Neuromuscular disorder in dogs. Myasthenia gravis in dogs: general information, diagnosis and treatment

Clinical physiology of excitable tissues

Myasthenia gravis
Drugs affecting neuromuscular conduction
Eclampsia

1. Myasthenia gravis in dogs(or myasthenia gravis, Myasthenia gravis) is a neuromuscular transmission disorder characterized by muscle weakness and excessive fatigue in dogs. Myasthenia can be congenital or acquired (as autoimmune disease).

Myasthenia gravis in dogs- a neuromuscular disorder that leads to weakness of the skeletal, esophageal, facial, pharyngeal and laryngeal muscles. Frequent signs Canine myasthenia gravis includes exercise intolerance, megaesophagus, neck ventroflexion, difficulty swallowing, hypersalivation, regurgitation, inability to blink, and dysphonia (loss of voice). Careful history taking and clinical examination important facts for staging correct diagnosis. The most specific test for this disease is the immunoprecipitation radiotest for circulating antibodies against acetylcholine receptors. Various therapeutic methods but treatment must be tailored to the needs of the individual patient. The prognosis is cautious, since the likelihood of developing severe aspiration pneumonia is high.

Pathophysiology of myasthenia gravis in dogs

The lack of transmission of impulses from the neuromuscular junction (NMC) comes from structural and functional abnormalities of nicotinic acetylcholine receptors (AchR) in congenital myasthenia gravis and from destruction of AchR and postsynaptic membrane by antibodies in acute myasthenia gravis. The neuromuscular system is affected, as a result of abnormalities and destruction of the AChR, and the respiratory system, if aspiration pneumonia secondary in megaesophagus. Congenital forms of myasthenia are Jack Russell Terriers, Springer Spaniels, Smooth Fox Terriers with an autosomal recessive inheritance mechanism. Acute myasthenia gravis, like other autoimmune diseases, requires an appropriate genetic background for its manifestation. The development of the disease is multifactorial, including environmental conditions, infections, hormonal factors. This is a disease of neuromuscular transmission, in which muscle weakness occurs due to autoimmune damage to AChR in neuromuscular synapses. The congenital form of myasthenia gravis is Jack Russell Terriers, Springer Spaniels, Smooth Fox Terriers. Acute myasthenia gravis - several breeds are predisposed, including Golden Retrievers, german shepherds, labrador retrievers, dachshunds, scotch terriers. Acquired myasthenia gravis is uncommon in dogs and even rarer in cats.

Age range Congenital form - 6-8 weeks Acute form - bimodal range of onset - young group 1-4 years and senior group 9-13 years old.

Sexual predisposition The congenital form of myasthenia gravis in dogs - there is no gender predisposition. Acute - there may be a slightly increased chance of occurrence in females in the young group and no sexual predisposition in the old group.

Anamnesis

General comments Acute myasthenia gravis can have severe clinical manifestations ranging from focal involvement of the esophageal, pharyngeal, and extraocular muscles to acute generalized collapse.

Myasthenia must be included in differential diagnosis any dog with acquired megaesophagus or lower motor neuron weakness. Anamnesis Owners frequently report vomiting. It is important to differentiate vomiting from regurgitation in this case.

Weakness

Acute collapse

Clinical examination findings

While resting, dogs or cats may look quite normal. Excessive salivation, regurgitation, or repeated swallowing attempts. Muscle atrophy is usually not detected. Dyspnea if there is aspiration pneumonia. Fatigue, cramps or spasms during moderate exercise. On careful neurological examination, subtle signs include decreased or absent palpebral reflex and weakness or absence of the swallowing reflex. Spinal reflexes are usually normal or weak. Rarely, spinal reflexes are absent and the animal is unable to hold its body.

The reasons

Congenital

immune-mediated

Paraneoplastic

Risk factors Appropriate genetic predisposition. Neoplasia, in particular thymoma. Treatment of cats with methimazole for hyperthyroidism can cause reversible myasthenia gravis.

Differential Diagnosis Exclusion of other neuromuscular transmission disorders, including tick paralysis, botulism, and cholinesterase poisoning. Acute and chronic polyneuropathies.

Differentiation of myasthenia gravis from other neuromuscular disorders depending on the exact historical analysis, through physical and neurological examinations and special laboratory tests.

Blood and urine tests

There are no abnormalities on standard blood and urine laboratory tests.

Serum levels of kratinkinase are normal in myasthenia gravis. Serum levels creatine kinases may be elevated if there is polymyositis associated with the concomitant presence of thymoma.

Laboratory tests The titer of serum antibodies against acetylcholine receptors is diagnostic for the acute form of myasthenia gravis. Assessment of thyroid and adrenal function, abnormalities may be present in association with acute myasthenia gravis.

Visual diagnostic methods Radiography chest cavity, megaesophagus, and cranial mediastinal masses.

