Miotoniya Becker — the pathology with autosomno-recessive type of inheritance caused by hyper excitability of muscle fibers of skeletal muscles and which is shown violation of relaxation of muscles after their reduction. The clinical picture of a disease consists of the miotonichesky simptomokompleks which is shown in the beginning in lower and then and in the top extremities. The careful research of the anamnesis, data of neurologic survey, EMG and biopsy of muscles, genetic consultation helps to establish the diagnosis. Treatment is based on application of the medicines reducing miotonichesky spasms, diuretics and medicines of calcium. The physical therapy and LFK is shown to patients.
The first medical description of a congenital miotoniya belongs to 1876. It was made by Dane Julius Tomsen. A long time Tomsen's miotoniya was considered as the only option of this disease. However in 1971 German Emil Peter Becker described more severe form of a congenital miotoniya having other order of inheritance. In modern neurology it is known as Becker's miotoniya.
Both diseases represent allelic options of mutations of a gene CLCN1 which is localized on a long shoulder of the 7th chromosome. Joint frequency of their occurrence in Europe makes about 1 case on 100 thousand families, and in Scandinavia — 1 case on 10 thousand families.
Etiology and pathogenesis of a miotoniya of Becker
The reason of development of a disease of Becker is covered in the descended defect of a gene of CLCN1 coding protein of chloric channels of muscle fibers of skeletal muscles. At functional inferiority of protein or its absence ability of chloric channels to pass chlorine ions in muscle fiber decreases. Thereof ionic balance is broken and there is an electric instability of a membrane of fiber that results in hyper excitability of the last. In response to usual nervous impulses the increased excitement of muscle fibers which is clinically shown the slowed-down relaxation of muscles after their reduction results.
The disease is inherited autosomno-retsessivno, i.e. its development in the child happens only when both parents are carriers of a pathological gene.
Symptoms of a miotoniya of Becker
Unlike Tomsen's disease which manifestation of the first symptoms of a neonatology is observed at once after the birth or in the neonatality period Becker's miotoniya demonstrates at more senior children. For girls the age of display of a disease varies from 4 to 12 years, at boys most often it makes 18 years.
Basis of a clinical picture of a miotoniya of Becker is the miotonichesky phenomenon. It is characterized by the miotonichesky spasm coming after the active movement with the subsequent slowed-down relaxation of the muscles participating in the movement; emergence of a generalized miotonichesky spasm in attempt to make the bystry motive act; decrease in a spastichnost at the repeated movements. Reduction of a proyavlennost of a miotonichesky syndrome when finding the patient in heat and its increase on cold is typical.
Treat the most typical and available signs of a miotonichesky phenomenon to identification: a fist symptom — impossibility to quickly unclench fingers after their compression in a fist, bending and reduction of a thumb of a brush at blow by a neurologic hammer on an eminence of his tenor, emergence of characteristic local reduction in a roller form at percussion by a hammer on a muscle.
At Becker's disease the miotonichesky phenomenon is more expressed, than at Tomsen's disease; at a number of patients it is followed by muscle pains. Except defeat of disteel muscular groups, the miotoniya of muscles of proximal departments of extremities can be noted. Emergence of the first symptoms of a disease in muscles of legs is characteristic. Then, after several years, the miotonichesky phenomenon appears in muscles of hands. At late stages of a disease of Becker mimic muscles are involved in pathological process. Decrease in muscular force can be observed. Muscular hypertrophies, typical for Tomsen's miotoniya, meet quite seldom.
Diagnostics of a miotoniya of Becker
Identification during neurologic inspection of manifestations of a miotonichesky phenomenon and lack of other pathological deviations in the status allows to diagnose a miotoniya without difficulties. Much bigger complexity is represented for the neurologist by definition of its look. Here an important role is played by the anamnesis of a disease (his debut, an order of development of symptoms, features of a current), the family anamnesis (presence of cases of a miotoniya of Becker at relatives), features of clinic (for example, absence of a muscular hypotrophy, typical for a dystrophic miotoniya).
Diagnostic search usually includes: biochemical blood test, electromyography (EMG) or elektroneyrografiya (ENG), biopsy of muscles, consultation of the geneticist and carrying out the genetic analysis. In respect of differential diagnostics it is necessary to exclude Tomsen's miotoniya, a dystrophic miotoniya, myopathies, a syndrome of the regidny person, a psevdomiotoniya at a hypothyroidism.
Specific biochemical markers for Becker's miotoniya do not exist. At a number of patients in serum of blood substantial increase of activity of a kreatinfosfokinaza is observed. Data of an electromyography MU (motive units) allow to reveal existence of categories, patognomonichny for miotoniya, at preservation of parameters of potentials. The morphological research of muscular bioptat finds a hypertrophy of fibers and centralization of their kernels, however is not specific to Becker's miotoniya. As confirmation of a disease serve the data of the molecular and genetic analysis testifying about existence of a mutation in CLCN1 gene.
Treatment of a miotoniya of Becker
As well as the majority of gene pathologies the disease has no radical specific treatment. Therapy is directed mainly to reduction of the phenomena of a miotonichesky spasm. For this purpose application of a difenin, novokainamid, carbamazepine, a fenitoin, etc. is recommended. For reduction of deviations in ionic balance to patients diuretics (acetazoleamide) and medicines of calcium are appointed, the diet limiting receipt in an organism of salts of potassium is offered. From methods of physical therapy the electrophoresis with calcium is applied. An important element of treatment is development by the patient of the LFK special complex.
Sick with Becker's miotoniya it is necessary to avoid sharp and bystry movements, overcoolings, stay in cold. It will allow them to reduce considerably the frequency of miotonichesky attacks and to facilitate a course of disease.
Forecast and prevention of a miotoniya of Becker
Forecast of recovery adverse. At systematic and complex treatment, an exception of the factors provoking miotonichesky spasms it is possible to achieve slower progressing of a disease. As difficulties cause only the bystry movements in patients, most of patients adapt to the disease, successfully undergo social and labor adaptation, though have limited working capacity. As a rule, adult patients become disabled III group.
With the preventive purpose genetic consultation when planning pregnancy, conducting pregnancy with performing prenatal DNA diagnostics is recommended to families in which cases of a miotoniya of Becker were noted.