The occurrence of muscle pain (myalgia) directed immediately to a muscle disease, or exclusive (myopathy) or as part of multiple pathologies (systemic disease or non-organic pathology).
Muscle tissue does not have nociceptors.
muscle pain mechanisms are not fully known to date, especially as most genetic chronic myopathies have little or no pain.
Inflammation spreading the pain receptors overlying was raised in certain muscle diseases but many primary or secondary inflammatory myopathies are painless. Currently, the most likely mechanisms causing muscle pain sensation would be the existence of hypoxic muscle micro-phenomena and metabolic alterations.
Currently, fifty muscle diseases have been identified on clinical grounds, histopathological and molecular for some of them (Box 1).
Box 1. Key muscle disorders categorized by pathophysiology (according to Mr. Burden)
It is characterized by a primary alteration of the muscular fibers (or the component) and a progressive disappearance thereof (Duchenne muscular dystrophy: related to the absence of a protein called dystrophin).
The development of the muscle fiber during the fetal period is disrupted, leading to deterioration of the internal structure of the fibers.
They are secondary to a dysfunction of sugars degradation pathway (GSD), fat metabolism (lipidoses), or of the mitochondrial respiratory chain (mitochondrial myopathies).
They are due to abnormal membrane excitability (myotonic syndromes, periodic paralysis).
acquired muscle diseases, and inflammatory, toxic and iatrogenic, endocrine
They are due to disruption of neuromuscular transmission.
Must evoke a muscular disorder before: myolysis acute (sudden muscle necrosis table with high elevated creatine phosphokinase [CPK] and myoglobinuria);
– Progressive motor deficit predominant roots;
– A change in muscle size (muscle atrophy, sometimes hypertrophy);
– Other circumstances: neonatal hypotonia, chronic ophthalmoplegia (ptosis without diplopia), muscle spasms, exercise intolerance (painful stiffness of muscles (± cramps), power loss (fatigue) and shortness of breath during exercise;
– Misleading circumstances: distal topography, intermittent disorders (paresis acute attacks, myasthenic fatigue), heart or central nervous system (mitochondrial disease).
It must meet the arguments of the etiologic diagnosis:
– Nature of the symptoms;
– Chronological profile: age at onset, rapid evolution of symptoms;
– Family transmission: family tree, history of fetal death, heart disease, cataracts, inbreeding;
– Looking for iatrogenic or toxic environment.
Clinical arguments include:
– Myogenic motor deficit:
– Proximal predominance (although some muscular diseases are characterized by a predominantly distal reached: Steinert’s disease, distal myopathy)
– Bilateral, often symmetrical,
– Compliance with refl exes tendon,
– No twitching;
– Tired muscles after a few squats the patient can get up,
– It can reach out permanently (normal delay greater than 2 and a half minutes), or keep the legs bent (normal delay greater than 75 seconds)
– The notion of predominant fatigue on exertion (± pain and stiffness) moving towards two etiologies: myasthenia gravis or metabolic myopathy;
– Pain in the muscles of pressure (inflammatory myopathy), tendon contracture, change in muscle size (atrophy Association thigh-calf hypertrophy: Duchenne or Becker);
– Spontaneous myotonia (clenching the hand in flexion, with difficulty to extend the fingers, improving the repetition of movement) and caused by the percussion of the thenar with the reflex hammer: muscular disorder with myotonia, and first rise to myotonic dystrophy;
– Extrinsic ophthalmoplegia (gravis and ocular myopathy, usually mitochondrial);
– Other signs that muscle involvement, guiding immediately to:
– Deterioration of general condition, skin rash, arthritis: myositis or polyarteritis nodosa, sensory impairment (hearing loss, retinitis pigmentosa, cataract), central nervous system (ataxia, seizure disorders), and / or heart: mitochondrial myopathy.
Measurement of serum CPK:
The elevated serum CPK, fickle, reflects alteration of the muscular membrane facing necrotic areas. It is observed in many muscle disorders but is inconsistent and not specifi (CPK elevation in neurological disorders or anterior horn).The dosage of other muscle enzymes (aldolase, lactate dehydrogenase [LDH], aspartate and alanine aminotransferases [AST and ALT]) is more relative value.
The presence of autoantibodies directed towards an autoimmune muscle disease, polymyositis types (PM), dermatomyositis (DM) or rarely inclusion body myositis. Rheumatoid factors are positive in 20% of PM / DM.Antinuclear and cytoplasmic factors are present in 30-50% of cases. It can be antibodies against muscle proteins or other non-specific nuclear protein of PM / DM (anti-RNP, anti-PM-Scl, anti-SSA / Ro and anti-SSB /
The anti-Ku), also present in other autoimmune diseases.
