What is myopathy, what are its classification, symptoms and treatment? Rigid person syndrome, myotoxic drugs and steroid myopathy.

Translation: Alexandra Varshal (translation is provided with structural rearrangements and abbreviations)

Adapted from Khan and Larson: Acute myopathy secondary to oral steroid therapy in a 49-year-old man: a case report. Journal of Medical Case Reports 2011 5:82.

In 1932, Cushing described myopathy as one of the symptoms of hypercortisolism. Corticosteroids entered medical practice in 1948, and in 1958 Dubois described the first patient with iatrogenic myopathy caused by corticosteroids. Since corticosteroids became widely used in practice, clinicians quite often encounter acute and chronic forms steroid myopathy. Chronic steroid myopathy developing against the background long-term use steroids, is more common. Acute steroid myopathy (ASM) is less common and develops early in treatment, usually with intravenous administration high doses of steroids.

The first cases of ASM were described in asthmatics receiving high-dose intravenous corticosteroids for status asthmaticus. MacFarlane and Rosenthal reported a patient receiving intravenous hydrocortisone in whom ACM manifested as difficulty weaning from mechanical ventilation. About OSM that occurs when oral intake steroids, rarely reported. Kumar described a patient who developed myopathy after a single dose of a corticosteroid. We present a similar case in which a patient developed acute myopathy after taking methylprednisolone twice.

Disease history

A 49-year-old man contacted orthopedic clinic with complaints of pain in the plantar surface of the foot. He was diagnosed with plantar fasciitis and prescribed methylprednisolone. On the second day of therapy, he felt vague pain in the neck. He didn't pay attention to it at first, but the pain intensified and became more widespread.

On the third day of treatment, myalgia and muscle weakness affected the shoulder and thigh muscles, and the patient stopped taking the medication. He was examined by a doctor on the fourth day of treatment: the pain and muscle weakness had progressed and spread more and more. The patient reported that he could not open the car door due to muscle weakness and pain in his arm. The muscles were painful on palpation, and the pain did not decrease even while taking paracetamol - 500 mg every 6 hours. He did not have fever, shortness of breath, flu-like symptoms, facial weakness, difficulty swallowing, or urinary or gastrointestinal symptoms. There was only a history of gastroesophageal reflux disease.

Upon inspection: Blood pressure - 130/85 mm Hg, pulse - 80 beats per minute, respiratory rate - 15 per minute, body temperature - 37.2 ° C, blood oxygen saturation 98% (normal: 96-98%). The muscles of the arm, including the small muscles of the hand, are painful on palpation. Sensitivity of the cranial and peripheral nerves intact and symmetrical. Muscle strength of the shoulder and forearm is significantly reduced: 2 points out of 5. The tone of the facial muscles is normal. The patient's handshake was weak and he had difficulty rising from a sitting position. Gait has not changed, deep tendon reflexes were not injured, Babinski's symptom was negative. Cardiovascular, respiratory system and the abdomen upon examination was unremarkable.

Test results: UAC and main biochemical parameters- without deviations from the norm. IN biochemical analysis blood, a significant increase in the level of CPK was noted - 891 U/l (normal - 22-198 U/l) and C-reactive protein- 14.86 mg/l (normal<5 mg/L). Незначительно повышены АСТ - 64 МЕд/л (норма 10-40 МЕд/л) и АЛТ - 69 МЕд/л (норма 9-60 МЕд/л). Биопсия мышц и электромиография не проводились.

Treatment

The patient was prescribed 400 mg of ibuprofen every 6 hours, as usual for myalgias, and re-examined after a week. Seven days later, during a routine examination, the patient noted that his health had improved significantly: muscle pain had decreased and muscle strength had been restored. Upon examination, the tone in all muscle groups was 5 points out of 5. A repeated biochemical blood test revealed that CPK and AST decreased to normal, and ALT remained slightly elevated (82 IU/l). Myoglobin in urine is negative.

The doctor met with the patient again 30 days after the onset of the disease. The patient felt well and returned to his usual lifestyle and agricultural work. The pain in the leg persisted, becoming worse with physical activity. For this reason, the patient continued to take ibuprofen at a dosage of 400 mg as needed.

