Fibromyalgia overview

# Overview
Fibromyalgia (FM) is a disorder characterized by the presence of chronic, widespread pain and tactile allodynia. The criteria for this disease have not yet been thoroughly developed. The recognition that fibromyalgia involves more than just pain has led to the frequent use of the term "fibromyalgia syndrome." It is not contagious and recent studies suggest that some people with fibromyalgia may be genetically predisposed. The disorder is not directly life-threatening. The degree of symptoms may vary greatly from day to day with periods of flares (severe worsening of symptoms) or remission; however, the disorder is generally thought to be non-progressive.

# Historical Perspective
In 1900, the first case study of fibromyalgia was conducted. It was known by other names such as muscular rheumatism and fibrosita. In 1904, Sir William Gowers coined the term fibrositis. In 1976, Dr. P.K. Hench used the term "fibromyalgia" for the first time.

# Classification
ICD11 classifies fibromyalgia as category of chronic widespread primary pain.
DSM 5 divides fibromyalgia into four groups based on the differences in psychological and autonomic nervous system profiles among affected individuals. These four groups are: extreme sensitivity to pain with no associated psychiatric conditions, fibromyalgia with comorbid pain-related depression, depression with concomitant fibromyalgia syndrome, and fibromyalgia due to somatization.

# Pathophysiology
The exact cause of fibromyalgia is unknown. Multiple factors are believed to influence the development of fibromyalgia. Various hypotheses have been offered describing the pathogenesis of fibromyalgia. It is understood that Lyme disease may be a trigger of the symptoms of fibromyalgia. It is suggested that more than one clinical entity may be involved in the pathogenesis of fibromyalgia, ranging from a mild, idiopathic inflammatory process to clinical depression.

# Causes
The exact cause of fibromyalgia is not known. Common trigers of fibromyalgia include is unknown physical or emotional trauma, abnormal pain response (areas in the brain that are responsible for pain may react differently in fibromyalgia patients), sleep disturbances, or infection, such as a virus, although no specific viruses have been identified as a triger of fibromyalgia.

# Differentiating Fibromyalgia from other Diseases
Fibromyalgia must be differentiated from other diseases that present with pain, fatigue, and sleep disturbance, and symptoms of cognitive dysfunction and psychiatric disease which include rheumatoid arthritis, SLE, chronic fatigue syndrome, spondyloarthritis, and polymyalgia rheumatica.

# Epidemiology and Demographics
The prevalence of fibromyalgia in the United States was reported to range from 500-5,000 per 100,000 people. Females are more commonly affected than males with a ratio of 9:1. People between 20 and 50 years old are more commonly affected. Fibromyalgia has no racial predilection.

# Risk Factors
Common risk factors in the development of fibromyalgia include stressful or traumatic events, such as car accidents or post-traumatic stress disorder (PTSD), injuries from repetitive stress on a joint such as frequent knee bending, illness (such as viral infections), or obesity. Family history of fibromyalgia is also a common risk factor.

# Screening
There is insufficient evidence for the screening of fibromyalgia.

# Natural History, Complications and Prognosis
Fibromyalgia is a long-term disorder. If left untreated, chronic pain could cause permanent changes in how the body perceives pain. Complications that can develop as a result of fibromyalgia include marked functional impairment, depression, anxiety, insomnia, obesity, and allodynia. Factors associated with poor outcomes are female gender, low socioeconomic status, and being unemployed. Even with appropriate treatment, though symptoms of fibromyalgia sometimes improve, the pain may get worse and continue for months or years.

# Diagnosis

## Diagnostic Criteria
The most widely accepted set of diagnostic criteria for fibromyalgia was elaborated in 2010 by the Multicenter Criteria Committee of the the American College of Rheumatology. A patient satisfies diagnostic criteria for fibromyalgia if the following 3 conditions are met:
- Widespread pain index (WPI) > 7 and symptom severity (SS) scale score >5 or WPI 36 and SS scale score >9.
- Symptoms have been present at a similar level for at least 3 months.
- The patient does not have a disorder that would otherwise explain the pain.

## History and Symptoms
The defining symptoms of fibromyalgia are chronic, widespread pain and tenderness to light touch.

## Physical Examination
A physical examination helps not only to confirm the diagnosis of fibromyalgia but also to rule out other systemic diseases. A careful physical examination also helps in identifying associated conditions. The tender-point examination is the most important aspect of the physical examination; other aspects of the examination are typically normal in fibromyalgia patients.

## Laboratory Findings
Blood and urine tests are usually normal in a patient with fibromyalgia. However, tests may be done to rule out other conditions that may have similar symptoms.

## Fibromyalgia X-ray Findings
There are no X-ray findings associated with fibromyalgia.

## CT
There are no CT findings associated with fibromyalgia.

## MRI
There are no MRI findings associated with fibromyalgia.

## Ultrasound
There are no ultrasound findings associated with fibromyalgia.

## Other Imaging Findings
There are no other imaging findings associated with fibromyalgia.

## Other Diagnostic Studies
There are no other specific diagnostic findings associated with fibromyalgia.

# Treatment
There is no universally accepted treatment or cure for fibromyalgia, and treatment typically consists of symptom management. Treatment options include medications, patient education, aerobic exercise, and cognitive behavioral therapy, which have been shown to be effective in alleviating pain and other fibromyalgia-related symptoms.

## Medical Therapy
Medical therapy includes analgesics, antidepressants, skeletal muscle relaxants, anticonvulsants, and anti-anxiety medications.

## Psychotherapy
Although there is no universally accepted cure, some doctors have claimed to have successfully treated fibromyalgia stemming from a psychological cause. As the nature of fibromyalgia is not well understood, some physicians believe that it may be psychosomatic or psychogenic. Cognitive behavioral therapy has been shown to improve the quality of life and coping in fibromyalgia patients and other sufferers of chronic pain.

## Surgery
Surgical intervention is not recommended for the management of fibromyalgia.

## Primary Prevention
There is no established method of prevention of fibromyalgia.

## Secondary Prevention
There are no specific secondary preventive measures available for fibromyalgia. However, proper treatment and lifestyle changes can help reduce the frequency and severity of symptoms. Secondary preventive measures for fibromyalgia include adequate sleep, reducing emotional and mental stress, regular exercise, following a balanced diet, and monitoring one's own symptoms.

## Future or Investigational Therapies
Several drugs, including milnacipran, guaifenesin, and dextromethorphan, are being investigated as potential therapies for fibromyalgia. Milnacipran is a serotonin-norepinephrine reuptake inhibitor (SNRI), and a Phase III study demonstrated statistically significant therapeutic effects of the drug as a treatment for fibromyalgia syndrome. Guaifenesin is a more controversial potential therapy, and a study by researchers at Oregon Health Science University in Portland failed to demonstrate any benefits from this treatment, though results of the study have since been contested. Dextromethorphan is an over-the-counter cough medicine that has been used in research settings to investigate the nature of fibromyalgia pain, but there are no controlled trials of its safety or efficacy in clinical use.