Generalized Pain Disorders

Introduction to MCCQE1 Objectives

Generalized pain disorders represent a significant portion of primary care and rheumatology consultations in Canada. For the MCCQE1, candidates must demonstrate the ability to differentiate between non-inflammatory pain syndromes (like Fibromyalgia) and inflammatory conditions (like Polymyalgia Rheumatica), while adhering to the CanMEDS roles of Medical Expert, Communicator (validating patient suffering), and Health Advocate (avoiding unnecessary testing and opioid prescription).

This guide focuses on the assessment, diagnosis, and management of generalized pain, with a specific emphasis on Fibromyalgia and Polymyalgia Rheumatica (PMR), adhering to current Canadian guidelines.

Fibromyalgia Syndrome (FMS)

Fibromyalgia is the most common cause of chronic widespread pain in the general population. It is characterized by abnormal central pain processing (central sensitization).

Epidemiology in Canada

• Prevalence: Affects approximately 2% to 3% of the Canadian population.
• Gender: Female to Male ratio is roughly 3:1 (historically thought to be higher, but changing criteria have captured more men).
• Age: Can occur at any age but prevalence rises with age.

Pathophysiology

The prevailing theory is Central Sensitization. There is an amplification of neural signaling within the central nervous system (CNS) that elicits pain hypersensitivity.

Clinical Presentation

Patients typically present with a constellation of symptoms often referred to as the “Fibro Fog” and pain.

• Chronic Widespread Pain: Above and below the waist, affecting both sides of the body (duration > 3 months).
• Fatigue: Unrefreshing sleep is a hallmark.
• Cognitive Dysfunction: “Fibro Fog” (trouble concentrating, memory lapses).
• Somatic Symptoms: IBS, headaches, paresthesias, interstitial cystitis.

Diagnosis

Diagnosis is clinical and based on positive identification of symptoms + exclusion of other causes.

Polymyalgia Rheumatica (PMR)

PMR is a vital differential diagnosis for generalized pain in the elderly population. Unlike Fibromyalgia, PMR is an inflammatory condition.

Key Characteristics

• Age: Almost exclusively >50 years old (peaking 70-80).
• Symptoms: Bilateral pain and stiffness in the shoulder and hip girdles.
• Morning Stiffness: Profound, lasting >45 minutes (often hours).
• Association: Strongly associated with Giant Cell Arteritis (GCA).

Diagnostic Criteria

1. Age >50.
2. Bilateral shoulder aching.
3. Abnormal CRP and/or ESR.

Differential Diagnosis Comparison

Use this table to distinguish between common causes of generalized pain for the MCCQE1.

Management of Fibromyalgia

Management follows the 2012 Canadian Guidelines for the Diagnosis and Management of Fibromyalgia Syndrome. The approach must be multimodal, emphasizing non-pharmacologic strategies first.

1. Education (The Foundation)

Validate the patient’s symptoms. Explain that the pain is real but not damaging to tissues. Reassure them that it is not a progressive disease leading to wheelchair use.

2. Non-Pharmacologic Therapy (First-Line)

Evidence suggests these interventions have the highest yield.

• Aerobic Exercise: Start low, go slow. Graded aerobic exercise is the single most effective intervention.
• CBT (Cognitive Behavioral Therapy): Addresses maladaptive pain behaviors and sleep hygiene.
• Sleep Hygiene: Crucial for symptom management.

3. Pharmacologic Therapy

Used to facilitate exercise and sleep, not to “cure” pain.

Canadian Guidelines Summary

Relevant guidelines for MCCQE1 preparation:

1. 2012 Canadian Guidelines for the Diagnosis and Management of Fibromyalgia Syndrome:
   • Diagnosis does not require a specialist (Rheumatologist). Primary care management is preferred.
   • Focus on function rather than complete elimination of pain.
2. Choosing Wisely Canada (Rheumatology):
   • “Don’t order ANA testing without clinical symptoms suggestive of a connective tissue disease.”
   • “Don’t prescribe opioids for the treatment of fibromyalgia.”