Other diagnostic procedures

Ultrasound-guided biopsy of cranial mediastinal masses may support the diagnosis of thymoma. A strong increase in muscle contraction after intravenous administration of edrophonium chloride (0.1 mg/kg IV) may be a false negative or a false positive. If the patient has a weakening or absence of a palpebral reflex, the introduction of edrophonium chloride may lead to its recovery. With the increasing availability of an anti-acetylcholine receptor antibody test, the need for an electrophysiological evaluation to confirm myasthenia gravis remains questionable. Many animals with acute myasthenia do not tolerate anesthesia well. If bradycardia is present, an ECG should be performed. Recent studies have confirmed the presence of third-degree blockade in some patients with acute myasthenia gravis.

Histopathological Findings

Biopsy of cranial mediastinal masses may reveal thymoma or thymic hyperplasia.

Patient Monitoring

The return of muscle strength should be noticeable.

Chest x-ray should be repeated every 4 to 6 weeks to monitor the development of megaesophagus.

An anti-AChR antibody test should be performed every 6-8 weeks.

Prevention of myasthenia gravis

AT this moment effective prevention no myasthenia gravis in dogs.

Possible Complications

Aspiration pneumonia Respiratory arrest (diaphragm)

Expected course and forecast

In the absence of severe aspiration pneumonia and laryngeal weakness, the prognosis for complete recovery is good. The time required for resolution is 4-6 months. In the presence of thymoma, the prognosis is fatal until complete surgical removal of the tumor and control of myasthenic signs.

Clinical signs typical for myasthenia gravis

Tachycardia
Anorexia
Difficulty grasping, chewing, and swallowing food
Dysphagia, swallowing disorder
Excess salivation
Vomiting movements
Vomiting or regurgitation
Abnormal proprioceptive positioning, abnormal posture in space
Ataxia, discoordination
Dehydration, dehydration
exercise intolerance
Fever
Generalized lameness
Generalized weakness
Weakness in the head, paresis, paralysis
Lameness hind limbs
Inability to stand, prostration
Neck weakness, paresis, paralysis, ventroflexia
Paraparesis, weakness of both hind limbs
Refusal to move
Tetraparesis, weakness, paralysis of all four limbs
Tremor, trembling, fasciculation
Lack of weight and fatness
Abnormal forelimb reflexes, increased or decreased
Abnormal hindlimb reflexes, increased or decreased
Muscle hypotension
No or reduced response to a threat
Fallout of the third century
Strabismus
Abnormal breath odor
Abnormal upper airway breathing sounds
Abnormal lung or pleural sounds
Voice changes
Cough
Dyspnea
Tachypnea
Enlargement, overflow of the bladder
Urinary incontinence, urine leakage

Treatment of myasthenia gravis in dogs

Initial treatment should be carried out in a hospital until an adequate dose of anticholinesterase drugs is selected. Patients with aspiration pneumonia may require intensive care. A gastrostomy tube may be required in animals that cannot eat or drink without regurgitation.

Activity

severity muscle weakness and the degree of aspiration pneumonia will independently limit the activity of the animal. Bowls for water and food should be raised higher to facilitate swallowing food. Must try different types food, choose what suits best in a particular situation (soft or hard, dry food or canned food).

Information for owners

It is important for owners to understand that although myasthenia gravis is a treatable disease, most patients will need months of special feeding regimen and drug therapy. Explain to the owners about the favorable outcome of the disease in the acute form.

Feeding a dog with myasthenia gravis with megaesophagus must be carried out in an upright position.

Surgical aspects Cranial mediastinal masses (thymoma) - surgery is required. Before attempting surgical removal, the animal must be stabilized with anticholinesterase drugs and the aspiration pneumonia treated. Weakness may not be present initially. Any animal suspected of having a thymoma should be tested for acute myasthenia gravis before surgical intervention.

Drug therapy Anticholiesterase drugs prolong the action of acetylcholine in neuromuscular damage. Pyridostigmine bromide syrup (Mestinon syrup, Roche Laboratories) 1-3 mg/kg every 8-12 hours diluted orally with water. Kalimin tablets. If there is no response to pyridostigmine or if there is no response to test administration of edrophonium chloride, a course of corticosteroids 0.5 mg/kg daily every 24 hours should be initiated. Prednisone at immunosuppressive doses may worsen debility on initial use.

Contraindications: drugs that reduce the safety of neuromuscular transmission - aminoglycosides, antiarrhythmic drugs, phenothiazines, anesthetics, narcotics, muscle relaxants and magnesium.
2. Drugs that increase or block transmission at the neuromuscular junction

Drugs that stimulate muscle fiber like acetylcholine. Many chemical compounds, including methacholine, carbachol and nicotine, have the same effect on muscle fiber as acetylcholine. The difference between the action of these medicinal substances and acetylcholine is that drugs are not broken down by cholinesterase or are destroyed so slowly that their action often lasts from several minutes to several hours. These drugs cause local depolarization of the muscle fiber membrane in the region of the motor end plate, where acetylcholine receptors are located. As a result, each time a muscle fiber recovers from a previous contraction, these areas depolarized by ion leakage initiate a new action potential, causing a state of muscle spasm.

Drugs that stimulate the neuromuscular junction by inactivating acetylcholinesterase.

