Why lack of muscle activity is harmful. Influence on the body of insufficient physical activity. The effect of physical activity on the body

Muscle flaccidity is a lack of their strength and a decrease in tone. It can be present in one muscle or a whole group, and be a manifestation of a variety of diseases. For successful treatment, it is important to understand the cause of this symptom. Muscle flaccidity can cause normal overwork or a viral infection in combination with general weakness and malaise.

It is necessary to distinguish true muscle flaccidity from asthenia (muscle fatigue).

True flaccidity in the muscles

It manifests itself with such symptoms:

• Muscles become smaller and look sluggish.
• A person is unable to perform certain actions.
• There is a significant decrease in strength in the muscles.

These symptoms are manifested in diseases such as:

• Stroke.
• Muscular dystrophy.
• Heart attack.
• Obliterating endarteritis.
• After broken arms or legs.

True muscle weakness can also be present in other, no less serious diseases, where the vascular and nervous systems are simultaneously affected.

muscle fatigue

Asthenia (a state of general weakness of the body, impotence) is manifested by the following symptoms:

• The appearance of the muscles does not change.
• Muscles do not lose their functions, but get tired faster.
• For execution various activities using arms or legs requires more force than usual.

The causes of muscle fatigue and lethargy are varied.

For example, this:

• Insomnia.
• Diet abuse.
• Bad habits.
• Overwork.
• various chronic diseases.

Muscle lethargy associated with their fatigue and rapid fatigue can also be caused by pathological conditions that affect metabolic processes in the muscles, described below.

Insufficient amount of protein in the body. Protein must be present in the diet of children and adults. It consists of muscles, internal organs, skin and blood cells.

With a protein deficiency, there is a weak muscle tone, a decrease in immunity, fragility of hair and nails.

Myasthenia gravis is an autoimmune disease characterized by severe muscle weakness and lethargy. This pathology affects the muscles of the eyes, the larynx, pharynx, muscles of the face and body can be affected. Also, patients complain of increased fatigue and lethargy in the muscles of the legs, arms and neck.

Diabetes

A chronic disease that occurs due to insufficient production of insulin in the pancreas is diabetes mellitus. As a result, glucose cannot be fully absorbed and accumulates in the blood.

Diabetes mellitus is characterized by the following symptoms:

• Lethargy in the muscles and weakening of their tone.
• Decreased performance.
• Fast fatiguability.
• Skin itching.
• Decreased immunity.
• Feeling of heaviness and weakness in the legs.
• Patients often feel uncontrollable muscle sluggishness, this is a consequence of the formation of toxic substances due to impaired metabolism. Especially the legs are affected.

Important! In diabetes, special attention should be paid to the lower extremities. Pain in the legs is highly undesirable. The cessation of pain is no less alarming. Especially, in combination with the disappearance of the sensitivity of the legs, dryness and pallor of the skin. It is urgent to consult a doctor and start treatment for diabetic neuropathy

Depression

After experiencing a strong shock, such as the loss of a loved one, depression may set in. And also due to chronic stress, systematic dissatisfaction with life for a certain number of years. A person is in a depressed emotional state, apathy, irritability appears, loses the ability to enjoy life. There is chronic fatigue, muscle weakness, irritability and insomnia.

At the first symptoms of this disease, it is necessary to consult a doctor - a psychiatrist or psychotherapist, and start using a medicine that relieves this condition. Modern antidepressants do not cause dependence and are well tolerated by patients who take them. Close cooperation with the doctor will help the patient to positively tune in, and over time, fully return to normal life.

In addition to all these diseases, lethargy and muscle weakness can develop due to arthritis, arthrosis, osteochondrosis, and electrolyte imbalance. And also, as a result of various infections, anorexia and injuries.

Treatment

The treatment for muscle flaccidity depends on what causes it. To find the root of the problem, you need to contact a therapist or neurologist. The specialist will order an examination. Further, depending on the diagnosis, he will select effective injectable drugs and tablets.

With muscle weakness caused by overwork or physiological overstrain, for example, in the gym, you can take a warm bath, have a relaxing massage and drink tea from mint, lemon balm or chamomile.

Muscle tone can be raised with the help of water procedures and physiotherapy (ultrasound, darsonval).

A sedentary lifestyle, lack of physical activity, adversely affect health at any age. Over the years, the muscles become flabby, sluggish and smaller in volume. In older people who lead a sedentary lifestyle, the whole body suffers due to the weakening of the muscular corset. It is advisable, for preventive purposes, to contact an instructor in physical therapy, who will be able to select the physical exercises that are necessary, taking into account age and individual characteristics person.

Muscle weakness (myasthenia gravis) can occur as an independent disease or be a manifestation of various pathological processes occurring in the human body. For example, protein deficiency, intoxication, anemia and arthritis. Short-term muscle weakness often occurs after a sleepless night, severe overwork and stress. Prolonged myasthenia gravis should be regarded as a symptom and in case of any of its manifestations, consult a doctor.

myasthenia gravis

Myasthenia gravis ¾ muscle weakness. Refers to autoimmune diseases. It has a chronic, inevitably progressive course with frequent exacerbations. In the vast majority, it is diagnosed for the first time in patients aged 20-40 years. Women suffer from myasthenia gravis more often than men. It is extremely rare in children. Among the reasons that provoke true muscle weakness are ¾ of the genetic factor, immune disorders, stress and infections. Also, this disease can be a companion of oncological pathologies in the thymus, ovaries, lungs and mammary glands.

With myasthenia gravis in the body, the supply of impulses among neurons is disrupted. As a result, the interaction between muscles and nerves disappears, gradually the body becomes completely uncontrollable.

Myasthenia is manifested by the following symptoms:

• Great weakness in the muscles.
• abnormal fatigue.
• The condition worsens after physical exertion. The more severe the patient's disease stage, the less exercise may be needed to cause muscle weakness.
• In more severe cases, it is difficult to breathe.
• The voice becomes nasal.
• It is difficult for the patient to keep his head straight due to fatigue of the neck muscles.
• Dropping of the eyelids.

All of the above symptoms tend to increase. Sometimes patients completely lose the ability to serve themselves. The main danger is myasthenic crises, which are manifested by severe muscle weakness with severe respiratory failure.

Depending on the symptoms, muscle weakness (myasthenia gravis) is divided into several types. The following forms of the disease are distinguished:

• Eye. Only the muscles of the eyes are affected. Sometimes within 2-3 years it can be a symptom of a generalized form of myasthenia gravis. The patient has droopy eyelids and double vision.
• Bulbar. The patient complains that it is difficult for him to speak, swallow, breathe. All these manifestations tend to increase, as a result, the patient may completely or partially lose all of the above functions.
• Generalized. Muscle weakness affects almost all muscle groups. The most common form of the disease.
• Lightning. The most dangerous. Most often provoked by a malignant process in the thymus gland. The course of the disease is so rapid that drug treatment does not have time to give the proper therapeutic effect. More often than not, it ends in serious consequences.

The diagnosis is made on the basis of a blood test for antibodies, CT of the thymus, and electromyography. The prozerin test is considered especially reliable. If a subcutaneous injection of prozerin has a positive effect on the patient and the symptoms of muscle weakness subside for a short time, then we can talk about various forms ah myasthenia gravis. It is not possible to completely recover from this disease. The patient must be under constant medical supervision and take medications for life.

