Myasthenia gravis
Myasthenia gravis is a pathology of the neuromuscular system, which is expressed by hyper-fatigue of the muscles. In clinical practice, there is another name — asthenic bulbar paralysis. The facial, masticatory and ocular muscles are most often affected, less often the muscles involved in the breathing process. Myasthenia gravis has an autoimmune character, since a large number of autoantibodies are determined during the study of the serum of patients with myasthenia gravis. In this pathology, antibodies to the receptors of the postsynaptic membrane are formed, during which the membrane is destroyed and neuromuscular transmission is blocked.
The content of the article:
Causes of myasthenia gravis
Symptoms of myasthenia gravis
Diagnosis of myasthenia gravis
Treatment of myasthenia gravis
Prognosis and prevention of myasthenia gravis
Myasthenia gravis
There are three forms of myasthenia gravis, which differ in the nature of the course: stationary, progressive and myasthenic episodes. Based on the nature of clinical manifestations, localized and generalized myasthenia gravis are distinguished.
Diagnosis of this disease involves the analysis of anamnestic data, as well as the results of laboratory and instrumental studies. Therapeutic tactics can be conservative or operative and is determined depending on the characteristics of the course of the disease.
The first mention of pathological fatigue is found in the medical literature of the XVI century. To date, there is a tendency to a rapid increase in the number of clinical cases of myasthenia gravis. According to statistics, this disease is diagnosed in 6-7 people, in relation to every 100 thousand healthy people. Most often, women aged 20-30 years suffer from myasthenia gravis, among elderly patients it is more common in men, who in most cases suffer from the pelvis. This disease also occurs in children.
Children ‘s myasthenia gravis are divided into the following forms:
neonatal;
innate;
early childhood;
juvenile.
Causes of myasthenia gravis
To date, the etiology of myasthenia gravis has not been fully clarified. In medical practice, cases of familial myasthenia gravis are diagnosed, but the heredity of the disease has not been proven. Quite often, patients with asthenic bulbar palsy are diagnosed with hyperplasia or neoplasm of the thymus gland. Also, a factor contributing to the development of myasthenia gravis is the penetration of viruses and mycoplasmas into the human body.
The main pathogenetic feature of this disease is the dysfunction of neuromuscular transmission, which causes the characteristic clinical manifestations. The synaptic block is interconnected with a failure in the synthesis of acetylcholine. Antibodies to skeletal muscles and epithelial cells of the thymus gland are detected in the blood serum, which gives grounds for classifying myasthenia gravis as an autoimmune disease. The results of the study of the causes of myasthenia gravis prove that insufficient potassium levels in the body, hyperthyroidism and hormonal imbalance significantly increase the risks of this disease.
Symptoms of myasthenia gravis
The main clinical signs of myasthenia gravis will be muscle weakness and pronounced fatigue, which are graded with the repetition of movements. In the morning and after sleep, patients may feel satisfactory, and by the evening there is a significant increase in symptoms of the disease. As a rule, at the initial stage, patients have drooping eyelids, patients complain of double vision, these phenomena indicate a lesion of the oculomotor musculature. Over time, fatigue occurs when chewing and expressing emotions on the face.
Bulbar dysfunction is manifested by difficulty swallowing both solid and liquid food. In the process, food can get into the nose. The voice of patients with myasthenia gravis has nasal properties and often tends to “fade out”. Due to these symptoms, patients are forced to take breaks during meals, which can provoke weight loss, and in some severe cases, alimentary exhaustion. Against the background of bulbar dysfunction, the risk of developing aspiration pneumonia increases. Pathological weakness and fatigue gradually affects most of the patient’s body, starting with the upper extremities, then spreads to the neck muscles, respiratory muscles and leg muscles. Tendon reflexes are usually preserved, but in some cases they undergo exhaustion of the myasthenic type. During the examination of the patient, manifestations of muscular atrophy can be visualized, which, with proper treatment, can completely disappear.
The most dangerous manifestation of generalized myasthenia gravis is considered to be peripheral respiratory dysfunction, which acts as an absolute indication for the use of artificial lung ventilation.
A feature of the myasthenia gravis clinic in elderly patients will be the rapid spread of the pathological process and the development of respiratory disorders.
Also, the features of the clinical manifestations of this pathology depend on the age of the patient and the presence of a genetic predisposition. For example, neonatal myasthenia gravis occurs in children whose mothers suffer from bulbar asthenic paralysis, and this form is manifested by pronounced hypotension, weak newborn cry, shallow breathing, weak sucking reflex, weakness or lack of motor activity immediately after the birth of the child.
With congenital myasthenia gravis, weak fetal movement is diagnosed, in the postnatal period there is a weak cry (often a squeak), difficulty breathing, sucking, swallowing and sluggish movements. This clinical form of myasthenia gravis is extremely rare.