Discussion

ASM is a rare pathology, and its pathogenesis is unclear. There are several theories, one of which is that corticosteroids activate a ubiquitin-dependent proteolytic system that affects muscle cells. Another model suggests that insulin-like growth factor-1 (IGF-1), which prevents cell apoptosis, is inhibited by steroids, leading to increased apoptosis in muscle cells.

Askari et al. recorded ASM in six of nine patients receiving oral prednisolone from July 1972 to November 1973. In one of the patients, ASM began a few days after the start of treatment. Five patients took maintenance doses (15-60 mg) for 60-240 days without any evidence of myopathy. However, four of these five patients experienced symptoms of corticosteroid myopathy as the maintenance dose was increased. The researchers concluded that the development of myopathy in patients receiving corticosteroids was independent of patient age, dosage, or duration of use.

A typical picture with ASM is diffuse myalgia and muscle weakness. Involvement of the pelvic girdle is most common. In some patients, ASM is expressed in the fact that it is difficult for them to remain without a ventilator due to damage to the respiratory muscles.

A number of laboratory tests can help establish the diagnosis of ASM. In particular, these are serum CPK, AST, ALT and myoglobin in the urine. Electromyography and muscle biopsy can also help clarify the diagnosis. No analysis, however, is specific. Elevations of serum enzymes are an inconsistent finding in ACM. In our patient, as in other described cases, the levels of CPK, AST and ALT were increased. However, Askari et al. not all patients with ASM showed an increase in CPK. A more consistent feature of ASM in their patients was an increased level of urinary creatinine excretion. Electromyography may be normal; a reduced amplitude of the muscle action potential is often found with preserved speed of sensory and motor impulses.

Muscle biopsy for ASM usually shows diffuse necrosis of type 1 and type 2 fibers; however, biopsy often does not help establish the diagnosis.

There are currently no recommendations regarding steroid doses that would reduce the likelihood of developing myopathy. Our patient took methylprednisolone twice: 24 mg and 20 mg. A similar case was described when taking 40 mg prednisolone. We were unable to find in the literature descriptions of cases of the development of ASM when taking prednisolone in a lower dosage.

There is no specific treatment for steroid myopathy. The literature mainly describes cases where myopathy goes away on its own without any intervention when steroid therapy is stopped.

Conclusion

Steroids, as a class of medications, are the treatment of choice for a number of diseases. They are prescribed by doctors of almost all specialties. Although ASM is very rare, it should be recognized as early as possible in order to stop glucocorticoids in time.

The patient gave written consent for the publication of his case. A copy of the written consent is available from the editor-in-chief of the journal (JOURNAL OF MEDICAL CASE REPORTS).

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Congenital myopathies usually present in infancy with “floppy baby” syndrome with poor muscle strength. Plasma creatine kinase levels are normal, and EMG is of the myopathic type. Central core disease usually presents with mild, nonprogressive muscle weakness in the neonatal period, leading to delays in walking and other physical development. This disease is inherited in an autosomal dominant manner. Nemaline myopathy (congenital non-progressive myopathy, thread-like myopathy) is a more severe disease manifested by muscle weakness and hypotension. The disease results in difficulty feeding, delayed walking and sometimes weakness of the respiratory muscles. The disease progresses slowly; Older children or adults with this myopathy are characterized by decreased muscle mass and an abnormally long face with a protruding lower jaw. Nemaline myopathy is inherited either in a dominant or recessive manner. Centronuclear (myotubular) myopathy again manifests itself in the neonatal period. Damage to the extraocular muscles is typical.

Muscular dystrophies

The onset and severity of diseases varies. Specific genetic tests are available to diagnose many of these diseases, and genetic counseling should be provided to all patients/families. The onset of diseases usually occurs in childhood, although some forms appear later. The following commonly encountered muscular dystrophies are distinguished.

Myotonic dystrophy

This is the most common hereditary muscle disease. Myotonic dystrophy type 1 is inherited in an autosomal dominant manner and occurs due to the expansion of cytosine-thymine-guanine (CTG) trinucleotide repeats in the 3"-untranslated region of the gene encoding muscle protein kinase (DMPK), located on chromosome 19q13.3. In addition to myopathy , possible disturbances of consciousness, subcapsular cataracts, cardiac conduction disorders, sensorineural hearing loss, baldness in the frontal region and hypogonadism. Myotonic dystrophy type 2 is also an autosomal dominant disease, resulting from the expansion of cytosine-cytosine-thymine-guanine nucleotide repeats (CCTG). ) in intron 1 of the ZNF9 gene, located on chromosome 3q. It causes a proximal muscular dystrophy, sometimes with pain and hypertrophy, but without impairment of consciousness. Myotonic dystrophy types 1 and 2 leads to alternative splicing of the voltage-gated chloride channel (. C1C-1) and is therefore considered together with channelopathies.