Other causes of muscle weakness

Often patients confuse the symptoms of muscle weakness with the usual overwork, which is manifested by a decrease in muscle strength. For example, prolonged wearing of uncomfortable shoes or work associated with lifting weights often cause a feeling of reduced tone in the most involved muscle group. Also, muscle weakness may be present in such pathological conditions of the body as:

• Stoop, scoliosis, round back. The main cause of poor posture is a weak muscular corset.

• Depression.
• Neurosis.
• Anorexia.
• Insomnia.
• Alcoholism.
• Addiction.

Muscle weakness is not uncommonly a manifestation of disease.

Diabetes

Diabetes mellitus is a chronic endocrine disease that causes muscle weakness throughout the body. As a result of the production of an insufficient amount of the hormone insulin in the pancreas, a violation of carbohydrate metabolism occurs in the body, which provokes a persistent increase in the patient's blood sugar. Depending on the causes that cause it, diabetes is divided into two types:

1. Diabetes mellitus of the first type. A complete lack of insulin production develops due to the effect of the immune system on the cells of the pancreas. As a result, a metabolic disorder occurs, which can cause various complications (blindness, kidney failure, gangrene). Patients are forced to monitor their blood sugar daily and inject certain doses of insulin.
2. Diabetes mellitus of the second type. There is a relative deficiency of insulin in the body. Obesity, pancreatitis, low physical activity, long-term use of corticosteroids often provoke the development of this form of diabetes. At the initial stage of the disease, light exercise, a low-carbohydrate diet, and weight loss can have a positive effect. If left untreated, there is a high risk of complications consistent with type 1 diabetes.

Diabetes is manifested by the following symptoms:

• The most important symptom of diabetes is extreme thirst and dry mouth.
• Frequent urination, especially at night.
• Poor wound healing.
• Itching and dry skin.
• Reduced immunity (frequent viral infections, furunculosis).
• Visual impairment.
• Irritability.
• Pain in the abdomen.
• Pain in the legs.
• Lethargy.
• Weakness in all muscles.

Important! If a diabetic has symptoms such as severe hunger, trembling all over the body, irritability, pallor skin, heavy sweating, anxiety, frequent heartbeat, you need to give him sweet tea or eat candy. These are the signs of hypoglycemia (low blood glucose), a dangerous condition that precedes a hypoglycemic coma.

sports sickness

Sometimes any sport begins with great enthusiasm and ends with overtraining (sports sickness). A state when the desire to attend classes disappears, mood worsens, apathy appears. It occurs in cases where the body is not able to fully recover in the intervals between workouts due to inadequate excessive load. It's getting main reason conditions when muscle weakness appears, performance decreases, physical performance and endurance are lost. Also, there are symptoms such as:

• Loss of appetite.
• Lethargy.
• Irritability.
• Depressive state.
• Insomnia.
• Wandering pain in the muscles.
• Aversion to training.

If at least four of the above signs of sports disease appear, it is necessary to take a break in classes for about two weeks until full recovery. Also, massages, calm swimming in the pool or in open water, no more than 20 minutes, a warm bath with the addition of 5 drops will help to cope with overtraining. essential oil pines.

The causes of muscle weakness in the body are varied. Sometimes it is overwork, lack of sleep, deficiency of vitamins, trace elements, amino acids. Not infrequently, myasthenia gravis may be a manifestation various diseases. It is necessary to try to avoid stress, reasonably approach sports activities, fully relax and eat. If you experience unreasonable prolonged muscle weakness, you should consult a doctor. Very often, timely treatment helps to avoid severe complications of the disease or prevent further development of pathologies.

Muscle weakness or myasthenia is a decrease in the contractility of one or more muscles. This symptom can be observed in any part of the body. Muscle weakness in the legs and arms is more common.

A variety of diseases can act as causes of muscle weakness, from injuries to neurological pathologies.

Manifestations of muscle weakness can begin to develop from the age of 20. Muscle weakness in a child is less common. Most often, myasthenia gravis occurs in women.

Treatment of muscle weakness - medication and physiotherapy.

Causes of muscle weakness

The main cause of muscle weakness is damage to the junctions of nerve endings with muscles (synapses). As a result, the primary cause of the disease is a disorder of innervation, all other factors are its consequences.

Muscle innervation is provided by a special substance - acetylcholine. With myasthenia gravis, acetylcholine is perceived by the patient's immune system as a foreign substance, and in connection with this, it begins to produce antibodies to it. The conduction of the nerve impulse to the muscle is disrupted, which leads to the development of weakness in the muscles. But at the same time, the muscles continue to retain their capabilities, since alternative life support systems are launched in the human body, compensating to some extent for this shortcoming.

Muscle weakness can be a symptom of various diseases. In some cases, it simply indicates fatigue, while in others it indicates damage to tendons, muscles, joints, bones, diseases. nervous system. Some weakness in the muscles always occurs during illness and, as a rule, is one of the signs of aging.

Immediate causes of muscle weakness include:

• Neurological diseases: multiple sclerosis, stroke, cerebral palsy, amyotrophic lateral sclerosis, Guillain-Barré syndrome, nerve damage, Bell's palsy;
• Diseases of the endocrine system: Addison's disease, thyrotoxicosis, low levels of calcium or potassium in the body, hyperparathyroidism, diabetes mellitus;
• Various intoxications: organophosphate poisoning, botulism;
• Muscle diseases: muscular dystrophies, polymyositis, mitochondrial myopathies;
• Other causes: poliomyelitis, anemia, emotional overload, stress, asthenic syndrome, rheumatoid arthritis.

Muscle weakness in the legs can also occur with varicose veins, arthritis, scoliosis, and herniated discs.

Muscle weakness in a child is most often caused by pathologies of the nervous system. Decreased muscle tone in newborns is usually the result of birth trauma.

Symptoms of muscle weakness

The state of muscle weakness is characterized by a pronounced decrease in strength in one or more muscles. Weakness in the muscles must be distinguished from a state of general fatigue.

Muscle weakness can be:

• Objective. The fact of a decrease in strength in the muscle is confirmed by a medical examination;
• Subjective. It is characterized by the fact that the patient himself feels weakness in a certain muscle, but the results of a medical examination indicate the preservation of strength in it.

Signs of myasthenia gravis first appear on those muscles that are weak due to the reflex nature of their functioning. The first symptoms of the disease can be observed on the muscles of the eyes. This results in drooping of the eyelids and dual perception of the image. The severity of this symptom may vary depending on the time of day and the amount of physical activity.

Then there are the so-called bulbar signs, which are associated with disorders in the activity of the swallowing, speech, chewing muscles. After a short conversation, a person’s voice may “sit down”, it becomes difficult for him to pronounce some sounds (voiced, hissing), he begins to “swallow” the endings of words.

Quite serious consequences threaten the violation of the functioning of the muscles that provide breathing.

Muscular weakness in the legs is manifested by rapid fatigue of the lower extremities, trembling in them. These symptoms may occur due to prolonged standing work, wearing shoes with high heels.

Diagnosis of muscle weakness

To determine the causes of weakness in the muscles, the doctor conducts a patient interview and physical examination. Additional laboratory tests, including a muscle biopsy, may also be prescribed.