There are three well-known drugs ( neostigmine, physostigmine and diisopropylfluorophosphate), which inactivate acetylcholinesterase in synapses, resulting in no hydrolysis of acetylcholine. With each subsequent nerve impulse, additional acetylcholine accumulates, restimulating the muscle fiber. It causes muscle spasm even with a small number nerve impulses coming to the muscle. Unfortunately, this can lead to death due to suffocation due to laryngospasm.

Neostigmine and physostigmine, when combined with acetylcholinesterase, can inhibit its action for several hours, then these substances are separated from acetylcholinesterase, and it becomes active again. In contrast, diisopropyl fluorophosphate, which is a military poison nerve gas, inactivates acetylcholinesterase within weeks, making the gas deadly.

Drugs that block transmission at the neuromuscular junction. A group of drugs known as curariform substances, can prevent the conduction of impulses with nerve ending on the muscle. For example, D-tubocurarine blocks the action of acetylcholine on the acetylcholine receptors of the muscle fiber, preventing an increase in the permeability of the channels of the muscle membrane to a level sufficient to generate an action potential.
3. Eclampsia (postpartum tetany, lactational tetany, postpartum hypocalcemia) convulsive state, which develops due to hypocalcemia in dogs and cats during pregnancy.

Predisposition. Eclampsia is more common in dogs small breeds and almost never occurs in large breed dogs and rarely in cats. Dogs with a history of eclampsia can be expected to re-develop at subsequent litters.

The reasons. Calcium is used to build the skeleton of the fetus and is lost in milk during lactation. Insufficient intake of calcium may be due to poor nutrition during pregnancy and lactation. During lactation, the animal is in a state of stress, which leads to a deterioration in appetite and a decrease in calcium intake in the body, even with an adequate diet. Excess calcium in the diet of a pregnant dog causes atrophy of the parathyroid glands and a decrease in the release of parathyroid hormone, which affects the processes of calcium mobilization from the depot and the utilization of calcium from food, in postpartum period. Metabolic factors such as alkalosis also play a role in the development of eclampsia. Against the background of alkalosis, the binding of calcium to proteins increases, due to which the content of ionized calcium decreases.

clinical symptoms. Early signs of eclampsia include restless, agitated state of the animal, irritability, frequent and heavy breathing. These symptoms increase within a few minutes or hours, then there are signs of the development of generalized convulsions - hypersalivation, gait stiffness and ataxia. Severe tetany is characterized by the development of clonic-tonic muscle spasms, which are provoked by sound and tactile stimuli. The animal lies in depressed state state, then jumps up, looks around, but immediately calms down. These symptoms are accompanied by tachycardia, miosis and fever. Death occurs as a result of severe respiratory depression, hyperthermia and cerebral edema.

Eclampsia usually develops in the first 2 weeks after delivery, but can also occur on later dates pregnancy or during childbirth, when hypocalcemia becomes one of the main factors contractile activity uterus.

Diagnosis set on the basis of anamnestic data, clinical symptoms and the effectiveness of therapy. Before starting treatment, blood should be taken to determine the calcium content, but treatment should not be delayed until a response from the laboratory is received. The serum calcium concentration is usually less than 0.7 mg/l. Blood glucose should also be assessed to detect concomitant hypoglycemia.

Treatment consists in slow (within 15-30 minutes) intravenous administration 10% calcium gluconate solution until therapeutic effect. The total dose can be 1.5-2.5 ml per kg of body weight. During the infusion, an electrocardiogram is recorded, and the heart rate is counted. With the development of bradycardia or arrhythmia, the infusion is suspended until the frequency and rhythm of heart contractions normalize, after which the infusion is resumed; at the same time, the rate of administration of the drug should be 2 times less than the initial one. At the same time, hypoglycemia, hyperthermia and cerebral edema are eliminated. Corticosteroids should be avoided because they reduce serum calcium levels by promoting urinary calcium excretion, decreasing intestinal absorption of calcium, and inhibiting osteoclast function. If the clinical symptoms do not disappear with the introduction of a calcium solution, then diazepam or phenobarbital is used to stop seizures. Other causes of seizure activity should be considered, including concomitant hypoglycemia, cerebral edema, toxicosis, or primary neurological disease associated with eclampsia.

Prevention. The animal should receive calcium in the form of calcium gluconate, calcium lactate or calcium carbonate tablets. Doses of these drugs vary: a dog can be given 10–30 mg/kg calcium carbonate 3 times daily or 150–250 mg/kg calcium gluconate 3 times daily. Any antacid is used as a source of calcium carbonate. The dog's diet must be well balanced, taking into account its body weight and age. Puppies older than 3 weeks are weaned. If the puppies are under 3 weeks old, then the dog can be allowed to feed them, however, in order to reduce the need for babies in mother's milk, they are artificially fed. If a recurrence of eclampsia occurs, puppies are weaned, regardless of their age, and fed artificially.

