Classification of Myopathies: By Pathologic Features

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• Neurogenic Muscle disease

• Disorders of Neuromuscular transmission

• Channelopathies and defects on ion transportation

• Muscular dystrophies (dystrophic myopathy)

• Rhabdomyolysis/necrotizing myopathy

• Inflammatory myopathy

• Infection of the muscle

• Congenital myopathy

• Mitochondrial myopathy

• Metabolic myopathy

• Myopathy due to systemic disorders

• Myopathy due to endocrine disorders

• Toxin and drug induced myopathy

• Others

• Comment

Neurogenic Muscle disease Head

• Neurogenic atrophy due to peripheral nerve pathology

• Spinal muscular atrophies

• Others

Disorders of Neuromuscular transmission Head

Non-paraneoplastic

• Myasthenia gravis

Paraneoplastic

• Stiff-man syndrome

• Other paraneoplastic neuromuscular disorders

• Myasthenia gravis

Channelopathies and defects on ion transportation Head

Inherited

• Hyperkalemic periodic paralysis (sodium channel)

• Hypokalemic periodic paralysis (uncommon) (calcium channel, dihydropyridine receptor)

• Paramyotonica congenita (sodium channel)- Pure type, Potassium sensitive type

• Myotonia congenita

• Potassium sensitive type (autosomal dominant, sodium channel)

• Becker’s generalized type (autosomal recessive, choride channel)

• Thomsen’s type (autosomal dominant, choride channel)

• Schwartz-Jampel syndrome

• Malignant hyperthermia (ryanodine receptor)

• Myotonic dystrophy (protien kinase of sodium channel)

Sporadic

• Lambert-Eaton myasthenic syndrome

Muscular dystrophies (dystrophic myopathy) Head

Congenital (neonatal onset) muscular dystrophy

• Congenital muscular dystrophy- Merosin deficient type

• Congenital muscular dystrophy- Merosin-positive type

• Congenital muscular dystrophy- others

• Facioscapulohumeral Dystrophy (Landouzy-Déjerine Dystrophy)

• Fukuyama congenital dystrophy

• Walker-Warberg syndrome

• Muscle-eye-brain disease of Santavuori

• Marinesco-Sjögren syndrome

• Ullrich congenital muscular dystrophy

Non-congenital (non-neonatal onset) muscular dystrophies

• Duchene muscular dystrophy

• Becker’s muscular dystrophy

• Emery-Dreifuss muscular dystrophy

• Facioscapulohumeral dystrophy (Landouzy-Déjerine) and facio-scapulo-humeral syndromes

• Limb-girdle muscular dystrophy

• Distal muscular dystrophies

• Late adult type 1 (Welander)- Autosomal dominant

• Late adult type 2 (Marksberry)- Autosomal dominant

• Early adult type 1 (Nonaka)- Autosomal recessive

• Early adult type 2 (Miyoshi)- Autosomal recessive

• Ocular muscular dystrophy

Rhabdomyolysis/necrotizing myopathy Head

Idiopathic recurrent myoglobinuria

Hyperthemic conditions

• Malignant hyperthermia

• Exertional heat strokes

Non-drug/toxin induced

• Crush injury and torture

• Ischemia

• Physical exhaustion and overexertion

• Subacute necrotizing carcinomatous myopathy

• Others

Drug induced

• High-dose corticosteroids in critical illness

• Clofibrate, gemfibrozil

• Epsilon-aminocaproic acid

• Lavostatin, pravastatin, simvastatin

• Mevacor (Lovastatin) induced

• Zidovudine (AZT)

• Others

Intoxication or poisoning

• Acute alcoholic rhabdomyolysis (Acute alcoholic myopathy)

• Cocaine

• Mushroom poisoning (Amanita phalloides)

• Snake venoms

• Hypervitaminosis E (Vitamin E intoxication)

• Organophosphates

• Others

Metabolic

• Hypokalemia

• Diabetic ketoacidosis

• Nonketotic hyperglycemic/hyperosmolar states

• Hypo-/hypernatremia

• Hypophosphatemia

• Hythyroidism

• Near drowning

• Renal tubular acidosis

• Pancreatitis

• Crohn’s disease with elemental diet

• Others

Infection

• Legionella

• Streptococci

• Influenza A and B

• Other infection

Predisposing conditions

• Duchenne’s muscular distrophy

• Mitochondrial myopathy

• McArdle’s disease

• Others

Inflammatory myopathy Head

Primary inflammatory myopathies (the inflammation is primarily against fibers)

• Polymyositis

• Dermatomyositis

• Inclusion body myositis

• Localized nodular myositis (focal myositis)