When questioning the patient, the doctor determines when the first signs of muscle weakness appeared, in which muscle groups they are localized, with what they are associated.

When making a diagnosis, it is also important to know what diseases the patient has suffered, what is his neurological heredity, concomitant diseases.

During the study of the musculature, the volume of muscle tissue, its turgor and symmetry of the location are established, tendon reflexes are evaluated.

To clarify the diagnosis, functional tests are carried out with the patient making certain movements.

Treatment of muscle weakness

Methods for treating muscle weakness depend on what disease it is caused by.

Patients with muscle weakness are prescribed drug symptomatic treatment and a certain set of physiotherapy procedures that help restore normal muscle function.

Naturally, the main treatment for muscle weakness is medication. For each patient, a scheme for taking drugs that block the destruction of acetylcholine is individually selected. These drugs include metipred, prozerin, prednisolone, kalimin. The use of these drugs helps to quickly restore muscle strength. But since high doses of these drugs are used, the initial treatment of muscle weakness is carried out only in a hospital setting.

At the same time, the patient is prescribed drugs that suppress the immune system. Exchange plasmapheresis can also be used.

Periodic maintenance therapy should be carried out throughout life.

If muscle weakness is caused by muscle overwork, then in this case it is necessary to provide the muscles with regular rest, reconsider their lifestyle, and reduce physical activity.

If there is severe pain and weakness in the muscles after training, it is necessary to revise the set of exercises, taking into account the general condition of the body and existing chronic diseases.

Also of great importance is a balanced diet, adequate drinking regime, wearing comfortable shoes.

Thus, muscle weakness is a symptom that indicates the presence of certain problems in the human body or an unhealthy lifestyle (excessive physical and psycho-emotional stress, malnutrition, wearing uncomfortable shoes). If muscle weakness is caused by certain diseases, then special treatment is necessary to eliminate it (sometimes throughout life); in other situations, it is enough to correct the system of attitude to one's health.

The causes of muscle weakness are many and there are a wide range of conditions that can cause muscle weakness. These can be both well-known diseases and rather rare conditions. Muscle weakness can be reversible and persistent. However, in most cases, muscle weakness can be treated with exercise, physiotherapy, and acupuncture.

Muscle weakness is a fairly common complaint, but weakness has a wide range of meanings, including fatigue, decreased muscle strength, and the inability of the muscles to work at all. There is an even wider range possible causes.

The term muscle weakness can be used to describe several different conditions.

Primary or true muscle weakness

This muscle weakness manifests itself as an inability to perform the movement that a person wants to perform with the help of muscles the first time. There is an objective decrease in muscle strength and strength does not increase regardless of effort. That is, the muscle does not work properly - this is abnormal.

When this type of muscle weakness occurs, the muscles appear to have fallen asleep, smaller in volume. This can happen, for example, after a stroke. The same visual picture occurs with muscular dystrophy. Both conditions lead to weakening of the muscles that cannot perform the usual load. And this is a real change in muscle strength.

Muscle fatigue

Fatigue is sometimes referred to as asthenia. This is the feeling of tiredness or exhaustion that a person feels when the muscles are used. The muscles don't really get weaker, they can still do their job, but doing muscle work takes a lot of effort. This type of muscle weakness is often seen in people with chronic fatigue syndrome, sleep disorders, depression, and chronic heart, lung, and kidney disease. This may be due to a decrease in the rate at which the muscles can receive the required amount of energy.

muscle fatigue

In some cases, muscle fatigue mainly has increased fatigue - the muscle starts to work, but quickly gets tired and takes more time to restore function. Fatigue is often associated with muscle fatigue, but this is most noticeable in rare conditions such as myasthenia gravis and myotonic dystrophy.

The difference between these three types of muscle weakness is often not obvious, and a patient may have more than one type of weakness at once. Also, one kind of weakness can alternate with another kind of weakness. But with a careful approach to diagnosis, the doctor manages to determine the main type of muscle weakness, since certain diseases are characterized by one or another type of muscle weakness.

Main causes of muscle weakness

Lack of adequate physical activity- inactive (sedentary) way of life.

Lack of muscle loading is one of the most common causes of muscle weakness. If the muscles are not used, then the muscle fibers in the muscles are partly replaced by fat. And over time, the muscles weaken: the muscles become less dense and more flabby. And although muscle fibers do not lose their strength, but their number decreases, and they are not reduced as effectively. And the person feels that they have become smaller in volume. When you try to perform certain movements, fatigue sets in faster. The condition is reversible with reasonable regular exercise. But as we age, this condition becomes more pronounced.

The maximum muscle strength and a short period of recovery after exercise is observed at the age of 20-30 years. That is why most great athletes achieve high results at this age. However, strengthening muscles through regular exercise can be done at any age. Many successful distance runners have been in their 40s. Muscle tolerance during a long activity, such as a marathon, remains high for longer than during a powerful, short burst of activity, such as a sprint.

It is always good when a person has sufficient physical activity at any age. However, recovery from muscle and tendon injuries is slower with age. At whatever age a person decides to improve their physical fitness, a reasonable training regimen is important. And it is better to coordinate training with a specialist (instructor or exercise therapy doctor).

Aging

As we age, muscles lose strength and mass, and they become weaker. While most people accept this as a natural consequence of age - especially if the age is decent, however, the inability to do what was possible at a younger age often brings discomfort. However, exercise is still beneficial in old age, and safe exercise can increase muscle strength. But the recovery time after an injury is much longer in old age, as involutional changes in metabolism occur and bone fragility increases.

infections

Infections and diseases are among the most common causes of temporary muscle fatigue. This occurs due to inflammatory processes in the muscles. And sometimes, even if the infectious disease has regressed, the restoration of muscle strength can take a long period of time. Sometimes this can cause chronic fatigue syndrome. Any disease with fever and inflammation of the muscles can be a trigger for chronic fatigue syndrome. However, some diseases are more likely to cause this syndrome. These include the flu, Epstein-Barr virus, HIV, Lyme disease, and hepatitis C. Other less common causes are tuberculosis, malaria, syphilis, polio, and dengue fever.

Pregnancy

During and immediately after pregnancy, high levels of steroids in the blood, combined with iron deficiency, can cause a feeling of muscle fatigue. This is a completely normal muscle reaction to pregnancy, however, certain gymnastics can and should be carried out, but significant physical exertion should be excluded. In addition, in pregnant women, due to a violation of biomechanics, low back pain often occurs.

chronic diseases

Many chronic diseases cause muscle weakness. In some cases, this is due to a reduction in the flow of blood and nutrients to the muscles.

Peripheral vascular disease is caused by narrowing of the arteries, usually due to cholesterol deposits and triggered by poor diet and smoking. The supply of blood to the muscles is reduced, and this becomes especially noticeable during exercise, when the blood flow cannot cope with the needs of the muscles. Pain is often more characteristic of peripheral vascular disease than muscle weakness.

