Persisting Pain States & Fibromyalgia

Fibromyalgia core features:

• •Widespread musculoskeletal pain - diffuse, bilateral, above and below the waist, including the axial skeleton, persistent for more than 3 months and disproportionate to identifiable peripheral pathology.
• •Profound, unrefreshing fatigue - often as disabling as the pain.
• •Non-restorative sleep - difficulty initiating and maintaining sleep; waking unrefreshed.
• •Cognitive dysfunction ('fibro fog') - impaired concentration, word-finding difficulty, short-term memory problems.

Common comorbidities: irritable bowel syndrome (IBS), chronic fatigue, mood disorders (depression and anxiety in around 30-50%), sleep disturbance, TMJ dysfunction, headaches, non-dermatomal paraesthesiae, temperature sensitivity, bladder irritability, and dry eyes and mouth (distinguish from Sjogren's).

2016 ACR fibromyalgia classification criteria provide the modern structured framework:

• •Widespread Pain Index (WPI) of 7 or more out of 19 body areas PLUS Symptom Severity Scale (SSS) of 5 or more, OR
• •WPI of 4-6 PLUS SSS of 9 or more.
• •Generalised pain present in at least 4 of 5 body regions for 3 months or more.
• •Symptoms not better explained by another diagnosis - but importantly the criteria do NOT exclude other diagnoses; fibromyalgia can coexist with RA, OA, SLE, or any other condition. The older 1990 ACR tender point criteria are largely historical.

Examination: diffuse tenderness without anatomical correspondence; no objective inflammation (no synovitis, no effusion, no warmth); normal neurological examination; allodynia and hyperalgesia may be demonstrable; normal muscle bulk and power; joint hypermobility frequently coexists.

Red flags (exclude before diagnosing chronic primary pain): unexplained weight loss, night sweats, progressive symptoms (malignancy); new neurological deficit (structural pathology); raised inflammatory markers (inflammatory disease); abnormal blood count or raised calcium (myeloma, hyperparathyroidism); focal nocturnal bone pain (metastases, myeloma); fever (infection); progressive weakness (inflammatory myopathy, MND); saddle anaesthesia or bladder/bowel dysfunction (cauda equina - emergency MRI).

Mimics to actively exclude on first assessment: hypothyroidism, vitamin D deficiency, inflammatory arthritis (RA, PsA, axSpA), inflammatory myopathy, and myeloma.

There is no diagnostic test for fibromyalgia. Investigations exclude alternative or coexisting diagnoses based on history and examination.

Baseline blood tests to exclude common mimics:

• •FBC, ESR and CRP (typically normal in fibromyalgia - if raised, investigate inflammatory or malignant pathology).
• •TFTs (hypothyroidism), 25-hydroxyvitamin D (deficiency is common in the UK and produces widespread MSK pain).
• •Corrected calcium and bone profile (hyperparathyroidism, myeloma).
• •CK (typically normal; raised CK points to inflammatory myopathy, hypothyroidism, or statin-related myopathy).
• •Renal and liver function, HbA1c (diabetic neuropathy and fatigue).

Targeted second-line when clinical features warrant: RF and anti-CCP only if synovitis is clinically present; ANA only with CTD features (around 5-15% of healthy adults are ANA-positive, so blanket requesting in widespread pain causes unnecessary anxiety and referrals); coeliac screen if GI symptoms or unexplained iron deficiency; protein electrophoresis or serum free light chains in older patients with bone pain, anaemia, or raised ESR.

Imaging is NOT used to diagnose fibromyalgia. Request only when clinical features suggest structural pathology. Incidental disc bulges and degenerative changes are common and do not explain widespread pain - communicating this is a therapeutic part of management. Over-investigation reinforces the biomedical model, delays appropriate treatment, fuels health anxiety, and risks inappropriate intervention.

NICE NG193 (2021) is the definitive UK guideline. The approach is biopsychosocial; pharmacology is limited and adjunctive.

For chronic primary pain - NG193 specific recommendations:

OFFER:

• •Supervised group exercise programme; encourage physical activity.

CONSIDER:

• •Acceptance and commitment therapy (ACT) or cognitive behavioural therapy (CBT) for pain.
• •A single course of acupuncture or dry needling (maximum 5 hours total, delivered in a community setting).
• •Antidepressants for adults after discussion of benefits and harms - prescribed for pain modulation via descending serotonergic and noradrenergic pathways, not for depression: amitriptyline 10-50 mg at night (also improves sleep; anticholinergic side effects; cautious use in elderly); duloxetine 30-60 mg daily (SNRI; good fibromyalgia evidence; better tolerated in older patients); SSRIs (citalopram, fluoxetine, paroxetine, sertraline).

