Progressive Muscular Dystrophy1.mansfans.com

Pr og r essi ve muscul ar dystr ophi es

By Prof Dr / Ahmed Gamal Azab

-: Definition –

It is a group of genetically determined primary degenerative muscular disorders characterized by muscular weakness and wasting (myopathy).

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Pathogenesis - A defect in muscle fibre plasma membrane > uncontrolled entery of calcium > activation of calcium dependent protease > muscle fibre necrosis. -The missing gene product is a protein called (Dystrophin).

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-:Classification A) X- linked recessive:1- Severe (Duchenne). 2- Benign (Becker). 3- Benign with acanthocytes. 4- Benign with early contractures (Emery-Dreifuss).

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B- Autosomal recessive:

 

Limb girdle (usually scapulo-humeral, rarely pelvi-femoral). Childhood type, resembling Duchenne. Congenital muscular dystrophy.

C- Autosomal dominant:    

Facioscapulohumeral. Scapuloperoneal. Distal. Ocular. Oculopharyngeal.

-:Pathology 

The microscopic changes are the same in all types: Swelling of some muscle fibres.  Multiplication of sarcolemmal nuclei.  Striations become less marked.  Increased C.T and fat deposition () the fibresbulky muscle.  Later on, longitudinal splitting of muscle fibres and fibrosis.  Heart : May show cardiomyopathy.

Investigations for muscular -:dystrophies 1. 2. 3. 4.

EMG : diminished duration& amplitude of MUAP. Urine : ↓creatinine + app of creatine. ↑serum enzymes :used to detect ♀ carriers & for preclinical diagnosis in♂. Muscle biopsy.

-:Treatment of muscular dystrophies 1. 2. 3. 4. 5. 6. 7. 8.

Long term treatment of steroids (prednisone). Gene therapy. Myoblast transfer. Calcuim antagonists. Supportive therapy. Fasciotomy for gastrocnemeus. Assisted respiration when needed. Psychological support. www.MansFans.com

Myotonic Disorders Definition :- A group of myopathies characterised by slow relaxation of skeletal muscles after voluntary, mechanical or electrical stimulation.

Pathogenesis :It is due to reduced chloride conductance and permeability of the plasma membrane of muscle fibre (as it persists after section of motor nerve or curarization).

-:Types 1. 2. 3. 4. 5. 6.

Myotonia congenita. Myotonia paradoxica. Paramyotonia congenita. Acquired myotonia. Dystrophia myotonica. Chondrodystrophic myotonia. www.MansFans.com

-:Pathology  The

same as muscular dystrophy but without atrophic changes in case of myotonia congenita + typical sarcoplasmic masses.

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-:Prognosis  Congenita

:- non progressive  Muscular hypertrophy persists & Myotonia improves.  Dystrophia myotonica: slowly progressive, bed ridden patient whithin 15-20 years, death before normal age from respiratory infection or heart failure.

-:Treatment 1. 2. 3. 4. 5. 6.

Quinine HCL. Procainamide HCL (local anaesthetic). Ca gluconate. Epanutin. K exchange resins. Corticosteriods. www.MansFans.com