Myopathies & muscular dystrophies

Myopathies & Muscular dystrophies

1. Myopathies & Muscular Dystrophies Why am I Feeling Weak!! Fatigue? ( extreme tiredness resulting from mental or physical exertion or illness ) Asthenic ? ( abnormal physical weakness or lack of energy. ) Or Malaise!! ( a general feeling of discomfort, illness, or unease whose exact cause is difficult to identify. )

2. Inherited myopathies and muscular dystrophies are a diverse group of muscle diseases presenting with common complaints and physical signs:weakness , motor delay,respiratory and bulbar dysfunction. MUSCULAR DYSTROPHIES are diseases of muscle membrane or supporting proteins. Muscular dystrophies – literally means “deficient nutrition” . Generally characterized by pathological evidence of ongoing muscle degeneration and regeneration. Inherited diseases result in progressive muscle injury in patients who usually appear normal at birth. Congenital muscular dystrophies are progressive, early-onset diseases. Some are associated with central nervous system manifestations.

3. MYOPATHIES are caused by genetic defects in the contractile apparatus of muscle. . Defined by distinctive histochemical or ultrastructural changes on muscle biopsy often have a perinatal or early childhood presentation . result in relatively static deficits.

4. Important Definitions WASTING--- related to muscle MYALGIA– muscle pain FIBRILLATIONS - when muscle fibers lose contact with their innervating axon producing a spontaneous action potential, "fibrillation potential" that results in the muscle fiber's contraction not visible under the skin and are detectable through needle electromyography (EMG) and ultrasound.-pathological FASCICULATIONS – visible spontaneuos contractions. SPASM/CRAMP – sudden PAINFUL involuntary contraction of muscle TONE – continuous and partial contraction of the muscles AT REST(resting muscle tension) CLONUS –series of involuntary muscle contractions. MYOKYMIA – INVOLUNTARY ,groups of fasciculations –continuous undualtions of muscle.

5. Investigations 1.SERUM MUSCLE ENZYMES :most sensitive CK . Parallels disease activity (active -50 fold) Normal when CTD +PM,DM Serum LDH,aldolase – elevated. 2.EMG – short duration,low amplitude polyphasic units on voluntary activation,spontaneuous fibrillations,positive sharp waves. Mixed potentials –IBM Identifies acute/ chronic,excludes nuerogenic 3.MRI –muscle biopsy 4.muscle biopsy – definitive test Inflammation is the hallmark

6. Muscular Dystrophies Muscular dystrophy refers to a group of hereditary progressive diseases each with unique phenotypic and genetic features

7. Duchenne’s muscular dystrophy Also called pseudo hypertrophic muscular dystrophy. It is an X linked recessive disorder. Dystrophin is deficient. Clinical features: It is present at birth but becomes evident at 3-5 years. Gower’s maneuver Joint contractures, scoliosis, decreased pulmonary functions.

8. By 16 to 18 years patients die of severe pulmonary infections or aspiration pneumonia. Respitatory failure in 2 nd Or 3 rd decade. IQ <~1 SD of the mean. Laboratory findings Serum CK levels are raised 20 to 100 times EMG shows reduced amplitude. Muscle biopsy: small group of necrotic and regenerating muscle fibres . Connective tissue and fat replace muscle fibres .

9. Definitive diagnosis is by demonstrating dystrophin deficiency and mutation of gene coding for dystrophin . Treatment Prednisolone – 0.75mg/kg/day significantly slows down the progression of disease.