Diabetes - this disease can lead to muscle weakness and loss of fitness. High level blood sugar puts the muscles at a disadvantage, their functioning is impaired. In addition, as diabetes progresses, there is a disturbance in the structure of the peripheral nerves (polyneuropathy), which in turn impairs the normal innervation of the muscles and leads to muscle weakness. In addition to the nerves, diabetes causes damage to the arteries, which also leads to poor blood supply to the muscles and weakness. Heart disease, especially heart failure, can lead to impaired blood supply to the muscles due to a decrease in myocardial contractility and actively working muscles do not receive enough blood (oxygen and nutrients) at the peak of the load and this can lead to rapid muscle fatigue.

Chronic lung disease, such as chronic obstructive pulmonary disease (COPD), lead to a decrease in the body's ability to consume oxygen. Muscles require a fast supply of oxygen from the blood, especially during exercise. Decreased oxygen consumption leads to muscle fatigue. Over time, chronic lung disease can lead to muscle atrophy, although this mostly happens in advanced cases when blood oxygen levels begin to drop.

Chronic kidney disease can lead to an imbalance of minerals and salts in the body, and may also affect the level of calcium and vitamin D. Kidney disease also causes the accumulation toxic substances(toxins) in the blood, as a violation of the excretory function of the kidneys reduces their excretion from the body. These changes can lead to both true muscle weakness and muscle fatigue.

Anemia - it is a lack of red blood cells. There are many causes of anemia, including poor nutrition, blood loss, pregnancy, genetic diseases, infections, and cancer. This reduces the ability of the blood to carry oxygen to the muscles in order for the muscles to contract fully. Anemia often develops rather slowly, so that by the time of diagnosis, muscle weakness and shortness of breath are already noted.

Diseases of the central nervous system

Anxiety: General fatigue can be caused by anxiety. This is due to the increased activity of the adrenaline system in the body.

Depression: General fatigue can also be caused by depression.

Anxiety and depression are conditions that tend to cause a feeling of tiredness and "fatigue" rather than true weakness.

chronic pain - the overall effect on energy levels can lead to muscle weakness. As with anxiety, chronic pain stimulates the release of chemicals (hormones) in the body that respond to pain and injury. These chemicals lead to feelings of tiredness or fatigue. With chronic pain, muscle weakness can also occur, as the muscles cannot be used due to pain and discomfort.

Muscle damage in trauma

There are many factors that lead to direct muscle damage. The most obvious are injuries or injuries such as sports injuries, sprains and dislocations. Performing exercises without "warming up" and stretching the muscles is a common cause of muscle damage. With any muscle injury, bleeding occurs from damaged muscle fibers within the muscle, followed by swelling and inflammation. This makes the muscles less strong and also painful when performing movements. The main symptom is localized pain, but later on weakness may appear.

Medicines

Many medications can cause muscle weakness and muscle damage as a side effect or allergic reaction. It usually starts out as fatigue. But damage can progress if medication is not stopped. The most commonly reported medications are statins, certain antibiotics (including ciprofloxacin and penicillin), and anti-inflammatory pain medications (such as naproxen and diclofenac).

Long-term use of oral steroids also causes muscle weakness and atrophy. It's expected by-effect steroids for long-term use and therefore doctors try to shorten the duration of steroid use. Less commonly used medications that can cause muscle weakness and muscle damage include:

• Certain cardiac drugs (eg amiodarone).
• Preparations for chemotherapy.
• HIV drugs.
• Interferons.
• Medicines used to treat an overactive thyroid.

Other substances.

Long-term alcohol use can lead to weakness of the shoulder and hip muscles.

Smoking can indirectly weaken muscles. Smoking causes narrowing of the arteries, which leads to peripheral vascular disease.

Cocaine abuse causes marked muscle weakness, just like other drugs.

Sleep disorders

Problems that disrupt or reduce the duration of sleep lead to muscle fatigue, muscle fatigue. These disorders may include: insomnia, anxiety, depression, chronic pain, restless leg syndrome, shift work, and having young children who stay awake at night.

Other causes of muscle weakness

chronic fatigue syndrome

This condition is sometimes associated with certain viral infections, such as the Epstein-Barr virus and influenza, but the genesis of this condition is not fully understood. Muscles are not inflamed, but get tired very quickly. Patients often feel the need for greater effort to perform muscle activities that they previously performed easily.

In chronic fatigue syndrome, the muscles are not collapsed and may have normal strength when tested. This is reassuring, as it means that the chances of recovery and full functional recovery are very high. CFS also causes psychological fatigue when performing intellectual activities, such as long reading and communication also becomes tiring. Patients often show signs of depression and sleep disturbances.

fibromyalgia

This disease resembles the symptoms of chronic fatigue syndrome. However, in fibromyalgia, the muscles become tender to the touch and tire very quickly. Muscles in fibromyalgia do not collapse and remain strong on formal muscle testing. Patients tend to complain more of pain than fatigue or weakness.

Thyroid dysfunction(hypothyroidism)

In this condition, the lack of thyroid hormones leads to general fatigue. And if hypothyroidism is not treated, then muscle degeneration and hypotrophy may develop over time. Such changes can be serious and in some cases irreversible. Hypothyroidism is a common disease, but, as a rule, with timely selection of treatment, muscle problems can be avoided.

Lack of fluid in the body (dehydration) and electrolyte imbalance.

Problems with the normal balance of salts in the body, including as a result of dehydration, can cause muscle fatigue. Muscle problems can be very serious only in extreme cases such as dehydration during a marathon. Muscles work worse when there is an imbalance of electrolytes in the blood.

Diseases associated with muscle inflammation

Inflammatory muscle diseases tend to develop in the elderly and include both polymyalgia, as well as polymyositis and dermatomyositis. Some of these conditions are well corrected by steroids (which have to be taken for many months before healing effect). Unfortunately, steroids themselves can also cause muscle loss and weakness when taken for a long time.

Systemic inflammatory diseases such as SLE and rheumatoid arthritis often cause muscle weakness. IN a small percentage cases of rheumatoid arthritis, muscle weakness and fatigue may be the only symptoms of the disease for a significant amount of time.

Oncological diseases

Cancer and other cancers can cause direct muscle damage, but cancer in any part of the body can also cause generalized muscle fatigue. In the advanced stages of cancer, body weight loss also leads to true muscle weakness. Muscle weakness is usually not the first sign of cancer and occurs more often in the later stages of cancer.

Neurological conditions leading to muscle damage.

Diseases that affect the nerves usually result in true muscle weakness. This is because if the nerve of the muscle fiber stops working properly, the muscle fiber cannot contract and, as a result of the lack of movement, the muscle will atrophy. Neurological diseases: Muscle weakness can be caused by cerebrovascular diseases such as stroke and cerebral hemorrhages or spinal cord injuries. Muscles that become partially or completely paralyzed lose their normal strength and eventually atrophy. In some cases, muscle changes are significant and recovery is very slow or function cannot be restored.

Diseases of the spine: when the nerves are damaged (compressed at the exit of the spine by a hernia, protrusion or osteophyte), muscle weakness can occur. When a nerve is compressed, conduction disturbances and motor disturbances occur in the zone of nerve root innervation, and muscle weakness develops only in the muscles innervated by certain nerves that have undergone compression

Other nervous diseases:

Multiple sclerosis is caused by damage to nerves in the brain and spinal cord and can lead to sudden paralysis. With multiple sclerosis, partial restoration of functions is possible with adequate treatment.

