Fibromyalgia
Fibromyalgia is a form of chronic primary pain.
Chronic pain is pain that persists or recurs for >3 months and may be classified as:
- Chronic secondary pain: pain attributable to an underlying condition, such as osteoarthritis, rheumatoid arthritis, endometriosis or ulcerative colitis
- Chronic primary pain: pain for which no underlying condition adequately accounts for the symptoms, or where the pain and its impact are disproportionate to any observable injury or disease
Causes and Risk Factors
Fibromyalgia is a chronic primary pain condition and is considered a complex, multifactorial disorder. [Ref]
- Females
- Onset is typically 30-35 y/o
- Genetic factors
- Physical / emotional trauma
- Chronic stress
- Psychiatric comorbidities
- Obesity
Pathophysiology
A very simplified and high-yield extract of pathological mechanisms: [Ref]
- Central sensitisation (amplification of neuronal signals in the CNS, driven by ↑ excitatory neurotransmitters and ↓ inhibitory neurotransmitters)
- Peripheral abnormalities, including
- Structural changes in pain nerve fibres (C fibres and Aδ fibres)
- Tissue damage
- Local neurogenic inflammation
- Dysregulation of the hypothalamic-pituitary-adrenal axis
- Sleep disturbances are a possible causative factor that precedes and predicts the onset of pain
- Neurogenic inflammation
- Fibromyalgia patients often have elevated circulating pro-inflammatory cytokines (e.g. IL-8, IL-6, IL-1β, and TNF-α) that can sensitise pain receptors
Clinical Features
Hallmark symptom: chronic, widespread MSK pain [Ref]
- Pain is typically bilateral (occurring both above and below the waist)
- The pain spreads across all quadrants of the body
Other associated features: [Ref]
- Muscle and joint stiffness
- Severe fatigue
- General inability to carry out normal daily activities
- Sleep disturbances
- Cognitive dysfunction
- Mood disorders (esp. anxiety and depression)
- Other functional disorders (e.g. IBS, interstitial cystitis)
Diagnostic Criteria
No single objective test (laboratory test / biomarker / imaging) can be used to diagnose fibromyalgia
Fibromyalgia can be diagnosed in the presence of: [Ref]
- Chronic (lasting >3 months), primary pain (no clear underlying cause or its impact is out of proportion to any observable injury or disease), with
- Diffuse pain (formally assessed via a diffuse pain index), and
- Somatic symptoms, and
- Cognitive difficulties (formally assessed via a symptom severity scale)
The older 1990 ACR classification criteria may still occasionally be encountered. These involved applying pressure to 18 predefined tender-point sites across the body. [Ref]
Fibromyalgia was diagnosed when the patient had: [Ref]
- Pain in at least 11 out of 18 tender points, and
- Widespread pain for at least 3 months
This strict tender-point requirement is no longer included in current diagnostic criteria, as it does not adequately capture the broader cognitive and somatic symptoms of fibromyalgia. However, tender points may still be assessed during examination, particularly when considering alternative diagnoses.
Management
Fibromyalgia may coexist with secondary chronic pain (i.e. those with an attributable organic cause). The following apply to fibromyalgia, any concurrent secondary chronic pain should be assessed and managed according to its underlying cause.
Conservative / General Management
Offer:
- Supervised group exercise programme
- Encourage patient to remain physically active for long-term general health benefits
Consider:
- Psychological therapy
- Acceptance and commitment therapy (ACT), or
- Cognitive behavioural therapy (CBT)
- Acupuncture
Do NOT offer any of the following due to the lack of evidence of benefit:
- TENS
- Ultrasound
- Interferential therapy
Pharmacological Management
Consider management with an antidepressant (in >18 y/o after a full discussion of benefits and harm), options include:
- Amitriptyline (TCA)
- Citalopram, fluoxetine, paroxetine, or sertraline (SSRIs)
- Duloxetine (SNRI)
Antidepressants may help with quality of life, pain, sleep and psychological distress, even in the absence of a diagnosis of depression.
Fibromyalgia typically responds poorly to conventional analgesics, including paracetamol, NSAIDs and opioids. Therefore, these are not recommended for managing fibromyalgia itself.
Do NOT offer any of the following to manage fibromyalgia (or any other chronic primary pain):
- Antiepileptics, including gabapentinoids
- Antipsychotics
- Benzodiazepines
- Corticosteroid trigger point injections
- Ketamine
- Local anaesthetics