Do NOT initiate (NG193 specific):

• •Paracetamol, NSAIDs, opioids, benzodiazepines, antiepileptics INCLUDING gabapentinoids (gabapentin, pregabalin), ketamine, corticosteroid trigger-point or local anaesthetic injections, cannabis-based medicinal products.
• •TENS, ultrasound, interferential therapy, biofeedback.

Pregabalin caveat: historically prescribed for fibromyalgia (and licensed for it in some jurisdictions), but NICE NG193 advises against initiating it in chronic primary pain. Established users without another indication should be reviewed individually. Gabapentinoids ARE appropriate for neuropathic pain under NICE CG173, where identifiable nerve disease exists.

Education and supported self-management: pain neuroscience education (pain is real but does not equal ongoing damage), goal-setting using valued activities rather than pain-free targets, pacing (avoid boom-and-bust), flare management plans, sleep hygiene. Validation is therapeutic - feeling believed predicts engagement and outcomes.

Multidisciplinary team approach: physiotherapy, clinical psychology, occupational therapy, pain medicine, and GP. Multidisciplinary pain management programmes are indicated for significant functional impairment despite first-line management - by NICE definition these include at least two components (one physical, one psychological) delivered by trained clinicians with coordination.

For chronic secondary pain (which can coexist with chronic primary pain): treat the underlying condition (DMARDs for RA, exercise for OA per NICE NG226, neuropathic agents per NICE CG173). If central sensitisation features develop, apply NG193 principles alongside.

Opioid deprescribing: gradual, patient-agreed reduction; never abrupt cessation. Specialist pain service input when on more than 120 mg oral morphine equivalent. Explain that opioids are ineffective for this pain type and may be worsening symptoms via opioid-induced hyperalgesia.

Rehabilitation IS the treatment for chronic primary pain - the primary intervention, not a supplement to pharmacology. Graded exercise starts at a level the patient can manage consistently and progresses gradually; transient flares are expected and do not signify harm. Pacing avoids the boom-and-bust pattern.

Aerobic exercise (walking, cycling, swimming), strengthening, and flexibility work are all beneficial; aquatic exercise is often well-tolerated. NICE NG193 recommends supervised group programmes - peer support and social interaction enhance outcomes. Goals are framed around valued activities (walking to the shops, returning to work) rather than 'be pain-free'.

Sleep hygiene is essential: consistent sleep/wake times, wind-down routine, avoid caffeine and screens before bed, comfortable environment. Non-restorative sleep perpetuates pain, fatigue, and cognitive dysfunction.

Vocational rehabilitation supports return to work through graded activity, workplace adaptations, and occupational health liaison. Prolonged absence worsens outcomes. Self-management strategies include mindfulness, relaxation, flare management plans, and peer support groups (Versus Arthritis, Pain Concern, FibroAction).

• •NICE NG193 (Chronic pain in over-16s: assessment and management, 2021) - the definitive UK guideline; biopsychosocial framework; OFFER supervised group exercise; CONSIDER CBT/ACT, acupuncture (max 5 hours total), and antidepressants; do NOT initiate analgesics, opioids, or gabapentinoids for chronic primary pain.
• •NICE CG173 (neuropathic pain - distinct entity): amitriptyline, duloxetine, gabapentin, or pregabalin first-line where identifiable nerve disease exists.
• •2016 ACR fibromyalgia classification criteria - WPI + SSS scoring framework; pain in 4 of 5 regions for 3 months or more; does not exclude other diagnoses (replaces the 1990 tender point criteria).
• •IASP nociplastic pain category (2017) - the third pain mechanism alongside nociceptive and neuropathic; fibromyalgia is the prototype.
• •Faculty of Pain Medicine (RCoA) opioid deprescribing guidance - gradual, supported, patient-agreed reduction; never abrupt.

• •Three pain mechanisms: nociceptive, neuropathic, nociplastic; fibromyalgia is the prototype nociplastic syndrome.
• •2016 ACR criteria: WPI + SSS; pain in 4 of 5 regions for 3 months or more; does not exclude other diagnoses.
• •NICE NG193: offer exercise; consider CBT/ACT, acupuncture, antidepressants; do NOT initiate opioids or gabapentinoids.
• •Fibromyalgia can coexist with RA, OA, or SLE; inflammatory markers normal in pure fibromyalgia.
• •Pain-fear avoidance cycle is broken by graded exercise and pain neuroscience education.
• •Cauda equina: saddle anaesthesia, bladder or bowel dysfunction - emergency MRI.