Myasthenia gravis

Introduction to myasthenia gravis Myasthenia gravis (MG) is an autoimmune disease caused by dysfunction of the nerve-muscle junction. The main clinical manifestations are partial or systemic skeletal muscle weakness and fatigue, increased symptoms after activity, and reduced symptoms after rest. . The prevalence rate is 77 to 150/1 million, and the annual incidence rate is 4 to 11/1 million. The prevalence of females is higher than that of males, about 3:2, with morbidity in all ages, and children are mostly 1 to 5 years old. basic knowledge The proportion of illness: 0.005%-0.01% Susceptible people: no specific population Mode of infection: non-infectious Complications: myasthenia gravis crisis

Myasthenia gravis

Thymus (25%):

Myasthenia gravis is an autoimmune disease that affects the transmission of neuromuscular junctions. The exact pathogenesis is still unclear, but there are still many studies on the disease. Among them, the most studied are myasthenia gravis and thymus. Relationship, and the role of acetylcholine receptor antibodies in myasthenia gravis, and a large number of studies have found that the number of acetylcholine receptors (AchR) on the postsynaptic membrane at the neuromuscular junction of patients with myasthenia gravis is reduced, and there is anti-AchR at the receptor site. Antibodies, and deposition of IgG and C3 complexes on the postsynaptic membrane, and demonstrated that the increase in anti-AchR antibodies in serum and the reduction in the number of effective AchRs caused by deposition on the postsynaptic membrane is the occurrence of this disease. The main cause of the thymus is the main site of AchR antibody production. Therefore, the occurrence of this disease is generally closely related to the thymus. Therefore, the regulation of human AchR is increased, the number of the AchR is increased, and the deposition on the postsynaptic membrane is inhibited. The production of AchR antibodies is the key to curing this disease.

Genetic susceptibility (15%):

In recent years, human leukocyte antigen (HLA) studies have shown that the incidence of MG may be related to genetic factors. According to the age of MG, gender, thymoma, AChR-Ab positive, HLA correlation and treatment response, MG can be divided into three groups. Two subtypes: MG patients with HLA-A1, A8, B8, B12 and DW3 are mostly female, 20 to 30 years old, with thymic hyperplasia, AChR-Ab detection rate is low, taking anticholinesterase The curative effect of the drug is poor, and the early thymus removal effect is better; the MG patients with HLA-A2 and A3 are mostly male, 40 to 50 years old, and more thymoma, the detection rate of AChR-Ab is higher, and the corticosteroid effect is better; Among the 850 MG patients diagnosed and treated by Xu Xianhao in China, there are 2 pairs of twins (both sisters).

Other (10%):

Recent studies have found that MG is associated with non-MHC antigen genes such as T cell receptor (TCR), immunoglobulins, cytokines, and apoptosis (apoptosis). TCR gene rearrangement is not only associated with MG, but may also be associated with thymoma. Correlation, to determine the TCR gene rearrangement in MG patients can not only help early diagnosis of thymoma, but also the basis of MG-specific treatment. In MG patients, peripheral blood mononuclear cells (MNC) have decreased adrenal glucocorticoid receptors and normal plasma cortisol levels. Animal experiments suggest that reduction of adrenal glucocorticoid receptors is prone to EAMG.

Myasthenia gravis prevention

To enhance physical fitness, pay attention to the following aspects:

1. Encourage your spirits and keep your emotions comfortable

Spiritual emotional activities are closely related to the physiological changes of the human body. The spirit is comfortable and the spirit is pleasant. The air is smooth, the blood and blood are harmonious, the function of the organs is coordinated, the vitality is strong, and it is not easy to occur. Even if it happens, it can recover quickly; on the contrary, If the emotions are not smooth and the spirit is depressed, the air can be reversed, the yin and yang will be dysfunctional, the viscera will be dysfunctional, and the righteousness will be weakened, which will occur. The clinical occurrence of this disease often has long-term mental stress or excessive thinking, sadness. It is related to emotional changes. If the patient's emotional fluctuations often cause the disease to develop or worsen during the recovery period, the patient must pay attention to mental health during the treatment and recovery process, and keep the mind calm and clean, not greedy and delusional. Infuriating and insatiable, the only way to make this disease recover soon.

