Myopathy is a progressing muscular dystrophy.
It is a group of diseases characterized by the primary dystrophic process in muscular tissue. The diseases are rather frequent, chronic and of hereditary character. Various exogenous negative factors (injuries, infections, intoxications) can elicit the available pathology or induce the exacerbation of the pathological process. To establish familial character, the family history must be studied as well as the detailed examination of all members of the family to detect the minor signs of the disease is recommended. Sporadic cases do not exclude hereditary nature of the disease. The pathogenesis has not been fully established. The primary biochemical defect is not known so far. Most significant changes are observed in the protein and carbohydrate metabolisms in the muscular tissue. For practical purposes we distinguish:
- Progressing muscular dystrophies or myopathies in a strict sense;
- Neural type involving peripheral nerves;
- Spinal type involving spinal cord (cells of anterior horn).
The clinical picture is characterized by growing atrophies of voluntary muscles. While the muscle reduction increases, the paresis are observed, but usually the muscle weakness is less pronounced than the degree of atrophies. The disease develops slowly beginning with fatigue during work or walk. The atrophies often manifest in the shoulder girdle in early period, then in the pelvic area and after that spread to other groups of muscles. As the atrophies progress, various retractions, abnormal poses and configurations of the limbs are observed. The hypertrophies of the muscles, especially of gastrocnemius muscle are common. Winged scapulas appear. The head is hanging when the neck muscles are involved. If the muscles of lumbar region are damaged, the lordosis develops. In the shoulder-scapular types of myopathies the atrophies of the shoulder girdle, back, chest and abdomen muscles are observed. The aspen waist appears. The face muscles are significantly atrophied: the specific myopathic expressionless face is observed with sunken cheeks, bilateral ptosis, and inability to close the eyes and to elevate the corners of the mouth, due to muscle weakness. In the pseudohypertrophic form of myopathy, the disease starts with pelvic muscles damage inducing specific sway known as goose gait.
As the disease progresses, the weakness in the limbs increases, the tendon reflexes weaken and then disappear, the electroexcitability in the damaged muscles decreases, the contractures are observed. The prognosis is unfavorable. The treatment is symptomatic.