In the second half of pregnancy and during lactation, the dog should receive a balanced diet. Calcium supplementation is not required during pregnancy, but if the dog has had eclampsia in the past, calcium supplementation is required during lactation (eg, calcium carbonate at a dose of 10-30 mg/kg 3 times a day).

annotation Myasthenia gravis in dogs, as well as in humans, is an autoimmune neuromuscular disease. In dogs, autoantibodies to AChR (Garlepp M. et al., 1979) and other antigens characteristic of myasthenia gravis, to titin protein and ryanodine SR receptors (Shelton G.D. et al., 2001) are detected in the blood serum of dogs. Most common compared to outbred dogs Terriers, Golden Retrievers and Chihuahuas are sick. Dewey C.W. et al. (1997) describe three clinical variants of myasthenia gravis in dogs—central, acute burst, and generalized. Most often, myasthenia gravis debuts with generalized weakness and megaesophagus in combination with dysphagia (Shelton G.D. et al., 1997). Idiopathic megaesophagus is a poor prognostic sign. Pathological changes in the thymus, identified in dogs include thymomas, carcinomas and hyperplasia - 15% (Breton L. et al., 1981). In order to diagnose myasthenia (Breton L. et al. (1981) a test with neostigmine is performed. Aubrey A., Webb et al. (1997) do not recommend an EMG study with positive sample with neostigmine because of the difficulties associated with giving anesthesia. An x-ray examination of the esophagus is mandatory to detect megaesophagus. Given the presence of megaesophagus and the risk of developing aspiration pneumonia (the main cause of death), there are features of their feeding: the food should not be dry, during and 10 minutes after eating the dog should be in vertical position. In the presence of thymoma, a thymothymectomy is necessary. A 3-year-old St. Bernard male was under our supervision. Fell ill 3 months ago, lost 10 kg, could not swallow, sagged lower jaw, ptosis, facial weakness, hypersalivation with lumps of mucus in the mouth, difficulty in breathing, fatigue of the muscles of the limbs were noted (he could not run for a long time, often sat down). Most of the symptoms were compensated for 2 hours after the introduction of 1 ml of prozerin. X-ray revealed megaesophagus. Due to the impossibility of stopping oropharyngeal disorders, prednisolone was prescribed at a dose of 1 mg/kg every other day, potassium chloride, kalimin (60 mg 3 times a day). The hostess was given recommendations on feeding a sick animal in a standing position. hind legs, in small portions. After 2 months, the dog's condition improved, with x-ray examination megaesophagus was not detected, which made it possible to completely abandon kalimin and begin a gradual decrease in the dose of prednisolone. With the abolition of prednisolone after 2 months, all the symptoms of myasthenia gravis returned. A second course of glucocorticoids with AChE inhibitors was prescribed. Azathioprine could not be prescribed due to chronic infection urinary tract(the dog almost constantly received antibiotic therapy). Thus, the treatment of animals with autoimmune myasthenia gravis can be carried out according to the scheme used in humans.

What it is? Myasthenia is a classic autoimmune disease, which is characterized by a violation of the transmission of excitation at the level of the neuromuscular synapse, manifested by pathological impotence, fatigue, mainly of skeletal muscles designed to perform various actions.

The danger of the disease lies in the development critical conditions- myasthenic crises, which can be fatal.

Although it should be said that modern methods diagnostics and treatment allowed to reduce the mortality rate as much as possible, and most patients achieve stable remission.

Causes of myasthenia gravis

How does myasthenia gravis develop, and what is it? Most often, the disease begins to manifest itself in adolescence, but the peak incidence occurs in 20-40 years. According to statistics, women are more susceptible to it, but in last years men are getting sick more and more.

This form is extremely rare and manifests itself from the first minutes of a child's life with difficulty breathing due to muscle atrophy. Mortality is high.

Acquired form myasthenia gravis is more common. It is often caused by an infectious disease. Stress can be a contributing factor. Under the influence different reasons disrupted work immune system, and the body begins to produce antibodies that act against its own cells.

The role of autoimmune processes is obvious, since in the course of research, antibodies were found in muscles and the thymus gland (thymus). Often, myasthenia gravis is associated with thymoma (tumor of thymic epithelial cells) because this is the most common syndrome associated with this disease.

Changes in the thymus in the form of hyperplasia are found in most patients with myasthenia gravis. Its cells can be generators of autoantigens and trigger a pathological process, the mechanisms of which are not yet fully understood.

The disease is not inherited, but there is high probability its reappearance in predisposed families. Tandems are very common - mother-daughter or sister-sister. There is evidence that some medications can cause the onset or relapse of the disease. They block neuromuscular transmission and provoke only short-term myasthenic symptoms in otherwise healthy people.

But if the synapse defect proceeds latently, drugs can provoke the occurrence of pathological processes. These drugs include antibiotics, antiarrhythmic drugs, calcium channel blockers.

Symptoms of myasthenia gravis

For the first time, myasthenia gravis in many cases begins with a sudden attack, when swallowing and breathing are disturbed. This condition is called a crisis, the indirect factors of which may be:

Determining the cause of the primary crisis is quite difficult.

