Myasthenia gravis is a disease that is characterized by a violation of neuromuscular transmission (that is, a violation of the process of muscle contraction that occurs in response to an impulse traveling along a nerve fiber). The cause of myasthenia gravis is often an autoimmune process, as a result of which the body produces antibodies to the structures of the neuromuscular synapse. According to statistics, myasthenia gravis occurs in every 5 out of 100 thousand people. It is a chronic disease with acute or gradual onset. The main manifestation is transient muscle weakness; ptosis (drooping) of the upper eyelids, impaired swallowing, and a “nasal” voice may also occur. In severe cases and as the disease progresses, weakness of the respiratory muscles may occur, including respiratory arrest.
The dangerous disease progresses rapidly, clinical manifestations may subside and worsen again. Pathological muscle fatigue is diagnosed more often in women than in men, and much less often in children. The average age of patients is from 15 to 45 years, thus, the maximum number of cases is registered in the most active part of the population.
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About the reasons
Currently, the causes of myasthenia gravis are not fully understood. Sometimes it is impossible to say unambiguously why a particular patient developed a disease. It is generally accepted that the following factors play a significant role:
- Family predisposition. Very often it turns out that the diagnosis of myasthenia gravis has already been made to the patient’s close relatives.
- Frequent stress, disorders in the immune system, the harmful effects of viruses, bacteria and other microorganisms. These factors “shatter” the immune system, and the body begins to synthesize antibodies against its own tissues, in particular, against the receptor proteins of the postsynaptic membrane. This leads to a delay in the transmission of signals from nerves to muscles, even blocking impulses.
- Myasthenia gravis can be a consequence of certain diseases. For example, when the thymus gland (thymus) grows, antibodies to synapse receptors also begin to be produced.
When malignant neoplasms appear in the ovaries, respiratory organs or mammary glands, they speak of Lambert-Eaton myasthenic syndrome. Muscle weakness, sometimes mistaken for myasthenia gravis, occurs with Charcot-Marie disease, dermatomyositis (destruction of connective tissue), various forms of myopathies, ALS syndrome (amyotrophic lateral sclerosis) and many other pathologies.
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The difficulty of diagnosis is that patients with myasthenia gravis at the onset of the disease may not have any clear complaints and symptoms. Neuroimaging (or MRI) shows no significant abnormalities in the structures of the central nervous system. Only in 30% of patients the thymus becomes enlarged or neoplasms are detected in it. When examined, the muscles are also not changed in any way; pathology can only be detected by microscopic examination.
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Lambert-Eaton syndrome
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Classification
Forms of myasthenia:
- congenital
- acquired
Congenital myasthenia gravis can be caused by genetic mutations. The fetus can also receive antibodies to the receptors of the postsynaptic membrane from the mother, in this case we are talking about neonatal myasthenia.
Acquired myasthenia gravis can develop in patients of any age. This diagnosis is given to adolescents, young adults and pensioners. The disease most often occurs in active age, from 20 to 30 years. The causes can be external (infectious agents) and internal (chronic diseases, heredity).
Conventionally, according to the prevalence of muscle weakness, myasthenia gravis is divided into the following types:
- Generalized, when neuromuscular synapses throughout the body are affected.
- Ocular, bulbar, when predominantly the muscles localized in the head and neck are affected.
- With predominant damage to the muscles of the extremities.
This division is relative, since an in-depth study most often reveals damage to all muscles, but clinical manifestations of myasthenia gravis can occur only in certain muscle groups of a certain localization.
According to the nature of the flow, they are distinguished:
- The progressive course of myasthenia gravis is when the manifestations of the disease become more severe over time, more and more muscles are involved, and therapy becomes less and less effective.
- Remitting course – episodic myasthenic conditions. With this form of condition, improvements alternate with exacerbations.
- Myasthenic crisis is characteristic of a generalized form of the disease. Such conditions require urgent help. The patient experiences a sharp increase in weakness, difficulty swallowing and breathing, which may require resuscitation in the form of artificial ventilation.
