¶ Fibromyalgia
Merged from 2 sources — review for redundancy.
¶ From neuroscience/
¶ Definition
A chronic pain syndrome characterized by widespread musculoskeletal pain, profound fatigue, sleep disturbance, and cognitive dysfunction ('fibro fog'), representing central sensitization and amplified pain processing without identifiable peripheral tissue damage. In cPNI, fibromyalgia is understood as a yellow flag condition—symptoms not explained by measurable peripheral pathology but reflecting neuroinflammation, HPA axis dysregulation, and failed resolution of inflammation. The condition represents a systemic failure of stress resilience, descending pain modulation, and homeostatic recovery mechanisms, often triggered and perpetuated by chronic stress.
¶ Picture It
Imagine a smoke alarm system in a house where the control panel (your brain) has been rewired by months of false alarms. At first, there were real fires—maybe an injury, infection, or trauma. But after constant activation, the wiring itself changed. Now the smoke detectors are so sensitive that cooking toast triggers a full evacuation alarm. Worse, the override button (your descending pain system) is broken—you can't turn the alarm off even when you know it's a false alarm. The house's stress response system (HPA axis) is exhausted from constantly preparing for emergencies that never materialize, so it starts producing erratic amounts of stress hormones—sometimes flooding, sometimes barely trickling. The maintenance crew (your immune cells) keeps patrolling for fires, releasing inflammatory signals even when there's nothing burning, creating a state of chronic low-grade alert. Meanwhile, the electrical system (mitochondria) is running on backup power because the constant alarms have drained the main supply, leaving you exhausted. The security guards (endorphins) who used to patrol and reassure everyone that things are safe have quit showing up for work. What started as a response to real threat has become a self-sustaining cycle where the alarm system itself is the problem—not because it's imaginary, but because the detection and modulation circuitry has been fundamentally reprogrammed by chronic activation.
¶ Mechanism
Fibromyalgia emerges from multi-system dysregulation centered on failed pain resolution and stress adaptation:
Central Sensitization Cascade:
Chronic stress → persistent nociceptive input → sustained dorsal horn neuron activation → increased NMDA receptor expression and phosphorylation → removal of Mg²⁺ block → enhanced glutamate signaling → long-term potentiation in pain pathways → expansion of receptive fields → Secondary Hyperalgesia and allodynia throughout the body
HPA Axis Dysregulation:
Prolonged stressor exposure → sustained CRH release from hypothalamus → initial ACTH hypersecretion → eventual adrenal gland exhaustion → flattened cortisol awakening response → loss of normal circadian rhythm (normal peak 06:00-08:00, 15-25 μg/dL becomes blunted to <10 μg/dL) → failed negative feedback at Glucocorticoid Receptor → cytokine resistance and Cortisol resistance
Descending Modulation Failure:
Stress → reduced serotonin and norepinephrine synthesis → impaired periaqueductal gray (PAG) and rostroventral medulla (RVM) function → loss of descending pain modulation → increased descending facilitation via ON-cells → unopposed pain amplification → CSF Substance P levels elevated 2-3× normal (>350 pg/mL vs normal <150 pg/mL)
Neuroinflammatory Component:
Chronic stress → microglia activation → IL-1β, IL-6, TNF-α release in dorsal horn and brain regions → neuroinflammation → sensitization of nociceptive neurons → amplified pain signaling → further microglial priming (positive feedback loop)
Endogenous Opioid Failure:
HPA axis dysfunction → reduced POMC processing → decreased beta-endorphin production (50-70% reduction in CSF levels) → impaired mu opioid receptor activation → loss of endogenous analgesia → Opioid tolerance even to endogenous opioids
Genetic Vulnerability:
5-HTTLPR short allele (s/s or s/l) → reduced serotonin transporter expression → lower synaptic serotonin clearance paradoxically leading to receptor downregulation → impaired serotonergic descending inhibition → 1.5-2× increased pain sensitivity to heat (>44°C) and pressure (>4 kg/cm²)
COMT Val158Met polymorphism (Met/Met) → slower catecholamine degradation → altered norepinephrine and dopamine dynamics → 2-3× higher fibromyalgia risk → reduced pain threshold by 20-30%
Small Fiber Pathology (subset):
neuroinflammation → axonal degeneration → reduced intraepidermal nerve fibre density (<7 fibers/mm vs normal >10 fibers/mm) → altered TRPV1 and TRPA1 channel expression → peripheral neuropathy contributing to pain and autonomic dysfunction
Metabolic Consequences:
Pain chronicity → HPA axis activation → Cortisol drives gluconeogenesis → insulin resistance → mitochondrial dysfunction → reduced ATP production → fatigue → metabolic exhaustion → further pain amplification
¶ Clinical Significance
Fibromyalgia is not psychosomatic but represents real neurobiological dysfunction—a yellow flag condition where the alarm system has become the disease. This distinction is critical: patients experience genuine pain from altered CNS processing, not imagined symptoms.