There are more myositis-specific antibodies:
– The cytoplasmic antibodies against aminoacyl-tRNA synthetase enzymes, which fix each amino acid to its t-RNA in protein synthesis. It is anti-Jo-1 antibody (histidyl-tRNA), PL7 (threonyl-tRNA), PL12 (alanine-tRNA), OJ (isoleucyl-tRNA), EJ (glycyl-tRNA) and KS (asparaginyl-tRNA). These antibodies are found in 10-30% of PM, constituting the anti-JO1 or antisynthetase syndrome, often associated with interstitial lung disease specific;
– The cytoplasmic antibody anti-SRP.
These anti-SRP antibodies are noted in 5% of myositis characterized by a severe deficiency, extremely high levels of CPK, the frequent association with myocarditis, resistance to corticosteroids and immunosuppressive agents, responsible for a poor prognosis (25% survival at 5 years).
It may also be of antinuclear antibodies much more specifi c DM called anti-Mi-1 and anti-Mi-2. These antibodies are seen in 5-10% of very classical steroid-DM and an excellent prognosis.
Additional tests :
In muscle disease, it can find items reflecting a process of denervation-reinnervation, myotonia, neuromuscular block.
In most muscular diseases, there is no electrical activity at rest. Two types of defects can be saved: myotonic bursts characteristic of myotonia (Steinert’s disease), and pseudomyotoniques bursts encountered especially in dystrophies (Duchenne dystrophy belts), polymyositis, and chronic polyneuropathy (Charcot-Marie-Tooth ).
It allows to assess volumetric abnormalities of the affected muscles (which appear hypodense), revealing a hidden selectivity clinically. Thus elective respect of the medial compartment of thigh is very characteristic myopathy Duchenne and Becker.
With gadolinium, STIR sequence and / or fat suppression looking for hyperdense elements, it is useful once the inflammatory myopathy is mentioned.
Exercise test on a cycle ergometer:
It confirms the existence of an exercise intolerance (reducing power and oxygen consumption, elevated CPK year-end) and the precise mechanism. No elevation of lactic acid for a glycogenosis (including McArdle disease), or orienting hyperlactatemia to mitochondrial dysfunction (track lipolysis or respiratory chain).
It is an essential consideration subject to sampling and analytical conditions of the perfect biopsy interpretation impossible when the biopsied muscle is too reached (replaced by connective tissue) or after an electromyogram responsible focal necrosis of fibers.
The biopsy should be studied with morphological techniques, histoenzymologiques, immunological (immunostaining on cut, gel immunoprecipitation) and ultrastructural (specialized laboratory).
In some cases, structural abnormalities are characteristic of a precise etiology:
– Marked overload glycogen, fat, major accumulation of mitochondria in metabolic myopathies (not biopsy the immediate waning of myolysis); perifascicular atrophy in dermatomyositis, or tunneling myocyte by a CD8 cell in polymyositis or inclusions myositis;
– Structural alteration characteristic of certain congenital myopathies (to stick to the central core, myotubular).
Other complementary examinations are designed to:
– Specify any multisystem disease (heart, cataract etc.);
– Seek an inflammatory background (erythrocyte sedimentation rate, immunological tests), endocrine (dosage of thyroid hormone, cortisol, etc.), abnormal calcium and phosphate;
– Assess the seriousness of the disease (deficiency
respiratory, heart disease);
– Characterize gene anomaly genetic muscle diseases (location, knowledge of mutations), for neonatal screening (eg, for Duchenne muscular dystrophy or Steinert) and deduct through reverse genetics, characteristics (structure , function) of the defective or absent muscle protein.
Rhabdomyolysis therapeutic emergency:
Rhabdomyolysis is the destruction by catabolic muscle cells of skeletal muscles, associated with a release of muscle enzymes and myoglobin (muscle protein) in the blood and urine (myoglobinuria).
The causes listed in Box 2. The toxic factors (alcohol, toxic drugs) represent the majority of rhabdomyolysis causes.
In 60% of cases, several causes are intertwined.
Box 2. Key rhabdomyolysis etiologies
Trauma with muscle compression (Bywaters syndrome)
Mushroom poisoning (equestrian tricholome [Tricholoma fl avovirens], etc.)