Danger
Myasthenia gravis is an insidious disease. Among its complications:
- A sharp increase in muscle fatigue, leading to breathing problems (the patient may suffocate).
- Dysregulation of the heart (possible cardiac arrest).
During pregnancy, myasthenia gravis may either temporarily stop progressing or, on the contrary, lead to an increase in the number of affected muscles. To exclude dangerous complications, a woman should be observed by a neurologist for all nine months.
Symptoms
Clinical manifestations of myasthenia gravis depend on the form of the disease.
Symptoms characteristic of the generalized form:
- Transient muscle weakness. This is the first sign that a sick person pays attention to. At first, muscle weakness worries you in the evening or after prolonged physical work. Then myasthenia gravis progresses, and the volume of feasible exercise decreases significantly.
- The work of all striated muscles is disrupted. The muscles of the arms and legs, neck, and torso cannot work at full strength.
- Facial muscles are affected.
- Against the background of general muscle flaccidity, tendon and periosteal reflexes are preserved.
- Difficulty breathing, shortness of breath due to weakness of the respiratory muscles.
- Inability to self-care, need for constant assistance due to severe muscle weakness.
Symptoms characteristic of the ocular form:
- Ptosis (or drooping eyelids), diplopia (“double vision”), strabismus. All these symptoms are caused by weakness of the extraocular muscles.
- Difficulty swallowing as the pharyngeal muscles are affected in a patient with myasthenia gravis.
- The voice changes, notes of nasality appear, speech becomes slow and unclear. These signs can be recognized through prolonged communication with the patient. Often, during a long conversation, due to increased muscle fatigue, speech disorders arise and increase.
The difficulty of diagnosing myasthenia gravis is due to the fact that the above symptoms may appear and disappear. They are most pronounced when a person plays sports, reads for a long time or works at the computer. That is, at those moments when the striated muscles are most involved. After all, even maintaining a certain posture or reading requires constant tension of certain muscle groups.
In the absence of adequate treatment, there is a risk of not only disability, but also death. At a time when the level of development of medicine did not allow long-term artificial ventilation, 8 out of 10 patients died from myasthenia gravis. If you notice alarming symptoms of myasthenia gravis, you must make an appointment with a neurologist. If necessary, a specialist will refer you for examination and select effective therapy.
How does myasthenia gravis manifest?
Severity and symptoms can vary greatly between patients. According to the time of onset of the disease, they are distinguished:
- Congenital form - manifestations arose in childhood and are associated with heredity or gene mutations.
- Acquired - develops throughout life, is associated with adverse environmental influences, stress, and previous diseases.
Clinical classification takes into account the location of the disease, that is, which muscle group is affected more than others.
Eye shape
Main symptoms – eye complaints:
- It is difficult for the patient to raise the eyelids; ptosis is often observed - drooping of the eyelids on one or both sides.
- It is difficult to focus on the subject, the image appears double.
- Visual acuity decreases.
- The patient has difficulty moving his eyes left and right and up and down.
- Since the muscles that hold the eyes in the correct position do not work, strabismus develops.
It is typical that after a night's rest the symptoms significantly decrease or disappear completely, and after visual stress they increase.
Bulbar form
The muscles innervated by the cranial nerves are affected. As a result, symptoms appear in the tongue, pharynx, and larynx:
- Unintelligible quiet speech.
- Nasality.
- Difficulty chewing and swallowing food, choking. Over time, this can lead to inflammation of the lower respiratory tract due to the entry of liquid and food particles into them.
If the facial muscles are affected, this affects the facial expression: it is difficult for a person to smile, express surprise, frown, bare his teeth, or purse his lips.
Generalized form
The most severe, since symptoms occur in a variety of muscle groups. The muscles of the eyelids are often affected first, then the muscles of the upper and lower extremities are involved. Patients complain that they quickly get tired when walking, it is difficult for them to stand on their feet, walk up the stairs, or raise their arms. Later, it becomes difficult for a person to perform ordinary actions - getting dressed, washing, combing his hair, eating.