Myasthenia, the main symptoms of which are muscle weakness and fatigue. More often than others, the oculomotor, facial, chewing, as well as the muscles of the upper and lower extremities are affected. Weakness progresses with continued movement and resolves with rest. There are explicit and hidden symptoms myasthenia. The most frequent include:

The symptoms of the disease are similar to the condition that occurs in humans under the influence of toxic substances of animal or plant origin - snake venom or curare.

Myasthenia - chronic illness, which progresses and eventually causes muscle atrophy. Pathology requires constant control and treatment, because it often leads to disability.

Diagnosis of myasthenia gravis

For the diagnosis of myasthenia gravis, there are many effective methods. They are recommended to be used in a complex manner in order to avoid errors in the diagnosis. Often at first, the clinic may not be clear, since the symptoms are similar to those of many other diseases. The professional level of the doctor is very important.

Diagnostics is carried out using:

1) Electromyography - a method for studying bioelectric potentials that occur in skeletal muscles when fibers are excited;
2) Electroneurography, which allows you to explore the speed of impulses passing through the nerves;
3) genetic analysis that is carried out to detect congenital pathology;
4) Prozerin test, when a solution of prozerin is injected subcutaneously (up to 3 ml). The sample is evaluated after about 20-30 minutes. With myasthenia gravis, after the introduction of this drug, the symptoms completely disappear, and the person feels healthy, but after a few hours they resume;
5) Laboratory methods for the detection of antibodies;
6) Magnetic resonance imaging, capable of detecting a tumor thymus. There are also special tests for muscle fatigue. The patient is asked to quickly open and close his mouth, stand with outstretched arms, do squats, squeeze and unclench his hands. With repeated movements, weakness occurs or increases.

Treatment of myasthenia gravis

Treatment of myasthenia gravis has been carried out for years with the use of anticholinesterase drugs (ACEP), which include kalimin, prozerin, galantamine. These drugs differ mainly in the duration of action.

Usually preference is given to kalimin (acts 4-5 hours). Additionally, potassium preparations are prescribed, since they have the property of prolonging the action of AHEP.

The appointment of glucocorticoids (prednisolone) and immunoglobulins is highly effective. The dose is adjusted depending on the severity of the course of the disease. On the basis of therapy, a stable remission occurs. In the presence of progressive malignant thymoma, surgery is indicated or x-ray exposure thymus.

In order for the treatment of myasthenia gravis to be effective, the following rules must be observed:

Not required for myasthenia gravis special diet, but preference should be given to foods that contain potassium. There is a lot of it in dried apricots, jacket potatoes, and also in raisins.

Which doctor should I contact for treatment?

If, after reading the article, you assume that you have symptoms characteristic of this disease, then you should seek the advice of an endocrinologist.

Myasthenia gravis is a chronic autoimmune disease of the neuromuscular system, accompanied by severe fatigue, especially of the striated muscles. They say that myasthenia gravis hereditary disease. The literature describes individual familial cases of the disease, but hereditary forms of myasthenia gravis are rare. There is information about myasthenia gravis on Wikipedia. For the treatment of patients suffering from myasthenia gravis, the necessary conditions in the Yusupov hospital:

innovative methods

Patients have the opportunity to consult with the attending physician free of charge before hospitalization, receive a detailed extract and recommendations for treatment after discharge from the neurology clinic. Patients with severe myasthenia gravis can undergo the most complex examinations and treatment in the partner clinics of the Yusupov Hospital located in Moscow.

Causes and forms of myasthenia gravis

The exact causes of myasthenia gravis have not been established by scientists. The disease is associated with thymoma (tumor of the thymus) or a previous infectious disease. In myasthenia gravis, antibodies and autoreactive T cells attack antigenic targets that are located on the postsynaptic membrane and in the muscle cell. Violation of the neuromuscular transmission is manifested by muscle weakness and pathological fatigue.

According to the age criterion, the following variants of the disease are distinguished:

myasthenia gravis in newborns; congenital myasthenia gravis; juvenile myasthenia gravis; myasthenia gravis in adults; late option.

By clinical signs allocate ophthalmic, pharyngeal-facial, musculoskeletal, bulbar and generalized forms of myasthenia gravis.

Symptoms of myasthenia gravis

The ocular form of myasthenia is manifested by the development of eyelid weakness on one side or unevenly on both sides. At the beginning of the disease, ptosis (drooping of the eyelid) occurs in the late afternoon, after visual stress. Often the patient is worried about double vision and other transient disorders vision. With myasthenia gravis, photophobia does not develop.

The ocular form of myasthenia is not life threatening. If within 2 years from the moment of appearance initial signs disease, the process has not moved to other anatomical zones, then further generalization of the process becomes unlikely.

With the pharyngeal-facial form of myasthenia, weakness of the chewing and facial muscles is noted. Difficulties in swallowing and speaking occur after eating, more or less long conversation. Fatigue and weakness of the muscles of the tongue develops, a nasal tone of voice appears.