Duchenne muscular dystrophy

It is an X-linked disease and therefore affects boys; associated with deletion of the dystrophin gene. Usually appears between the ages of 2 and 6 years. As a rule, the patient has been confined to a wheelchair since early adolescence. Most patients do not live beyond 20 years of age. Duchenne muscular dystrophy is characterized by weakness of the proximal muscle groups and muscles of the lower and upper extremities, pseudohypertrophy of the calf muscles, and possible cardiac conduction disorders and scoliosis.

Becker muscular dystrophy

It is also an X-linked disorder and has a distribution of muscle weakness similar to Duchenne muscular dystrophy (considered a variant of Duchenne muscular dystrophy). It is usually milder than Duchenne myopathy, but the severity may vary. Symptoms may not appear until 10 years of age or later, and patients may have a long life expectancy, although with varying degrees of disability.

Amery-Dreyfus muscular dystrophy

An X-linked disease associated with a mutation in the emerin gene. The disease manifests itself at the age of about 5 years with weakness of the muscles of the upper and lower extremities. Weakness of the proximal muscle group develops later. It is possible to develop contractures and movement disorders in the joints; patients are at risk of sudden cardiac death due to conduction disturbances.

Pelvic-brachial muscular dystrophy Leiden-Mobius

Both dominant (type I) and recessive (type II) types of inheritance are possible. Several gene abnormalities can cause this syndrome, so the prognosis is variable. Cardiac abnormalities may occur. Boys and girls get sick with the same frequency; symptoms usually appear in late childhood.

Landouzy-Dejerine muscular dystrophy

It is an autosomal dominant disorder that affects both males and females. The onset usually occurs in late childhood or early adulthood. Symptoms may be mild, although generalization is possible; the lower extremities are affected later.

Channelopathies are a recently identified group of diseases in which there is a defect in the genes of one of the ion channels involved in the regulation of normal muscle tissue. Myotonia is caused by repeated bursts of action potentials where muscle contraction is spontaneously activated. The result is an inability to relax the muscle. Symptoms usually improve with physical activity. Conversely, paramyotonia worsens in the cold and after exercise. Becker's disease is the most common form, while Thomsen's disease, although less common, is usually milder. Hyperkalemic periodic paralysis can be triggered by potassium intake, and glucose may help relieve symptoms of the disease. The opposite applies to hypokalemic periodic paralysis. Andersen syndrome is an autosomal dominant disorder in which attacks of paralysis are triggered by prolonged inactivity (including sleep), calorie deprivation, and cold. It is accompanied by a prolongation of the Q-G interval on the electrocardiogram and a tendency to tachycardia. Malignant hyperthermia can be provoked by vapor anesthetics, depolarizing muscle relaxants, or excessive physical activity. Sustained increases in intracellular calcium concentrations in skeletal muscle lead to excessive muscle contraction with hyperthermia, metabolic acidosis, hypoxia, and hyperkalemia.

Mitochondrial myopathies are increasingly being identified in clinical practice, but they are still considered rare diseases.

  • MELAS syndrome - episodic encephalopathy, stroke-like episodes; a progressive neurodegenerative disease, in many cases also causing diabetes mellitus.
  • MERRF syndrome - optic atrophy, peripheral neuropathy, dementia, myoclonic epilepsy, cerebellar ataxia and sensorineural hearing loss.
  • Kearns-Sayre syndrome - progressive symptoms of damage to the extraocular muscles, including ptosis, pigmentary retinal degeneration, sensorineural hearing loss, proximal myopathy and cardiac conduction abnormalities.
  • CPEO syndrome (chronic progressive external ophthalmoplegia) is similar to Kearns-Sayre syndrome, but has a later onset and is not accompanied by retinal degeneration.

Congenital metabolic diseases should be considered in the differential diagnosis of muscle lesions, especially when they occur early in life or when there is a relevant family history. Differential diagnosis includes glycogenosis. Listed below are diseases in the clinical picture of which muscle symptoms primarily appear.

