Fibromyalgia — Multidisciplinary Pain Management

Pathophysiology and clinical assessment

Fibromyalgia is understood as a disorder of central pain processing, with amplified pain signalling (central sensitisation), disordered neurotransmitter balance (reduced serotonin, norepinephrine, and dopamine; elevated substance P), and neuroinflammation (activated glial cells on PET imaging). Functional MRI studies demonstrate enhanced pain-related neural activation and altered connectivity in default mode and salience networks. Comorbid conditions are common: irritable bowel syndrome (30-70%), chronic fatigue syndrome (25-50%), depression and anxiety (40-80%), temporomandibular disorder, and interstitial cystitis. Assessment uses the Widespread Pain Index (WPI, 0-19) and Symptom Severity Scale (SSS, 0-12), with diagnosis requiring WPI >=7 and SSS >=5, or WPI 3-6 and SSS >=9.

• Widespread Pain Index: 19 areas (left/right shoulder, upper arm, lower arm, hip, buttock, knee, jaw, upper back, lower back, abdomen); count painful areas
• Symptom Severity Scale: fatigue, waking unrefreshed, cognitive symptoms (0-3 each) + somatic symptoms (0-3)
• Central sensitisation: enhanced pain from stimuli that would not normally be painful (allodynia)
• Comorbidities: IBS, CFS, depression, anxiety, TMJ, IC/PBS, restless legs syndrome
• Exclusion: normal inflammatory markers, normal thyroid function, no RA or SLE features
• Female predominance: 7:1 ratio; peak onset age 20-50; family clustering (50% first-degree relative risk)

Pharmacological management

Pharmacotherapy targets the neurobiological mechanisms underlying central sensitisation. FDA-approved agents include duloxetine (SNRI, 60-120 mg/day), pregabalin (alpha-2-delta ligand, 150-450 mg/day), and milnacipran (SNRI, 50-100 mg BD). Amitriptyline (10-25 mg nocte) is widely used off-label and has the strongest evidence base from older trials. Opioids are contraindicated as they worsen central sensitisation, increase disability, and carry dependence risk. The EULAR 2017 recommendation conditionally recommends amitriptyline and duloxetine while conditionally recommending against pregabalin (insufficient evidence of clinically meaningful benefit in some meta-analyses), though clinical practice varies significantly.

• Duloxetine: 60-120 mg/day; first-line; addresses pain, fatigue, depression; titrate from 30 mg
• Pregabalin: 150-450 mg/day in divided doses; reduces pain and sleep disturbance
• Amitriptyline: 10-25 mg nocte; low-dose tricyclic; strongest older evidence; dry mouth, weight gain
• Opioids: contraindicated in fibromyalgia; worsen central sensitisation, increase disability and mortality
• Gabapentin: alternative to pregabalin; less evidence; titrate to 1800-3600 mg/day
• Combination therapy: low-dose amitriptyline + duloxetine may have synergistic effect in refractory cases

Guidelines referenced:

• EULAR 2017 updated recommendations for fibromyalgia management
• ACR 2022 clinical practice guideline for fibromyalgia diagnosis and management
• Canadian Pain Society and Canadian Rheumatology Association position statement on fibromyalgia

Exercise and non-pharmacological interventions

Exercise is the most evidence-supported non-pharmacological intervention for fibromyalgia, with aerobic exercise demonstrating moderate-to-large effect sizes for pain, physical function, and global impression of change. The key challenge is the exercise-pain spiral: patients decondition, exercise provokes post-exertional pain, leading to further deconditioning. Graded exercise therapy with initial low-intensity sessions (walking, aquatic therapy) gradually increasing in duration and intensity over 8 to 12 weeks breaks this cycle. CBT addresses pain catastrophising, fear-avoidance beliefs, and sleep hygiene, with meta-analyses showing small-to-moderate effects on pain and disability that persist at 6-month follow-up.

• Aerobic exercise: walking, cycling, swimming; start low, progress slowly; 20-30 min, 3x/week
• Aquatic therapy: warm water (33-36 degrees C); reduces mechanical loading; particularly beneficial
• Strength training: moderate intensity; improves functional capacity and pain tolerance
• CBT: 8-12 sessions; targets catastrophising, fear-avoidance, sleep hygiene, pacing
• Mindfulness-based stress reduction: 8-week program; reduces pain interference and psychological distress
• Sleep hygiene: fixed sleep-wake schedule, caffeine avoidance, cool dark room, screen restriction before bed