Fibromyalgia

Synonyms: fibromyalgia syndrome, fibrositis

Fibromyalgia is a chronic pain disorder. The cause of fibromyalgia is unknown, but there is some evidence for a genetic predisposition, abnormalities in the stress response system or hypothalamic-pituitary axis, and possible triggering events.¹

Epidemiology^{2 3}

• It is thought that the condition is common and underdiagnosed.

• The estimated prevalence in America and other countries is 2-3%.

• Women are 10 times more commonly affected than men.

• Usual age of presentation is 20-50 years but it has been diagnosed in children, adolescents and older people.

• There is a link to failing to complete education, low income and being divorced.

• It is more common in people who have a rheumatic disease.

Pathophysiology

• The exact pathophysiology is not known. Hypotheses include:
  

  • Peripheral and central hyperexcitability at spinal or brainstem level.

  • Altered pain perception.

  • Somatisation.

• The nociceptive system has links with the stress regulating, immune and sleep systems which may explain some of the clinical features.⁴ Recent studies have postulated the involvement of mast cells and their products, such as tumour necrosis factor (TNF), interleukin (IL)-1 and IL-6, which cause hyperalgesia in rodents. Several studies have also reported an association between reduced levels of 25 hydroxyvitamin D3 (25(OH)D3) and chronic pain in patients with arthritis and fibromyalgia.⁵

• Research has reported a consistent association among genetic factors, psychological symptoms and pain associated with fibromyalgia.⁶

History

Symptoms of fibromyalgia are chronic widespread pain associated with unrefreshing sleep and tiredness. Fibromyalgia is not a diagnosis of exclusion and often occurs in patients with other conditions, such as inflammatory arthritis and osteoarthritis.⁷ The patient may complain of:

• Pain at multiple sites. Low back pain with/without radiation to the buttocks and legs and pain in the neck and across the shoulders are common complaints.² Patients may complain of "pain all over".

• Fatigue.

• Sleep disturbance (sleep may exacerbate symptoms and contribute to depression).⁸

• Morning stiffness.

• Paraesthesiae.

• Feeling of swollen joints (with no objective swelling).

• Problems with cognition (eg, memory disturbance, difficulty with word finding).

• Headaches (may be migrainous).

• Light-headedness or dizziness.

• Fluctuations in weight.

• Anxiety and depression.

Symptoms are generally reported as worse in cold, humid weather and under times of stress.²

Diagnosis²

• The American College of Rheumatology produced classification criteria for fibromyalgia. However, these criteria are not meant to be used for diagnosis.

A patient fulfils the diagnostic criteria for fibromyalgia if the following three conditions are met:

• Widespread pain index (WPI) is 7 and symptom severity (SS) scale score is 5, or WPI equals 3 to 6 and SS scale score of 9.

• Symptomatology has been present at a similar level for at least three months.

• The patient does not demonstrate any other disorder that would otherwise explain the pain.

• Routine blood testing can help to exclude other differential diagnoses: eg, ESR, TFTs, antinuclear antibodies. However, be careful not to over-investigate.

• Peripheral nerve dysfunction is increasingly being associated with the pathophysiology of fibromyalgia, small nerve fibre neuropathy being identified as being central to the aetiology of this condition. Electrodiagnostic study, including testing of distal (sural and plantar) nerve action potentials and quantitative sudomotor axon reflex testing, has been used in the research arena, and may well be incorporated into mainstream investigative procedures in the future.⁹

Assessment

• The Fibromyalgia Impact Questionnaire can be used to assess function.¹⁰ It also has a role in review and assessment of treatment interventions.

• A full social, personal, family and psychological history should be taken. There may be an interplay with stress, psychosocial experiences, the psychosocial situation and sociocultural factors.

Associated conditions²

• Generalised anxiety.

• Depression.

• Irritable bowel syndrome.

• Irritable bladder.

• Dysmenorrhoea.

• Premenstrual syndrome.

• Restless legs syndrome.

• Non-cardiac chest pain.

• Temporomandibular joint pain.

• Raynaud's phenomenon.

• Sicca syndrome (dryness of the eyes, mouth and other body parts).

• Rheumatoid arthritis: approximately 25% of patients with rheumatoid arthritis also have fibromyalgia.

• Systemic lupus erythematosus (SLE): approximately 50% of patients with SLE also have fibromyalgia.

Differential diagnosis

• Chronic fatigue syndrome.

• Hypothyroidism.

• Polymyalgia rheumatica.

• Inflammatory and metabolic myopathies.

• Polymyositis.

