Myasthenia gravis: symptoms

Symptoms of myasthenia gravis are manifested by weakness and pathological fatigue of muscles, the severity of which can fluctuate significantly throughout the day and from day to day. Weakness usually increases in the second half of the day and with physical activity and decreases after rest. Initially, the external muscles of the eyes and the muscles of the eyelids are often involved, which causes doubling and ptosis. Usually the symptoms are symmetrical. In a relatively small proportion of patients (10-15%), the disease involves only the muscles of the eyes, but more often the symptoms gradually become more generalized. In this case, the muscles of the extremities are involved, especially their proximal parts (for example, ilio-lumbar and deltoid muscles). The triceps muscles of the shoulder, flexors and extensors of the fingers are also involved. With weakness of the muscles of the pharynx and larynx, difficulty in swallowing, attacks of asphyxia, aspiration of the writing and secretion of the respiratory tract. The main danger of the disease is associated with the weakness of the respiratory muscles, which can lead to inadequate breathing and in severe cases - to the myasthenic crisis. Deterioration can be triggered by emotional stress, infections, changes in hormonal status (especially hypothyroidism or thyrotoxicosis), various drugs, such as antibiotics-aminoglycosides, antiarrhythmics, diuretics, magnesium salts, beta-adrenoblockers.

Transient neonatal myasthenia gravis, characterized by a breach of sucking, a weak cry, a swallowing and breathing disorder, develops in 12% of newborns born to mothers suffering from myasthenia gravis. Symptoms of myasthenia gravis usually appear already in the first few hours after birth and can last from several weeks to 2 months, later not renewing. Correlation between the severity of the disease in the mother and the baby is usually absent, despite the fact that the neonatal myasthenia gravis is most likely caused by the transition of antibodies to acetylcholinesterase through the placenta. Myasthenia gravis in children, including young children, can also be a sporadic acquired autoimmune disease, similar to that that occurs in adults. At birth, in early childhood, in children of a later age, as well as in adults, congenital myasthenic syndrome, which is associated with genetically determined anomalies of presynaptic or postsynaptic structures that disrupt the neuromuscular transmission, can manifest itself. These conditions are usually inherited by an autosomal recessive type. The degree of generalization of muscle weakness in various syndromes is variable: in some cases it is manifested only by diplopia and ptosis, in others it is more diffuse.

Eye symptoms of myasthenia gravis

Eye symptoms occur in 90% of cases, and in 60% - are the main ones. They are characterized by the following manifestations.

• Ptosis develops gradually, bilaterally and often asymmetrically.
• More pronounced at the end of the day, least of all - on waking.
• Strengthens after a long look up due to fatigue.
• If one eyelid is raised by hand, when the patient looks upwards, small oscillatory movements of the pair age will appear.
• The symptom of Cogan is the twitching of the eyelid upwards after lowering the glance from above to the primary position.
• Positive test with ice: ptosis decreases after applying ice to the eyelid for 2 minutes. The test is negative for non-miasthenic ptosis.

Diplopia is often vertical, but it can affect any or all extraocular muscles. There may be pseudo-interventional ophthalmoplegia. A patient with stable deviation is assisted by surgery on the muscles, injection of a toxin CI. Botulinum or a combination thereof.

Nystagmoid movements can be noted in the extreme directions of the gaze.

Test with eudrophonia

Edrophonia is an anticholoneterase agent of short action that increases the amount of acetylcholipa in the neuromuscular junction. In myasthenia gravis, this leads to a transient decrease in symptoms, such as weakness, ptosis and diplopia. The sensitivity of the test: 85% - with ocular and 95% - with systemic myasthenia. Potential, but rare complications include bradycardia, loss of consciousness; it is possible and a lethal outcome, so the test can not be performed without an assistant, and the reanimation gurney should be half a hand in case of sudden caries-respiratory complications. The test is conducted as follows:

Objectively assess the baseline level of ptosis or diplopia with the Hess test.

1. Intravenously injected with 0.3 mg of atropine, which minimizes muscarinic side effects.
2. Intravenous 0.2 ml (2 mg) of edrophonium hydrochloride is administered. If the symptoms decrease, the test is immediately stopped.
3. In the absence of hypersensitivity after 60 seconds, add the remaining 0.8 ml (8 mg).
4. Conduct the final measurement and / or repeat the test Hess and compare the results, remembering that the action lasts only 5 minutes (Figure 18.1121.

[1], [2], [3], [4]