Muscle Disorders

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Author:
Bobopudge
ID:
57896
Filename:
Muscle Disorders
Updated:
2011-01-03 13:47:07
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  1. define hypertrophy
    • Increase in quantity of actin + myosin filiments
    • Enlarges muscle fibers
    • Takes 6-10 weeks
    • Caused by strong contractions
  2. Define atrophy
    • Partial or complete wasting away of part of body
    • Breakdown + reabsorption of tissues
    • Can be normal or pathological
  3. Define muscle atrophy
    • Total muscle mass decreases
    • Loss of strength
    • Due to bedrest / cast
    • Reversed with excersize unless severe (cachexia)
  4. State diseases which lead to muscle atrophy
    • AIDS and Cancer
    • Congestive heart failure
    • Liver disease
    • Sarcopenia
  5. Discuss sarcopenia
    • A gradual decrease in the ability to maintain skeletal muscle function and mass during aging
    • Unknown cause
    • Failure of satellite cells and growth factor
  6. What is Astemizole?
    • Second generation anti-histamine drug
    • Prevents muscle atrophy
  7. My name is Astemizole, and I am given...
    To patients who have become bed-ridden
  8. Differentioate between upper and lower motor neurons
    • Upper:
    • - cortex to cranial nerve nucleus OR anterior horn
    • - lesions associated with spastic paralysis / hypertonicity
    • Lower:
    • - cranial nerve nucleus OR anterior horn to skeletal muscle
    • - lesions associated with falccid paralysis / hypotonicity
  9. Define neuropathy and its classifications
    • Pathological process affecting peripheral nerves
    • Classicfications: mononeuropathy (one nerve affected), polyneuropathy (many nerves affected), radiculopathy (nerve root affected)
  10. Define motor neuron diseases and its effect
    • Group of neurological disorders that destroy motor neurons
    • Result in loss of control of voluntary activity i.e. speaking, walking, breathing, swallowing
  11. Discuss spinal muscle atrophy (inheritance, effect, cause, symptoms, subtypes)
    • Inheritance: genetically inherited – autosomal recessive
    • Effect: Degeneration of anterior horn cells in spinal chord
    • Symptom: symmetric proximal muscle weakness
    • Cause: deletion of SMN1 gene
    • Subtypes:
    • - Type 1: severe hypotonia, presents in weeks, no sit no walk, respitory failure within 2 years
    • - Type 2: proximal muscle weakness before 18 months, sit but no walk, survial past 4 years
    • - Type 3: proximal muscle weakness before 2 years, can walk, survival past 40 years
  12. Discuss Myasthenia gravis (classification, types, presentation, effects, characteristics)
    • Classifiaction:
    • - Autoimmune disease
    • - Junctionopathy
    • 2 types:
    • - Seropositive – anibodies agaisnt NAchR at NMJ’s
    • - Seronegative – antibodies against Muscle Specific Protein Kinase
    • Presentation:
    • - First peak in 3rd decade
    • - Second in 6th decade
    • - Initially presents as ocular muscle weakness (ptosis and diplopia)
    • Progression:
    • - Craniocaudal
    • Effect:
    • - Fatigue of voluntary muscles
    • - Shortness of breath
    • - Characteristics:
    • - Worsen in exertion
    • - May come and go
  13. Discuss diagnosis of MG
    • Tensilon (may cause hypotension and arrythmias)
    • Ice test
    • AchR antibodies
    • EMG (repetetive nerve stimulation)
    • MuSK antibodies
    • Chest MRI (for thymic tumors)
    • Brain MRI
  14. Discuss Lambert Eaton Myasthenic-myopathic syndrome (LEMS)
    • Antibodies against calcium channels
    • Inhibits Ach release at NMJ
    • Rarely associated with small cell carcinoma of bronchus
  15. Define myopathy
    Any condition related to muscle defects; affects muscle function
  16. Discuss Malignant Myperthermia (definition, inheritance, characteristic, treatment, cause, tests, pathophysiology, symptoms)
    • Genetic myopathy that presents when patient is under anasthesia
    • Inheritance: autosomal dominant
    • Characteristics: Triggered by volatile anasthtic (halothane) or muscle relaxant (suxamethonium)
    • Treatment: Using other relaxants (Dantroline) and improved monitoring
    • Tests: Caffein-halothane contracture test on fresh muscle biopsy
    • Cause: mutation in RyR1 gene
    • Pathophysiology: MASSIVE release of Ca+ from SR
    • Symptoms: Rigidity, hypoxemia, tachycardia, fever, increased serum creatine kinase,
    • Warning: Symptoms may be clouded by Sepsis
  17. Define dystrophy
    Any condition of abnormal develoment, usually due to malnutrition
  18. Discuss muscular dystrophy and genetic and heredatory disease
    • Caracteristics:
    • - Progressive skeletal muscle weakness
    • - Muscle protein defects
    • - Death of tissue
  19. Discuss Duchenne Muscular dystrophy (inheritance, presentation, effects, progression, cause)
    • Most severe form of muscular dystrophy
    • Inheritance: X-linked
    • Presentation: kids apear normal at birth; symptoms at 5-7 i.e. toe walking
    • Effects: difficulty running, climbing stairs, lordosis; Pseudohypertrophy, gower’s sign
    • Progression:
    • - 8-12 yo: wheelchair bound
    • - late teens: arms affected
    • - 20’s: suprainfections i.e. pneumonia
    • Cause:
    • - mutations in dystrophin gene
    • - absence of dystrophin
    • - no connectivity between ECM and actin+myosin
  20. Discuss fratures of a muscle biopsy taken in a patient with Duchenne Muscular dystrophy
    • Variable fiber size
    • Hypercontracted muscl fibers
    • Immature muscle fibers
    • Degenration of muscle fibers
    • Dystrophen is absent
    • Reduced sarcoglycan and aquaporins

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