Myotonia

Myotonia is a group of hereditary diseases, a characteristic feature of which is delayed muscle relaxation after contraction (myotonic phenomenon). The phenomenon of myotonia is accompanied by myotonic discharges, which are diagnosed during needle EMG. This disease refers to channelopathy (relationship with the pathology of ion channels). The manifestations of myotonia depend on the form of the disease.

The content of the article:
Classification of myotonia
Etiology and pathogenesis of myotonia
Clinical picture of myotonia
Diagnosis of myotonia
Treatment of myotonia
Prognosis for myotonia
Myotonia
Treatment tactics include the elimination of symptoms, correction of metabolic processes, electrical stimulation, exercise therapy and massage.

Classification of myotonia
According to the common classification , the following types of myotonia are distinguished:

congenital myotonia, known as Thompson’s disease;
cold paramyotonia (Eulenburg’s disease);
atrophic myotonia (Rossolimo-Batten-Steinert-Kurschmann disease dystrophic myotonia);
paradoxical myotonia;
Schwartz-Jumpel syndrome.
In addition, there is a classification based on etiological factors that trigger the mechanism of development of the myotonic phenomenon. Based on this classification, there are:

percussive myotonia;
myotonia of action;
electromyographic myotonia.
Patients with a percussive appearance have muscle contractions with a vigorous hammer blow. With myotonia of action, the patient feels difficulty during an attempt to quickly clench and unclench the fist. In the case of electromyographic myotonia, during an electromyogram, discharges are detected, the frequency of which initially increases and then decreases. In this situation, the phenomenon of myotonia is caused by the aggravation of the instability of the membrane in the structure of the muscle fiber.

Etiology and pathogenesis of myotonia
The main etiological factor provoking the development of myotonia is autosomal dominant or autosomal recessive hereditary transmission. Often this disease occurs as a result of consanguineous marriage.

Muscle dysfunction in myotonia is provoked by a disorder of cell membrane permeability, a change in mediator and ion metabolism.

The pathogenesis of atrophic myotonia is represented by a violation of the regulation of the hypothalamic-pituitary system. During a pathomorphological examination, changes in muscle tissue are diagnosed. Histological examination makes it possible to concretize the reduction in size and increase in the number of type I fibers.

Clinical picture of myotonia
The clinical manifestations of this disease depend on its form. With congenital myotonia, in most cases, the first symptoms occur in childhood (10-12 years). A child with a congenital type of myotonia develops a change in voice, which is noticeable during crying. The child undergoes an attack of suffocation, and after he calms down and stops crying, the facial muscles gradually relax. At an older age, patients develop a typical myotonic phenomenon. It is not uncommon for patients to complain of local muscle hypertonicity, which is accompanied by normal muscle contraction and difficult muscle relaxation. This is due to a spasm or a characteristic muscle contracture. These difficulties in most cases are localized in the masticatory muscles, hands and fingers, and in the case of severe course, all muscle groups can be affected.

During the examination of the patient, signs of mechanical hyperexcitability of the muscles are visualized. After a hammer blow, a deformation in the form of a fossa or a roller may be present on the affected muscle for 1-1.5 minutes. In the process of gradation of the disease, patients with congenital myotonia develop muscle hypertrophy, against which an athletic physique is formed. At the same time, the appearance of the patient does not correspond to the strength of the muscles, as a rule, it is significantly lower.

The symptoms increase under the influence of cold or excessive physical exertion. In women, the clinical picture may worsen during pregnancy.

Thompson’s myotonia in most cases is characterized by a mild course, and in some patients the symptoms weaken with age.

The first symptoms of atrophic myotonia occur in patients aged 15-35 years. The onset of the disease is accompanied by myotonic syndrome, which subsides over time, as atrophy and paresis develop. After the myotonic syndrome subsides, patients experience a gradation of myopathic symptoms. Along with muscular atrophy, there is a decrease in muscle strength. Initially, this type of myotonia is characterized by atrophy of the muscles of the face, neck, chewing muscles, over time, the muscle structures of the upper and lower extremities are involved in the pathological process.

