Myopathies and Their Etiology
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Questions and Answers

What is a common cause of respiratory muscle weakness in bedridden patients?

  • Dermatomyositis
  • Infection, especially pneumonia (correct)
  • Cardiomyopathy
  • Hyperkalemic periodic paralysis

    • Which of the following is NOT a cause of myositis?

  • Muscle overuse (correct)
  • Systemic infection
  • Collagen disease
  • Immunization

    • In dermatomyositis, which symptoms are likely to be observed?

  • Prolonged duration of weakness beyond days
  • Skin manifestations and weakness of proximal muscles (correct)
  • No muscle pain or tenderness
  • Only weakness of distal muscles

    • What is the primary treatment for acquired myositis?

    <p>Prednisolone at a daily dosage of 60mg (D)</p> Signup and view all the answers

    What is the serum potassium level associated with hypokalemic periodic paralysis?

    <p>&lt; 3 mEq (C)</p> Signup and view all the answers

    What is the primary genetic disorder associated with myopathies?

    <p>Muscular dystrophies (B)</p> Signup and view all the answers

    Which symptom is characteristic of myopathies?

    <p>Clumsy gait (A)</p> Signup and view all the answers

    What is a common laboratory investigation used in diagnosing myopathies?

    <p>Serum creatinine phosphokinase level (D)</p> Signup and view all the answers

    Which type of muscular dystrophy is x-linked recessive?

    <p>Becker muscular dystrophy (C)</p> Signup and view all the answers

    Which of the following describes the muscle weakness in myopathies?

    <p>Symmetric bilateral weakness (C)</p> Signup and view all the answers

    What kind of physical examination finding is often seen in myopathies?

    <p>Winging of scapulae (A)</p> Signup and view all the answers

    What is one of the treatment options for managing myopathies?

    <p>Physiotherapy (D)</p> Signup and view all the answers

    Which of the following is NOT a known etiology of myopathies?

    <p>Allergic reactions (A)</p> Signup and view all the answers

    Flashcards

    Familial Periodic Paralysis

    A group of inherited disorders that cause temporary muscle weakness due to changes in potassium levels in the blood.

    Hypokalemic Periodic Paralysis

    A type of familial periodic paralysis where low potassium levels trigger muscle weakness.

    Hyperkalemic Periodic Paralysis

    A type of familial periodic paralysis where high potassium levels trigger muscle weakness.

    Myositis

    An autoimmune disease that causes inflammation and weakness in the muscles.

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    Dermatomyositis

    Inflammation of the muscles that affects the skin, causing a rash.

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    What are myopathies?

    Progressive muscle weakness and degeneration due to genetic, metabolic, or other factors.

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    What are muscular dystrophies?

    They are genetic, progressive disorders affecting the muscles.

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    What is proximal muscle weakness?

    A clinical sign of myopathies where the weakness is more pronounced in the proximal muscles (closer to the torso) compared to the distal muscles (farther away).

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    What is pseudohypertrophy?

    An abnormal increase in the size of a muscle, despite actual muscle weakness. This often happens in the calves, thighs, and shoulders in some types of muscular dystrophies.

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    Why is serum creatinine phosphokinase (CPK) used in myopathy diagnosis?

    A diagnostic test for myopathies that measures the levels of a muscle enzyme in the blood, which are often elevated. It is often elevated in muscular dystrophies.

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    How does electromyography (EMG) help diagnose myopathies?

    A diagnostic technique that uses electrical signals to assess muscle function. It can show characteristic alterations in myopathies.

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    What is Fascioscapulohumeral muscular dystrophy?

    A genetic muscular dystrophy that primarily affects the shoulder and upper arm muscles, often causing weakness and difficulty with tasks like raising arms or combing hair.

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    What is Limb Girdle Muscular Dystrophy?

    A genetic muscular dystrophy that mainly affects the pelvic girdle muscles, often causing weakness in the hips, thighs, and legs. This can lead to difficulty walking and climbing stairs.

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    Study Notes

    Myopathies

    • Myopathies are gradual, progressive, degenerative disorders affecting muscles.
    • Muscular dystrophies are a genetically determined type of myopathy, featuring a gradual, progressive degeneration of muscles.