Clinical Presentation:
- Widespread pain (American College of Rheumatology criteria: pain in ≥4 of 5 body regions)
- Profound fatigue (>6 months, not relieved by rest)
- sleep disturbance (alpha-delta sleep anomaly on polysomnography)
- Cognitive dysfunction ('fibro fog'): impaired working memory, processing speed, executive function
- autonomic dysfunction: orthostatic intolerance, temperature dysregulation
- High comorbidity with depression (40-80%), anxiety disorders (60%), irritable bowel syndrome (30-70%)
Diagnostic Markers:
- CRP typically
mg/L (excludes inflammatory arthropathies) - ESR usually normal (<20 mm/hr)
- CSF Substance P >300 pg/mL (2-3× normal)
- CSF beta-endorphin <10 pmol/L (50-70% reduction)
- cortisol awakening response blunted (<2.5 nmol/L rise)
- Skin biopsy showing intraepidermal nerve fibre density <7 fibers/mm (in 40-50% of patients)
Evolutionary Mismatch Context:
Fibromyalgia represents failure of ancient stress-recovery cycles in the context of modern chronic psychosocial stressors. In ancestral environments, stressors were episodic (predator, famine, conflict) with recovery periods. Modern life presents unrelenting low-grade stressors (chronic stress, sleep deprivation, processed foods, social isolation) without resolution intervals, overwhelming evolutionarily conserved allostasis mechanisms.
Selfish Brain Connection:
The Selfish Brain prioritizes its own glucose supply under perceived threat. In fibromyalgia, chronic pain signals erroneously signal ongoing threat → continuous brain energy prioritization → peripheral energy deficit → muscle pain and fatigue → reinforcing the pain-threat cycle.
Intervention Strategy (cPNI Approach):
-
Stress Axis Restoration:
- stress management techniques: mindfulness, Cognitive Behavioral Therapy, EMDR for trauma
- Circadian rhythm optimization: strict sleep-wake schedule, morning light exposure (>1000 lux, 30 min), darkness at night
- Ashwagandha (300-600 mg standardized extract): reduces cortisol, improves HPA function
- Rhodiola rosea (200-400 mg): adaptogenic support for stress resilience
-
Neuroinflammation Reduction:
- Omega-3 fatty acids (EPA+DHA 2-4 g/day): shift toward Specialized pro-resolving mediators (SPMs)
- Curcumin (1000 mg with piperine): inhibits NF-kB, reduces microglia activation
- Diet: eliminate processed foods, gluten (if sensitive), high-AGEs foods
- Intermittent fasting: 14-16 hour overnight fast promotes autophagy and metabolic switching
-
Descending Modulation Enhancement:
- Exercise: graded, low-intensity initially (walking, swimming, tai chi) → gradual increase prevents post-exertional malaise
- Pain neuroscience education: reduces threat sensitivity, alters pain perception (20-30% pain reduction in trials)
- Serotonin support: 5-HTP (100-200 mg) or Tryptophan (1-2 g) with B6 (50 mg)
- Magnesium (400-600 mg glycinate): NMDA antagonism, muscle relaxation
-
Microbiome Restoration:
- Lactobacillus and Bifidobacteria probiotics: reduce systemic inflammation
- Prebiotic fiber (25-35 g/day): support Akkermansia-muciniphila, Faecalibacterium prausnitzii
- Fermented foods: kimchi, sauerkraut, kefir for microbial diversity
- Address SIBO if present: breath test, targeted treatment
-
Mitochondrial Support:
- Coenzyme Q10 (200-400 mg): improves ATP production
- Creatine (5 g/day): energy buffer, neuroprotection
- B-complex: cofactors for energy metabolism
- Magnesium, Zinc: mitochondrial enzyme function
-
Sleep Optimization:
- Sleep hygiene: cool room (16-18°C), darkness, noise reduction
- Melatonin (1-3 mg): circadian rhythm support, antioxidant
- Magnesium (before bed): GABA support, muscle relaxation
- Address sleep apnea if present (common comorbidity)
Prognosis:
Fibromyalgia is manageable but requires comprehensive, sustained intervention. Passive treatments (opioids, prolonged rest) worsen outcomes. Active coping strategies (Exercise, psychological therapy, dietary modification) show 30-50% improvement in pain and function over 6-12 months. The condition often improves when underlying chronic stress is addressed and psychological resilience is rebuilt.