2. Reasonable, don't be partial

Reasonable and sufficient is the necessary condition to ensure the growth and development of the human body. "Five flavors of the entrance, hidden in the stomach, to raise the five Tibetan gas", lack of deficiency, affecting blood and blood biochemistry, leading to physical weakness, on the contrary, excessive damage can also damage the spleen and stomach For a long time, the body constitution is declining. Therefore, patients with muscle weakness are required to mix with the fine grains and coarse grains. Children must correct bad habits, so that the patient's physical condition can be enhanced and the vitality is strong, so that the disease can recover as soon as possible.

3. Work and rest, living is always

The onset of muscle weakness has a lot to do with overwork. The patients are often overworked, overexposed, labored day and night, or dysfunctional because of running around, consuming blood and physique, and the body is declining. And development, so patients in this disease in the recovery process, must have a regular life, work and rest, the only way to cooperate with drug treatment, gradually increase the physical fitness, and restore soon.

4. For patients with clear diagnosis, any drugs that can affect neuromuscular conduction function should be avoided, such as: aminoglycoside antibiotics - streptomycin, kanamycin and gentamicin, etc. Tetracyclines - chlortetracycline, oxytetracycline, and creatinine-exciting drugs - quinine, quinidine, procaine, etc., in addition to the withdrawal of propranolol, phenytoin and penicillamine.

Myasthenia gravis complications Complications myasthenia gravis crisis

Because the muscle weakness patients are unable to maintain their basic life due to breathing and difficulty swallowing, the vital signs are called muscle weakness, and the incidence rate is about 9.8%~26.7% of the total muscle weakness.

According to the causes of myasthenia gravis, it can be divided into three types: myasthenia gravis, cholinergic crisis and ruminant crisis.

1. The muscle weakness is caused by the development of the disease and the lack of anti-cholinesterase drugs. The clinical manifestations are swallowing, coughing, respiratory distress, difficulty and even stop. The physical examination shows that the pupil is enlarged, sweating and bloating. The bowel sounds are normal and the symptoms of the neostigmine are improved after injection.

2. Cholinergic crisis accounts for 1.0%~6.0% of the number of crisis cases. Due to the anti-cholinesterase excess, in addition to the common features of muscle weakness, the patient's pupils shrink, sweating, muscles beating The bowel sounds are hyperthyroidism, and the symptoms of the intramuscular neostigmine are aggravated.

3. The rumination crisis is caused by infection, poisoning and electrolyte imbalance, and can be temporarily relieved by the application of anti-cholinesterase drugs, followed by a critical state of aggravation.

Myasthenia gravis may be associated with other diseases, such as thymoma, followed by hyperthyroidism, a small number may be associated with rheumatoid arthritis, lupus erythematosus and autologous hemolytic anemia.

Myasthenia gravis symptoms common symptoms sensory disorder fatigue muscle tone abnormal muscle pseudo-hypertrophy over the shoulder scapula with muscle atrophy dysarthria dyspnea sleep sputum closed incomplete hands weak and unconscious...

Women with this disease are more common than men, usually starting between the ages of 20 and 40, or at any age. The most common symptoms are eyelid weakness (hangarness), eye muscle weakness, which causes diplopia, and muscles are particularly prone to fatigue after activity. In patients with myasthenia gravis, 40% of the eye muscles are first affected, and finally 85% of patients are affected. It is also common to have difficulty speaking and swallowing and weakness of both upper and lower limbs.

Myasthenia gravis

The following checks can be made for the diagnosis:

1.1 Neostigmine test: 0.5 mg intramuscular or subcutaneous injection of neostigmine methyl sulphate can be diagnosed if the muscle strength is significantly improved within half to 1 hour. If there is no reaction, you can try again with 1mg, 1.5mg, up to 2mg the next day, such as 2mg still no reaction, generally can rule out the disease. In order to prevent the new toxic base-like reaction, it is necessary to intramuscularly atropine 0.5-1.0 mg.

2 Tengxilong test: suitable for patients with critical illness, ball paralysis or muscle weakness. 10 mg was dissolved in 10 ml of physiological saline and slowly intravenously administered until 2 mg, and 8 mg was injected if there was no reaction. Symptom improvement can be diagnosed.

2. Electrophysiological examination:

Commonly used inductive electrical stimulation, damaged muscle response and rapid disappearance. In addition, the EMG repeat frequency stimulation test is also feasible. The amplitude of the low frequency stimulation is more than 10%, and the amplitude of the high frequency stimulation is more than 50%. The single fiber EMG showed a prolonged jitter, and it was also positive if it was extended by more than 50 microseconds.

