Myasthenia gravis
The content of the article:
- Myasthenia gravis causes and risk factors
- Forms of the disease
- Symptoms
- Features of the course in pregnant women
- Diagnostics
-
Treatment of myasthenia gravis
- Surgery
- Radiation therapy
- General recommendations
- Possible complications and consequences
- Forecast
- Prevention
- Video
The term "myasthenia gravis" is made up of the Greek words for muscle and weakness and usually refers to a condition known as myasthenia gravis (Latin for serious, severe), a chronic autoimmune disorder that progressively worsens muscle weakness and abnormal fatigue.
A variety of muscle groups can be involved in the pathological process - muscles of the limbs, chewing, swallowing, oculomotor and others. At some point, a person begins to feel a strange fatigue in the muscles, which interferes with the usual movements. After rest, the fatigue disappears, but reappears within a short time. Daily changes are one of the characteristic manifestations of myasthenia gravis. The disease proceeds with alternating remissions and exacerbations.
Ptosis is one of the characteristic symptoms of myasthenia gravis.
The disease can develop in people of any gender and age, but women from 20 to 40 years old and men from 50 to 70 years old are most vulnerable.
Synonyms: Erb-Goldflam disease, asthenic ophthalmoplegia, asthenic bulbar palsy.
Myasthenia gravis causes and risk factors
The signal from the brain to the muscles goes through special receptors using the neurotransmitter acetylcholine. A neurotransmitter is an intermediary substance that makes contact between the brain and muscles. By binding to receptors, it instructs the muscles to contract. Acetylcholine receptors are located on the postsynaptic membrane, which is part of the neuromuscular junction. With myasthenia gravis, specific antibodies accumulate in the blood, which attack the postsynaptic membrane and destroy acetylcholine receptors, thereby preventing the signal from the brain to the muscles. This leads to a deterioration in muscle function, their weakening - asthenia.
Specific antibodies are produced due to the erroneous actions of the immune system, which, for a still unclear reason, ceases to recognize the body's own cells, mistaking them for foreign ones, attacks them, due to which they are damaged and gradually destroyed. Diseases with a similar pathological mechanism are called autoimmune, a failure can occur in relation to different types of cells. In the case of myasthenia gravis, the acetylcholine receptors of the postsynaptic membrane are exposed to the immune attack.
The exact cause of the immune failure is unknown, but it has been established that in many cases myasthenia gravis is associated with a dysfunction of the thymus gland, or thymus. This small gland is located in the upper part of the chest and is one of the central organs of the immune and hematopoietic system, in which the differentiation of T-lymphocytes, the most important link of immunity, takes place. In all likelihood, the thymus gland either causes the synthesis of specific antibodies directed at acetylcholine receptors, or maintains it. In most patients with myasthenia gravis, the thymus gland is enlarged, and in 15% thymomas are found - tumors of the thymus gland, which can be both benign and malignant.
Forms of the disease
There are the following clinical forms of myasthenia gravis:
| The form | Description |
| Ophthalmic | It is a predominant lesion of the oculomotor muscles and muscles of the eyelids (often this is the initial stage of the disease, in the future other muscle groups are also involved). |
| Bulbar | In this case, the muscles responsible for chewing and swallowing are affected, and speech also suffers. |
| Trunk | Affects the muscles of the limbs, neck and trunk, bulbar and ocular manifestations are absent. |
| Generalized |
All skeletal muscles are involved, making it difficult to perform the most common activities, including chewing, swallowing, pronunciation; the functions of the limbs are impaired. In the future, the pathology can also cover the muscles involved in breathing, which poses a threat to life. |
| Neonatal | Develops in a newborn child of a mother suffering from asthenia. The cause is the mother's specific antibodies that enter the baby's blood. This condition can be dangerous and requires close medical supervision. After a few weeks, the child's blood is cleared of antibodies, and the symptoms of myasthenia gravis disappear. |
| Myasthenic crisis | An acute condition that can be triggered by various causes, for example, bronchopulmonary infection. It is characterized by a sharp and significant deterioration in the patient's condition, manifested by ptosis, asymmetric ophthalmoparesis, hypomimia, bulbar syndrome, respiratory disorders, weakness of the limb muscles. |
| Myasthenic syndrome | Secondary pathology that accompanies some diseases, for example, cancer of the lung, bronchus, stomach, ovaries and other types of malignant tumors, poisoning, a number of infectious diseases (especially neuroinfections, such as encephalitis). |
Symptoms
The condition develops gradually, and often its onset remains unnoticed, since it is taken for ordinary overwork. The first signs of myasthenia gravis are diplopia (double vision) and ptosis (drooping of the eyelid). Later, after several months, and sometimes years, problems with chewing and swallowing appear. A person notices that he becomes unable to chew and swallow food, speech becomes slow, and nasal sounds appear. Symptoms intensify in the evening and after exercise, and decrease after rest.
All symptoms of myasthenia gravis can be divided into three groups: ocular, muscle and respiratory.
Ocular include ptosis, diplopia, oculomotor disorders (a characteristic sign of muscular nystagmoid, which consists in the deviation of the eyeballs in the extreme abductions when fixing the gaze with returning to the place).
Muscular muscles are characterized by weakness of various groups of skeletal muscles:
- weakness of facial muscles (hypomimia) - one of the characteristic signs of myasthenia gravis; manifested by difficulty in closing your eyes, smiling, puffing out your cheeks;
- bulbar syndrome - swallowing is disturbed (a person often chokes, coughs while eating, while liquid can flow into the nasal passages; problems intensify when eating hot food), nasalism appears, speech becomes indistinct;
- weakness of the chewing muscles - it is tiring for a person to chew food, to the point that sometimes he is forced to hold the lower jaw with his hand so that it does not sag;
- weakness of the muscles of the trunk and neck - it becomes difficult to hold the head, because of which it can hang down or toss back, it is difficult to maintain posture (hunched posture);
- weakness of the muscles of the arms and legs - more often affects the extensor muscles than the flexors, more often the proximal muscles than the distal ones. Weakness increases after exercise, for example, having run to the bus, a person does not have the strength to enter it, arriving home after work, cannot climb the stairs.