¶ Key Facts
- Yellow flag condition: genuine symptoms without identifiable peripheral tissue pathology—the CNS processing is the pathology
- Always involves chronic stress as a causal or perpetuating factor—no fibromyalgia without stress axis dysregulation
- CSF Substance P elevated 2-3× normal (>300 pg/mL vs <150 pg/mL)—reflects central pain amplification
- CSF beta-endorphin reduced 50-70% (<10 pmol/L)—failed endogenous analgesia system
- Cortisol awakening response blunted (<2.5 nmol/L rise vs normal 7-10 nmol/L)—HPA axis exhaustion marker
- 5-HTTLPR short allele (s/s) increases heat pain sensitivity 1.5-2× and pressure pain threshold reduction by 20-30%
- COMT Met/Met polymorphism confers 2-3× higher fibromyalgia risk through impaired catecholamine metabolism
- Small fiber neuropathy present in 40-50% of patients: skin biopsy shows <7 fibers/mm (normal >10 fibers/mm)
- 40-80% comorbid depression, 60% anxiety disorders, 30-70% irritable bowel syndrome—shared neuroinflammatory mechanisms
- Pain neuroscience education alone reduces pain 20-30% by decreasing threat sensitivity and fear-avoidance
- Opioids are contraindicated: worsen outcomes through tolerance, hyperalgesia, and HPA suppression
- Responds to Exercise (graded), stress management, anti-inflammatory diet, microbiome restoration—active interventions, not passive treatments
¶ Connections
- central sensitization — the core neuroplastic mechanism driving pain amplification without peripheral pathology
- chronic stress — primary causal factor initiating and perpetuating HPA dysregulation, neuroinflammation, and central sensitization
- HPA axis — dysregulated in fibromyalgia with flattened cortisol rhythm, failed negative feedback, and glucocorticoid resistance
- endorphins — profoundly reduced beta-endorphin production (50-70% deficit) eliminates endogenous analgesia
- descending pain modulation — failed inhibition from PAG-RVM circuit combined with increased descending facilitation
- neuroinflammation — microglial activation in dorsal horn and brain amplifies pain signaling and impairs resolution
- serotonin — low serotonin impairs descending inhibition and contributes to comorbid depression and sleep disturbance
- norepinephrine — reduced norepinephrine compromises descending pain control and contributes to fatigue
- Substance P — elevated 2-3× in CSF (>300 pg/mL), pro-nociceptive neurotransmitter amplifying pain signals
- 5-HTTLPR — short allele polymorphism increases pain sensitivity through reduced serotonin transporter expression
- COMT — Val158Met polymorphism affects catecholamine degradation; Met/Met variant increases fibromyalgia risk 2-3×
- small fiber neuropathy — peripheral nerve degeneration found in 40-50% via skin biopsy; contributes to pain and autonomic dysfunction
- chronic pain — fibromyalgia is the prototypical chronic pain syndrome with central rather than peripheral pathology
- fatigue — severe, unrelenting fatigue from metabolic exhaustion, mitochondrial dysfunction, and sleep disturbance
- sleep — alpha-delta sleep anomaly disrupts restorative sleep; sleep disturbance both causes and results from pain
- pain neuroscience education — educational intervention reducing threat perception and pain catastrophizing by 20-30%
- microbiome — gut dysbiosis contributes to systemic inflammation and pain; restoration improves outcomes
- stress resilience — loss of psychological resilience perpetuates the condition; rebuilding resilience is therapeutic
- depression — 40-80% comorbidity reflecting shared neuroinflammatory, serotonergic, and HPA axis dysfunction
- allostatic load — fibromyalgia represents accumulated physiological wear from chronic stress exceeding adaptive capacity
- Cortisol resistance — tissues become insensitive to cortisol despite elevated levels, impairing anti-inflammatory responses
- inflammatory cytokines — IL-1β, IL-6, TNF-α released by activated microglia drive central sensitization
- glutamate — excitatory neurotransmitter driving NMDA receptor-mediated central sensitization in dorsal horn
