Skeletal muscle diseases, or myopathies, are disorders that cause structural or functional problems in muscles. They are classified as either acquired or hereditary. Acquired myopathies include inflammatory myopathies like polymyositis and dermatomyositis, endocrine myopathies, and toxic or drug-induced myopathies. Hereditary myopathies include muscular dystrophies, congenital myopathies, and metabolic myopathies. Muscular dystrophies are a group of inherited disorders characterized by progressive muscle weakness and wasting that can affect the heart and other organs. There are several major types of muscular dystrophies classified by inheritance pattern, age of onset, distribution, progression rate, and prognosis

1. Skeletal muscle diseases
Made by: Mahmoud Bassiony Abdallah

2. Definition
• Skeletal muscle diseases or myopathies are disorders
with structural changes or functional impairment of
muscles.
• Diagnosis of myopathies is based upon clinical
features of patients and investigations.

3. Classification
• Acquired myopathies
 Inflammatory myopathies
 Endocrine myopathies
 Toxic or drug-induced myopathies
• Hereditary myopathies
• Muscular dystrophies
• Congenital myopathies
• Metabolic myopathies
• Mitochondrial myopathies

4. Inflammatory myopathies
• Largest group of acquired and potentially treatable
causes of skeletal muscle weakness .
 Inclusion body myositis(IBM
 Polymyositis (PM)
 Dermatomyositis (DM)
 Non-specific myositis (NSM)
 Immune-mediated necrotizing myopathy (IMNM)

5. Cross section of normal skeletal muscle
Epimysium
perimysium

6. LM picture of PM,DM and IBM
Rimmed vacuoles

7. Muscular Dystrophies(MD)
• Group of inherited myopathies characterized by
progressive muscle weakness and wasting.
• Heart and other organs can also be affected.
• Subdivided on the basis of mode of inheritance, age
at onset, distribution, rate of progression and
prognosis.
• 9 major types

8. Classification of muscular dystrophies
• Sex-linked:
 Duchene muscular dystrophy
 Becker’s muscular dystrophy
 Emery-dreifuss muscular dystrophy
• Autosomal recessive:
 Limb girdle muscular dystrophy
 Fascioscapulohumeral dystrophy
• Autosomal dominant:
 Oculopharyngeal muscular dystrophy
• Myotonic dystrophy
• Distal myopathy
• Congenital muscular dystrophy

9. LM picture of DMD,BMD,EDMD,MMD and FSHD

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