The musculoskeletal form of myasthenia gravis is extremely rare. It is manifested by increased weakness of individual parts of the body, especially the upper and lower extremities. Patients have difficulty moving around the apartment or cannot hold a mobile phone in their hand.

The bulbar form of myasthenia gravis is characterized by muscle weakness. soft palate, pharynx, tongue. The patient suffers from speech and swallowing disorders. The severity of symptoms dynamically changes during the day, with different loads, which distinguishes this form of myasthenia gravis from the true bulbar syndrome.

Generalized myasthenia gravis is a common muscle weakness. At the onset of the disease, it becomes difficult for the patient to hold his head. Gradually, the disease passes to other muscle groups, paresis of the muscles of the extremities develops. The patient's gait is disturbed, facial expressions are distorted. In the morning, after daytime sleep or after a long rest his condition improves. The slightest physical exertion sometimes leads to severe weakness.

At malignant tumor thymoma, a malignant type of the course of the disease is noted. The disease occurs at the age of fifty and progresses rapidly. Within a few weeks or months, the patient becomes disabled. At the extreme stages of the disease, the skeletal respiratory muscles are involved in the pathological process. With this form of myasthenia gravis, death can occur from suffocation.

A special manifestation of generalized myasthenia gravis is myasthenic crisis. It often develops against the background of menstruation, fever, psycho-emotional overstrain. Insufficient dosage leads to the development of a crisis medicines in the treatment of the disease. During a crisis, a pronounced weakness of all muscle groups develops, including the respiratory muscles. The duration of the crisis varies, it can last from several tens of minutes to weeks.

Diagnosis of myasthenia gravis

Diagnosis of the disease is not difficult, because all manifestations of myasthenia gravis in most cases are quite pronounced. During a standard neurological examination, doctors detect rapid muscle fatigue, myasthenic tendon reflexes, and gradual exhaustion.

Neurologists at the Yusupov hospital, if myasthenia gravis is suspected, use special tests and additional methods research:

characteristic look

For the tensilone test, edrophonium chloride (tensilone) is administered intravenously. If the severity of ptosis or diplopia decreases, then they are caused by generalized myasthenia gravis. Laboratory assistants determine the presence of antibodies to acetylcholine receptors.

An electroneuromyogram reveals a characteristic myasthenic reaction of neuromuscular transmission, rapid fatigue muscles upon re-stimulation. At the initial diagnosis of myasthenia gravis, to exclude thymoma, the doctors of the neurology clinic perform computed tomography or magnetic resonance imaging. If the patient shows signs of respiratory failure, urgent neurological examination. The need for inpatient treatment is determined at a meeting of the expert council with the participation of professors and doctors the highest category. Leading neurologists collegially draw up an optimal treatment regimen.

Treatment of myasthenia gravis

The treatment of myasthenia gravis is a difficult task. Neurologists at the Yusupov Hospital individually select treatment regimens and optimal doses medicines, use the most effective drugs, which have a minimum spectrum side effects. The patient is set to permanent or very long-term use anticholinesterase drugs that act on the mechanisms of the development of the disease.

Carefully toziruyut drugs kalimin and prozerin. The weight and age of the patient, the severity of symptoms, and other factors are taken into account. With the acute development of symptoms and their rapid progression, hormonal drugs are used. First, pulse therapy is carried out with high doses of corticosteroid hormones, then they switch to minimal dosages. In the Yusupov hospital, patients suffering from myasthenia gravis undergo plasmapheresis sessions (blood purification from circulating autoimmune complexes) against the background of the use of pulse therapy with glucocorticoid hormones.

Treatment of myasthenic crisis begins with maintenance vital functions. Gradually move on to plasmapheresis, hormone therapy. At the same time, check the presence malignant neoplasm thymus. In the presence of a rapidly growing thymoma in combination with frequent myasthenic crises carry out prompt removal tumors.

Patients are prescribed pure potassium preparations (with the exception of panangin), potassium-sparing diuretics (veroshpiron), metabolic drugs (group B vitamins, riboxin). Pregnancy is not a contraindication to the appointment of the main drugs for the treatment of myasthenia gravis. During pregnancy, they refuse plasmapheresis sessions, hormone therapy, and the use of large doses of potassium-containing drugs.

Rehabilitators of the Yusupov hospital with myasthenia gravis conduct classes physical therapy. The main tasks of exercise therapy are:

respiratory system

When compiling a complex of exercise therapy, the form of the disease, the severity and the presence of concomitant pathological conditions. Individual physiotherapy exercises are carried out in the absence of severe bulbar and respiratory disorders. Apply elements of exercise therapy during the day (short-term walks with rest, morning exercises). Simple gymnastic and breathing exercises are used, taking into account the patient's condition and the severity of the clinical symptoms of the disease.

general developmental gymnastic exercises perform from all initial positions, provide a smooth increase in load. To prevent fatigue, alternate them with relaxation techniques and breathing exercises. To maintain emotional tone, increase efficiency, sedentary games. If there is a more severe youthful form myasthenia gravis, individual sessions of therapeutic physical culture are carried out in the period of spontaneous remissions.