Respiratory symptoms can be caused by muscle weakness in the diaphragm, intercostal muscles, and sometimes by a sinking of the epiglottis as a result of weakening of the laryngeal muscles. It is difficult to breathe in, it is difficult to clear your throat. In the event of breathing disorders, the patient needs hospitalization connected to a ventilator, since the condition is life-threatening.
Features of the course in pregnant women
It is difficult to predict how pregnancy will affect myasthenia gravis. According to the available clinical data, in about a third of cases, pregnancy does not have a significant effect on the course of the disease, in a third of cases it increases the symptoms, and in another third, the woman's condition, on the contrary, improves. Regardless of this, all pregnant women with myasthenia gravis should be under special obstetric supervision throughout the gestation and during childbirth, and after childbirth, the same close supervision by a pediatrician is necessary for newborns until maternal antibodies disappear from their blood.
Diagnostics
It is not always possible to diagnose the disease immediately, often the patient visits different doctors for a long time, trying to find out the reasons for the strange fatigue. Diagnosis is also complicated by the fact that after rest the symptoms usually resemble, or are significantly weakened.
The diagnosis is confirmed after an examination, which includes:
- analysis for antibodies to muscle specific receptor tyrosine kinase;
- test with anticholinesterase agents (Kalimin, Proserin);
- electromyography;
- muscle biopsy followed by morphological analysis of the sample (performed in diagnostically difficult cases).
The main method is the anticholinesterase test, for which Proserin is usually used. The drug is usually administered subcutaneously at a dose corresponding to 0.125 mg / kg of the patient's body weight, the condition is assessed after 30-40 minutes. The test is considered positive in the presence of positive changes: disappearance of bulbar and eye symptoms, restoration of muscle strength.
After confirming the diagnosis of myasthenia gravis, a computed or magnetic resonance imaging of the chest is performed in order to identify a possible tumor of the thymus gland.
Differential diagnosis is carried out with hereditary forms of myasthenia gravis, myasthenic syndromes (search for the underlying disease), amyotrophic lateral sclerosis, multiple sclerosis, hereditary and inflammatory myopathies, Rossolimo-Courchner-Steinert-Batten disease, paroxysmal myoplegia, structural myopathies, central neuroendocrine disorders systems (tumor, vascular diseases), chronic fatigue syndrome, secondary asthenia.
Treatment of myasthenia gravis
Drug therapy consists in the appointment of drugs that increase the content of acetylcholine (Kalimin, potassium chloride), as well as drugs that suppress an overly active immune system (immunosuppressants). In some cases, glucocorticoids are indicated. Anabolic steroids can be used as a means of choice in the absence of effect from other drugs (and the presence of contraindications to surgery).
Kalimin is an anticholinesterase agent used in the diagnosis and treatment of myasthenia gravis
In severe cases, intravenous administration of immunoglobulin is indicated, as well as plasmapheresis, a method that allows you to clear the blood of specific antibodies circulating in it. In case of severe respiratory disorders, the patient is connected to artificial ventilation.
Surgery
The operation is indicated when a tumor of the thymus gland is detected - the affected gland is removed (thymectomy). However, in some cases, thymectomy is performed in the absence of thymoma. As clinical practice shows, in many cases this makes it possible to reduce the symptoms of myasthenia gravis and stop its progression (the clinical effect can appear both immediately and after six months or a year later), however, like any surgical intervention, the operation is associated with a certain risk, therefore it is considered only in severe cases, in the absence of the effect of conservative therapy. Nevertheless, the efficiency of the operation is the higher, the less time has passed since the onset of severe symptoms.
Radiation therapy
In order to suppress the hyperfunction of the thymus gland, its irradiation may be indicated. This method is used for inoperable thymomas and other contraindications for surgery.
General recommendations
To improve the effectiveness of treatment, the patient must comply with a number of restrictions:
- Give up bad habits (smoking can significantly worsen symptoms).
- Limit sun exposure.
- Avoid excessive physical exertion.
- Maintain an optimal work and rest regime for yourself.
Some medications are not recommended for patients with myasthenia gravis, including:
- diuretics (with the exception of spironolactones);
- aminoglycosides, fluoroquinolones;
- magnesium-containing preparations;
- antipsychotics, tranquilizers, derivatives of gamma-hydroxybutyric acid (except for grandaxin);
- muscle relaxants;
- fluoride corticosteroids;
- quinine derivatives; and a number of others.
Possible complications and consequences
Possible complications of myasthenia gravis include various disorders caused by the weakness of a particular muscle group. The most dangerous is breathing disorder.
Forecast
Myasthenia gravis belongs to incurable diseases, however, the prognosis is conditionally favorable: with proper treatment, the patient can live a long time and at the same time maintain an acceptable quality of life. Currently, this disease is no longer considered fatal, and before the advent of effective therapy, about 70% of patients died. In the absence of treatment, the symptoms of myasthenia gravis progress, there is a generalization of the process with the involvement of the respiratory muscles, which can be fatal.
Prevention
Since it is not known what is the trigger mechanism of the immune disorder underlying the onset of myasthenia gravis, specific prevention has not been developed. Non-specific preventive measures include all general strengthening and supporting the immune system measures that are combined into the concept of a healthy lifestyle.
Video
We offer for viewing a video on the topic of the article.
Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
