DISEASES OF MUSCLE

(Myopathies)

MUSCULAR DYSTROPHY

DISEASES OF MUSCLE are primary affections of muscles in the form of pathological, biochemical or electrical changes characterized by involvement of proximal muscle group, ultimate wasting, absence of fibrillation, bilateral involvement, absence of involvement of central or peripheral nervous system, downhill course and absence of remission. Some of these are generally determined and may have hereditary transmission. No definite cause is known.

CLASSIFICATION

No classification is satisfactory. However, the following classification might be helpful for clinical purpose.

Genetically determined Myopathy

Muscular dystrophy

(a) X-linked muscular dystrophy.

(i) Pseudohypertrophic muscular dystrophy (Duchenne type). (хp 21)

(ii) Benign X-linked muscular dystrophy of Becker. (хр 21).

(b) Autosomal recessive muscular dystrophy

(i) Limb-girdle muscular dystrophy (Erb).

(ii) Congenital muscular dystrophy.

(c) Autosomal dominant muscular dystrophy.

(i) Facio-Scapulo-Humeral type (Landouzy-Dejering type) (4q 35)

(ii) Distal form of Gower. (2q13, 2p13)

(iii) Ocular dystrophy.

(iv) Oculo-pharyngeal dystrophy (14q 11.2-q13)

(v) Emery-Dreifuss.

It is inherited as an autosomal dominent or X linked recessive. The disease usually starts at 5-10 years. Muscles of the humero peroneal or scapuloperoneal group are affected usually. Genetic locii have been found in Xq 28, Iq II, Iq 21.2. Prognosis is uncertain.

Myotonia (Myotonic muscular dystrophy)

(a) Myotonia dystrophica. (19q 13.2 q13.3, 3q 21.3)

(b) Myotonia congenita.

(c) Paramyotonia congenita.

Periodic paralysis

Rare type

(a) Glycogen storage disease.

(b) Malignant pyrexia, etc.

(c) Mitochondrial myopathy.

Acquired Myopathy

Inflammatory

(a) Polymyositis, viral.

(b) Bacterial or Parasitic infection.

(c) Sarcoidosis

Endocrine

(a) Hypo and hyperthyroidism.

(b) Hyperparathyroidism.

(c) Hyperadrenalism.

(d) Hyperpituitarism

Metabolic

(a) Calcium.

(b) Ethanol.

(c) Chronic hypokalaemia.

(d) Chronic alcoholism.

Drugs

Lithium, Clofibrate, Chloroquin, Diamorphine, Corticosteroids, Lovastatins, Colchicine, Emetine, Aminocaproic acid, Bretylium Tosylate, Penicillamine etc.

DISEASES OF MUSCLE

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