The myasthenia is the autoimmune disease causing weakness of muscles because of violation in neuromuscular transmission work. Muscle work of eyes, facial and chewing muscles, sometimes – respiratory muscles is most often broken. It defines symptoms, characteristic of a myasthenia: omission of a lower eyelid, twang of a voice, violation of swallowing and chewing. The diagnosis of a myasthenia is established after prozerinovy test and blood test on existence of antibodies to receptors of a postsynaptic membrane. Specific treatment of a myasthenia consists in purpose of antikholinesterazny medicines, such as an ambenoniya chloride or pyridostigmine. These means restore neuromuscular transmission.
Myasthenia (either false/asthenic bulbarny paralysis, or Erba-Goldflam's disease) call a disease which main display is bystry (painfully bystry) fatigue of muscles. The myasthenia is absolutely classical autoimmune disease at which cages of immune system, for any of several reasons destroy other cages of own organism. Such phenomenon can be considered usual reaction of immunity, it is only directed not to alien cages, and to the.
Pathological fatigue of muscles was described by clinical physicians in the middle of the 16th century. Since then incidence of a myasthenia promptly grows and comes to light at 6-7 people on each 100 thousand population. Women are ill a myasthenia three times more often than men. The most large number of cases of development of a disease is observed at aged people from 20 to 40 years though the disease can develop at any age or to be congenital.
The congenital myasthenia is a consequence of a gene mutation because of which neuromuscular synapses cannot normally function (such synapses are something like "adapters" which allow a nerve to interact with a muscle). The acquired myasthenia meets more often congenital, but will easier respond to treatment. There are several factors which under certain conditions can become the reason of development of a myasthenia. The most often pathological muscular fatigue is formed against the background of tumors and a good-quality giperplaziya (growth of fabrics) of a thymus - a timomegaliya. Other autoimmune pathologies become more rare the cause of a disease, for example – dermatomiozit or a sklerodermiya.
Enough cases of detection of miastenichesky weakness of muscles at patients with oncological diseases are described, for example, with tumors of genitals (ovaries, a prostate gland), is more rare - lungs, a liver, etc.
As it was already mentioned, the myasthenia is a disease of the autoimmune nature. The mechanism of development of a disease is based on development by an organism of antibodies to proteins receptors which are on a postsynaptic membrane of the synapses which are carrying out neuromuscular transmission.
Schematically it can be described so: the shoot of neuron has a permeable membrane through which specific substances – mediators can get. They are necessary for transfer of an impulse from a nervous cage to muscular on which there are receptors. The last on muscle cells lose ability to connect a mediator acetylcholine, neuromuscular transmission considerably is at a loss. It also occurs at a myasthenia: antibodies destroy receptors on "the second party" of contact between a nerve and a muscle.
The myasthenia is called "false bulbarny paralysis" because symptoms of these two pathologies are really similar. Bulbarny paralysis is a damage of kernels of three craniocereberal nerves: yazykoglotochny, wandering and hypoglossal. All these kernels settle down in a medulla and their defeat is extremely dangerous. Both at bulbarny paralysis, and at a myasthenia, there is a weakness of chewing, pharyngeal and facial muscles. As a result it leads to the most terrible manifestation - a dysphagy, that is swallowing violation. Pathological process at a myasthenia, as a rule, the first affects face muscles and an eye, then – lips, a throat and language. At long progressing of a disease weakness of respiratory muscles and muscles of a neck develops. Depending on what groups of muscle fibers are struck, symptoms can be combined in different options. There are also universal signs of a myasthenia: change of expressiveness of symptoms during the day; deterioration in a state after the long tension of muscles.
At an eye form of a myasthenia the disease affects only glazodvigatelny muscles, a circular muscle of an eye, the muscle raising an upper eyelid. As a result, the main manifestations will be: doubling in eyes, squint, complexity in focusing of a look; impossibility to look long at the objects located very far or very close. Besides, there is almost always very characteristic symptom – or omission of an upper eyelid. Feature of this symptom at a myasthenia is that it appears or amplifies by the evening. Can not be at all in its morning.
Pathological fatigue of facial, chewing muscles and the muscles responsible for the speech leads to change of a voice, difficulties with meal and the speech. The voice at patients with a myasthenia becomes deaf, "nasal" (such speech sounds approximately the same as if the person just spoke, having held a nose). At the same time to speak very hard: the short conversation can tire so the patient that it will need several hours on restoration. The same concerns also weakness of chewing muscles. Chewing of firm food can be for the person with a myasthenia physically excessive task. Patients always try to plan accurately food time to eat food at the time of the maximum action of the taken medicine. Even during the periods of relative improvement of health, patients prefer to eat in the first half of day as by the evening symptoms amplify.
Damage of muscles of a throat – more dangerous state. Here the problem, on the contrary, consists in impossibility to eat liquid food. In attempt to drink something patients often poperkhivatsya, and it is fraught with hit of liquid in airways with development of aspiration pneumonia.
All described symptoms considerably amplify after load of this or that group of muscles. For example, the long conversation can become the reason of a bigger weakness, and chewing of firm food often leads to additional deterioration in work of chewing muscles.