Guillain-Barré syndrome is a post-viral nerve lesion resulting in paralysis and muscle weakness or loss of muscle function from the fingers to the toes. This condition can last for many months, although there is usually a full recovery of function.

Parkinson's disease: This is a progressive disease of the central nervous system, both the motor sphere and the intellectual and emotional sphere. It mainly affects people over the age of 60 and in addition to muscle weakness, Parkinson's patients experience tremors and muscle stiffness. They often have difficulty starting and stopping movement, and are often depressed.

Rare causes of muscle weakness

Genetic Diseases Affecting Muscles

Muscular dystrophies- hereditary diseases in which muscles suffer are quite rare. The most famous such disease is Duchenne muscular dystrophy. This disease occurs in children and leads to a gradual loss of muscle strength.

Some rare muscular dystrophies may debut in adulthood, including Charcot-Marie-Tooth syndrome, and Facioscapulohumeral dystrophy syndrome. They also cause a gradual loss of muscle strength and often these conditions can lead to disability and wheelchair confinement.

Sarcoidosis - is a rare disease in which clusters of cells (granulomas) form in the skin, lungs, and soft tissues including muscles. The condition may heal on its own after a few years.

Amyloidosis - also a rare disease in which there is an accumulation (deposits) of an abnormal protein (amyloid) throughout the body, including in the muscles and kidneys.

Other rare causes: Direct muscle damage can occur in rare hereditary metabolic diseases. Examples include: glycogen storage diseases and, even more rarely, mitochondrial diseases, which occur when the energy systems within muscle cells do not work properly.

Myotonic dystrophy - is a rare genetic muscle disease in which the muscles tire quickly. Myotonic dystrophy is passed on from generation to generation, and, as a rule, with each subsequent generation, the manifestations of the disease become more pronounced.

motor neuron disease is a progressive nerve disease that affects all parts of the body. Most forms of motor neuron disease begin in the distal extremities and gradually involve all the muscles of the body. The disease progresses over months or years, and patients rapidly develop severe muscle weakness and muscle atrophy.

Motor neuron disease is most commonly seen in men over 50, but there have been many notable exceptions to this rule, including famous astrophysicist Stephen Hawking. There are many different forms of motor neuron disease, but no successful treatment has yet been developed.

Myasthenia gravis: - This is a rare muscle disease in which the muscles tire quickly and take a long time to recover from contractile function. Muscle dysfunction may be so severe that patients cannot even hold their eyelids and speech becomes slurred.

Poisons - poisonous substances also often cause muscle weakness and paralysis due to the effect on the nerves. Examples are phosphates and botulinum toxin. In case of exposure to phosphates, weakness and paralysis may be persistent.

Addison's disease

Addison's disease is a rare disorder in which the adrenal glands become underactive, leading to a lack of steroids in the blood and an imbalance in blood electrolytes. The disease usually develops gradually. Patients may notice a change in skin color (tanning) due to skin pigmentation. There may be weight loss. Muscle fatigue can be mild and is often an early symptom. The disease is often difficult to diagnose and special examinations are required to diagnose this disease. Other rare hormonal causes of muscle weakness include acromegaly (excessive production of growth hormone), an underactive pituitary gland (hypopituitarism), and severe vitamin D deficiency.

Diagnosis of muscle weakness and treatment

In the presence of muscle weakness, it is necessary to consult a doctor who will be primarily interested in answers to the following questions:

• How did muscle weakness appear and when?
• Are there any dynamics of muscle weakness, both increase and decrease?
• Is there a change in general well-being, weight loss, or have you traveled abroad recently?
• What medications is the patient taking and has anyone in the patient's family had muscle problems?

The physician will also need to examine the patient to determine which muscles are susceptible to weakness and whether the patient has actual or suspected muscle weakness. The doctor will check to see if there are signs of the muscles becoming softer to the touch (which could be a sign of inflammation) or if the muscles are tiring too quickly.

The doctor should then check the nerve conduction to determine if there are any conduction disorders from the nerves to the muscles. In addition, the doctor may need to check the central nervous system, including balance and coordination, and may order laboratory tests to determine changes in hormone levels, electrolytes, and other indicators.

If this does not allow determining the cause of muscle weakness, then other diagnostic methods may be prescribed:

• Neurophysiological studies (ENMG, EMG).
• Muscle biopsy to determine the presence of morphological changes in the muscles
• Tissue scanning using CT (MSCT) or MRI in those parts of the body that can affect muscle strength and function.

The combination of medical history data, symptoms, objective examination data and the results of laboratory and instrumental research methods allows in most cases to find out the true cause of muscle weakness and determine the necessary treatment tactics. Depending on the genesis of muscle weakness (infectious, traumatic, neurological, metabolic drug, etc.), the treatment should be pathogenetic. Treatment can be either conservative or surgical.

Muscle weakness may be present in a few muscles or in many muscles and develop suddenly or gradually. Depending on its cause, the patient may have other symptoms. Weakness of certain muscle groups can lead to oculomotor disorders, dysarthria, dysphagia, or difficulty breathing.

Pathophysiology of muscle weakness

Voluntary movements are initiated by the motor cortex in the posterior frontal lobe. The neurons of this area of ​​the cortex (central or upper motor neurons, or neurons of the corticospinal tract) transmit impulses to the motor neurons of the spinal cord (peripheral, or lower motor neurons). The latter contact the muscles, forming a neuromuscular junction, and cause them to contract. The most common mechanisms for the development of muscle weakness include damage to the following structures:

• central motor neuron (damage to the corticospinal and corticobulbar tracts);
• peripheral motor neuron (for example, with peripheral polyneuropathy or damage to the anterior horn);
• neuromuscular junction;
• muscles (for example, with myopathies).

Localization of the lesion at certain levels motor system leads to the development of the following symptoms:

• When the central motor neuron is damaged, inhibition is removed from the peripheral motor neuron, which leads to an increase in muscle tone (spasticity) and tendon reflexes (hyperreflexia). Damage to the corticospinal tract is characterized by the appearance of an extensor plantar reflex (Babinski's reflex). However, with the sudden development of severe paresis due to the suffering of the central motor neuron, muscle tone and reflexes may be inhibited. A similar picture can be observed when the lesion is localized in the motor cortex of the precentral gyrus away from the associative motor areas.
• Dysfunction of the peripheral motor neuron leads to a rupture of the reflex arc, which is manifested by hyporeflexia and a decrease in muscle tone (hypotension). Fasciculations may occur. Over time, muscle atrophy develops.
• The defeat in peripheral polyneuropathies is most noticeable if the most extended nerves are involved in the process.
• With the most common disease with damage to the neuromuscular junction - myasthenia gravis - muscle weakness usually develops.
• Diffuse muscle damage (for example, in myopathies) is best seen in large muscles (muscle groups of the proximal limbs).

Causes of muscle weakness

Numerous causes of muscle weakness can be categorized according to the location of the lesion. As a rule, when the focus is localized in one or another part of the nervous system, similar symptoms occur. However, in some diseases, the symptoms correspond to lesions at several levels. When the focus is localized in the spinal cord, the pathways from the central motor neurons, peripheral motor neurons (neurons of the anterior horn), or both of these structures may suffer.