  • Pompe disease (glycogenosis type II) occurs due to deficiency of the lysosomal enzyme α-1,4-glucosidase (acid maltase), which leads to unregulated glycogen accumulation with impaired muscle structure and function.
  • Measles disease (glycogenosis type III; limited dextrinosis) occurs due to deficiency of amylo-1,6-glucosidase, leading to the accumulation of abnormal glycogen, which cannot be broken down to release glucose.
  • McArdle's disease (type V glycogenosis) occurs due to myophosphorylase deficiency, which also leads to impaired glycogen breakdown. Swelling and tenderness of muscle tissue are observed, creatine kinase concentrations are generally very high, and episodes of rhabdomyolysis may occur.
  • Tarui disease (glycogenosis type VII) results in clinical manifestations similar to McArdle disease and is associated with a deficiency of muscle phosphofructokinase.
  • Carnitine palmitoyl transferase deficiency causes episodes of muscle pain and weakness, periodic increases in creatine kinase concentrations, and myoglobinuria.

In clinics for adults, in addition to highly specialized centers, acquired muscle diseases are much more common than congenital ones. Among them, myopathy caused by alcohol abuse or drugs, including glucocorticoids, is identified.

Acute alcoholic myopathy is relatively rare and leads to muscle necrosis; an inflammatory infiltrate of varying volume causes muscle weakness and muscle pain. Plasma creatine kinase levels are significantly elevated, and this disease may cause myoglobinuria and rhabdomyolysis with concomitant renal failure. Recovery in most cases occurs after stopping alcohol consumption and using supportive measures. Chronic alcoholic myopathy primarily affects type II fibers (fast twitch, anaerobic, glycolytic). Classically, acute alcoholic myopathy is observed after 10 years of drinking alcohol daily in quantities exceeding 100 g (10-12 units) in terms of ethanol. The etiology is not exactly known. Factors include ethanol's induction of mitochondrial dysfunction, which in turn leads to impaired ATP production and fatty acid utilization; accumulation of acetaldehyde, which suppresses protein synthesis; impaired protein synthesis due to reduced amino acid availability and growth hormone/IGF-1 activity; the formation of free radicals causes damage to cell membranes.

Steroid myopathy does not always occur with long-term use of high doses of glucocorticoids. It develops more often when taking strong fluorinated glucocorticoids (dexamethasone, betamethasone and triamcinolone). As with alcoholic myopathy, acute and chronic forms are distinguished. Acute steroid myopathy usually occurs after acute exposure to high doses of glucocorticoids and may require many months to recover. A subacute, necrotizing form of myopathy has been described when taking glucocorticoids; it is characterized by severe symptoms, the concentration of creatine kinase exceeds the norm by more than 10 times. Exposure of myocytes to glucocorticoids impairs protein synthesis and results in loss of the protective effects of IGF-1. Moreover, increased cellular protease activity increases muscle protein breakdown. Biopsy reveals a variety of fiber sizes, loss of type II fibers, and necrotic and basophilic fibers throughout the muscle. As with other metabolic myopathies, the proximal muscles are usually affected, although in severe cases there may be more generalized involvement, including the respiratory muscles. In patients receiving glucocorticoids for a long time, other clinical manifestations of glucocorticoid excess usually exist by the time myopathy occurs. Treatment consists of minimizing glucocorticoid exposure by reducing the dose, using topical formulations, taking the drug every other day, and avoiding fluorinated glucocorticoids. Performing resistance-intensified exercise is beneficial in restoring normal muscle function and muscle mass. Recovery in chronic cases is slow and complete recovery may not occur.

A fully developed form of acute myopathy with tetraparesis is rare. This disease is characterized by an acute onset with generalized weakness. It is similar to steroid myopathy, but has a more severe and more generalized course. Muscle relaxants also play a role in etiology.

EMG shows low or normal action potentials. Biopsy may reveal type II fiber atrophy or necrosis, similar to steroid myopathy. There is no specific treatment. Recovery is usually complete, but can be lengthy.

Latest research results

Critical illness myopathy is associated with prolonged hospitalization, increased risk of requiring mechanical ventilation, and increased mortality. Patients are at increased risk of developing critical illness myopathy if they have sepsis, hyperglycemia, or if they require treatment with glucocorticoids. Among the etiological factors are systemic inflammation (especially in sepsis), increased proteolysis, oxidative and metabolic stress. Neurological symptoms often develop and there are disturbances in electromechanical coupling. Intensive insulin therapy is recognized as a measure to protect patients from the consequences of critical illness myopathy.

