Definition

Rheumatic muscle pain can range from being a little uncomfortable to causing extreme pain. The pain is chronic when it has been daily for more than three months. Rheumatic muscle pain contributes to reduced quality of life, drug use and long-term sick leave. Often the symptoms are harmless, but they can also be signs of serious illness.

Causes

Muscle pain is usually not a disease sign. Painful, rigid and sore muscles are a natural reaction after unfamiliar physical activity or have slept in an uncomfortable position or part of normal aging.

• Leg cramps are very common in the population and occur most often without a particular disease cause
• With increasing age, the muscles often become more rigid and sore, especially after being inactive. Age-related rheumatic pain is common
• However, stronger new muscle pain that persists over days and weeks may be signs of muscle disease or underlying other disease

New-onset and chronic muscle pain without known cause should be further investigated by a doctor (please read more about the medical investigation below on this page).

Muscle pain may be separated in two main groups:

1. Pain due to inflammation (rheumatic inflammation or infection)
2. Pain not related to inflammation

1. Muscle pain with inflammation (Disease sensation, signs of inflammation in blood tests)

• Cancer treatment with checkpoint inhibitors can trigger muscle inflammation
• Polyarteritis nodosa (PAN)
  • A very rare form of systemic vasculitis
  • Strong, unexplained pain, often in the calves. High inflammation tests and clearly affected general condition with night sweats, fever tendency and weight loss
• Polymyalgia rheumatica
  • Most are aged 65-80 years (never before 50 years of age)
  • Beginning in a few days with severe stiffness in the shoulders, neck, upper arms and pelvis, hips and thighs
  • Blood tests show high CRP and Sedimentation rate (ESR). Creatine kinase (CK) are normal
  • Prednisolone 15-20 mg / day has good effect in a few days

• Polymyositis / dermatomyositis
  • Rare condition, all age groups
  • Increasing weakness in muscles (difficulty with stairs and hills, difficulty getting out of squatting)
  • Not everyone has pain
  • Creatinine kinase (CK) in blood sample is high
    • At slightly elevated value (<1000) new sample is taken after 2-3 days without physical activity.
  • Dermatomyositis has typical rash (resulting in red skin, over the basics of the fingers and middle, chest, neck or around eyes)
  • The lungs can be attacked (heavy breathing, dry cough). See also Antisynthetase syndrome
  • Inclusion body myositis develops gradually and causes weaker muscles over several years, most often from the age of 50-60. Slightly elevated CK in blood samples
• Rheumatoid arthritis (RA, arthritis)
  • Arthritis, swelling and joint pain are most typical
  • Among elderly people, muscle pain is common at the onset of disease
  • In blood tests, CRP is high. Anti-CCP is often present. Creatine kinase (CK) is normal
• Tetanus (tetanus)
  • Few weeks after animal bites or other infection
  • Muscle cramps
  • The jaw-locking
• Trichinosis (infected, raw pork)
• Tropical disease (infection)
  • Dengue Fever ("Breakbone fever")
• Viral infections (transient symptoms of flu, Hepatitis B )
• Vasculitis diseases
  • Polyarteritis nodosa (PAN) (Rare disease with fever, weight loss, pain)
  • Granulomatous polyangiitis (GPA) / Wegener's granulomatosis

2. Muscular pain without inflammation

• Depression
• Diabetes mellitus with muscle infarction (reduced blood circulation)
• Vitamin D deficiency (Rare symptom, 25-OH vitamin D in blood sample is low)
• Fibromyalgia
• Generalized chronic muscle pain syndrome
• Claudication (Pain in the leg (s) or arm (s) at physical stress or when the arm / legs are kept high. Due to poor blood circulation (by blood clots, atherosclerosis or vasculitis like Takayasu arteritis)
• Compartment syndrome, Muscle injury syndrome (after injury or strain or exercise, localized severe pain due to pressure and reduced blood circulation in the muscle)
• Hyperparathyroidism (High calcium and PTH in blood test by primary form, low 25-OH vitamine D by secondary form (with normal or low calcium in blood samples)
• Mitochondrial disease
• Multiple Sclerosis (MS)
• Muscular Dystrophy
• Muscle cramps (Usually without the underlying disease)
• Muscle pain syndrome (localized, chronic pain in parts of the body. May include arms, legs, neck, pelvis and back), normal blood tests
• Muscle tension (usually in the neck, tension headache), normal blood tests
• Parkinson's disease (Stiffness, tremor on hands, reduced mimicry). Neurological disease. Normal blood samples
• Post-polio syndrome
• Rhabdomyolysis (after injury, physical overload. Poisoning. Creatine kinase (CK) is very high; above 10.000-100.000)
• Statins (Cholesterol-lowering drugs)
• Stiff person syndrome
• Metabolic disorder (hypothyroidism), Blood tests with high TSH, low f-T4
• Fatigue syndrome (CFS / ME)

Diagnosis

• Disease history (disease start, disease progression, muscle groups, medications, other diseases)
• Medical Surveys: Visible changes (atrophy, infection signs, eczema), pain at palpation / light pressure, power failure (rising from the chair and from squatting without supporting)
• Blood tests: CRP, blood drop reaction (SR), electrolytes with potassium and calcium, CK (creatine kinase), ANA: anti-nuclear factors; ANCA: anti-neutrophil cytoplasmic antibody; TSH, F-T4, Glucose
• EMG (electromyalgia)
• MRI (with contrast) of muscles (usually thighs)
• Biopsy (tissue test)

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