• Myositis ossificans

• Myositis associated with connective tissue diseases

• Scleroderma

• Systemic lupus erythematosus (SLE)

• Rheumatoid arthritis

• Mixed connective tissue disease

• Eosinophilic polymyositis

• Benign acute childhood myositis (BACM) (myalgia cruris epidemica)

Secondary inflammatory myopathy (the inflammation is primarily not against fibers)

• Non-granulomatous Infection

• Granulomatous infection

• Vasculitis

Infection of the muscle Head

• Virus infection

• Bacterial infection

• Fungal infection

• Parasites

• Trichinosis

• Cysticerosis

• Toxoplasmosis

• Sarcosporidiosis

• Microsporidiosis

Congenital myopathy Head

• Myotonic dystrophy, congenital type

• Minimal change myopathy (non-specific congenital myopathies)

• Central core disease

• Multicore (minicore) myopathy

• Nemaline myopathy

• Congenital fiber type disproportion myopathy

• Myotubular myoathy (centronuclear myopathy)

• Integrin-alpha-7/beta-1 deficiency muscular dystrophy

• Zebra-body myopathy

• Hyaline body myopathy

• Fingerprint body myopathy

• Reducing body myopathy

• Cytoplasmic body (spheroid body) myopathy

• Sarcotubular myopathy

• Trilaminar myopathy

• Specific type 1 hypertrophy

• Cylindrical spiral myopathy

• Uniform type 1 fibers myopathy

• X-linked vacuolar myopathy with excessive autophagic vacuoles myopathy  

• X-linked vacuolar myopathy with cardiomyopathy and mental retardation

• Mixed myopathy

Mitochondrial myopathy Head

Metabolic myopathy Head

Disorders of lipid metabolism

• Carnitine deficiency

• Primary muscle carnitine dficiency

• Deficits in carnitine-palmitoyl transferase

Lysosomal storage disease

• Acid maltase deficiency myopathies (glycogen storage disease type II)

• Batten’s disease

• Fabry’s disease

• Fucosidosis

• Mannosidosis

• Samdhoff’s disease

Non-glycogen Non-lysosomal storage disease

• Lafora’s disease

Glycogen storage disease (GSD)

• Acid maltase deficiency (Pompe’s disease or GSD type II)

• Debranching enzyme deficiency (Cori’s disease, Forbe’s disease or GSD type III)

• Branching enzyme deficiency (GSD type IV)

• Myophosphorylase deficiency (McArdle’s disease or GSD type V)

• Phosphofructokinase deficiency (Tarui’s disease or GSD type VII)

• Phosphorylase b kinase deficiency (GSD type VIII)

• Phosphoglycerate kinase deficiency (GSD type IX)

• Phosphogylcerate mutase deficiency (GSD type X)

• Lactate dehydrogenase deficiency (GSD type XI)

Others

• Myoadenylate (AMPD) deaminase deficiency

Myopathy due to systemic disorders Head

• Polymyalgia rheumatica

• Carcinoma associated muscle disease

• Cachetic atrophy

• Chronic carcinomatosis myopathy

• Subacute necrotizing carcinomatous myopathy

• Dermatomyositis associated with carcinoma

Myopathy due to endocrine disorders Head

• Hyper- and hypothryodism

• Parathyroid diseases

• Pituitaty disorders

• Crushing's syndrome

• Carcinoid myopathy

Toxin and drug induced myopathy Head

• Steroid myopathy, acute and chronic

• Chronic alcoholic myopathy

• Colchicine associated vacuolar myopathy

Others Head

• Trauma

• Ischemia

• Intensive care unit myopathy (steroid myopathy)

• Myositis ossificans

• Familial cardioneuromyopathy with hyaline mases and nemaline masses

• Congenital myopathy with excess of thin myofilaments

• Myopathy associated with infection

• HIV related myopathies

• Schistosomiasis

Comment: Head

Musclar dystrophies: Traditionally, muscular dystrophies are viewed as a group of genetically determined disorders with progressive degeneration of skeletal abnormalities that are not associated with abnormalities in the CNS or PNS.

Congenital muscular dystrophy:

·      This is a family of disease characterized by onset at or shortly after birth of muscle weakness associated with dystrophic myopathy in muscle biopsy.

·      They tend to remain relatively static. Some patients may have slow progression while others may have functional improvement and eventually be able to walk.

·      Many of them are associated with abnormalities of the nervous system and the most severe variants are related to the eye-muscle-brain diseases (Walker-Warburg disease, Fukuyama muscular dystrophy, and muscle-eye-brain disease of Santavuori). Congenital muscular dystrophy can also be caused by merosin deficiency, integrin-a₇/b₇ deficiency. Merosin-positive congenital muscular dystrophy has no identified genetic deficit thus far.