In older people, the muscles of the limbs and neck are most often affected, and the disease progresses rapidly.
Diagnostics
A neurologist diagnoses myasthenia gravis based on complaints, medical history, examination and research. The specialist compares the patient's complaints with symptoms characteristic of this disease. Diagnostic studies are performed to confirm the diagnosis.
Electroneuromyography for myasthenia gravis is the “gold standard” and a mandatory study. A special ENMG mode is used - “decrement test”. During testing using electrical stimulation, the muscle being tested is forced to contract at a high frequency. As a result, with myasthenia gravis or myasthenic syndrome, a decrease in the intensity of muscle contraction is recorded.
Proserine test. Performed independently or after a decrement test. Prozerin is a substance that improves neuromuscular transmission. A small amount is injected subcutaneously, 30 minutes after this the patient is examined again by a doctor or a repeat ENMG is performed. The test is considered positive if there is clinical improvement or positive dynamics when performing the decrement test.
Laboratory diagnostics. Blood test for the content of specific antibodies to receptors and muscles. Antibodies are not detected in all cases of myasthenia gravis.
Computed tomography of the mediastinum. Used to rule out thymoma, a tumor of the thymus gland that can produce antibodies.
As a rule, these methods in combination with a consultation with a neurologist are sufficient to establish a diagnosis.
During the examination, the doctor may test for increased muscle fatigue. First, a load is given to a specific muscle group, then their condition is assessed. In the ocular form of myasthenia, the extraocular muscles are loaded; for this, the patient is asked to look at one point for 30 seconds. If there are complaints of pathological fatigue of the neck muscles, the patient is placed on his back and asked to keep his head raised for 1 minute. If there is weakness in the legs, the patient needs to do several squats or walk on his toes. To determine the degree of fatigue of the muscles of the hand and forearm, a person is asked to intensively bend and straighten the hand several times.
Recommendations for a patient with Myasthenia gravis
Myasthenia gravis is a serious disease that requires increased attention and has many features and restrictions, which, if not observed, can easily provoke a deterioration of the condition.
With myasthenia gravis, significant physical activity and prolonged exposure to the sun are contraindicated. Deterioration can also be caused by staying in a sauna or steam room.
Many medications are contraindicated:
- Magnesium preparations;
- Curare-like muscle relaxants;
- Neuroleptics and tranquilizers (except tofisopam);
- Diuretics (except spironolactones);
- Many antibiotics: aminoglycosides (gentamicin, streptomycin, kanamycin, tobramycin, sisomycin, amikacin, etc.), fluoroquinolones (norfloxacin, ciprofloxacin, ofloxacin, etc.);
- Fluorinated corticosteroids (Dexamethasone, Dexazone, Polcortolone);
- Quinine derivatives;
- Penicillamine;
- B-blockers;
- Calcium channel blockers;
- Carbamazepine;
- Oral contraceptives;
- Narcotic analgesics.
Treatment
Surgical intervention
- Thymectomy is the complete or partial removal of the thymus in the presence of tumors in this area. Performed on patients no older than 60 years.
- It is possible to affect the thymus through radiation therapy.
Drug therapy
- Anticholinesterase drugs serve to improve the conduction of nerve impulses to muscle tissue. The number of drugs, frequency and duration of administration depends on the severity of symptoms and type of disease.
- Glucocorticosteroids are used to “inhibit” autoimmune reactions.
- Potassium-sparing diuretics (allow you to retain some potassium in the body) and drugs containing potassium. Potassium helps improve neuromuscular transmission.
- Immunosuppressants also serve to suppress autoimmune processes.
