MYOPATHY

MR. SUNIL MEHTA-DNEP(INK)

Neuroelectrophysiologist

NEOTIA GETWEL HEALTHCARE CENTRE

MYOPATHY :-

MUSCLE ATROPHY

◦Muscle atrophy is the wasting or loss of muscle tissue

◦Causes-

§peripheral neuropathy

§Poliomyelitis

§Multiple sclerosis

§AIDS

§Anorexia nervosa

§Osteomalacia

§CJD.etc  

§MUSCLE HYPERTROPHY

◦Muscle hypertrophy involves an increase in size of skeletal muscle through a growth in size of its component cells.

◦Two factors contribute to hypertrophy: SARCOPLASMIC HYPERTROPHY, which focuses more on increased muscle glycogen storage; and MYOFIBRILLAR

◦HYPERTROPHY, which focuses more on increased myofibril size.

§CAUSES-

§Anabolic steroids

§Becker muscular dystrophy

§Berardinelli lipodystrophy syndrome

§Bruch-de Lange syndrome

§Cornelia de Lange syndrome

§Exercise

§Facio-scapulo-humeral muscular dystrophy

§Hypothyroidism

§Myhre syndrome

§Myostatin-related muscle hypertrophy

§Myotonia congenita

§Myotonic Dystrophy - muscle hypertrophy

§Myotonic hypertrophy

§Weight training  

                                              

§MYOPATHY:

◦Myopathy is a common term for a muscle disease that is unrelated to any disorder of innervation or neuromuscular junction.

◦Myopathies are characterized by motor symptoms in the absence of any sensory involvement. Most myopathies manifest with weakness involving the proximal muscles. Commonly, pelvic girdle muscles are involved before and much more severely than shoulder girdle muscles.

§TYPES-

§hereditary 

§acquired

§HEREDITARY.MYOPATHIES 

◦muscular dystrophies,

◦congenital myopathies,

◦metabolic myopathies

◦mitochondrial myopathies,

◦myotonias and

◦channelopathies. 

§MUSCULAR DYSTROPHIE

◦Dystrophinopathy (Duchenne muscular dystrophy,  
 Becker muscular dystrophy)

◦Myotonic dystrophy 1 and 2

◦Facioscapulohumeral muscular dystrophy

◦Oculopharyngeal muscular dystrophy

◦Limb girdle muscular dystrophy 

§CONGENITAL MYOPATHIES

◦NEMALINE MYOPATHY - causes weakness and poor tone (hypotonia) in the muscles of the    face, neck and upper limbs, and often affects the respiratory muscles (those that control breathing) - the muscle cells contain abnormal clumps of threadlike material — probably disorganized filament proteins — called nemaline bodies (nema is Greek for “thread”).

◦CENTRAL CORE MYOPATHY - causes problems with the tone and contraction of skeletal muscles. 

Malignant hyperthermia is a common complication.

§METABOLIC MYOPATHIES
◦Acid maltase or acid alpha-1,4-glucosidase deficiency (Pompe's disease)◦Glycogen storage disorders 3-11
◦Carnitine deficiency
◦Fatty acid oxidation defects
◦Carnitine palmitoyl transferase deficiency
§MITOCHONDRIAL MYOPATHIES:Caused by damage to the mitochondria — small, energy-producing structures that serve as the cells' "power plants." Nerve cells in the brain and muscles require a great deal of energy, and thus appear to be particularly damaged when mitochondrial dysfunction occurs
 ◦Myoclonic epilepsy and ragged red fibers (MERRF)

◦Mitochondrial myopathy, lactic acidosis, and strokes (MELAS)
◦Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)

◦Progressive external ophthalmoplegia (PEO)

§ACQUIRED MYOPATHIES 

◦Inflammatory
◦infective
◦toxic myopathies and
◦Myopathy Associated with Systemic Diseases
§INFLAMMATORY MYOPATHY
◦POLYMYOSITIS : Polymyositis is an idiopathic inflammatory myopathy that causes symmetrical,   proximal muscle weakness; elevated skeletal muscle enzyme levels
◦DERMATOMYOSITIS : idiopathic, inflammatory myopathy associated with characteristic       
dermatologic manifestations
◦INCLUSION BODY MYOSITIS : slowly progressive, idiopathic, inflammatory myopathy with characteristic pathologic findings that is generally found in older males.
§INFECTIVE MYOPATHY
◦Viral infections (HIV, influenza virus, Epstein-Barr virus)
◦Bacterial pyomyositis (Staphylococcus aureus and streptococci are common organisms)
◦Spirochete (Lyme disease)
◦Parasitic infections such as trichinosis
§MYOPATHY ASSOCIATED WITH SYSTEMIC DISEASES
Endocrine disorders:

◦Thyroid
◦Parathyroid
◦Pituitary or adrenal dysfunction
Systemic inflammatory diseases :◦Systemic lupus erythematosus
◦Rheumatoid arthritis
◦Scleroderma
◦Sjögren's syndrome
◦Mixed connective disease
◦Sarcoidosis  
TOXIC MYOPATHY  
Medications :
◦Steroids
◦Cholesterol-lowering medications: statins, fibrates, niacin, and ezetimibe
◦Propofol
◦Amiodarone
◦Colchicine
◦Chloroquine
◦Antivirals and protease inhibitors
◦Omeprazole
◦Tryptophan
Toxins :
◦AlcoholToluene      
CONTD…..     

Electrolyte imbalance :◦
Potassium or magnesium abnormalities     
◦Hypophosphatemia
Critical illness myopathy :
◦Nondepolarizing neuromuscular blocking agents
◦Steroids
Amyloid myopathy :
◦Primary amyloidosis
Familial amyloidosis (TTR utation)