Key Points to Remember for MCCQE1

• Diagnosis: Fibromyalgia is a clinical diagnosis of exclusion. Do not rely on tender points.
• Red Flags: Always rule out inflammatory causes (check ESR/CRP) and endocrine causes (TSH).
• PMR vs. Fibro: High ESR/CRP + Age >50 points to PMR. Normal labs points to Fibro.
• Treatment Hierarchy: Education & Exercise > Pharmacotherapy.
• Medications: Amitriptyline, Duloxetine, Pregabalin are first-line meds. Avoid Opioids.
• CanMEDS: Validate the patient (Communicator). Do not over-investigate (Resource Steward).

Abbreviations

ACR    : American College of Rheumatology
ANA    : Antinuclear Antibody
CBT    : Cognitive Behavioral Therapy
CRP    : C-Reactive Protein
ESR    : Erythrocyte Sedimentation Rate
GCA    : Giant Cell Arteritis
PMR    : Polymyalgia Rheumatica
RF     : Rheumatoid Factor
SNRI   : Serotonin-Norepinephrine Reuptake Inhibitor
TCA    : Tricyclic Antidepressant
TSH    : Thyroid Stimulating Hormone

Sample Question

Clinical Scenario

A 42-year-old female presents to your family medicine clinic with a 6-month history of generalized body pain, particularly in her neck, shoulders, and lower back. She reports feeling exhausted despite sleeping 9 hours a night and describes having “brain fog” that affects her work. Review of systems is negative for fever, weight loss, rash, or joint swelling. Physical examination reveals diffuse soft tissue tenderness but no joint synovitis, erythema, or limited range of motion. Neurological exam is normal. Previous blood work done 2 weeks ago showed a normal CBC, TSH, ESR, and CRP.

Which one of the following is the most appropriate initial management step?

• A. Initiate Prednisone 15 mg daily
• B. Order an Antinuclear Antibody (ANA) test
• C. Prescribe Oxycodone/Acetaminophen 5/325 mg as needed for pain
• D. Provide education on the diagnosis and recommend graded aerobic exercise
• E. Refer urgently to a Rheumatologist for confirmation of diagnosis

Explanation

The correct answer is:

• D. Provide education on the diagnosis and recommend graded aerobic exercise

Detailed Analysis:

• D is correct: This patient presents with classic signs of Fibromyalgia (chronic widespread pain, unrefreshing sleep, cognitive dysfunction, normal inflammatory markers). According to Canadian Guidelines, the cornerstone of management is patient education (validating the condition) and non-pharmacologic therapy, specifically graded aerobic exercise. This has the strongest evidence for improving function and symptoms.
• A is incorrect: Prednisone is the treatment of choice for Polymyalgia Rheumatica (PMR) or other inflammatory conditions. This patient has normal inflammatory markers (ESR/CRP) and is younger than the typical PMR demographic (>50), making an inflammatory etiology unlikely.
• B is incorrect: Choosing Wisely Canada specifically advises against ordering ANA testing in patients with generalized pain and fatigue unless there are specific clinical features of SLE (e.g., malar rash, photosensitivity, pleuritis). A positive ANA in this context is likely a false positive and leads to unnecessary anxiety and referrals.
• C is incorrect: Opioids are contraindicated in Fibromyalgia. They are ineffective for central sensitization pain and carry high risks of dependence and opioid-induced hyperalgesia.
• E is incorrect: Fibromyalgia is a condition that should primarily be managed in primary care. Referral is reserved for atypical cases or diagnostic uncertainty. The Canadian Guidelines explicitly state that a specialist is not required for diagnosis in straightforward presentations.

References

1. Fitzcharles, M. A., et al. (2013). 2012 Canadian Guidelines for the diagnosis and management of fibromyalgia syndrome: Executive summary. Pain Research and Management, 18(3), 119–126.
2. Medical Council of Canada. (n.d.). MCCQE Part I Clinical Decision-Making and Multiple-Choice Question Objectives.
3. Choosing Wisely Canada. (2023). Rheumatology: Five Things Physicians and Patients Should Question.
4. Toronto Notes. (2023). Rheumatology Chapter: Fibromyalgia and Polymyalgia Rheumatica. Toronto Notes for Medical Students, Inc.
5. Goldenberg, D. L. (2023). Clinical manifestations and diagnosis of fibromyalgia in adults. UpToDate.