In order to undergo an effective course of treatment for myasthenia gravis, call the Yusupov hospital, where the contact center is open 24 hours a day, seven days a week. You will be booked into an appointment with a neurologist. After the examination, the doctor will prescribe a comprehensive treatment, which includes drug therapy, plasmapheresis and physiotherapy exercises.

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Autoimmune diseases- a group of conditions characterized by the "improper functioning" of the immune system - it "does not recognize" its tissues and produces cells (autoantibodies) against its own structures.

What is the reason for this unusual reaction?

This issue has not been studied to the end. There are suggestions that the development of autoimmune diseases can be caused by the impact of a number of adverse factors: viral or bacterial infections, taking certain medications (sulfonamides, immunostimulants), any neoplastic diseases. An important role is assigned to the genetic predisposition of the organism.

The most common autoimmune diseases in dogs are:

autoimmune hemolytic anemia
Thrombocytopenia idiopathic
Systemic lupus erythematosus
Pemphigus vulgaris
Rheumatoid arthritis
Pseudoparalytic myasthenia gravis

Autoimmune hemolytic anemia

The most common autoimmune disease in dogs, it is characterized by cells of the immune system attacking red blood cells, destroying them. The disease occurs in two forms: acute and chronic.

Symptoms. Acute manifestations are as follows: general state the dog is depressed, her temperature rises, which lasts for two or three days, shortness of breath appears, the gums become pale pink color, urine darkens (becomes dark brown or bloody), sometimes blood impurities are found in the stool. Chronic form proceeds in waves - the subsidence of the disease (remission) alternates with an exacerbation (relapse).

Thrombocytopenia idiopathic

A decrease in the number of platelets in the blood with a violation of its coagulability. Dogs of small and medium breeds are most prone to the disease during the first years of life. It is noticed that females get sick more often.

Symptoms. The debut of the disease is sudden - appear small hemorrhages on mucous membranes (conjunctiva of the eyes, oral cavity) and skin, in places of increased trauma. Sometimes massive bleeding from the nose, gums, intestines, vagina, bladder develops. At the beginning of the disease, the general condition does not suffer, as the process progresses and blood loss increases, signs of anemia increase - the animal quickly gets tired, eats poorly, the skin and mucous membranes become pale, shortness of breath appears, and the heart rate increases.

Systemic lupus erythematosus (SLE)

A disease characterized by the involvement of many organs and systems in the process simultaneously or gradually. Dogs most likely to develop SLE certain breeds(collie, sheltie, siberian husky, canadian-american white shepherd). Living in a hot climate also increases the risk of developing SLE.

Symptoms. The very first sign is nosebleeds, indicating thrombocytopenia. Further, anemia develops - the skin becomes pale, sometimes icteric, weakness and fatigue increase. The disease necessarily affects the kidneys, which leads to the appearance of protein and nitrogen in the urine. Often death occurs from kidney failure. The joints are involved in the process, which causes an increase in temperature. As the disease progresses, the joints are destroyed. It should be noted that bitches at the age of 2-8 years get sick more often.

Rheumatoid arthritis

A disease characterized by inflammation of the periarticular tissues, mainly large and medium joints. The disease has a progressive course with frequent periods of exacerbation.

Symptoms. AT acute period the state of the animal is depressed, the temperature rises periodically. In the affected joints, there is a restriction of movement, swelling, tension, soreness. The following joints are the first to be involved in the process: knee, elbow, hock, carpal. A specific syndrome is characteristic: with passive movements, a sound appears, reminiscent of bone rubbing against bone. This suggests that the joints are being destroyed.

Pemphigus vulgaris

An autoimmune process that affects the skin and mucous membranes. Characteristic manifestations diseases - rashes in the form of bubbles and the formation of extensive erosions.

Symptoms. Rashes go through several metamorphoses (transformations) - at the beginning, erythema (redness) appears, in its place a bubble forms, which breaks on its own. In place of the ruptured bladder, non-healing erosion remains, subsequently it becomes covered with a crust. Joins very quickly secondary infection aggravating general course diseases.

The most frequently affected areas of the skin and mucous membranes in the transitional areas. The first rashes, as a rule, are localized on the lips and skin of the nose. In the future, the rash appears on the oral mucosa and conjunctiva of the eyes. In such sick animals comes out of the mouth putrid smell, salivation of a purulent-foamy character is noted. Often the area around the anus, the vaginal mucosa and the prepuce are affected. Most frequent skin lesions- popliteal region, interdigital spaces, skin at the base of the claws.

Pseudoparalytic myasthenia gravis

An autoimmune disease that rapidly affects the nervous and muscular system. This disease is characterized by rapid fatigue and pathological weakness of certain muscle groups - mainly respiratory and muscles innervated by cranial nerves. Dogs of large breeds are most prone to developing myasthenia gravis.

Symptoms. After a short and insignificant load, the sick animal weakens, can hardly stand on its feet, settles down, moves in small steps, more like a hare's jumps. characteristic appearance: stiff parts of the body, arched back, muscle trembling. After a short rest, all changes pass.