The most common causes of localized weakness include the following:

• stroke;
• neuropathies, including conditions associated with trauma or compression (eg, carpal tunnel syndrome), and immune-mediated diseases; « damage to the root of the spinal nerve;
• compression of the spinal cord (with cervical spondylosis, metastases of a malignant tumor in the epidural space, trauma);
• multiple sclerosis.

The most common causes of widespread muscle weakness include the following:

• dysfunction of muscles due to their low activity (atrophy from inactivity), which occurs due to illness or poor general condition, especially in the elderly;
• generalized muscular atrophy associated with prolonged stay in the intensive care unit;
• polyneuropathy of critical conditions;
• acquired myopathies (eg, alcoholic myopathy, hypokalemic myopathy, corticosteroid myopathy);
• the use of muscle relaxants in a critically ill patient.

Fatigue. Many patients complain of muscle weakness, referring to general fatigue. Fatigue can prevent the development of maximum muscle effort when testing muscle strength. Common causes of fatigue include acute severe illness of almost any nature, malignant tumors, chronic infections (eg, HIV, hepatitis, endocarditis, mononucleosis), endocrine disorders, kidney failure, liver failure, and anemia. Patients with fibromyalgia, depression, or chronic fatigue syndrome may complain of weakness or fatigue, but they have no objective impairment.

Clinical examination for muscle weakness

On clinical examination, it is necessary to distinguish true muscle weakness from fatigue, then to identify signs that will allow you to establish the mechanism of the lesion and, if possible, the cause of the violation.

Anamnesis. The history of the disease should be assessed using questions such that the patient independently and in detail describes his symptoms, which he regards as muscle weakness. Following this, follow-up questions should be asked, which, in particular, assess the patient's ability to perform certain activities, such as brushing teeth, combing, talking, swallowing, getting up from a chair, climbing stairs and walking. It should be clarified how the weakness appeared (suddenly or gradually) and how it changes over time (remains at the same level, increases, varies). In order to distinguish between situations where the weakness developed suddenly and when the patient suddenly realized that he had weakness, appropriate detailed questions should be asked (the patient may suddenly become aware that he has muscle weakness only after gradually increasing paresis reaches such a degree making it difficult to perform normal activities such as walking or tying shoelaces). Important concomitant symptoms include sensory disturbances, diplopia, memory loss, speech impairment, seizures, and headache. Factors that exacerbate weakness, such as overheating (suggesting multiple sclerosis) or repetitive muscular exertion (characteristic of myasthenia gravis), should be clarified.

Information about organs and systems should include information that suggests possible causes of the disorder, including rash (dermatomyositis, Lyme disease, syphilis), fever (chronic infections), muscle pain (myositis), neck pain, vomiting or diarrhea ( botulism), shortness of breath (heart failure, lung disease, anemia), anorexia and weight loss (cancer, other chronic diseases), discoloration of urine (porphyria, liver or kidney disease), heat or cold intolerance and depression, impaired concentration , agitation and lack of interest in daily activities (mood disorders).

Past illnesses should be assessed to identify conditions that may cause weakness or fatigue, including thyroid, liver, kidney, or adrenal disease, cancer, or risk factors for cancer, such as heavy smoking (paraneoplastic syndromes), osteoarthritis, and infections. Risk factors for possible causes of muscle weakness should be assessed, including infections (eg, unprotected sex, blood transfusion, exposure to tuberculosis patients) and stroke (eg, hypertension, atrial fibrillation, atherosclerosis). It is necessary to find out in detail which drugs the patient used.

Family history should be assessed for hereditary disorders (eg, hereditary muscle disorders, channelopathies, metabolic myopathies, hereditary neuropathies) and the presence of similar symptoms in family members (if a previously undetected hereditary pathology is suspected). Hereditary motor neuropathies often remain unidentified due to their variable and incomplete phenotypic presentation. Undiagnosed hereditary motor neuropathy may be indicated by the presence of hammertoes, high instep, and low performance in sports.

Physical examination. To clarify the localization of the lesion or identify symptoms of the disease, it is necessary to conduct a complete neurological examination and examination of the muscles. Of primary importance is the assessment of the following aspects:

• cranial nerves;
• motor function;
• reflexes.

Assessment of cranial nerve function includes examination of the face for gross asymmetry and ptosis; a slight asymmetry is normally allowed. The movements of the eyeballs and mimic muscles are studied, including the determination of the strength of the masticatory muscles. Nazolalia indicates soft palate paresis, while swallowing reflex testing and direct examination of the soft palate may be less informative. Weakness of the muscles of the tongue can be suspected by the inability to clearly pronounce some consonant sounds (for example, "ta-ta-ta") and slurred speech (ie, dysarthria). Slight asymmetry when protruding the tongue may be normal. The strength of the sternocleidomastoid and trapezius muscles is assessed by turning the patient's head and by how the patient overcomes resistance with a shrug. Also, the patient is asked to blink to detect muscle fatigue with repeated opening and closing of the eyes.

The study of the motor sphere. The presence of kyphoscoliosis (which in some cases may indicate long-term weakness of the back muscles) and the presence of scars from surgery or trauma are assessed. Movement may be impaired due to the appearance of dystonic postures (eg, torticollis), which may mimic muscle weakness. Assess for the presence of fasciculations or atrophy, which can occur in ALS (locally or asymmetrically). Fasciculations in patients with advanced ALS may be most prominent in the muscles of the tongue. Diffuse muscular atrophy may be best seen in the arms, face, and muscles of the shoulder girdle.

Muscle tone is assessed during passive movements. Tapping of muscles (eg, hypothenar muscles) may reveal fasciculations (in neuropathies) or myotonic contraction (in myotonia).

The assessment of muscle strength should include examination of the proximal and distal muscles, extensors and flexors. To test the strength of large, proximal muscles, you can ask the patient to get up from a sitting position, sit down and straighten up, bend and straighten, turn his head, overcoming resistance. Muscle strength is often rated on a five-point scale.

• 0 - no visible muscle contractions;
• 1 - there are visible muscle contractions, but there are no movements in the limb;
• 2 - movements in the limbs are possible, but without overcoming the force of gravity;
• 3 - movements in the limbs are possible, capable of overcoming gravity, but not the resistance provided by the doctor;
• 4 - movements are possible that can overcome the resistance provided by the doctor;
• 5 - normal muscle strength.

Despite the fact that such a scale seems objective, it can be difficult to adequately assess muscle strength in the range from 3 to 5 points. With one-sided symptoms, a comparison with the opposite, unaffected side can help. Often detailed description of what the patient can and cannot do can be more informative than a simple score, especially if the patient needs to be re-examined in the course of the disease. In the presence of a cognitive deficit, the patient may experience varying scores on muscle strength (inability to concentrate on a task), repeating the same action, underperforming, or having difficulty following instructions due to apraxia. With simulation and other functional disorders, usually a patient with normal muscle strength "gives in" to the doctor when it is checked, simulating paresis.

Coordination of movements is checked using finger-nose and calcaneal-knee tests and tandem gait (putting the heel to the toe) to exclude disorders of the cerebellum, which can develop with circulatory disorders in the cerebellum, atrophy of the cerebellar vermis (with alcoholism), some hereditary spinocerebellar ataxias, disseminated sclerosis and the Miller Fisher variant in Guillain-Barré syndrome.