Loss of muscle mass in adynamia increases when combined with stress and is thought to be associated with hypercortisolemia. Essential amino acids, combined to reproduce the ratio found in muscle tissue, serve as a strong anabolic stimulus in myopathy caused by adynamia or the use of glucocorticoids. It is worth paying attention to the nutrition of patients receiving glucocorticoids, those who are critically ill, and patients who are likely to be immobilized for a long time.

The addition of creatine increases physical capabilities, the impairment of which is observed when glucocorticoids are administered to experimental animals in doses exceeding physiological ones. The supplement reduces the loss of muscle mass when taking glucocorticoids. Clinical studies of patients taking glucocorticoids or in the intensive care unit are needed to study this drug, the administration of which may be a safe prophylactic method.

Steroid myopathy is diagnosed after other causes of muscle weakness and wasting have been excluded. Apart from the acute necrotizing form of steroid myopathy, there is usually no activation of systemic inflammation or elevation of circulating muscle markers. To prevent the patient from developing myopathy, the dose of glucocorticoid should not be high and the duration of administration should not be long. A muscle biopsy may be required for a definitive diagnosis. The prognosis varies and is related to the severity of the disease. Improvement usually occurs if glucocorticoids are reduced or discontinued. If possible, other risk factors for muscle loss should be excluded. These include certain drugs and alcohol abuse. There is no specific treatment. Resistance exercise to restore muscle mass and the use of nutritional supplements are recommended, but there are no RCTs demonstrating their effectiveness.

Muscle weakness that does not go away after rest, flabby and flabby muscles, atrophy of muscle tissue, curvature of the spine - these symptoms characterize myopathy. This disease affects at any age and can manifest itself in varying degrees of severity - from minor problems with movement to complete paralysis. Muscle myopathy is incurable and is considered a progressive disease, but its development can be slowed down. The main thing is to make a diagnosis in time and begin therapy.

Overview of Myopathy

Neuromuscular diseases in which dystrophic lesions of certain muscles are observed, accompanied by steadily progressive degeneration of muscle tissue, are called myopathies. Pathology develops due to:

  • disturbances in the functioning of mitochondria, which ensure the oxidation of organic compounds and use the energy resulting from their breakdown for further actions;
  • destructive changes in the structure of myofibrils, which provide contraction of muscle fibers;
  • disturbances in the production of proteins and enzymes that regulate metabolism in muscles and contribute to the formation of muscle fibers;
  • changes in the functioning of the autonomic nervous system, which regulates the functioning of internal organs, endocrine glands, lymphatic and blood vessels, and is responsible for adaptive reactions.

Such disorders cause degenerative changes in muscle fibers, atrophy of myofibrils, which are replaced by connective and adipose tissue. The muscles lose their ability to contract, weaken and stop actively moving. Physical activity is unable to restore the strength of atrophied muscles, since their weakness is not due to “underdevelopment”, but due to systemic changes at the molecular level, which have led to biochemical processes in muscle tissue being disrupted and certain connections between cells being weakened or absent.

Muscles with myopathy are weakened unevenly, so weaker areas of muscle tissue are not used during physical stress, which leads to accelerated atrophy. At the same time, stronger muscles take on the entire load. At first, after physical exercise, a person is able to feel an improvement, but then the tone of the “pumped up” muscles decreases, and the condition worsens. Sometimes complete immobilization occurs.

Types of myopathies

In most cases, the pathology is hereditary in nature (primary), and therefore is diagnosed in young children.

Less commonly, the disease is a consequence of some illness (acquired or secondary pathology). There are many types of myopathies, the classification of which is based on the cause that provoked destructive changes in muscle tissue. A common option is the approach according to which the following types of disease are distinguished: Based on the location of the lesion, myopathy is divided into three types. Distal muscular dystrophy is characterized by damage to the muscles of the arms and legs.

  • In the proximal form, the muscle tissue closer to the center, the torso, is affected. The third option is mixed, when muscles located at different distances are affected. Another type of classification is by location:
  • facioscapulohumeral muscular dystrophy;
  • limb-girdle (Erb-Roth disease of the hip);
  • ocular myopathy – bulbar-ophthalmoplegic form;

distal myopathy is a disease of the final parts of the arms and legs (hands, feet).