Half of affected dogs have lesions digestive system in the form of difficulty swallowing, increased salivation, vomiting with mucus, a cough appears. These manifestations of myasthenia are due to paresis of the esophagus.

Treatment

The treatment of all autoimmune diseases consists in the appointment of massive doses of hormones (glucocorticoids) until relief. acute manifestations disease, followed by a transition to maintenance doses. A good effect is given by the appointment of drugs that suppress the excessive activity of the immune system. This group of diseases is difficult to treat. The prognosis, in many cases, depends on timely seeking medical help.

Myasthenia gravis is a disease that develops as a result of a deficiency in the body of the neurotransmitter acetylcholine, which transmits information from nerve fibers muscular. The disease can be either congenital or acquired.

Clinical signs

A characteristic symptom of the disease is episodic muscle weakness, which worsens after exertion and resolves after rest. At the same time, the level of consciousness, postural reactions and reflexes of the limbs remain normal. Also, hallmark in dogs, there is salivation and regurgitation due to the development of megaesophagus (noted in 90% of dogs with acquired generalized form of myasthenia gravis). Megaesophagus is less common in dogs with myasthenia gravis and rarely seen in cats.

Myasthenia gravis is a fairly common finding in dogs, while cats are rarely affected. Signs of the congenital form are noted already at a young age (6-9 weeks), more often several puppies from the litter get sick at the same time. The congenital form has been described in dog breeds such as the English Springer Spaniel, Smooth Fox Terrier, and several cats. An unusual form of transient myasthenia gravis has been described in miniature dachshunds, with signs resolving as the animals matured.

The acquired form can develop in animals of any age, sex and breed. Some predisposition to the disease reflects the popularity of the breed rather than a true increase in the incidence.

Acquired MG comes in three forms:

Focal form - characterized by weakness of individual muscle groups, which can manifest itself in the form of regurgitation (damage to the muscles of the esophagus and megaesophagus), dysphagia (damage to the muscles of the pharynx) and a decrease in the palpebral reflex (lesion facial muscles) without pronounced weakness of the muscles of the limbs. In the focal form, the only sign of myasthenia gravis may be megaesophagus. The reasons for the selective damage to individual muscle groups have not been determined.

Generalized form - characterized general weakness limb muscles. In dogs, this form can also affect the esophagus, causing regurgitation and aspiration pneumonia. Weakness of the facial muscles and pharynx is noted quite rarely.

The acute fulminant form, described in dogs, is characterized by frequent regurgitation of large volumes of fluid due to megaesophagus, and severe loss of limb muscle strength with refusal to move. Respiratory failure- a constant and formidable complication of this form of flow and the usual cause of death.

Diagnosis

The final diagnosis is established on the basis of the determination of the serum level of antibodies to acetylcholine receptors. This type research has high specificity and sensitivity, but in a small percentage of cases it can give false negative results.

If it is impossible to determine the antibody titer, a test is performed with the introduction of anticholinesterase drugs (tensilon test). More commonly used tensilon (edrophonium hydrochloride, tensilon), in its absence, neostigmine (prozerin) can be used. In myasthenia gravis, the introduction of these drugs causes a rapid resolution of signs of muscle weakness, which serves as a reliable confirmation of the proposed diagnosis. Sometimes the introduction of anticholinesterase drugs can lead to a cholinergic crisis, which is expressed in shortness of breath, bradycardia, profuse salivation, miosis, cyanosis and muscle tremor - this phenomenon is quite easily stopped by the introduction of atropine.

Differential Diagnosis

Tick paralysis.

Acute polyradiculoneuritis.

Botulism.

Acute metabolic or toxic neuropathy.

Treatment

In acquired myasthenia gravis, the primary treatment is anticholinergic drugs (often pyridostigmine). In order to avoid a cholinergic crisis, therapy begins with minimal doses, followed by an increase to the optimum. If it is impossible to give the drug through the mouth (for example, myasthenia gravis and severe regurgitation), neostigmine therapy is performed. Anticholinesterase drugs effectively control limb muscle weakness in most animals, but their effect on the muscles of the esophagus and pharynx is variable.

With insufficient effectiveness of anticholinesterase therapy, immunosuppressive drugs are added to the treatment. Initially, prednisolone therapy is carried out in anti-inflammatory doses, with insufficient effectiveness, the dose is gradually increased to an immunosuppressive dose.

With secondary MG, appropriate therapy for primary diseases is carried out. When megaesophagus is formed, nutritional support is likely to be provided through enteral feeding through a gastrostomy tube.

Forecasts

Congenital MG requires lifelong therapy and long-term prognosis for it is not favorable, only isolated cases of spontaneous remission have been described.

In the acquired form, some animals die or are euthanized within 12 months after diagnosis; in most animals (about 85%) that adequately respond to therapy, spontaneous clinical and immunological remission forms within 18 months after diagnosis (average 6.4 months). ). Unfavorable forecasts factors such as severe aspiration pneumonia, persistent megaesophagus, acute fulminant form, and thymoma as the underlying cause are determined.