Myasthenic syndrome

Myasthenic syndrome is characteristic of myasthenia gravis (Erb-Joly disease) - a neuromuscular disease accompanied by muscle weakness and fatigue.

It is often associated with hyperplasia or tumor of the thymus gland (up to 70% of cases), but the etiology is not fully understood.

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

Epidemiology

Myasthenic syndrome is most often observed in women aged 20-30, but can also occur in childhood and in people over 50. The development of the disease is subacute or chronic.

[ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ]

Pathogenesis

In pathogenesis, the leading role is played by the expansion of the synaptic cleft, up to the complete destruction of the synapse, atrophic and dystrophic changes in the striated muscles.

[ 10 ], [ 11 ]

Symptoms myasthenic syndrome

Myasthenic syndrome begins with weakness of the muscles of the eyes, pharynx, larynx with impaired swallowing, voice, speech, rapid fatigue of the eyes, especially when reading, less often - weakness in the limbs. All these symptoms are painless and quickly pass with rest. In addition, there is a violation of the function of the endocrine glands, primarily the thyroid (hyperfunction) and adrenal glands (insufficiency), and the mineral metabolism of potassium, which leads to heart failure. In all cases of involvement of the respiratory muscles in the process, ventilation suffers.

Crises develop with colds, intoxications, hormonal changes (including pregnancy), physical or mental stress. In this case, myasthenic syndrome is accompanied by a sharp deterioration in the condition with generalization of disorders. Oculomotor disorders, Erb-Goldflam bulbar palsy (aphonia, dysarthria, dysphagia, when the patient cannot swallow even saliva), difficulty breathing (shallow, frequent, ineffective), cardiac dysfunction, psychoemotional disorders (excitement is replaced by apathy), vegetative disorders - mydriasis, tachycardia, weak pulse, dry skin, intestinal atony and sphincters develop. With rapid progression, respiratory arrest may occur after 10-20 minutes. Distinctive feature: a positive reaction to proserin - 20-30 minutes after intramuscular injection of 2-3 ml of proserin, a sharp decrease in symptoms is noted.

It is necessary to differentiate myasthenic syndrome from Lambert-Eaton disease, which develops with lung carcinoma, breast cancer, prostate cancer, ovarian cancer: most often, muscles of the limbs and trunk are affected, there is no reaction to prozerin. The crisis may resemble cholinergic crises with an overdose of anticholinesterase drugs, but in this case it is distinguished by a vegetative reaction: hypersalivation, profuse sweating, vomiting, profuse diarrhea, frequent urination. Keep in mind that these two crises can be combined with each other in people using prozerin.

Forms

Myasthenic syndrome can be local with damage to one muscle group, most often the eyes, larynx, pharynx, facial muscles or trunk muscles, or generalized with or without respiratory distress. According to the course of myasthenic syndrome, the following are distinguished: progressive form; episodes (short crisis and long-term remission); stable form with periods of deterioration in the form of a crisis.

[ 12 ], [ 13 ], [ 14 ]