3. Other: Approximately 85% of patients with anti-AChRab in serum were elevated. Chest X-ray or thymus CT, thymic hyperplasia or with thymic tumors, also have diagnostic value.

Diagnosis and diagnosis of myasthenia gravis

diagnosis

When a person has general malaise, especially when the muscles are weak enough to affect the muscles of the eye muscles or face, or if the muscle weakness increases with the use of the affected muscles, and the recovery is resumed, the doctor should suspect that there is myasthenia gravis. Because acetylcholine receptors are blocked, various drugs that increase the amount of acetylcholine are beneficial. Experimental use of one of them can help confirm the diagnosis. Tengxilong is the most commonly used drug for diagnostic tests. It can temporarily increase the muscle strength of patients with myasthenia gravis when given intravenously.

Other diagnostic tests include measuring the function of nerves and muscles with electromyography and examining acetylcholine receptor antibodies in blood.

Some patients with myasthenia gravis suffer from thymoma, which may be the cause of abnormalities in the immune system. CT scans of the chest can determine the presence of thymoma.

Differential diagnosis

1. Lambert-Eaton syndrome (Lambert-Eaton syndrome) Most men over 50 years old, about 2 / 3 with cancer, most common with small cell lung cancer; mainly due to weakness of the trunk muscles of the proximal extremities, lower extremity symptoms than Upper limbs; weight loss and fatigue, slow movement, muscles feel tired after activity, but if you continue to contract, muscle strength can be temporarily improved; occasionally extraocular muscles and medulla obligate muscle involvement; about 1/2 cases have limbs feeling Abnormal, dry mouth, impotence; serotonin esterase inhibitors are ineffective for treatment, sputum reflexes are weakened but no muscle atrophy, and myasthenia gravis is more common in women under 40 years old; often with thymic tumors; whole body muscles can be affected, The muscles with the most activity are the earliest; the muscles are weak, the morning light is heavy, the activity is aggravated, and the rest is relieved or disappeared after the rest; the tendon reflex is usually unaffected; the cholinesterase inhibitor is effective.

2. MG with thyrotoxicosis Some authors believe that MG is associated with thyrotoxicosis. Oxidative ocular paralysis is usually judged by eyeball protrusion (early inconspicuous) and no response to neostigmine.

3. Lupus erythematosus and polymyositis have no extraocular muscle paralysis, but MG can coexist with autoimmune diseases.

4. Neurosis patients complained of muscle weakness is actually fatigue, self-reported double vision (short symptoms when tired) and throat tightness (sickness ball), but no sag, strabismus, etc., on the contrary, MG can also be misdiagnosed as neurosis Or snoring.

5. Progressive extraocular tendon and congenital muscle weakness can also be misdiagnosed as MG. The first two are attached to the extraocular muscles such as the diaphragm and are permanently damaged. They do not respond to neostigmine. The other may be confrontation. The cholinesterase drug did not respond, erroneously excluded MG, and attention should be paid to electromyography of other muscles.

6. MG patients with no sagging or strabismus, but dysarthria can be misdiagnosed as MS, polymyositis, inclusion body myositis, stroke, motor neuron disease and other neurological diseases, should be noted.

7. Progressive muscular dystrophy The early pharyngeal shoulder strap muscle type and the Guillain-Barré syndrome Fisher variant may have sag, but the Fisher type sputum reflex disappears or ataxia occurs, and EMG examination can be identified.

8. Botulism affects the presynaptic membrane, leading to NMJ transmission disorders and skeletal muscle spasm. It is improved with the symptoms of Tengxilong or Xinsi, which is easily confused with myasthenia gravis, and the early manifestation is blurred. Double vision, ptosis, strabismus and eye muscle spasm can be misdiagnosed as MG. Botulism is usually dilated, the photoreaction disappears, and the bulbar muscle, trunk muscles and limb muscles are rapidly involved.

9. Organophosphorus pesticide poisoning and snake bite can cause cholinergic crisis, but there is a clear history of poisoning, snake bite history, can be identified.

10. Progressive muscular dystrophy Eye muscle type (Kiloh-Nevin type) is more common in young adults, insidious onset, no fluctuations in the disease, mainly invading the extraocular muscles, severe eyeball fixation; family history, serum muscle zymogram and Muscle biopsy and the like can be identified.

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