Skeletal muscle cramp
Sudden, painful, involuntary skeletal muscle contraction, usually self-limiting.
A skeletal muscle cramp is a sudden, involuntary, and painful contraction of one or more skeletal muscles, often causing temporary immobility. It typically resolves on its own within seconds to minutes and is common at rest, particularly at night. While generally benign, cramps can be associated with various physiological and pathological conditions.
Quick Facts
- Symptoms
- Sudden muscle pain and a paralysis-like immobility
- Treatment
- Stretching
- massage
- and drinking liquids
Facts from the source article.
Causes
Skeletal muscle cramps may arise from muscle fatigue or electrolyte imbalances such as hyponatremia, hypokalemia, or hypomagnesemia. Some cramps have no identifiable cause. Motor neuron disorders like amyotrophic lateral sclerosis, metabolic conditions such as liver failure, certain medications including diuretics and inhaled beta-agonists, and haemodialysis can also trigger cramps. Additional contributing factors include hyperflexion, hypoxia, large temperature changes, dehydration, and low blood salt. Cramps may occur as a symptom or complication of pregnancy, kidney disease, thyroid disease, hypocalcemia, restless legs syndrome, varicose veins, and multiple sclerosis. Excess insulin, or hyperinsulinemia, has been linked to leg cramps and restless legs syndrome since 1965. Nocturnal leg cramps, particularly in the calves, are common during late pregnancy and in older individuals, though teenagers and some people exercising at night also experience them. Potential contributors to nocturnal cramps include dehydration, reduced blood flow from prolonged sitting or lying down, and low levels of minerals such as magnesium, potassium, calcium, and sodium, though evidence is mixed. Lactic acid buildup during anaerobic exercise can also trigger cramps. Medical conditions associated with leg cramps include cardiovascular disease, hemodialysis, cirrhosis, pregnancy, and lumbar canal stenosis. Differential diagnoses such as restless legs syndrome, claudication, myositis, and peripheral neuropathy can be distinguished through careful history and physical examination.
Treatment
Gentle stretching, massage, and adequate fluid intake may help relieve simple muscle cramps. For calf cramps, dorsiflexing the foot lifts the toes toward the shins and stretches the muscle. Quinine, once used for nocturnal leg cramps, is no longer recommended due to risks of fatal hypersensitivity reactions, thrombocytopenia, arrhythmias, cinchonism, and hemolytic uremic syndrome. Magnesium is commonly used but moderate-quality evidence shows it is not effective for preventing or treating cramps in older adults; its benefit for pregnancy-related, cirrhosis-related, or exercise-induced cramps is unknown. Oral magnesium may cause diarrhea and nausea in 11–37% of users. For exertional heat cramps involving potassium loss, appropriate fluids and potassium supplementation improve symptoms. Vitamin B complex, naftidrofuryl, lidocaine, and calcium channel blockers may also be effective.
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