Muscle pain (myalgic syndrome)

Muscle pain may be spontaneous, occur during physical activity or later, or at rest. Sometimes pain is detected only by palpation.

During physical exertion, ischemic pains develop (e.g., intermittent claudication or angina pain); delayed pains are more characteristic of structural changes in muscles (inflammatory changes in connective tissue). At the same time, patients may complain of stiffness, spasms, and cramps. Pains are usually described by patients as dull. Sharp lanceolate pains are rare (e.g., with myofascial syndrome). As a rule, pain intensifies with voluntary contraction.

Cramps are also accompanied by severe pain. Contracture is an extremely rare form of involuntary contraction and is caused by a decrease in muscle adenosine triphosphate; it is characterized by electrical silence in the muscles. Sometimes muscle spasm develops as a reflex reaction of the muscles around the damaged tissue. Carpopedal spasms in tetany are often painful. Less often, muscle pain is caused by myotonia or dystonia.

Swelling of painful muscles is quite rare, which always indicates a serious disease (polymyositis, dermatomyositis, myophosphorylase and phosphofructokinase deficiency, acute alcoholic myopathy). Muscle pain is sometimes paroxysmal and can disrupt nighttime sleep.

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Causes of Muscle Pain

Diffuse (generalized) muscle pain

1. Fibromyalgia
2. Polymyalgia rheumatica
3. Myalgia in common infectious diseases.
4. Polymyositis, dermatomyositis.
5. Painful fasciculations and cramps syndrome.
6. Metabolic myopathies
7. Myoglobinemia
8. Eosinophilia-myalgia syndrome.
9. Guillain-Barre syndrome
10. Electrolyte disturbances (hypokalemia, hypocalcemia, hypernatremia)
11. Endocrine myopathies (hypothyroidism, hypoparathyroidism, hyperparathyroidism)
12. Iatrogenic
13. Psychogenic myalgia
14. Parasitic myositis

Localized muscle pain

1. Arterial insufficiency (calf muscle ischemia)
2. Myalgia in chronic venous insufficiency
3. Myofascial pain syndrome
4. Temporal arteritis

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Diffuse (generalized) muscle pain

Fibromyalgia is defined as non-rheumatic extra-articular non-inflammatory chronic diffuse muscle pain with specific tension (stiffness) and weakness (fatigue) of muscles. Patients with fibromyalgia make up to 5% of all general practice patients. Moreover, 80-90% of them are women aged 25-45 years. Fibromyalgia is characterized by: spontaneous diffuse (bilateral and symmetrical) pain; presence of tender points (for diagnosis, 11 of the 18 described local points (tender-points) must be present; the duration of the disease must be at least 3 months); characteristic syndromic environment of pain syndrome in the form of vegetative, mental and somatic disorders (depression, asthenia, sleep disorders; tension headaches or migraines; frequent occurrence of Raynaud's phenomenon, hyperventilation disorders, panic attacks, cardialgia, syncopal states).

Polymyalgia rheumatica is a disease that affects patients over 55 years of age and is characterized by stiffness of the proximal muscles, especially in the shoulder girdle. Mild anemia, weight loss, and general malaise are common. ESR above 50 mm is typical. Unlike polymyositis, polymyalgia rheumatica is accompanied by normal creatine kinase, muscle biopsy, and EMG values. Corticosteroids (40-60 mg daily) usually provide dramatic therapeutic effect.

Myalgia (muscle pain) in common infectious diseases (flu, parainfluenza and other infections) is a common and well-known phenomenon. Myalgia is characteristic of the acute stage of infection. It is quite typical for brucellosis. Primary infectious myositis (viral, bacterial and parasitic) is rare. Epidemic myalgia (Bornholm disease) has been described; the disease occurs in outbreaks, more often in children's groups, or sporadically. Muscle pain is accompanied by fever, headache, sometimes vomiting, diarrhea. The pain is localized mainly in the muscles of the abdomen and chest, and occurs in severe paroxysms.

Poliomyositis and dermatomyositis. In polymyositis, muscle pain and weakness are often the leading complaints. The disease is more common among women and is characterized by acute or subacute development of weakness of proximal muscles (myopathic syndrome), early onset of dysphagia, muscle tension (painful compaction), preservation of tendon reflexes and involvement of the skin (dermatomyositis). Other systems are often involved (lungs, heart; in 20% of cases, dermatomyositis accompanies carcinoma). In men, poliomyositis is often paraneoplastic, in women - autoimmune. The diagnosis is confirmed by muscle biopsy, electromyography, increased ESR (in 60% of cases) and creatine phosphokinase (in 70%).

The syndrome of "painful fasciculations and cramps" (benign fasciculations syndrome; cramp-fasciculations syndrome) manifests itself only with these symptoms in the absence of signs of denervation on EMG; the speed of excitation conduction is also normal.

Metabolic myopathies associated with impaired energy metabolism include glycogen metabolism disorders (glycogenoses types V, VII, VIII, IX, X and XI); mitochondrial myopathies (insufficiency of carnitine palmithiol transferase

Myophosphorylase deficiency (McArdle disease, glycogen storage disease type V) usually begins in young adulthood with painful muscle stiffness, cramps, contractures, and weakness induced by intense exercise. Symptoms resolve with rest but may persist for several hours. The disease becomes less severe with age. Creatine phosphokinase levels are elevated. EMG may be normal or show myopathic abnormalities; biopsy shows excessive glycogen deposition with reduced or absent myophosphorylase.

Phosphofructokinase deficiency or Tarui disease, glycogen storage disease type VII, presents with symptoms similar to McArdle disease, but begins in early childhood and is less often accompanied by contractures. The diagnosis is confirmed by the absence of phosphofructokinase and the accumulation of glycogen in the muscles. Creatine phosphokinase increases between attacks of muscle pain. A similar picture has been described in other types of glycogenoses.