- mitochondrial dysfunction — impaired ATP production contributes to muscle pain and profound fatigue
- Exercise — graded, low-intensity exercise gradually restores function, reduces pain, and improves HPA axis regulation
- Omega-3 — EPA and DHA shift eicosanoid balance toward specialized pro-resolving mediators, reducing neuroinflammation
- Curcumin — inhibits NF-κB and microglial activation, reducing central nervous system inflammation
- Magnesium — NMDA receptor antagonist, reduces central sensitization, improves sleep and muscle pain
¶ Module References
- Module 1: Yellow flag conditions, stress-symptom relationships
- Module 2: Genetic polymorphisms (5-HTTLPR, COMT) and pain sensitivity
- Module 7: Chronic pain mechanisms, central sensitization, stress axis dysfunction
¶ From clinical-practice/
¶ Definition
A chronic pain syndrome characterized by widespread musculoskeletal pain, fatigue, sleep disturbance, and cognitive dysfunction (brain fog) without proportionate measurable structural pathology. Classified as a 'yellow flag' condition where symptoms exceed tissue damage, indicating central sensitization, altered descending pain modulation, and psychoneuroimmune dysregulation rather than peripheral tissue injury.
¶ Picture It
Imagine a home security system where the alarm keeps going off even though there's no burglar—the wiring has become hypersensitive after years of false alarms and real break-ins. The motion sensors (peripheral nociceptors) now trigger at the slightest vibration; the central control panel (spinal cord and brain) has lost its "ignore minor signals" filter; and the command center (prefrontal cortex) can't override the alarm anymore. Meanwhile, the building superintendent (HPA axis) is exhausted from too many midnight wake-ups and can't properly maintain the system. The security cameras (interoception) are stuck on "threat detected" mode, flooding the monitors with warnings about doors (muscles), windows (joints), and hallways (connective tissue) that aren't actually compromised. The fire station (immune system) keeps sending trucks for smoke that isn't there, creating traffic jams that make the whole neighborhood feel chaotic. The system isn't broken—it's recalibrated to a hair-trigger setting where normal household activity registers as an emergency.
¶ Mechanism
Central Sensitization Cascade:
-
Dorsal Horn Amplification:
- Chronic nociceptive input → increased NMDA receptor expression on dorsal horn neurons
- Substance P and CGRP release → NK cell receptor activation
- Glutamate accumulation → removal of Mg²⁺ block from NMDA receptors → Ca²⁺ influx
- PKC and PKA activation → phosphorylation of AMPA receptors → increased synaptic strength
- GABAergic interneuron dysfunction → loss of lateral inhibition
-
Descending Modulation Failure:
- Periaqueductal gray (PAG) dysfunction → reduced serotonin and norepinephrine release from Nucleus Raphei and locus coeruleus
- Rostral ventrolateral medulla (RVM) shift from inhibition to facilitation mode
- ON-cells (pronociceptive) dominate over OFF-cells (antinociceptive)
- Reduced endorphin and enkephalin release → diminished mu opioid receptor activation
- Endorphin resistance develops at MOR
-
Brain Network Reorganization:
- Default mode network hyperconnectivity → excessive self-focused attention
- Salience network overactivity (anterior insula, dACC) → heightened threat detection
- Thalamus hypersensitivity → amplified sensory relay to cortex
- Reduced prefrontal cortex (vmPFC) inhibitory control over amygdala
- Hippocampus volume reduction → impaired contextual learning about safety
-
Neuroimmune Interface:
- Microglia activation in dorsal horn, thalamus, and cortex → release of IL-1β, TNF-α, IL-6
- Astrocytes secrete BDNF → TrkA receptor activation → enhanced nociceptor excitability
- Peripheral immune activation → Low-Grade Inflammation with CRP often 3-10 mg/L (elevated but not acutely high)
- Mast cells degranulation near peripheral nerves → Histamine and NGF release → peripheral sensitization