Causes of the disease Myodystrophy is another name for genetic myopathy. The defective gene can be either recessive or dominant.

  • The development of pathology can be triggered by external factors:
  • infections – influenza, ARVI, pyelonephritis, bacterial pneumonia;
  • severe injuries - multiple tissue and organ damage, pelvic fracture, traumatic brain injury;
  • poisoning;.

An acquired disease can develop due to problems with the endocrine system (hypothyroidism, thyrotoxicosis, hyperaldosteronism, diabetes mellitus). The cause of secondary myopathy can be:

  • severe chronic disease (heart, kidney, liver failure, pyelonephritis);
  • malignant or benign neoplasms;
  • avitaminosis;
  • malabsorption (digestive disorder in the small intestine);
  • pregnancy (Becker myopathy);
  • pelvic fracture;
  • bronchitis;
  • scleroderma (a systemic disease based on impaired microcirculation, manifested by thickening and hardening of connective tissue and skin, damage to internal organs);
  • constant depression;
  • alcoholism, drug addiction, substance abuse, hazardous production and other factors under the influence of which constant intoxication of the body occurs;
  • salmonellosis (intestinal infection).

Symptoms of myopathies

Almost all types of myopathies develop gradually. At first, the disease makes itself felt by slight muscle weakness in the arms and legs, pain, body aches, and rapid fatigue after a short walk or other minor exertion.

Over the course of several years, the muscles weaken significantly, which makes it difficult for patients to rise from a chair, up stairs, run, jump, and a duck's gait appears. Dystrophic changes in the limbs occur symmetrically, changing them in size, highlighting them against the background of other parts of the body.

Simultaneously with the loss of strength, tendon reflexes fade, muscle tone decreases - peripheral flaccid paralysis develops, which over time can lead to complete immobilization. Lack of active movements leads to joints losing mobility. Curvature of the spine is possible due to the inability of the muscles to support the body in the desired position.

Signs of some forms

Erb's myopathy makes itself felt at the age of twenty to thirty years. Destructive processes first affect the muscles of the thigh, pelvic girdle, and waist, then quickly move to the shoulders and torso. The limbs lose mobility, become thin, a duck's gait appears, and the appearance of the legs changes. If the deformity appears at a young age, early immobility is possible. Older adults tolerate the disease more easily and maintain physical activity for a long time. Other complications are respiratory failure, intervertebral hernia, which can lead to death.

Landouzy Dejerine myopathy is known as glenohumeral-facial pathology. The first signs of the disease appear at the age of ten to twenty years in the form of damage to the muscles around the eyes and mouth. Over time, dystrophy spreads to the shoulders, upper arms, chest, legs, and abdominal muscles. Fixation of the joints in one position, slight hearing loss, and pathological processes in the retina may be observed. The patient remains able to work for a long time, although problems with the heart and breathing are possible.

Ocular myopathy is a drooping eyelid, limited mobility of the eyeballs, and pigmentary degeneration of the retina. The pathology leads to vision problems, difficulties opening and closing the eyes. After a few years, degenerative processes can spread to the face and shoulder girdle, and affect the muscles of the pharynx. In most cases, the disease develops after forty years of age.

Diagnostics

Having discovered symptoms of the disease, you need to consult a neurologist. To make a diagnosis, the doctor prescribes the following types of examination:

  • general blood analysis;
  • biochemical study of plasma for AST, ALT, LDH, CPK, creatinine, the level of which increases with muscle dystrophy;
  • biopsy of muscle tissue to determine the type of pathology and extent of damage;
  • electroneurography (ENG), electromyography (EMG) - assess the condition of muscles, nerves, signal transmission.

To determine the state of the cardiovascular system, the doctor prescribes a consultation with a cardiologist, electrocardiography, and ultrasound examination of the heart. If you suspect problems with the respiratory system or the development of pneumonia, you need to take an x-ray of your lungs and undergo an examination by a pulmonologist. To clarify the diagnosis, magnetic resonance imaging may be prescribed.

Treatment of myopathy

Therapy for acquired myopathy is aimed at combating the disease that provoked the pathology. The treatment of a hereditary disease is at the stage of study and scientific experiments. In clinical practice, symptomatic therapy is used, aimed at eliminating the symptoms of the disease and improving muscle metabolism.

