Cramp

A cramp is a sudden, involuntary, painful skeletal

Cramp definition is narrower than the definition of muscle spasm: spasms include any involuntary abnormal muscle contractions, while cramps are sustained and painful.^[1][7] True cramps can be distinguished from other cramp-like conditions. Cramps are different from muscle contracture, which is also painful and involuntary, but which is electrically silent. The main distinguishing features of cramps from dystonia are suddenness with acute onset of pain, involvement of only one muscle and spontaneous resolution of cramps or their resolution after stretching the affected muscle.^[2] Restless leg syndrome is not considered the same as muscle cramps and should not be confused with rest cramps.^[6]

Causes

Skeletal muscle cramps may be caused by

As early as 1965, researchers observed that leg cramps and restless legs syndrome can result from excess insulin, sometimes called hyperinsulinemia.^[12]

Skeletal muscle cramps

Under normal circumstances,

A lactic acid buildup around muscles can trigger cramps; however, they happen during anaerobic respiration when a person is exercising or engaging in an activity where the heartbeat rises. Medical conditions associated with leg cramps are cardiovascular disease, hemodialysis, cirrhosis, pregnancy, and lumbar canal stenosis. Differential diagnoses include restless legs syndrome, claudication, myositis, and peripheral neuropathy. All of them can be differentiated through careful history and physical examination.^[17]

Gentle stretching and massage, putting some pressure on the affected leg by walking or standing, or taking a warm bath or shower may help to end the cramp.^[19] If the cramp is in the calf muscle, dorsiflexing the foot (lifting the toes back toward the shins) will stretch the muscle and provide almost immediate relief. There is limited evidence supporting the use of magnesium, calcium channel blockers, carisoprodol, and vitamin B₁₂.^[17]

Various medications may cause nocturnal leg cramps:[17]^[20]

• Diuretics
  , especially potassium sparing
• Intravenous (IV) iron sucrose
• Conjugated estrogens
• Teriparatide
• Naproxen
• Raloxifene
• Long acting
  adrenergic beta-agonists
  (LABAs)
• Hydroxymethylglutaryl-coenzyme A reductase inhibitors (HMG-CoA inhibitors or
  statins
  )

Statins may sometimes cause myalgia and cramps among other possible side effects. Raloxifene (Evista) is a medication associated with a high incidence of leg cramps. Additional factors, which increase the probability for these side effects, are physical exercise, age, history of cramps, and hypothyroidism. Up to 80% of athletes using statins experience significant adverse muscular effects, including cramps;^[21] the rate appears to be approximately 10–25% in a typical statin-using population.^[22][23] In some cases, adverse effects disappear after switching to a different statin; however, they should not be ignored if they persist, as they can, in rare cases, develop into more serious problems. Coenzyme Q10 supplementation can be helpful to avoid some statin-related adverse effects, but currently there is not enough evidence to prove the effectiveness in avoiding myopathy or myalgia.^[24]

Treatment

Stretching, massage, and drinking plenty of liquids may be helpful in treating simple muscle cramps.^[25]

Medication

The antimalarial drug quinine is a traditional treatment that may be slightly effective for reducing the number of cramps, the intensity of cramps, and the number of days a person experiences cramps. Quinine has not been shown to reduce the duration (length) of a muscle cramp.^[6] Quinine treatment may lead to haematologic and cardiac toxicity. Due to its low effectiveness and negative side effects, its use as a medication for treating muscle cramps is not recommended by the FDA.^[26]

Magnesium is commonly used to treat muscle cramps. Moderate quality evidence indicates that magnesium is not effective for treating or preventing cramps in older adults.^[6] It is not known if magnesium helps cramps due to pregnancy, liver cirrhosis, other medical conditions, or exercising.^[6] Oral magnesium treatment does not appear to have significant major side effects, however, it may be associated with diarrhea and nausea in 11–37% of people who use this medicine.^[6]

With exertional heat cramps due to

Adequate conditioning, stretching, mental preparation, hydration, and electrolyte balance are likely helpful in preventing muscle cramps.[25]

References