-
HPA Axis Dysregulation:
- Chronic stress → Cortisol dysregulation (flattened diurnal curve, low morning peaks <10 μg/dL)
- Glucocorticoid Receptor downregulation → Cortisol resistance
- Loss of anti-inflammatory feedback → persistent systemic inflammation
- CRH dysregulation → disrupted sleep architecture (reduced slow-wave sleep)
-
Autonomic Imbalance:
- Sympathetic nervous system dominance → reduced HRV (often <50 ms RMSSD)
- Parasympathetic withdrawal → impaired vagus nerve anti-inflammatory signaling
- Catecholamine Resistance → reduced responsiveness to stress adaptation
¶ Clinical Significance
Yellow Flag Recognition:
Fibromyalgia is the quintessential yellow flag condition—symptoms vastly exceed measurable tissue pathology. This requires practitioners to shift from a tissue-damage model to a nervous system regulation model. Searching for structural "fixes" (imaging, surgeries, aggressive manual therapy) is contraindicated and may worsen central sensitization through nocebo effects and reinforced threat perception.
Metamodel Integration:
- Metamodel 0 (Energy Distribution): Metabolic Depression phenotype—low body temperature, profound fatigue, social withdrawal. The Selfish Brain prioritizes glucose for threat surveillance over muscle function, creating a vicious cycle where reduced movement worsens metabolic inflexibility.
- Metamodel 1 (Context & Meaning): Pain persists because the nervous system interprets bodily sensations through a threat-primed filter. Meaning response and Patient-Provider Relationship are critical—empathetic validation reduces anterior cingulate cortex activity.
- Metamodel 3 (Immune Regulation): Low-grade systemic inflammation (CRP 3-10 mg/L, IL-6 2-5 pg/mL) without acute infection. Trained immunity may be maladaptive—monocytes and microglia remain primed from past stressors.
- Metamodel 5 (Bonding System): Often comorbid with PTSD, Adverse Childhood Experiences, or Loneliness. Insecure attachment patterns correlate with higher pain intensity via amygdala-insula hyperconnectivity.
Population-Specific Considerations:
African ancestry individuals show higher sensitivity to heat and pressure pain stimuli in fibromyalgia, suggesting genetic polymorphisms in COMT, TRPV1, or opioid receptor genes modulate pain processing thresholds.
Intervention Priorities:
- Nervous System Regulation: Graded Exercise (VILPA-style), Meditation, breath work, vagus nerve stimulation
- Sleep Optimization: Address circadian disruption, reduce blue light, target 7-9 hours with emphasis on slow-wave sleep
- Anti-Inflammatory Nutrition: Omega-3 fatty acids (EPA 2-3g/day), Curcumin, reduce Low-Grade Inflammation drivers (processed foods, chronic stress)
- Context Modification: Pain neuroscience education, Reframing, reduce threat language, build safety cues
- NOT tissue-focused interventions: Avoid repeated imaging, invasive procedures, or language that reinforces structural damage beliefs
Clinical Thresholds:
- CRP: typically 3-10 mg/L (elevated but not acute)
- IL-6: 2-5 pg/mL (chronic low-grade elevation)
- Cortisol awakening response: <10 μg/dL (flattened)
- HRV: <50 ms RMSSD (autonomic dysfunction)
- Widespread pain for >3 months across >4 body regions
- Fatigue severity often 7-9/10 on visual analog scale
¶ Key Facts
- Affects 2-8% of global population, 75-90% female predominance (likely mediated by estrogen effects on pain processing and immune system priming)
- Symptoms NOT explained by proportionate tissue damage—cardinal yellow flag
- African ancestry populations show higher heat and pressure pain sensitivity thresholds in fibromyalgia
- central sensitization is primary driver—peripheral tissues are not significantly damaged
- Comorbidity cluster: irritable bowel syndrome (30-70%), chronic fatigue syndrome (30-50%), PTSD (up to 60%), Depression (50-70%)
- NMDA receptor antagonists (low-dose ketamine) show efficacy by reversing dorsal horn sensitization