  • For this purpose, the following drugs are prescribed:
  • Vitamins B1, B6, B12, E.
  • ATP (adenosine triphosphoric acid) - normalizes metabolic processes in the heart muscle, stimulates energy metabolism, reduces uric acid levels, increases the activity of ion transport systems in cell membranes.
  • Glutamic acid is a drug from the group of amino acids. Participates in carbohydrate and protein metabolism, promotes the work of skeletal muscles, activates oxidative processes, neutralizes and removes ammonia from the body.
  • Anticholinesterase drugs (Galantamine, Ambenonium, Neostigmine) are inhibitors of the cholinesterase enzyme, which is involved in muscle function at the stage of muscle relaxation.
  • Anabolic steroids (methandienone, nandrolone decanoate) - accelerate the renewal and formation of muscle structures, tissues, and cells.
  • Calcium and potassium preparations – provide the appearance of electrical potential and nerve impulses in muscle fibers and nerve cells, ensuring muscle contraction.

Thiamine pyrophosphate – promotes carbohydrate metabolism and is used as part of complex therapy.

In addition to drug treatment, massage, physiotherapy (ultrasound, electrophoresis with neostigmine, iontophoresis with calcium), and special gymnastics are prescribed.

Exercise therapy exercises should be gentle so as not to overload weakened muscles. You may need to consult an orthopedist, after which you should select orthopedic correction devices (shoes, corsets).

SM is one of the common causes of walking disorders in older people; SM aggravates respiratory disorders during the treatment of GCs in patients with bronchial asthma; long-term use of inhaled GCs is associated with the development of dysphonia due to the formation of myopathic changes in the muscles of the larynx; SM is the cause of some cases of "". Even in the absence of clinically pronounced symptoms of myopathy in patients receiving long-term GCs in low doses, histological studies reveal signs of myopathy (an increase in the concentration of glycogen in muscle fibers, combined with inhibition of the activity of the main regulatory enzymes that control the processes of glycogen degradation against the background of chronic exposure to GCs). Thus, SM is an important medical problem that requires in-depth study.

note! Practitioners should [ 1 ] be aware of the dangers of long courses of oral or parenteral GCs and [ 2 ] resort to hormonal therapy only when the potential therapeutic effect of GC outweighs the risk of developing severe complications of the disease (requiring the use of GC).

The physiological function of corticosteroid hormones is to mobilize the body's resources under stress by inhibiting homeostatic processes. GCs reduce the rate of synthesis and enhance the breakdown of muscle proteins, which leads to muscle atrophy. GCs suppress the transport of amino acids into muscles, block the stimulating effects of insulin, insulin-like growth factor and amino acids on protein synthesis, and suppress myogenesis by inhibiting the synthesis of myogenin. In addition, GCs inhibit the production of growth factors that control the increase in muscle mass at the local level. Inhibition of muscle proliferation and differentiation under the influence of GC occurs due to increased production of myostatin in muscles.

At the same time, different muscle groups have different sensitivity to the adverse effects of GCs: most often, atrophic changes develop in muscles containing a large number of fast-twitch fibers - type 2 fibers. In particular, the tibialis or digital extensor muscles are more susceptible to wasting in SM compared to the soleus muscle. These differences are due to the minimal content of type 2 fibers in the soleus muscle. In a study by M. Minetto et al. (2010) after a week of dexamethasone in healthy subjects, conduction velocity along muscle fibers decreased to the greatest extent (by 10.5%) in the biceps brachii muscle, to a slightly lesser extent in the vastus medialis muscle (by 10%), and even less in the vastus medialis muscle. the lateral muscle (by 9%) and to the least extent - in the tibialis anterior muscle (by 6%). This trend corresponds to the distribution of type 2 fibers in the listed muscles: 60% of type 2 fibers contain the biceps, 50% vastus femoris, and 30% tibialis anterior.