With atrophy of the masticatory muscles, the sinking of the cheeks and temporal pits is visualized. The spread of the process of muscular atrophy in the neck is indicated by tilting the head back or forward. During the examination, pathological changes in the muscles of the upper and lower extremities, a decrease in tendon reflexes are noted.

The endocrine system suffers, which manifests itself in dysfunctional disorders of the genital glands, thyroid gland, adrenal glands and pituitary gland. Patients have tooth loss, hair loss, weight loss and thinning of the skin. From the cardiovascular system, there is a high risk of bradycardia, arrhythmia, metral valve prolapse, hypotension. In some cases, the central nervous system is affected, which manifests itself in mental disorders of varying degrees.

The development of congenital Eidenburg paramyotonia most often occurs as a result of cold exposure. At the same time, the patient feels myotonic difficulty of muscle relaxation. Hypothermia can be local or general. In the case of local hypothermia, when the patient eats too cold food, a muscle spasm occurs, which manifests itself in the form of myotonic contracture in the tongue and pharynx, eliminated by warming. If hypothermia is of a general nature, a typical myotonic phenomenon develops, and some patients have muscle weakness, “cold paralysis”. This form of myotonia may regress over time.

Scientists have not established a clear hereditary predisposition in patients with paradoxical myotonia. This disease is extremely rare and its characteristic symptom is a typical myotonic spasm, but which, unlike other myotonic spasms, does not weaken with repeated movements, but on the contrary increases.

The first manifestations of the Schwartz-Jumpel syndrome occur in early childhood. Visually, this disease is evidenced by the child’s short neck, chest deformity, scoliosis, the child lags behind in growth from peers, intelligence remains normal. During an objective examination, painful muscle contractions of various localization are diagnosed.

Diagnosis of myotonia
Diagnosis of this disease consists in collecting anamnesis, examining the patient, analyzing the results of electromyographic examination and muscle tissue biopsy. In the process of electromyography, a pathognomic sign of myotonia is detected, in the role of which myotonic discharges act.

An important stage for early detection and diagnosis is antenatal diagnosis through amniocentesis.

Differential diagnosis
The essence of differential diagnosis of myotonia is to determine the form of this disease. To distinguish the congenital form of myotonia from dystrophic, an analysis of clinical manifestations will be required. But sometimes with congenital myotonia, slight weakness of the distal muscles of the upper extremities and weak activity in EMG is determined, which is represented by a symptom of dystrophic myotonia. Continuous muscle activity may indicate neuromyotonia, and this sign is also included in the symptom complex of a rigid person. A distinctive feature of the rigid man syndrome is a decline in muscle activity during sleep and after the administration of diazepam.

Treatment of myotonia
Treatment tactics have not yet been developed, with the help of which it is possible to completely eliminate the disease, therefore, myotonia therapy is aimed at eliminating clinical manifestations. The main therapeutic goal will be to reduce the activity of muscle structures and achieve the longest possible period of remission. Drug treatment involves the use of phenyontine and diuretics, in some cases, immunosuppressive therapy (prednisone, cyclophosphamide, immunoglobulin) is advisable.

Prognosis for myotonia
Patients with mild forms of myotonia have a favorable prognosis. The threat to the patient’s life occurs only in cardiopathology against the background of dystrophic myotonia of the first type. This disease affects the quality of life of the patient, but with a competent approach to the rhythm of life and proper treatment, it is possible to achieve fairly good results.

Post Views: 491

Myotonia

Myotonia

Epilepsy is a condition characterized by recurrent

Encephalitis

Traumatic brain injury

Most Popular

WHO: 1 billion people in the world are served by medical institutions without reliable power supply

Gastritis symptoms and what is it

Diarrhea

Rectal prolapse

Recent Comments