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Myopathies

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Myopathies

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Myopathies

  1. 1. MYOPATHIES
  2. 2. • Primary muscle disease resulting in chronic muscle weakness • 3 broad grps – 1. Hereditary ( muscular dystrophies) 2. Inflammatory – polymyositis, dermatomyositis 3. Toxic myopathies – thyrotoxic, ethanol, drug induced
  3. 3. Muscular dystrophies • Grp of genetically inherited primary muscle disease, progressive muscular weakness
  4. 4. Duchenne muscular dystrophy • Commonest, most serious Clinical features – muscle weakness in early childhood, death by late teens Morphology – muscle fibre necrosis, regeneration • Fibres atrophic, fibrosis, fatty replacement
  5. 5. Etiology – X linked recessive, boys • Dystrophin gene lies on the short arm of chromosome X • Lack of dystrophin leads to muscle cell degeneration
  6. 6. • Biopsy in early stages show lack of dystrophin using immunostaining • Becker type – milder form caused by mutation in dystrophin gene resulting in decreased levels of protein • Other muscular dystrophies – facio scapulohumoral, limb girdle, myotonic
  7. 7. Polymyositis – any age & sex, muscle pain, weakness, proximal muscle grps, deterioration rapid / slow Dermotomyositis – similar with skin lesions on face & hands • In adults may herald malignancy – bronchial CA, CT disorder - RA
  8. 8. Pathology • Muscle fibres show atrophy to necrosis • Few hypertrophied • Lymphocytic infiltrate • Autoimmune etiology
  9. 9. Toxic myopathy • Myopathy seen in acromegaly, hyperthyroidism, hypothyroidi sm & hyperaldosteronism, hyperparathyroidism & corticosteroid excess
  10. 10. • In alcoholics & drug induced - eg chlroquine, vincristine & vit D def.
  11. 11. Diagnosis - few condition curative therapy is available • General clinical findings – family history, age of onset, distribution of muscle weakness & rate of progress - neurological assesment
  12. 12. • Special investigation of neuromuscular electrical activity - rate of motor & sensory nerve conduction measured electrically - electromyogram records activity of grp / individual muscle fibre activity
  13. 13. • Lab test muscle biopsy – routine, EM, histochemistry serum enzymes muscle fibre destruction – CK & aldolase
  14. 14. Poliomyeltis • Poliovirus member of picorna grp of enteroviruses • Paralytic poliomyelitis has been effectively controlled by immunization in many parts of the world • Non immunized – infection subclinical / mild gastroenteritis • Secondarily invades nervous system
  15. 15. CNS infection – initially meningeal irritation • Progresses to spinal cord • Attacks ant.horn with loss of motor neurons produces flaccid paralysis with wasting & hyporeflexia in affected spinal segment
  16. 16. Acute disease – death may occur due to paralysis of resp muscles or myocarditis Morphology • Acute – mononuclear perivascular cuffs & neuronophagia of ant horn motor neurons of spinal cord • Inflammation can extend to post horns
  17. 17. • Post polio syndrome – 25 -35yrs after resolution of initial illness, progressive weakness ass.with muscle bulk & pain
  18. 18. Volkmann’s contracture • Young, muscles of forearm • Ass.with pressure of splints / tourniquet / with h’ge resulting from # • Within few hrs after injury pain develops in hands / forearm -> contractures of fingers which becomes fixed in flexed position
  19. 19. Morphology • Muscle – hard, homogenous, yellowish • Nuclei & cross striations are lost • Inflammatory cells & macrophages at the margins -> fibrosis • Cause arterial spasm resulting from injury to vessel wall

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