Plasmapheresis
Used to cleanse the blood of antibodies to acetylcholine receptors. The procedure is not effective for all forms of myasthenia gravis. Used in combination with drug treatment. The procedure for replacing plasma (plasmapheresis) with donor plasma or similar liquids requires a balanced approach and is carried out over several hours. Requires prior consultation with a transfusiologist, as there are a number of contraindications.
Thus, there are various algorithms for the conservative treatment of myasthenia gravis, which are used by the attending physician individually, depending on the clinical case. Self-medication, self-correction of therapy prescribed by a doctor can lead to deterioration and even death. Excessive use of drugs can lead to a life-threatening condition, a cholinergic crisis develops. Its symptoms are similar to myasthenic crisis, which occurs when treatment is insufficiently effective. Both conditions require monitoring in an intensive care setting.
Prevention
After diagnosis, you need to constantly monitor the course of the disease and regularly visit a neurologist. In addition to the indicated therapy, the doctor will monitor the general condition of the body.
The patient is prohibited from physical activity, as it can worsen health. You can't be in the sun.
It is extremely important to follow the specialist’s recommendations regarding taking medications.
Medical therapists and neurologists will do everything possible to treat the patient. If unusual symptoms appear, you should consult a doctor as soon as possible. You can make an appointment for a consultation in St. Petersburg by calling the phone number listed on the website.
Forecast
With timely contact with specialists, the patient receives effective treatment, allowing to achieve stable remission, without exacerbations and myasthenic crises. And in some cases, a complete cure is possible. Refusal of medical assistance can lead to disastrous consequences.
Make an appointment with CELT neurologists at a time convenient for you. The clinic has everything necessary to conduct high-quality diagnostics. Experienced specialists will conduct the necessary research and select adequate therapy.
Make an appointment through the application or by calling +7 +7 We work every day:
- Monday—Friday: 8.00—20.00
- Saturday: 8.00–18.00
- Sunday is a day off
The nearest metro and MCC stations to the clinic:
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- Partisan
- Enthusiast Highway
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LITERATURE
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2. Miller's anesthesia. 6th ed. Philadelphia: Elsevier Churchill Livingstone; 2005. 539-72; 1094-150.
3. Ponomareva E. N. Myasthenia: Clinic, pathogenesis, differential diagnosis, management tactics. Minsk: MET; 2002.
4. Vincent A., Palace J., Hilton-Jones D. Myasthenia gravis. Lancet. 2001; 357 (9274): 2122–8.
5. Carr AS, Cardwell CR, McCarron PO, McConville J. A systematic review of population based epidemiological studies in Myasthenia Gravis. bMc Neurol. 2010; 10: 1-9.
6. Kuzin M. I., Gekht B. M. Myasthenia. M.: Medicine; 1996.
7. Treshchinsky A. I., Shlapak I. P., Suslov V. V. Anesthesia in surgical endocrinology, urology and kidney transplantation. In the book: Bunyatyan A. A., ed. Guide to anesthesiology. M.: Medicine; 1994. 493-6.
8. Blichfeldt-Lauridsen L., Hansen BD Anesthesia and myasthenia gravis. Acta Anaesthesiol. Scand. 2012; 56 (1): 17-22.
9. WittbrodtE. T., PharmD. Drugs and myasthenia gravis. Arch. Intern. Med. 1997; 157: 399–408.
10. Cammu G., deKamP. J., De Graeve K. Repeated dosing of rocuronium
1.2 mg kg-1 after reversal of neuromuscular block by sugammadex
4.0 mg kg-1 in anaesthetized healthy volunteers: a modeling-based pilot study. Br. J. Anaesth. 2010; 105 (4): 487–92.
11. Bunyatyan A. A., Stamov V. I., Mizikov V. M., Peykarova A. V. Anticholinesterase drugs in anesthesiology: replenishment of the former arsenal. Anesthesiol. and resuscitator. 2011; 1:4-8.
12. Atkinson RS, Rushman GV, Lee JA A synopsis of anaesthesia. 9th ed. Bristol: John Wright Ltd.; 1982.
Received 12/11/12