This form of the disease was described in 1886 by Eulenburg . In classical cases, the disease appears only in the cold, when there is a myotonic difficulty in muscle relaxation. Local cooling, for example when eating ice cream, is accompanied by muscle spasm such as myotonic contracture in the throat and tongue, which disappears after warming. Outside of cooling, patients have only increased mechanical excitability of the muscles. In some cases, cooling, in addition to the myotonic phenomenon, leads to the development of significant muscle weakness (the so-called cold paralysis).
The disease is transmitted by an autosomal dominant type, is very rare. There is intra-family polymorphism: some members of one family may have only myotonia , while others only have attacks of muscle weakness; in the latter cases, the disease is very similar to episodic familial adynamia. With age, there is a tendency to improve.
Paradoxical myotonia . It is extremely rare. It manifests itself as a typical myotonic spasm, which, in contrast to Thomsen’s myotonia during repeated movements, not only does not decrease, but on the contrary increases and movements become impossible. Schwartz- Jumpel Syndrome . Described in 1962 by Schwarz and Jampel , its synonyms are chondrodystrophic mnotonia , osteochondromuscular dystrophy. The disease manifests itself in early childhood, when growth retardation, a number of developmental abnormalities (short neck, chest deformity, scoliosis), as well as pronounced constant tonic muscle tension, frequent painful muscle contractions in various muscle groups such as common ” crumps ” are noted . The most constant syndrome in the clinical picture is the myotonic phenomenon with a characteristic difficulty in relaxation and increased mechanical excitability of the muscles. Other symptoms may sometimes be absent. Intelligence does not suffer. The disease refers to hereditary with an autosomal recessive type of transmission, more often observed with consanguineous marriage. There is an indication of a very good effect of treatment with diacarb [Averyanov Yu. N., 1978].
Pathomorphology and pathogenesis of myotonia
Pathomorphological examination reveals mainly changes in muscle tissue. So, with Thomsen’s myotonia , some atrophy of muscle fibers and the movement of their nuclei to the center are detected. With dystrophic myotonia, atrophy of muscle fibers, proliferation of connective tissue takes place. The nuclei increase in number and are located under the sarcolemma, as well as in the thickness of the muscle fiber and form long chains. A histochemical study in patients with dystrophic myotonia shows a decrease in size and an increase in the number of type I fibers, while type II fibers (white) do not change or become slightly hypertrophied. Electron-microscopic examination are hypertrophy sarkotubulyarnoy system, increased size mitochondria, and in dystrophic myotonia detected further pronounced destruction of myofibrillar apparatus, mitochondrial disruption, increased number lizosom.Patogenez myotonic disorders muscle relaxation associated with impaired cell membrane permeability, a change in ionic and mediator exchange. The various syndromes that make up the clinical picture of atrophic myotonia can to some extent be explained by a dysregulation of the hypothalamic-pituitary system or by the pleiotropic effect of the mutant gene. The question of the nosological independence of Thomsen’s myotonia and atrophic myotonia can now be considered positively resolved. In addition to the originality of the clinical picture, patients have various pathomorphological changes and changes in some biochemical parameters. So, with atrophic myotonia , an increased catabolism of class G immune globulins is found, and a linkage group with a secretary is also established. Last: the fact is used for antenatal diagnosis of atrophic myotonia using the amniocentesis method .
Myotonia treatment
With Thomsen’s myotonia, quinine, procainamide , calcium preparations have a negligible effect. ACTH in large doses can eliminate myotonic symptoms, but due to many side effects, as well as the short duration of its action, such treatment cannot be recommended. In some cases (almost 50%), a satisfactory and even good effect was obtained with the use of diphenin (0.1 g 3-4 times a day in an intermittent course). Treatment for atrophic myotonia is ineffective. In the initial stages, when myotonic spasm is still expressed , which impedes active movements, diphenin is indicated . Synthetic androgen preparations are also prescribed, and general strengthening therapy is carried out. In the advanced stages of the disease, repeated courses of anabolic hormones in combination with fractional transfusion of blood or plasma, vitamin E, a complex of vitamins B, small doses of ATP should be prescribed .