    Etiology of Myopathies

    • Genetic disorders: Muscular dystrophies are one example.
    • Endocrine disorders: Thyrotoxicosis, acromegaly, Cushing's syndrome
    • Carcinomatous conditions: Bronchogenic and ovarian tumors
    • Metabolic conditions: Periodic paralysis
    • Drug-induced: Steroids, chloroquine, vincristine
    • Toxic agents: Alcohol
    • Infections: Trichinella spiralis

    Clinical Picture of Myopathies

    • Symptoms:
      • Clumsy gait
      • Inability to climb stairs
      • Protuberant abdomen
      • Weakness and wasting of specific muscle groups (selectivity)
    • Signs:
      • Weakness of skeletal muscles, specifically proximal muscles are affected more severely than distal muscles
      • Loss of muscle tone (hypotonia), diminished reflexes (hyporeflexia) in lower motor neuron type
      • Bilateral and symmetrical muscle involvement
      • Winging of scapulae, pot-belly abdomen, exaggerated lumbar lordosis, waddling gait, and positive Gower's sign (indicates proximal muscle weakness) can be associated with specific types of myopathies
    • Selectivity: In some dystrophies, specific muscle parts, like the sternal head of pectoralis major, are weaker than the clavicular head.
    • Facial muscles: Can be affected bilaterally in some types of myopathies
    • Pseudohypertrophy: Enlargement of certain muscles in some types, like quadriceps and gastrocnemius muscles in lower limbs, and deltoid, supraspinatus, and infraspinatus muscles in upper limbs
    • Contractures: Can lead to bone deformities
    • ECG changes: May be seen in specific types, like Duchenne muscular dystrophy
    • No sensory or sphincter issues: No signs of nerve damage or issues with bladder or bowel control

    Investigations

    • Laboratory investigation: Serum creatine phosphokinase (CPK) levels are usually elevated in some myopathy types. Urinary creatine levels are also sometimes investigated
    • Neurophysiology: Electromyography (EMG) often shows low amplitudes and durations of motor unit potentials, and early interference patterns.
    • Other: Muscle biopsies (especially in dystrophinopathies) and MRI scans may also be utilized

    Types of Muscular Dystrophies

    • Various types exist, categorized as shoulder girdle, limb girdle, and pelvic girdle muscular dystrophies.
    • Specific types include:
      • Fascioscapulohumoral myopathy (AD)
      • Limb girdle muscular dystrophies (AR)
      • Pseudo-hypertrophic muscular dystrophy (Duchenne's and Becker's MD – X-linked recessive)
      • Atrophic type (AR)

    Treatment

    • Physiotherapy
    • Orthopedic surgery: Tenotomy for contractures
    • Care of the bedridden
    • Genetic counseling: To identify carriers, especially significant in familial conditions

    Causes of Death in Myopathies

    • Respiratory muscle weakness
    • Infection (especially pneumonia)
    • Cardiomyopathy

    Myositis

    • Definition: Acquired autoimmune inflammatory disease of skeletal muscles
    • Etiology:
      • Systemic infection
      • Collagen disease
      • Immunization
      • Paraneoplastic conditions (related to cancer)
    • Clinical picture:
      • Acute or subacute onset with general symptoms like fatigue
      • Pain and tenderness over muscles
      • Weakness affecting proximal muscles of upper limbs (UL) and lower limbs (LL) , including posterior neck muscles and pharyngeal and laryngeal muscles
      • Deep reflexes remain intact
      • Skin manifestations may exist in dermatomyositis
    • Investigations:
      • Raised erythrocyte sedimentation rate (ESR)
      • Raised serum CPK levels
      • Electromyography (EMG) showing myopathic patterns with fibrillations
      • Detection of circulating antibodies (like antinuclear antibodies, rheumatoid factor)
    • Treatment:
      • Prednisolone (60mg daily)
      • Other immunosuppressive drugs
      • Addressing the underlying cause (if any) is also crucial

    Familial Periodic Paralysis

    • Definition: Episodes of transient paralysis from alterations in serum potassium levels
      • Hypokalaemic periodic paralysis is triggered by high carbohydrate intake, and rest after exercise, usually occurring upon waking in the morning
      • Hyperkalemic periodic paralysis is triggered by cold exposure or intensive exercise immediately after exercise
    • Symptoms:
      • Weakness in muscles, initially in lower limbs, then upper limbs developing into quadriplegia
      • Myotonia (muscle stiffness)
    • Duration and intensity of paralysis: Generally hours to days in Hypokalaemic, and less then an hour in hyperkalemic types
    • Serum potassium levels: Reduced in hypokalaemic and increased in hyperkalemic types
    • Treatment:
      • Intravenous potassium chloride (KCl) for hypokalaemia
      • Calcium gluconate infusion, and oral prophylactic acetazolmide, plus glucose and insulin infusions for hyperkalemia
      • Thiazide diuretics in hyperkalemia

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    Myopathies PDF Presentation

    Description

    Explore the world of myopathies, which are progressive disorders that affect muscle functions. This quiz delves into the various types of myopathies, their causes, and their clinical presentation. Test your understanding of genetic, endocrine, and other factors contributing to muscle degeneration.

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