Acute forms of SM manifest themselves with weakness in the proximal muscles of the extremities, myalgia with a concomitant increase in serum creatine phosphokinase (CPK) and creatine in daily urine (however, it should be remembered that even with severe motor or respiratory disorders, the level of CPK in SM may remain normal, so the level of creatine in daily urine urine may be a more reliable marker of SM). In the vast majority of these patients, acute muscle damage develops when the dose of GCs is increased during long-term use. Nevertheless, casuistic cases of acute SM have been described after a single oral dose of GC in relatively small doses (20 - 24 mg of methylprednisolone). Severe forms of acute SM in patients with status asthmaticus may be accompanied by rhabdomyolysis with an increase in serum CPK levels, myoglobinuria and the development of acute renal failure. In typical cases, rhabdomyolysis develops after the use of massive doses of GC in combination with muscle relaxants or other drugs with a myotoxic effect (aminoglycosides, etc.).

read also the article: Creatine kinase: a neurologist's guide(to the website)

It is believed that the most severe damage in acute SM develops in the quadriceps femoris muscles. However, rhabdomyolysis can also affect the respiratory muscles due to the pronounced load on this muscle group in status asthmaticus. SM may underlie some cases of “resistant” [bronchial] asthma. It should be emphasized that moderate weakness of the respiratory muscles is typical for patients with bronchial asthma receiving GCs both systemically and in the form of inhalations. It should also be noted that animal experiments have demonstrated the ability of GC to induce atrophic changes in the diaphragm.

Chronic forms of SM are characterized by a decrease in the level of CPK and myoglobin in the blood serum. Also, in patients receiving GCs (including inhaled GCs) for a long/chronic time (over a year or longer periods), weakness of the leg muscles is a common complaint. In patients with bronchial asthma who regularly use inhaled GCs, complaints of dysphonia and rapid fatigue of the laryngeal muscles during speech are common (in such patients, the cricothyroid muscle suffers most and the thyroarytenoid muscle suffers to a lesser extent).

Systemic side effects of GCs are more pronounced in patients with low body weight. In very obese patients, even many years of GC use may not be accompanied by either feelings of weakness in the legs or changes in muscle volume. This trend is logical, since in these cases GCs entering the bloodstream are distributed in the body tissues in significantly lower concentrations. However, obese patients are not spared from such local effects of GCs as candidiasis of the respiratory tract and esophagus, dysphonia, etc.

note! It is generally accepted that inhaled GCs are significantly superior in safety to systemic GCs. However, moderate manifestations of SM are expressed equally in both patients receiving GCs systemically and when using inhaled GCs.

Therapeutic tactics for the development of SM involve reducing the dose or discontinuing GCs (usually with the development of severe SM). Cancellation of GC leads to an improvement in both motor functions and electrophysiological patterns. Regular physical activity can also reduce the myopathic effects of GCs. A number of studies have demonstrated significant correlations between vitamin D levels and muscle function. The adverse catabolic effects of GC reduce the intake of mixtures of amino acids (in particular, leucine and glutamine), which enhance protein synthesis in muscles.

more details about SM in the article “Steroid myopathy” by A.G. Polunina, F.V. Isaev, M.A. Demyanova; Main Military Clinical Hospital of the FSB of Russia, Golitsyno; Moscow Scientific and Practical Center for Narcology, Moscow (Journal of Neurology and Psychiatry, No. 10, 2012) [read].

read also article: Muscle damage caused by taking statins (on the site) and article: Steroid myopathy (at http://polymyosit.livejournal.com) [read]


© Laesus De Liro


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Muscle weakness and wasting (steroid myopathy) is also a serious complication of corticosteroid therapy. Steroid myopathy most often develops with the use of dexamethasone and triamsinolone, while treatment with prednisolone and cortisone rarely leads to myopathy. Steroid myopathy begins insidiously, but sometimes it appears acutely and is accompanied by diffuse myalgia. The muscles of the pelvic girdle are involved earlier and more severely than the muscles of the shoulder girdle. The proximal muscles of the limbs are more affected than the distal ones. Severe weakness of the anterior tibialis muscles is rarely observed. Weakness is accompanied by pronounced atrophy of the muscles of the pelvic girdle, thighs and, to a lesser extent, legs and shoulders. Deep reflexes in the arms and legs decrease. The muscles are painful on palpation. The EMG reveals a mixed, neurogenic and myogenic nature of the lesions. Fibrillation and fasciculation potentials are observed at rest. CPK and LDH levels are within normal limits. Muscle biopsy reveals nonspecific myopathic changes.

Treatment: withdrawal of hormones or replacement of dexamethasone, triamsinolone with prednisolone, cortisone. Muscle strength is restored 1-4 months after stopping steroid treatment or changing the drug.

Under the editorship prof. A. Skoromets

"Muscle weakness and atrophy (steroid myopathy)" and other articles from the section