- GABA-glutamate imbalance measurable via MR spectroscopy—elevated glutamate in insula and posterior insula
- HPA axis dysfunction: flattened cortisol curve, low morning peak (<10 μg/dL), blunted response to stress
- HRV typically reduced (<50 ms RMSSD), indicating sympathetic dominance
- CRP often 3-10 mg/L—elevated but not acutely high, reflecting chronic low-grade inflammation
- cognitive dysfunction ("fibro fog") correlates with Hippocampus volume loss and default mode network dysregulation
- Exercise (graded, low-intensity start) is evidence-based first-line treatment—paradoxically improves pain despite initial discomfort
- SSRIs/SNRIs target descending pain modulation via serotonin-norepinephrine pathways, not depression per se
- Sleep disturbance is both consequence and driver—reduced slow-wave sleep impairs tissue repair and pain inhibition
- Genetic factors: COMT Val158Met polymorphism (Met/Met = lower pain threshold), 5-HTTLPR short allele (reduced serotonin transporter)
¶ Connections
- Central Sensitization — primary mechanism underlying fibromyalgia pain amplification
- Chronic Fatigue Syndrome — shares central sensitization, HPA axis dysfunction, immune dysregulation; 30-50% comorbidity
- HPA axis — dysregulated cortisol production and flattened diurnal rhythm contribute to symptom persistence
- Cortisol resistance — glucocorticoid receptor downregulation prevents anti-inflammatory feedback
- Descending pain modulation — impaired PAG-RVM-spinal cord inhibitory pathways allow pain amplification
- Periaqueductal gray — dysfunction reduces endogenous opioid and monoamine descending inhibition
- NMDA receptor — upregulation in dorsal horn drives wind-up and central sensitization
- Glutamate — excess excitatory signaling overwhelms inhibitory GABA systems
- GABA — reduced GABAergic interneuron function in dorsal horn removes lateral inhibition
- Microglia — activated in spinal cord, thalamus, and cortex; release pro-inflammatory cytokines
- IL-6 — chronically elevated (2-5 pg/mL), contributes to fatigue and pain via neuroimmune signaling
- TNF-α — microglial TNF-α enhances nociceptor excitability and NMDA receptor trafficking
- Interoception — altered interoceptive processing in insula amplifies bodily threat signals
- Anterior insula — hyperactive in salience detection; excess glutamate measurable via MR spectroscopy
- Default mode network — hyperconnectivity increases self-focused attention on pain and fatigue
- Prefrontal cortex — reduced vmPFC inhibitory control over amygdala threat responses
- Amygdala — hyperresponsive to pain and stress cues; enhanced connectivity with insula
- Hippocampus — volume reduction impairs contextual discrimination between safe and threatening stimuli
- Irritable bowel syndrome — 30-70% comorbidity; shared visceral hypersensitivity and central sensitization
- Depression — 50-70% comorbidity; bidirectional relationship via shared inflammatory and HPA axis pathways
- PTSD — up to 60% comorbidity; overlapping amygdala-insula hyperactivity and HPA dysregulation
- Low-Grade Inflammation — CRP 3-10 mg/L, chronic immune activation without acute infection
- Metabolic Depression — phenotype overlap with excessive sleep, fatigue, low body temperature, social withdrawal
- Exercise — graded aerobic exercise is first-line evidence-based treatment; improves HRV, reduces inflammation
- Sleep — disrupted architecture (reduced slow-wave sleep) both causes and is worsened by pain and inflammation
- Vagus nerve — reduced parasympathetic tone impairs cholinergic anti-inflammatory pathway
- HRV — typically <50 ms RMSSD; marker of autonomic dysfunction and reduced resilience
- COMT — Val158Met polymorphism modulates pain sensitivity (Met/Met = lower threshold, higher fibromyalgia risk)
- 5-HTTLPR — short allele variant reduces serotonin transporter function, increasing depression and pain risk
- Pain neuroscience education — reconceptualizes pain as nervous system output rather than tissue damage; reduces threat perception
¶ Module References
- Module 1
- Module 2