in pain perception.
- Tender points correspond with locations of connective tissue.
- Alterations in connective tissue morphology and biochemistry have been observed.
However, most experts argue the evidence does not conclusively prove that disturbances in connective tissues are the direct or sole cause of fibromyalgia pain and other symptoms.
Arguments Against Classifying Fibromyalgia as a Connective Tissue Disease
While fibromyalgia does involve widespread pain, most research indicates the underlying problem stems from abnormal sensory processing rather than damage to muscle or connective tissue:
- No consistent abnormalities in muscle strength, reflexes, or joint function have been found.
- No inflammation, damage, or fibrosis are seen when tender points are biopsied or imaged.
- Tender points are not the same as trigger points that occur in myofascial pain syndrome.
- Pain levels are not correlated with supposed tissue abnormalities.
- Medications that improve CNS pain processing often help fibromyalgia pain.
- The central nervous system plays a key role in pain perception and modulation.
Additionally, some features of fibromyalgia differ from classical connective tissue diseases:
- No autoantibodies or joint deformities characteristic of rheumatoid arthritis, lupus, or mixed connective tissue disease.
- No inflammation of the blood vessels, lungs, or kidneys seen in other connective tissue disorders.
- No abnormal immune system activation or damaged connective tissues.
For these reasons, many rheumatologists do not recommend classifying fibromyalgia as a primary connective tissue disease.
Fibromyalgia Has Some Similarities with Connective Tissue Diseases
Although the evidence does not indicate damaged connective tissues cause fibromyalgia, there are some overlaps and similarities with bonafide connective tissue disorders:
- Some research shows connective tissue differences in fibromyalgia patients, such as reduced collagen and elevated mast cells.
- Fibromyalgia commonly coexists and overlaps with autoimmune rheumatic diseases.
- Therapies that improve connective tissue inflammation may help some fibromyalgia symptoms.
- Dysregulation of the autonomic nervous system can result in pain amplification.
- Tender points in locations used to diagnose fibromyalgia correspond to connective tissue sites.
So while abnormalities in connective tissues do not appear to be the direct, underlying cause of fibromyalgia pain and fatigue, changes in connective tissues may contribute to increased pain perception in some patients. More research is needed to better understand the degree of interaction between the central nervous system and connective tissues in fibromyalgia.
Is Fibromyalgia an Autoimmune Disease?
Autoimmune diseases occur when the immune system mistakenly attacks healthy cells. Some connective tissue diseases like lupus and rheumatoid arthritis are autoimmune conditions. But most experts agree fibromyalgia does not fit the criteria for an autoimmune disease:
- No autoantibodies have been found.
- It lacks signs of inflammation commonly seen in autoimmune diseases.
- No specific organs are targeted or damaged.
- Immunosuppressant drugs typically used for autoimmune disorders are ineffective for fibromyalgia.
However, fibromyalgia does sometimes co-occur with autoimmune diseases for reasons not fully known. There are a few possible explanations:
- The stress of having an autoimmune disease could trigger fibromyalgia in some patients.
- Genetic factors could predispose someone to developing both conditions.
- Fibromyalgia could be an extension of central sensitization caused by inflammation from an autoimmune disorder.
- Shared neuroendocrine-immune factors may contribute to both conditions in susceptible people.
More research is needed, but most evidence indicates fibromyalgia does not meet the criteria for classification as an autoimmune disease.
Fibromyalgia Has Some Overlap with Chronic Fatigue Syndrome
Like fibromyalgia, chronic fatigue syndrome (CFS) is characterized by widespread pain, fatigue, cognitive dysfunction and sleep disorders. The two conditions have similar symptoms and often co-occur.
It has been estimated that between 20-70% of people with fibromyalgia also meet diagnostic criteria for CFS. Up to 90% of those with CFS experience symptoms of fibromyalgia.
Some key similarities:
- Widespread muscle aches and pain
- Extreme, persistent fatigue
- Sleep disturbances
- Problems with memory and concentration
- Headaches
- Irritable bowel syndrome
- Depression or anxiety
Due to the considerable overlap, some researchers have proposed that fibromyalgia and CFS represent different manifestations of a similar underlying condition affecting the nervous system and pain perception. However, there are also differences:
- CFS is more likely to arise suddenly after a viral infection.
- Those with CFS experience post-exertional malaise.
- Pain and tenderness may be more widespread in fibromyalgia.
- Fibromyalgia has a higher prevalence of anxiety disorders.
The cause of CFS is also unknown but thought to be related to immune, nervous system and stress response interactions. More study is needed to determine to what degree fibromyalgia and CFS share causal factors.
Treatment Options for Fibromyalgia
While there is no cure for fibromyalgia, many different medications and lifestyle approaches can help provide symptom relief. Common treatment options include:
- Pain relievers – Over-the-counter medications like acetaminophen, ibuprofen or naproxen can help mild pain. Prescription opioids or tramadol may be options for more severe pain.
- Antidepressants – Certain tricyclic antidepressants and SNRIs can reduce pain and improve sleep.
- Anti-seizure drugs – Medications like gabapentin and pregabalin can calm overactive nerves and reduce pain.
- Therapy – Cognitive behavioral therapy and counseling helps people cope with fibromyalgia.
- Exercise – Low-impact activities like walking, swimming, yoga, or tai chi are recommended.
- Massage – Massage therapy can help relax muscles and temporarily relieve pain.
- Acupuncture – Fine needles are inserted into trigger points that may reduce fibromyalgia pain.
- Improved sleep habits – Maintaining a regular sleep-wake cycle, limiting caffeine, and reducing stress can improve sleep.
An integrated treatment approach combining medications, lifestyle changes, and alternative therapies generally works best for most people with fibromyalgia.
Conclusion
Fibromyalgia is a complex disorder that shares some similarities with diseases affecting connective tissues but lacks key features of traditional connective tissue disorders. The bulk of evidence indicates fibromyalgia results primarily from disordered pain processing rather than identifiable abnormalities or damage to muscles, joints or connective tissues. While heightened pain perception may involve nervous system interactions with connective tissues, fibromyalgia does not meet criteria for classification as a connective tissue disease itself. More research is still needed to better understand the root causes of fibromyalgia which are likely multifactorial. A combination of medications, lifestyle changes, and complementary therapies focused on reducing widespread pain, fatigue and sleep disturbances typically provides the greatest relief. Ongoing management of fibromyalgia requires an individualized, patient-centered approach.