An extensive group of genetically heterogeneous diseases of the nervous system, which are inherited, are neuromuscular diseases. Myotonia is a type of such a pathology. This disease is represented by various syndromes. The work of the ion channels of chlorine and sodium is changing. There is an increase in the excitability of membranes in muscle fibers. Tonic disorders and persistent or transient muscle weakness become visible. This article will examine Thomsen's myotonia.
Types of myotonic syndromes
Myotonic syndromes can be dystrophic and non-dystrophic. The first group consists of dominantly inherited diseases, the clinical picture of which consists of three leading syndromes:
- myotonic;
- dystrophic;
- vegetative trophic.
The dystrophic form is accompanied by time-delayed muscle relaxation after muscle tension, increasing muscle weakness and degeneration (atrophy) of skeletal muscle.
Description of the disease
Thomsen's myotonia (Leiden - Thomsen) is a genetic disease in which striated muscles are affected. The beginning of tonic muscle spasms occurs at the end of vigorous activity, motility is impaired.
The disease has an autosomal dominant type of inheritance, which is quite rare: according to statistics, Thomsen's myotonia is found in seven people per million. The appearance of the first signs of the disease occurs at the age of 8 to 20 years, then they accompany a person all his life. Men are more likely to suffer from this type of myotonia.
Reasons for the development of pathology
Mutation of the CLCN1 gene leads to this hereditary disease. In etiopathogenesis, myoneural conduction is disturbed and the pathology of intracellular membranes is observed, which is caused by a decrease in the penetration of plasmolemma into the muscle fibers for chloride ions. The defect ultimately leads to ionic imbalance: chlorine ions do not penetrate inside, but accumulate on the surface of the microfibril, forming bioelectric instability in the muscle membrane.
How does Thomsen's congenital myotonia manifest?
Acetylcholine, an enzyme that regulates the excitability and contractility of muscle fibers, rises in the muscles. In cerebrospinal fluid and blood, it decreases its activity.
Such a tissue defect is typical of different myotonias. Using light microscopy, hypertrophy of certain muscle fibers can be detected. What does she face? The muscle tissue of the second type is reduced, moderate hypertrophy of the sarcoplasmic reticulum of muscle cells develops, the size of mitochondria increases, the telophragm of striated muscles expands - all this can be seen on electron microscopy.
Symptomatology
With Thomsen's myotonia, the detection of external clinical signs does not occur immediately after birth. Basically, the first signs appear in childhood and adolescence.
A feature of the myotonic phenomenon is:
- muscle hypotension in a calm state;
- hypertonicity, spasm of muscle fibers at the time of effort;
- prolonged muscle relaxation after the start of movement.
Myotonic attacks can touch the legs, arms, muscles of the shoulders, neck, face. The desire to spread fingers clenched into a fist, take a step, close the jaw, close your eyes is accompanied by muscle cramps.
With Thomsen-Becker myotonia, the physical development of the child is difficult if the first signs of the disease were found in early childhood. The kid cannot sit, get up, walk in the time prescribed for each action, his body is uncontrollable.
With any voluntary movement at a later age, myotonic attacks of skeletal muscles are manifested when walking, lifting from a place, maintaining balance. The first motor act in a patient is accompanied by a sharp muscle spasm, after which the person is immobilized. If he wants to get up, he definitely needs to lean on something. It is with great difficulty that the first step is given, sometimes tonic spasms lead to the fall of the patient. With maximum effort, it is difficult to unclench the fingers that are collected in a fist, it can last up to ten seconds. With subsequent movements, cramping stops.
Active work contributes to the fact that the affected muscles adapt to movement, there are no cramps at all. But a short rest leads to the manifestation of muscle hypertonicity with the same strength. With Thomsen's myotonia, the clinic is characteristic.
In adulthood, a patient with such a diagnosis has an athletic appearance, since the disease affects the muscles of the limbs and trunk and because of their constant overstrain, muscle mass increases. The muscles are hypertrophied and look large. They are very tense even with weak external stimuli. Even with a light blow to the affected muscles, their hypertonicity occurs. A tense cushion of muscles appears, which takes time to relax.
At the very beginning of an arbitrary movement, which requires the participation of diseased muscles, and when exposed to cold, a myotonic attack is observed. There are a large number of other provoking factors such as prolonged exposure to a static position, a sharp loud sound, an emotional outburst.
How to identify pathology?
The diagnosis of external signs can be determined easily. It is important to carefully collect a family history and features of clinical manifestations.
At the first appointment, a specialist uses a neurological hammer. With a light tapping on problematic muscle areas, a neurologist determines the ability of the muscles to contract and fixes the relaxation time after an irritating effect. If a cushion forms at the point of contact, this indicates a myotonic symptom.
The doctor suggests the patient to clench his fingers into a fist and try to unclench them. The first movements can be difficult, and then normalization of motility occurs, which means that there are tonic cramps.
Muscle tissue is in good shape even at rest; tendon reflexes show myotonic signs.
The tonic symptom complex is characteristic not only for Thomsen's myotonia. It accompanies Eilenburg paramiotonia, Becker myotonia, Steiner myotonia, as well as other neuromuscular and endocrine disorders. Differentiation of the diagnosis and designation of a certain type of myotonia are rather difficult to diagnose.
Diagnosis of the disease
So, with Thomsen's myotonia, the diagnosis is as follows. Appropriate assignment of invasive and laboratory tests:
- A muscle biopsy that reveals histological changes in the fibers that lead to muscle cell dysfunction.
- Biochemical blood test. There are no specific biochemical markers for this disease. In this way, the level of activity of creatine phosphokinase is determined in blood serum.
- DNA test. It allows you to determine the mutation of the CLCN1 gene. An analysis is needed to confirm the clinical diagnosis.
- Electromyography (EMG). A needle electrode allows this invasive examination. An instrument is inserted into the relaxed muscle, myotonic discharges are determined, and potential is recorded in the motor units. The muscles are stimulated with an electrode and tapping, which leads to their contraction. Repeated stimulation reduces the strength of myotonic spasms.
- Electroneurography (ENMG). When stimulated by an electrical impulse, the functional state of muscle tissue and the ability to contract are diagnosed. With ENMG, surface (cutaneous) and intramuscular (needle) electrodes are used. Graphic registration of the potential of motor units is carried out by needle electrodes. What is the treatment for mycotonia Thomsen?
Myotonia therapy
A complete cure cannot be achieved. The main goal of physiological and drug therapy is to eliminate the symptoms and achieve a stable remission. Effectively appointment:
- "Mexiletina" is a sodium channel blocker whose action is aimed at reducing muscle hypertonicity.
- Diuretic drugs - to maintain ionic balance, maintain magnesium levels and reduce potassium.
- Diphenin is an effective anticonvulsant.
- "Diacarba" - improves membrane permeability.
- "Quinine" - reduces the excitability of muscles, increases the refractory period.
All medicines have numerous side effects.
Physiotherapy
Improving metabolic processes in muscle tissue and its tonic spasm is achieved by:
- Exercise therapy;
- electrophoresis;
- acupuncture;
- medical swimming.
Preventive actions
The prevalence of Thomsen's myotonia is low. The disease has a favorable prognosis, but it is impossible to permanently get rid of myotonic attacks. Preventive measures relieve the patient’s condition and give a chance to live a full life.
It is necessary to exclude factors provoking myotonic seizures. Overcooling, stressful situations, intense physical exertion, sudden movements, prolonged stay in one position, emotional upheaval are unacceptable.
We examined Thomsen's myotonia, clinic, diagnosis, treatment.