Symptoms of early childhood myasthenia gravis usually occur in the first two years of a child’s life. Manifestations of this form of myasthenia gravis are represented by dysfunction of the oculomotor musculature, and in some cases disorders of the mimic and masticatory muscular system may be noted. Early childhood myasthenia gravis is mainly characterized by a mild course, which usually has a favorable outcome.
The juvenile form of this disease occurs most often, adolescents (mainly girls during puberty) belong to the risk group, the course of the juvenile form of myasthenia gravis is generalized. As a result of exposure to various adverse factors of an endogenous or exogenous nature, patients with juvenile myasthenia gravis, even with a mild form of the course, may develop a myasthenic crisis. Often, the main etiological factor is an insufficient dose of anticholinesterase agents. In addition, myasthenic crisis can occur against the background of general intoxication of the body, acute infectious disease, physical overstrain, surgical intervention for concomitant pathology, the use of tranquilizers, muscle relaxants, aminazine, psychoemotional disorder, etc. Most often, myasthenic crisis is burdened with life-threatening conditions.
Diagnosis of myasthenia gravis
The diagnosis of asthenic bulbar palsy is based on the analysis of anamnesis data, examination of the patient, the results of an electromyographic examination and a proserin test. In some cases, it is important to perform a biopsy of the affected muscle. The proserin test consists in subcutaneous administration of 1.5 to 3 ml of proserin solution (0.05%) and evaluation of further clinical manifestations of the disease. The test is considered positive if, 20-40 minutes after the injection, myasthenic symptoms are completely stopped. After 2.5 hours, the symptoms resume. By means of stimulation electromyography, the normal total evoked potential is recorded, its amplitude decreases during rhythmic stimulation with a frequency of 3-5 and 50 in one second. During the study of interstitial connective tissue samples obtained by biopsy, histiocytic and lymphocytic seals, as well as dystrophic and atrophic changes in some fibers are diagnosed.
When examining a patient with suspected myasthenia gravis, a differential diagnosis takes place, the purpose of which is to exclude other diseases with a similar clinic:
basal meningitis;
polioencephalitis;
myopathy;
multiple sclerosis;
intra -stem neoplasm;
McArdle’s disease, etc.
Treatment of myasthenia gravis
The tactics of treatment of myasthenia gravis depends on the form and nature of the course of the disease. If young patients have a rapid gradation of symptoms, removal of the thymus gland is recommended. As a rule, surgical intervention is the most productive if it is performed within the first twelve months from the onset of the disease. After removal of the thymus gland, the patient can fully recover. Patients need to adhere to a diet with a reduced content of carbohydrates and salt, a sufficient amount of protein.
In the course of treatment, anticholinesterase therapy is prescribed to all patients, taking into account the severity of the course, the form of the disease, as well as the individual tolerability of drugs of this group. Medications are administered orally. Patients with myasthenia gravis are shown a regular toilet of the nose, trachea, pharynx, bronchi, it is also necessary to give the patient a drainage position several times a day. To minimize salivation, an atropine solution (1%) is used.
With concomitant dysfunctional disorders of the cardiovascular system, cordiamine, corglycone, caffeine, strophanthin, etc. are used. If it is necessary to transfer the patient to artificial ventilation, tracheal intubation is performed, while all anticholinesterase drugs are canceled. Intubated patients are supported with vitamins, saline solutions and fluids through their administration through a nasogastric catheter.
The basic method of therapy for cholinergic crisis is the complete exclusion of anticholinergic drugs, in combination with plasmophoresis, artificial ventilation of the lungs, the appointment of glucocorticoids, as well as subcutaneous or intravenous administration of atropine solution (0.05%). The atropine solution must be re-administered 1-1.5 hours after the first injection, after that the patient should feel dry mouth, and his pupils should dilate, if this does not happen, the administration of atropine is repeated again, after the same period of time.
The positive dynamics of treatment, as a rule, is evidenced by the restoration of independent breathing in the patient.
If a severe generalized myasthenia gravis is diagnosed, the appointment of steroid drugs according to the prescribed scheme is indicated. In the process of corticosteroid therapy, the use of potassium preparations and anabolic steroids is not excluded. Cytostatic injections (methotrexate) may be indicated for patients with myasthenia gravis. Patients with this form of myasthenia gravis should be constantly under medical supervision, since it is very important to control the drainage of the respiratory tract.
Prognosis and prevention of myasthenia gravis
It is almost impossible to predict the exact outcome of this disease, since it depends on many factors: the time of onset, clinical form, gender and age of the patient, as well as the presence or absence of therapeutic measures. The most favorable course occurs in the case of the ocular form of myasthenia gravis, and the most severe course of the disease accompanies the generalized form. With proper treatment and constant medical monitoring, almost all forms of this disease have a favorable prognosis.
Since myasthenia gravis is a chronic disease in most cases, in order to prevent exacerbations, patients need to take medications almost all the time. The constant use of drugs causes some inconvenience, but in general, the quality of life of patients remains at a satisfactory level. The key point in the fight against this disease will be timely diagnosis and treatment before the development of irreversible processes.