Carnitine palmitoyltransferase deficiency manifests itself from an early, sometimes neonatal age with episodes of nausea, vomiting, non-ketonemic hypoglycemic coma. Episodes of coma are provoked by starvation, intercurrent infection, and in more mature age - and physical exertion. Young adults with muscle carnitine deficiency have proximal muscle weakness and muscle pain.

Attacks of muscle pain, weakness, and myoglobulinuria may occur, triggered by prolonged physical exertion, especially after fatty meals. Muscle biopsy shows lipid accumulation. CPK levels are usually elevated.

Other types of mitochondrial myopathies also present with muscle weakness, myalgia, which is provoked by physical exertion. Mitochondrial pathology is usually detected by electron microscopy.

Myoglobinemia. Myoglobin is a protein that plays an important role in storing oxygen and transporting it to skeletal muscles. Myoglobinemia is an early indicator of muscle damage. Myoglobinemia syndromes (with mechanical trauma such as crush syndrome; poisoning with myolytic toxins leading to toxic myositis; disorders of arterial or venous circulation in the extremities; burns; frostbite; convulsive states in tetanus, epilepsy, generalized torsion dystonia, malignant neuroleptic syndrome) are accompanied, in addition to other symptoms, by muscle pain and myoglobinuria.

Eosinophilia-myalgia syndrome has been described as an epidemic outbreak in individuals taking L-tryptophan. It consists of myalgia, fatigue, eosinophilia, pneumonia, edema, fasciitis, alopecia, skin manifestations, myopathy, arthralgia, and neuropathy. Marked cramps and spasms have been observed in the axial muscles as a late complication. Postural tremor and myokymia have also been described, as well as myoclonus as unusual delayed manifestations. The condition improves with time, although chronic myalgia and fatigue, as well as some somatic manifestations, may persist for a long time.

Myalgia is sometimes observed in Guillain-Barré syndrome as a symptom preceding the development of flaccid paresis, the appearance of which reveals the cause of myalgia.

Electrolyte disturbances (hypokalemia, hypocalcemia, hypernatremia) when using diuretics or laxatives; hyperaldosteronism or metabolic acidosis, nutritional disorders and malabsorption may be accompanied by myalgias and cramps. Here, the study of electrolyte balance acquires important diagnostic significance.

Endocrine myopathies (muscle pain) (associated with hypothyroidism, hyperthyroidism, hypoparathyroidism, and hyperparathyroidism). Hypothyroid myopathies vary among infants, children, and adults. In infants and children, hypothyroidism often causes generalized muscle stiffness and hypertrophy, particularly in the calf muscles, called Kocher-Debre-Semelaigne syndrome. Adults with hypothyroid myopathy have mild weakness of the shoulder and pelvic girdle muscles; three-quarters of these patients complain of muscle pain, cramps, or muscle tightness. Muscle hypertrophy sometimes accompanies this syndrome (Hoffman syndrome). Rhabdomyolysis is rare. Typically, both muscle contraction and relaxation are slowed (especially in the cold). Creatine phosphokinase levels may increase.

Muscle pain and cramps are common in hypoparathyroidism and hyperparathyroidism. In the latter case, the exact mechanism of these symptoms is unknown.

Iatrogenic muscle pain (and cramps) may be observed after gastrectomy, dehydration, and the administration of drugs such as gamma-aminocaproic acid, vincristine, lithium, salbutamol, emetine, amphetamine, alcohol, nifedipine, nicotinic acid, cyclosporine, levodopa, and penicillin. The identification of a connection between myalgia and the administration of the drug confirms the diagnosis.

Psychogenic muscle pain is typical for conversion disorders and is observed in the picture of other psychogenic syndromes (motor, sensory, vegetative). Another picture of chronic pain syndrome is characteristic of depression (pain-depression syndrome), which can be either overt or latent. Identification of emotional-affective and personality disorders and exclusion of organic causes of myalgia is of decisive importance for the diagnosis and therapy of these disorders. Muscle pain is also possible in psychosis.

Myalgia (muscle pain) is a typical symptom of parasitic myositis (trichinellosis, cysticercosis, toxoplasmosis); it is currently rare.

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Localized muscle pain

Arterial insufficiency of the lower limb (claudicatio intermittens) has characteristic clinical manifestations in the form of periodic pain in the calf muscle that occurs during walking and disappears after stopping, confirmed by ultrasound examination of the main arteries in the leg.

Myalgia in chronic venous insufficiency is usually observed in the legs and is accompanied by other symptoms of phlebopathy (varicose veins, trophic disorders); it is necessary to exclude other possible causes of pain syndrome.

Myofascial pain syndrome is characterized by trigger points and characteristic referred pains of one or another localization. For diagnosis, palpation examination of muscles and knowledge of typical zones of referred pain are important.

Temporal arteritis (systemic granulomatous vasculitis with predominant damage to extra- and intracranial arteries) is accompanied by unilateral or bilateral constant or pulsating pain in the temporal region. A tortuous, dense and painful temporal artery is revealed against the background of other neurological and somatic symptoms of this systemic disease, which mainly affects women of mature and elderly age (high ESR, fever, anemia, decreased vision, etc.). Biopsy reveals a picture of giant cell arteritis. The pain syndrome intensifies with palpation of the temporal artery and temporal muscles, but more often the myalgic syndrome has a more generalized character.

In healthy people, localized muscle pain most often develops after excessive physical exertion on certain muscles. It is transient in nature and usually goes away within a few hours or days.