Gait is assessed for difficulty at the beginning of walking (temporary freezing in place at the beginning of movement, followed by hurried walking with small steps, which occurs in Parkinson's disease), apraxia, when the patient's feet seem to stick to the floor (with normotensive hydrocephalus and other lesions of the frontal lobe), mincing gait (with Parkinson's disease), asymmetry of the limbs, when the patient pulls up the leg and / or, to a lesser extent than normal, swings his arms when walking (with hemispheric stroke), ataxia (with cerebellar damage) and unsteadiness when turning (with parkinsonism) . Walking on heels and on toes is assessed - with weakness of the distal muscles, the patient performs these tests with difficulty. Walking on the heels is especially difficult when the corticospinal tract is affected. Spasmodic gait is characterized by scissor or squinting leg movements and walking on toes. With paresis of the peroneal nerve, steppage and drooping of the foot may be noted.

Sensitivity is examined for abnormalities that may indicate the location of the lesion that caused muscle weakness (for example, the presence of a level of sensory abnormalities suggests damage to a segment of the spinal cord), or for a specific cause of muscle weakness.

Paresthesias distributed in a band may indicate spinal cord injury, which can be caused by both intraattacks and extramedullary lesions.

Study of reflexes. In the absence of tendon reflexes, they can be checked using the Jendrassik maneuver. Decreased reflexes may be normal, especially in the elderly, but in this case they should be reduced symmetrically and should be induced using the Jendrassik maneuver. Plantar reflexes (flexion and extension) are assessed. The classic Babinski reflex is highly specific for lesions of the corticospinal tract. With a normal reflex from the lower jaw and an increase in reflexes from the arms and legs, the lesion of the corticospinal tract can be localized at the cervical level and, as a rule, is associated with stenosis of the spinal canal. With damage to the spinal cord, the tone of the anal sphincter and the wink reflex may be reduced or absent, but with ascending paralysis in Guillain-Barré syndrome, they will be preserved. Abdominal reflexes below the level of spinal cord injury are lost. Preservation of the upper segments of the lumbar spinal cord and corresponding roots in men can be assessed by testing the cremaster reflex.

The examination also includes an assessment of tenderness on percussion of the spinous processes (indicative of inflammatory lesions of the spine, in some cases, tumors and epidural abscesses), an extended leg raise test (tenderness is noted with sciatica), and a check for the presence of winged scapula.

Physical examination. If the patient does not have objective muscle weakness, then the physical examination becomes especially important, in such patients, a disease that is not associated with damage to the nerves or muscles should be ruled out.

Note symptoms of respiratory failure (eg, tachypnea, weakness when inhaling). The skin is evaluated for jaundice, pallor, rashes, and striae. Other important changes that may be identified on examination include the moon face in Cushing's syndrome and parotid enlargement, smooth, hairless skin, ascites, and stellate hemangiomas in alcoholism. The neck, axillary and inguinal region should be palpated to rule out adenopathy; it is also necessary to exclude enlargement of the thyroid gland.

The heart and lungs are evaluated for dry and moist rales, prolonged exhalation, murmurs, and extrasystoles. The abdomen must be palpated to detect tumors, as well as suspected damage to the spinal cord, an overflowing bladder. An examination of the rectum is performed to detect blood in the stool. The range of motion in the joints is assessed.

If tick paralysis is suspected, the skin, especially the scalp, should be examined for ticks.

Warning Signs. Pay particular attention to the following changes.

• Muscle weakness that becomes more pronounced over several days or less time.
• Dyspnea.
• Inability to raise head due to weakness.
• Bulvar symptoms (eg, difficulty chewing, speaking, and swallowing).
• Loss of the ability to move independently.

Interpretation of survey results. Anamnesis data make it possible to differentiate muscle weakness from fatigue, determine the nature of the course of the disease, and provide preliminary data on the anatomical localization of weakness. Muscle weakness and fatigue are characterized by various complaints.

• Muscle weakness: Patients usually complain that they cannot perform a specific action. They may also note heaviness or stiffness of the limb. Muscle weakness is usually characterized by a specific temporal and/or anatomical pattern.
• Fatigue: Fatigue, by which we mean fatigue, usually has no transient (patients complain of fatigue throughout the day) or anatomical pattern (eg, weakness throughout the body). Complaints mostly indicate fatigue rather than an inability to perform a particular action. Important Information can be obtained by evaluating the temporal pattern of symptoms.
• Muscle weakness that worsens over minutes or even shorter times is usually associated with a severe injury or stroke. Sudden onset weakness, numbness, and severe pain localized to the extremity is most likely due to arterial occlusion and ischemia of the extremity, which can be confirmed by examination of the vascular system (for example, assessment of pulse, color, temperature, capillary filling, differences in blood pressure measured with Doppler scan).
• Muscle weakness that progresses steadily over several hours or days may be caused by an acute or subacute condition (for example, (spinal cord pressure, transverse myelitis, spinal cord infarction or hemorrhage, Guillain-Barré syndrome, in some cases, muscle atrophy can be associated with the patient being in a critical condition, rhabdomyolysis, botulism, organophosphorus poisoning).
• Muscle weakness that progresses over several weeks or months may be caused by subacute or chronic diseases(eg, cervical myelopathy, most hereditary and acquired polyneuropathies, myasthenia gravis, motor neuron disease, acquired myopathies, most tumors).
• Muscle weakness, the severity of which varies from day to day, may be associated with multiple sclerosis and sometimes metabolic myopathies.
• Muscle weakness, which varies throughout the day, may be associated with myasthenia gravis, Lambert-Eaton syndrome, or periodic paralysis.

The anatomical pattern of muscle weakness is characterized by specific actions that patients find difficult to perform. When assessing the anatomical pattern of muscle weakness, one can assume the presence of certain diagnoses.

• Weakness in the proximal muscles makes it difficult to raise the arms (for example, combing hair, lifting objects above the head), climbing stairs, or rising from a sitting position. This pattern is characteristic of myopathies.
• Weakness of the distal muscles interferes with activities such as stepping over the sidewalk, holding a cup, writing, buttoning, or using a key. This pattern of disorders is characteristic of polyneuropathies and myotonia. In many diseases, weakness in the proximal and distal muscles can develop, but one of the patterns of the lesion is more pronounced initially.
• Paresis of the bulbar muscles can be accompanied by weakness of the facial muscles, dysarthria and dysphagia, both with and without impaired eyeball movements. These symptoms are characteristic of certain neuromuscular diseases, such as myasthenia gravis, Lambert-Eaton syndrome, or botulism, but may be observed in some motor neuron diseases, such as ALS or progressive supranuclear palsy.

First, the pattern of impaired motor function as a whole is determined.