Management

The aim of treatment is not to cure fibromyalgia but to reduce symptoms and improve quality of life. Individual drugs are often ineffective or cause side-effects so it is important to consider a change in drug or a switch to non-drug approaches - eg, cognitive behavioural therapy or exercise.⁷

General points

• Pain and function should be assessed in a psychosocial context.

• A multidisciplinary approach to treatment should be used. GPs, rheumatologists, physicians experienced in dealing with chronic pain, psychologists, psychiatrists, physiotherapists, etc, may all need to be involved.¹¹

• Treatments should be discussed with the patient and tailored to their individual needs, including pain levels, function and associated features such as depression, fatigue and sleep disturbance.

Non-drug treatments

• Exercise programmes including aerobic exercise and strength training may help some patients with fibromyalgia.⁴ The Ottawa Panel also recommends aerobic fitness and strengthening exercise for the management of fibromyalgia.^{12 13}

• A Cochrane review reports 'gold-level evidence' that moderate-intensity supervised aerobic exercise improves overall well-being and physical function in fibromyalgia.¹⁴ From a practical point of view, they recommend:

  • Slowly increasing the intensity of exercise.

  • If symptoms worsen, cutting back on exercise until symptoms improve.

• There is some evidence that aquatic training is beneficial for improving wellness, symptoms and fitness levels in adults with fibromyalgia.¹⁵

• Moderate to high intensity resistance training may improve function, pain, tenderness and muscle strength in women with fibromyalgia.¹⁶

• Cognitive behavioural therapy may help some patients with fibromyalgia.¹⁷

• Therapies including relaxation, rehabilitation, physiotherapy and psychological support may help some people with fibromyalgia.

• A Cochrane review of acupuncture for fibromyalgia concluded:¹⁸
  

  • There is low- to moderate-level evidence that acupuncture improves pain and stiffness in people with fibromyalgia.

  • There is moderate-level evidence that the effect of acupuncture does not differ from sham acupuncture in reducing pain or fatigue, or improving sleep or global well-being.

  • Electro-acupuncture (EA) is probably better than manual acupuncture (MA) for pain and stiffness reduction and improvement of global well-being, sleep and fatigue. The effect lasts up to one month, but is not maintained at follow-up after six months.

  • MA probably does not improve pain or physical functioning.

  • Acupuncture appears safe. People with fibromyalgia may consider using EA alone or with exercise and medication.

  • Small sample size, scarcity of studies for each comparison, and lack of an ideal sham acupuncture weakened the level of evidence and its clinical implications.

Drug treatment

• The National Institute for Health and Care Excellence (NICE) has issued new guidance on chronic pain.¹⁹ It centres largely on the diagnosis and management of chronic primary pain, such as that seen in fibromyalgia. The main tenets of the guidance include:

  • The importance of a multidisciplinary approach.

  • The encouragement of self-management from an early stage of a pain condition and as part of a long-term management strategy.

  • Focus on non-pharmacological management.

  • Treatment aimed at improving function (with realistic goals) and changing pain behaviour.

  • Minimising or if possible avoiding use of opioids for chronic primary pain.

  • Recognition of the potential for dependence with pregabalin, gabapentin.

  • Cannabis-based medicinal products should not be used for managing chronic pain.

  • Consider an antidepressant, either amitriptyline, citalopram, duloxetine, fluoxetine, paroxetine or sertraline for chronic primary pain.

  • Do not initiate any of the following medicines to manage chronic primary pain:
    

    • Antiepileptic drugs, including gabapentinoids (eg, gabapentin or pregabalin).

    • Antipsychotic drugs.

    • Benzodiazepines.

    • Corticosteroid, or local anaesthetic/corticosteroid combination, trigger point injections.

    • Ketamine.

    • Local anaesthetics (topical or intravenous).

    • Non-steroidal anti-inflammatory drugs.

    • Opioids.

    • Paracetamol.

  Please see the separate Chronic Pain article for more details.

• Corticosteroids are not recommended. This is due to the lack of evidence from clinical trials and the long-term side-effects.

• Co-enzyme Q, a food supplement which enhances mitochondrial activity, has been shown in randomised controlled trials to be useful in combating fatigue and other symptoms associated with fibromyalgia.²⁰

Prognosis

• Awareness surrounding fibromyalgia has risen in recent years.

• Fibromyalgia continues to be associated with substantial socio-economic loss.²²

• It is difficult to predict the prognosis of fibromyalgia, due to the complex interplay of the social and psychological factors in the pathophysiology and symptomology of this condition.