Exercise Heat Stroke or malignant hyperthermia effort
malignant hyperthermia after succinylcholine or halogenated anesthetic
Neuroleptic malignant syndrome
especially metabolic myopathy
metabolic acidosis whatever the origin
Drug Cause: including aspirin, isoniazid, amphotericin B, barbiturates, amphetamines, neuroleptics, zidovudine, colchicine, statins, fibrates (not exhaustive)
Substance abuse by heroin
The symptoms are:
– Muscle spasms;
– Muscle pain or cramps;
– Painful muscle hardening and swelling;
– Decreased muscle strength;
– Urinary Syndrome: oliguria, myoglobinuria and especially kidney failure;
– Hemodynamic shock;
– Or multiple organ dysfunction syndrome (hypovolemic shock and diffuse vasoplegia, kidney failure, coma, acute respiratory distress syndrome or ARDS, disseminated intravascular coagulation, or DIC, liver failure) in heat stroke.
The biological signs are:
– Enzyme elevation: transaminases (ALT, AST) are always raised, as well as LDH and aldolase rule. CPK especially increases dramatically (by rule beyond 10 000 IU / L) with elevated CPK-MB;
– Myoglobinuria is early and short, sometimes associated with proteinuria or glycosuria.
The myoglobinémie is rarely found. myoglobin research techniques are only qualitative;
– Rapid increase in serum creatinine, reflecting tubular complications of myoglobin and muscle enzymes, hyperkalemia with rapidly threatening hypocalcemia and hyperphosphatemia initials, and hypophosphatemia.
In some etiological circumstances, the compression factor associated with coma (postural syndrome) comes to superimpose the actual effect of the toxic involved, and / or indirect consequences of poisoning: hypovolemia, hypotension by vasoplegia, hypothermia, acidosis , anoxia, and decreased metabolism.
The prognosis is related to the risk of oligoanuria and acute renal failure with tubular necrosis (noted in 20-50%) for release into the general circulation of various muscle metabolites, including myoglobin, which may result in patient death.
– General resuscitation;
– Treatment of a metabolic abnormality;
– Immediate stop of the administration of a suspected agent (halogenated anesthetics or succinylcholine);
– Hyperventilation with pure oxygen;
– Dantrolene administration in malignant hyperthermia related to anesthetics;
– Refrigeration and vascular filling of a heatstroke;
– Treatment of renal failure with alkalizing fight against acidosis and hyperkalemia;
– Volume expansion is essential to the fight against anuria;
– Renal replacement is sometimes necessary;
– Surgical treatment, rare indication is discussed whether there is a compartment syndrome or neuromuscular deficit signs.
Muscle cramp is a sudden contraction, intense, involuntary and fleeting of part or all of a muscle. Its duration is variable, usually brief. It is in the vast majority of cases, benign The occurrence of muscle cramps is usually a Benin phenomenon, occurring at rest (especially at night) or stress on a poorly heated or exhausted muscle (role training ).
Many factors are known to promote the onset of muscle cramps:
– The states of dehydration;
– Abuse of stimulants (coffee, tea), addictions;
– cold ;
– Pregnancy pill;
– Metabolic disorders (dysnatrémie, dyskaliémie, phosphate anomaly, hypomagnesemia);
– Peripheral neuropathy or anterior horn (amyotrophic lateral sclerosis, polio, drug-induced neuropathy, alcoholic or toxic);
– Myxedema, adrenal insufficiency, diabetes;
– Cardiovascular disease: cardiomyopathy, venous or arterial insufficiency, Raynaud’s disease;
– Myopathy, including infectious or metabolic.
In most cases, no treatment is justified:
– When the cramp, you must stretch the painful muscle;
muscle relaxants if annoying recurrence;
– Hexaquine® (quinine + thiamine) at a dose of 2 tablets / day;
– Possible etiological treatment.
Hereditary myopathy with very early onset neonatal:
The diagnostic approach concerning: clinical expression (neonatal hypotonia), family history, cardiomyopathy, metabolic context (lactic acidosis, organic aciduria), electromyography, muscle biopsy.
The main features are:
– Neonatal Steinert;
– Congenital myopathies (sticks, central core, multiminicore, myotubular, centronuclear) possible diagnosis in adulthood for mild;
– Metabolic diseases: abnormal respiratory chain of fat oxidation, acid maltase deficiency (metering);
– Congenital muscular dystrophy;
– Infantile spinal amyotrophy.
Myopathy inherited, slowly progressive:
The diagnostic approach concerning: transmission, distribution deficit, myotonia, cardiac, muscle biopsy (dystrophy, the dystrophin abnormalities of adhaline or related protein).
