Duchenne muscular dystrophy (mdd)
Duchenne muscular dystrophy is one of the most common forms of this disease. The disease becomes noticeable around the second year of life and occurs only in boys, which is associated with the X-linked recessive type of inheritance. The following symptoms are typical for DMD.
■ Muscular weakness. It becomes noticeable when the child has difficulty walking or limb movements. The child can start walking waddling, can not climb the stairs, gets up on his feet only with the help of hands. The last symptom arising from the weakness of the pelvic floor muscles is called the Gauer symptom.
■ Although the muscles do not ache at rest and there is no pain when pressed, the patient becomes difficult to perform certain actions. Affected muscles are weak, but often appear enlarged - this phenomenon is called pseudohypertrophy.
■ Limitation of mobility. Characteristic for the late stages of DMD. It often happens that when some muscles weaken, their antagonistic muscles remain strong, and sick children begin, for example, to walk on tiptoe. It becomes difficult to maintain the position of the body, and patients may require a wheelchair.
■ The patient develops progressive deformation and bending of the bones, exhaustion, and by the age of 10 years the majority of patients become disabled. Patients usually die before the age of 20 years. The cause of death is a pulmonary infection, accompanied by weakness of the respiratory muscles, or cardiac arrest.
Uncommon forms of muscular dystrophy
There are a number of other types of muscular dystrophy. Becker's muscular dystrophy is a disease linked to the X-chromosome, more benign than Duchenne's, which appears at the age of 5 to 25 years. People with this kind of dystrophy live longer than with DMD. Dystrophy of the shoulder girdle occurs with the same frequency in persons of both sexes and usually manifests itself at the age of 20-30 years. Approximately 50% of people suffering from this type of dystrophy, weakness appear in the humeral girdle and may not spread to the lower extremity belt, while in others the muscles of the lower extremity belly are affected first, and weakness in the shoulder girdle appears after about 10 years. The course of the disease is usually more benign in those patients who initially have upper limbs. Shoulder-flap facial muscular dystrophy is inherited by an autosomal dominant mechanism and affects equally often the faces of both sexes. It can occur at any age, but it usually appears for the first time in adolescents. This type of dystrophy is characterized by "pterygoid" scapula. Some people have a strong lumbar lordosis (curvature of the spine). The weakness of the face muscles leads to the fact that people can not whistle, pull their lips or close their eyes. Depending on which groups of muscles are affected, grasping and small finger movements may be weakened or a "hanging stop" may appear. There is no medical treatment for muscular dystrophy, but complications, such as respiratory and urinary tract infections, require antibiotics.
Treatment includes the following activities:
■ Physical exercise - this can slow the development of weakness and limitation of movement; exercise complexes under the supervision of a physiotherapist are very useful.
■ Passive stretching of tendons, which tend to be shortened.
■ With the appearance of deformities and curvatures of the spine, corrective corsets are required.
■ Surgical traction of shortened tendons.
■ Psychological help is very important; vital support for the family and home comfort.
Prognosis and morbidity
In some cases, especially with Duchenne's dystrophy, the prognosis of the disease is unfavorable. The degree of disability can be very significant, with time patients may stop walking. Most patients with dystrophy of the shoulder girdle can be helped to lead a full, albeit slightly changed life within 20-40 years, and sometimes more. People who develop muscular dystrophy in late adolescence usually have a better prognosis. Prophylaxis of muscular dystrophy is not yet possible, although the discovery of a defective gene has increased the likelihood of gene therapy.
Prevalence of the disease
Muscular dystrophy is a fairly rare disease, but it is common all over the world among people of all races. The most common form - Duchenne muscular dystrophy - occurs with a frequency of about 3 cases per 10,000 boys.
Causes
All types of muscular dystrophy are caused by genetic causes, although the exact cause of degeneration of the muscle tissue is unknown. Perhaps the main cause is a violation in the cell membrane, which uncontrollably passes calcium ions into the cell, which activates proteases (enzymes) that contribute to the destruction of muscle fibers. Possible prenatal diagnosis in the form of study of amniotic fluid before delivery. Nevertheless, parents suffering from muscular dystrophy, before having a baby, need medical genetic counseling.
Diagnostics
Typical slow progressing cases are clinically evident. In patients, especially with Duchenne's dystrophy, there is a high level of creatine kinase in the blood. In order to distinguish dystrophy from other disorders, it may be necessary to perform electromyography. Diagnosis usually confirms a biopsy; histochemical studies help distinguish dystrophy from other types of myopathies.