• Weakness, covering mainly the proximal muscles, suggests myopathy.
• Muscle weakness, accompanied by an increase in reflexes and muscle tone, suggests damage to the central motor neuron (corticospinal or other motor pathway), especially in the presence of an extensor reflex from the foot (Babinski reflex).
• A disproportionate loss of finger dexterity (eg, in small movements, playing the piano) with relatively intact hand strength indicates a selective lesion of the corticospinal (pyramidal) pathway.
• Complete paralysis is accompanied by a lack of reflexes and a pronounced decrease in muscle tone, which develop suddenly with severe damage to the spinal cord (spinal shock).
• Muscle weakness with hyperreflexia, decreased muscle tone (both with and without fasciculations), and the presence of chronic muscle atrophy suggest peripheral motor neuron involvement.
• Muscle weakness, most noticeable in muscles supplied by longer nerves, especially in the presence of sensory impairment in the distal regions, suggests impaired peripheral motor neuron function due to peripheral polyneuropathy.
• No nervous system symptoms (i.e., normal reflexes, no muscle atrophy or fasciculations, normal muscle strength or insufficient effort when testing muscle strength) or insufficient effort in patients with fatigue or weakness that is not characterized by any temporal or anatomical pattern , allows you to suspect the presence of fatigue in the patient, and not true muscle weakness. However, with intermittent weakness that is absent at the time of the examination, abnormalities may go unnoticed.

With the help of additional information, you can more accurately localize the lesion. For example, muscle weakness that is accompanied by signs of central motor neuron involvement, in combination with other symptoms such as aphasia, mental status disorders, or other symptoms of cerebral dysfunction, suggests a brain lesion. Weakness associated with damage to the peripheral motor neuron may be due to a disease that affects one or more peripheral nerves; in such diseases, the distribution of muscle weakness has a very characteristic pattern. With damage to the brachial or lumbosacral plexus, motor, sensory disturbances and changes in reflexes are scattered and do not correspond to the zone of any of the peripheral nerves.

Diagnosis of the disease that caused muscle weakness. In some cases, a set of identified symptoms allows us to suspect the disease that caused them.

In the absence of symptoms of true muscle weakness (eg, a characteristic anatomical and temporal pattern of weakness, objective symptoms) and the patient complains only of general weakness, fatigue, lack of strength, a non-neurological disease should be assumed. However, in elderly patients who have difficulty walking because of weakness, it can be difficult to determine the distribution of muscle weakness because gait disturbances are usually associated with many factors (see chapter "Peculiarities in elderly patients"). Patients with multiple diseases may be functionally limited, but this is not associated with true muscle weakness. For example, in heart and lung failure or anemia, fatigue may be associated with shortness of breath or exercise intolerance. Joint problems (eg, associated with arthritis) or muscle pain (eg, associated with polymyalgia rheumatica or fibromyalgia) can make it difficult to exercise. These and other abnormalities that present with complaints of weakness (eg, influenza, infectious mononucleosis, renal failure) are usually present or indicated by history and/or physical examination findings.

In general, if there are no symptoms suggestive of an organic disease during the history and physical examination, then it is unlikely to be present; the presence of diseases that cause general fatigue, but are functional, should be assumed.

Additional research methods. If the patient has fatigue rather than muscle weakness, additional testing may not be required. Although many additional investigations can be used in patients with true muscle weakness, they often play only a supporting role.

In the absence of true muscle weakness, clinical findings (eg, dyspnoea, pallor, jaundice, heart murmurs) are used to select methods of additional investigation.

In the absence of deviations from the norm during the examination, the results of the studies will also most likely not indicate any pathology.

In case of sudden development or in the presence of severe generalized muscle weakness or any symptoms of respiratory failure, it is necessary to evaluate the forced vital capacity of the lungs and the maximum inspiratory force to assess the risk of developing acute respiratory failure.

In the presence of true muscle weakness (usually after assessing the risk of developing acute respiratory failure), the study is aimed at finding out its cause. If it is not obvious, then routine laboratory tests are usually performed.

In the presence of signs of damage to the central motor neuron, MRI is the key method of investigation. CT is used if MRI is not possible.

If myelopathy is suspected, MRI can detect the presence of lesions in the spinal cord. Also, MRI can identify other causes of paralysis that mimic myelopathy, including damage to the cauda equina, roots. If MRI is not possible, CT myelography may be used. Other studies are also being carried out. Lumbar puncture and CSF examination may be optional if a lesion is identified on MRI (eg, if an epidural tumor is detected) and contraindicated if CSF block is suspected.

If polyneuropathy, myopathy, or pathology of the neuromuscular junction is suspected, neurophysiological methods of investigation are key.

After a nerve injury, changes in conduction along it and denervation of the muscle may develop several weeks later, therefore, in the acute period, neurophysiological methods may be uninformative. However, they are effective in diagnosing some acute diseases, such as demyelinating neuropathy, acute botulism.

If myopathy is suspected (the presence of muscle weakness, muscle spasm and pain), it is necessary to determine the level of muscle enzymes. Elevated levels of these enzymes are consistent with the diagnosis of myopathy, but can also occur in neuropathies (indicating muscle atrophy), and very high levels occur in rhabdomyolysis. In addition, their concentration does not increase with all myopathies. Regular use of crack cocaine is also accompanied by a long-term increase in the level of creatine phosphokinase (average up to 400 IU / l).

MRI can detect muscle inflammation, which occurs in inflammatory myopathies. A muscle biopsy may be required to definitively confirm the diagnosis of myopathy or myositis. Appropriate place for biopsy can be established using MRI or electromyography. However, needle insertion artifacts can mimic muscle pathology and it is recommended to avoid this and not take biopsy specimens from the same site as electromyography. Some hereditary myopathy may require genetic testing to confirm.

When motor neuron disease is suspected, investigations include electromyography and conduction velocity testing to confirm the diagnosis and rule out treatable diseases that mimic motor neuron disease (eg, chronic inflammatory polyneuropathy, multifocal motor neuropathy, and conduction blocks). In advanced ALS, brain MRI may show degeneration of the corticospinal tracts.

Specific tests may include the following.

• If myasthenia gravis is suspected, an edrophonium test and serological studies are performed.
• If vasculitis is suspected, the presence of antibodies should be determined.
• If there is a family history of a hereditary disease, genetic testing.
• If symptoms of polyneuropathy are present, other tests should be performed.
• In the presence of myopathy that is not associated with drugs, metabolic or endocrine diseases, a muscle biopsy may be performed.

Treatment of muscle weakness

Treatment depends on the disorder causing the muscle weakness. Patients with life-threatening symptoms may require mechanical ventilation. Physiotherapy and occupational therapy can help to adapt to irreparable muscle weakness and reduce the severity of functional disorders.

Features in elderly patients

In older people, there may be a slight decrease in tendon reflexes, but their asymmetry or absence is a sign of a pathological condition.

Since older people are characterized by a decrease in muscle mass (sarcopenia), bed rest can quickly, sometimes within a few days, lead to the development of disabling muscle atrophy.

Elderly patients take a large number of drugs and are more susceptible to drug-induced myopathies, neuropathies and fatigue. In this regard, drug therapy is a common cause of muscle weakness in the elderly.

Weakness that prevents walking often has many causes. These may include muscle weakness (eg, stroke, use of certain drugs, myelopathy due to cervical spondylosis, or muscle wasting) as well as hydrocephalus, parkinsonism, arthritis pain, and age-related loss of neural connections that regulate postural stability (vestibular system, proprioceptive pathways), motor coordination (cerebellum, basal ganglia), vision and praxis (frontal lobe). During the examination, special attention should be paid to correctable factors.

Often physiotherapy and rehabilitation can improve the condition of patients, regardless of the cause of muscle weakness.