The main features are:
– X-linked recessive (boy reached, mother-transmitting)
– Duchenne (early and severe)
– Becker (later and less severe), other dystrophinopathies in common: no facial involvement, large
– Calves, heart disease or abnormalities of dystrophin-related proteins,
– Emery-Dreifuss: bicipitales retractions, the headset’s disease;
– Autosomal dominant:
– Myopathy facial-glenohumeral: face, shoulder girdle, asymmetrical involvement,
– Steinert: face, myotonia, and distal symmetric deficit, cataract, cardiac conduction disorder that may require a pacemaker;
– Autosomal recessive: LGMD, Maghreb dystrophy (deficit adhaline), distal myopathy.
The diagnostic approach concerns: family history, myotonia (delayed muscle relaxation), paramyotonia, multisystem reached, study of DNA, characteristic muscle biopsy.
The main features are:
– Steinert’s disease, the most common etiology, topography evocative;
– Congenital myotonia: dominant (Thomsen) or recessive (Becker), early onset multisystem not reached;
– Paramyotonia von Eulenburg: dominant transmission, worsening of myotonia to the repetition of movement and cold, mutation of the sodium channel gene;
– Syndrome Schwartz-Jampel: dysmorphia, chondrodysplasie.
Ophthalmoplegia ± ± deficit disorders bulbar / fatigability members:
The diagnostic approach concerns: developing profile, family concept, multisystem reached, test Tensilon®, neuromuscular block on electromyography, anti-receptor antibody assay of acetylcholine (anti-AChR), muscle biopsy.
The main features are:
– Myasthenia: clinical, test Tensilon® +, neuromuscular block on electromyography, anti-AChR antibodies, thymus;
– Mitochondrial myopathy: family history, myalgias during exercise, heart disease, deafness, retinitis pigmentosa, cerebellar dysfunction, hyperlactatemia muscle biopsy ragged red fibers or ragged red fibers;
– Oculopharyngeal myopathy: Autosomal dominant, muscle biopsy: rimmed vacuoles.
Recurrent episodes paralytic:
The diagnostic approach concerns: serum potassium during the crisis, family history, myotonia, muscle biopsy, DNA study.
The main features are:
– Dominant hereditary transmission: Family hypokalemic paralysis, paralysis hyperkalemic family (myotonia gene mutation sodium channel, in both cases: vacuoles and tubular aggregates in muscle biopsy);
– Hypokalemic diarrhea, vomiting, diuretics, thyrotoxicosis, aldosteronism
– Hyperkalemic: renal failure, adrenal insufficiency, excessive exogenous supply.
Myolysis ± exercise intolerance:
The diagnostic approach concerns: search for episodes of acute muscle necrosis (myolysis), stress test (lactic acid), muscle biopsy (glycogen accumulation or lipid, enzyme assays).
The main features are:
– Glycogenoses: phosphorylase deficiency (McArdle), phosphorylase kinase enzymes of glycolysis myolysis, intolerance brief effort absence of elevated lactate during exercise, glycogen overload the muscle biopsy;
– Lipidoses: carnitine palmitoyl transferase deficiency: myolysis after fasting and / or prolonged effort, normal muscle biopsy or discrete lipid overload, decreased enzyme activity (lymphocytes and muscle); mitochondrial myopathies: no myolysis,
– Hyperlactacidemia, multisystem impairment, muscle biopsy (ragged red fibers);
– Other enzyme deficiencies: myoadenylate deaminase bêtaoxydation …
Myopathy acquired, rapidly progressive:
The diagnostic approach concerns: inflammatory context, multisystem, toxic, iatrogenic, endocrine, muscular biopsy.
The main features are:
– Inflammatory: myositis, sarcoidosis, polyarteritis nodosa (mononeuritis); toxic and iatrogenic: alcohol + drugs
– Endocrine: hyperthyroidism, hypothyroidism, Cushing, hyperparathyroidism.
With motor deficit:
The main causes widespread muscle pain with motor deficit are presented in Box 3.
Box 3. Etiology generalized myalgia with motor deficit
Inclusion body myositis
Myositis in connective
influenzae and related viruses, Coxsackie, Retrovirus
Leptospirosis, Lyme, Gram negative bacteria, toxic shock
syndrome, Kawasaki syndrome
metabolic and toxic disorders
acute alcoholic myopathy
Kaliopénie with or without hypokalemia
Total parenteral nutrition (deficiency in essential fatty acids)
Necrotizing myopathy paraneoplastic
Palmitoyl carnitine deficiency
enzymatic and congenital myopathies
With bone pain
No motor deficit:
The main causes generalized myalgia without motor deficit are presented in Box 4.
Box 4. Etiology generalized myalgias without motor deficit
Eosinophilia myalgia syndrome,
Myalgia during episodes of fever and infections
Hypophosphatemia, phosphate diabetes