And, at last, several words about the most dangerous form of a myasthenia – about generalized. It provides stable 1% of mortality among patients with this pathology (over the last 50 years the indicator of mortality decreased from 35% to 1%). The generalized form can be shown by weakness of respiratory muscles. Disorder of breath which arises for this reason leads to developing of a sharp hypoxia and death if the patient was not given help in time.
The myasthenia steadily progresses over time. Rate of deterioration can significantly differ at different patients, even the temporary termination of progressing of a disease is possible (however, it meets rather seldom). Remissions are possible: as a rule, they arise spontaneously and come to an end also – "in itself". Aggravations of a myasthenia can have incidental or long character. The first option is called a miastenichesky episode, and the second – a miastenichesky state. At "episode" symptoms pass quickly enough and completely, that is during remission no residual phenomena are observed. The Miastenichesky state – it is long the existing aggravation with existence of all symptoms which, nevertheless, do not progress. Such state can proceed within several years.
Diagnostics of a myasthenia
The most indicative research at a myasthenia which can give the neurologist the mass of information on a disease is a prozerinovy test. Prozerin blocks work of the enzyme splitting acetylcholine (mediator) in synapse space. Thus, the quantity of a mediator increases. Prozerin has very powerful, but short-term effect therefore for treatment this medicine is almost not used, and here in the course of diagnostics of a myasthenia is necessary. By means of the last several researches are conducted. At first the patient is examined to estimate a condition of muscles before test. After that it is hypodermically entered . The following investigation phase is made in 30-40 minutes after medicine reception. The doctor repeatedly examines the patient, finding out thereby reaction of an organism.
Besides, the similar scheme is applied to an electromyography – registration of electric activity of muscles. EMG is carried out twice: before introduction of a prozerin and in an hour after it. The research allows to define whether really the problem consists in violation of neuromuscular transmission or function separately of a muscle or a nerve is broken. Even if after EMG there are doubts in the disease nature, carrying out a number of researches of the conducting ability of nerves (elektroneyrografiya) can be necessary.
The blood test research on existence in it of specific antibodies is important. Their detection – a sufficient reason for diagnosis of a myasthenia. If necessary do biochemical blood test (according to individual indications).
The computer tomography of bodies of a sredosteniye can give valuable information. Owing to the fact that the big percent of cases of a myasthenia can be connected with volume processes in a thymus sredosteniye KT carry out by such patient rather often.
In the course of diagnosing of a myasthenia it is necessary to exclude all other options – diseases which have similar symptomatology. First of all it is, of course, the bulbarny syndrome which is already described above. In addition, differential diagnostics with any inflammatory diseases (encephalitis, meningitis) and tumoral educations in the field of a brain trunk (a glioma, a gemangioblastoma, etc.), other neuro and muscular pathology (the BASS, Giyen's syndrome, myopathies) is carried out. In some cases violation of brain blood circulation (an ischemic stroke) in the pool of a vertebral artery can give symptoms, similar to a myasthenia.
Treatment of a myasthenia
The treatment purpose at a myasthenia – to increase quantity of acetylcholine in neuromuscular synapses. It becomes not by increase in synthesis of this substance (it rather difficult), and by oppression of its destruction. For this purpose in practical neurology medicines from the same group into which enters are used. For long-term treatment medicines of other type are chosen: an optimal variant means with soft and long action is considered here. Most often derivatives of pyridostigmine and an ambenoniya are now used.
In case of the heavy course and rapid progressing of a disease the medicines oppressing the immune answer are appointed. As a rule, use glucocorticoids, is more rare – classical immunodepressants. At selection of steroids it is always worth showing the maximum care. The medicines containing fluorine therefore the range of drugs for the choice is not really big are contraindicated to patients with a myasthenia. All patient with a myasthenia 69 years are more senior removal of a thymus is carried out. Also resort to this method at detection in a timus of volume process and in case of a myasthenia, resistant to treatment.
Medicines for symptomatic treatment are selected individually, proceeding from features of each patient. The person with a myasthenia has to follow some rules in the way of life to accelerate recovery or to prolong remission. It is not recommended to spend too much time under sunshine and to transfer excessive physical activities. Before independently beginning to take any medicine, consultation with the doctor is absolutely necessary. At a myasthenia some means are contraindicated. For example, reception of certain antibiotics, diuretics, the calming medicines and drugs containing magnesium - the last can worsen a condition of the patient considerably.
Forecast and prevention of a myasthenia
The forecast at a myasthenia depends on the mass of factors: from a form, beginning time, like a current, conditions, a sex, age, quality or existence/lack of treatment etc. The easiest the eye form of a myasthenia proceeds, it is the heaviest – generalized. At the moment at strict observance of recommendations of the doctor almost all patients have the favorable forecast.
As the myasthenia is a chronic disease, most often patients are forced to accept constantly treatment (courses or it is continuous) for maintenance of good health, but quality of their life suffers from it not really strongly. It is very important to diagnose in due time a myasthenia and to stop its progressing until emergence of irreversible changes.