A cramp refers to a sudden, and often severe involuntary muscle contraction.
See muscle cramps.
Generally a temporary and non-damaging process.
Can cause mild-to-excruciating pain, and immobility of the affected muscle.
Onset is usually sudden.
Usually resolves on its own over a period of several seconds, minutes, or hours.
May occur in a skeletal or smooth muscle.
Skeletal muscle cramps may be caused by muscle fatigue, or a lack of electrolytes such as sodium, potassium, or magnesium.
Cramps of smooth muscle may be due to menstruation or gastroenteritis.
Causes include hyperflexion, hypoxia, changes in temperature, dehydration, low blood sodium, complication of pregnancy, kidney disease, thyroid disease, hypokalemia, hypomagnesemia, hypocalcemia, restless-leg syndrome, varicose veins, and multiple sclerosis.
Electrolyte disturbance may cause cramping and muscle tetany.
Sweating profusely causes loss of large amounts of interstitial fluid consisting of water and sodium disturbing the osmotic balance and results in shrinking of muscle cells.
Sweating also causes hypokalaemia and hypocalcaemia which short circuits muscle sarcoplasm and sarcoplamic reticulum leaving calcium ions to remain bound to the troponin causing muscle contraction.
Leg cramps and restless-leg syndrome can result from excess insulin found with hypoglycemia and reactive hypoglycemia.
Smooth muscle contractions may be seen with endometriosis and menstrual cramps may occur both before and during a menstrual cycle.
Skeletal muscles that cramp the most often are the calves, thighs, and arches of the foot.
Skeletal muscle cramping is associated with strenuous physical activity and may be intense.
Nocturnal leg cramps to involuntary muscle contractions that occur in the calves, soles of the feet, or other muscles in the body during the night or while resting.
Treatments for Nocturnal Leg Cramps
Calcium channel blockers or B vitamins may lead to short-term improvement in nocturnal leg cramps.
Stretching has mixed results.
Quinine is effective but is no longer recommended, and it is not approved for treatment of leg cramps because of potential toxicity.
Three systematic reviews found that oral quinine (300 mg at bedtime) significantly reduced the frequency, intensity, and number of cramps, and number of days with cramps.
Quinine’s most common minor adverse effects included tinnitus, headache, and gastrointestinal effects.
Major adverse effects of quinine include thrombocytopenia, acute hypersensitivity reactions, and QT prolongation, which may lead to hemodialysis or death.
Effect of stretching calves and hamstrings at bedtime in adults older than 55 years who had leg cramps, not treated with quinine: After six weeks, the frequency of cramps decreased more in the exercise group compared with the control group.
Previous systematic reviews evaluated nonpharmacologic therapies, including calf stretching, for nocturnal leg cramps in patients older than 60 years who were also taking quinine: Stretching three times per day for 12 weeks did not decrease the frequency of cramps or number of cramp-free nights compared with sham exercise.
Older adults in Taiwan who were not known to be vitamin B deficient: daily supplementation with vitamin B complex induced remission of muscle cramps in 86% of treated patients, compared with no improvement in the control group.
Diltiazem reduced the number of cramps: 5.8 to 0.16 cramps per two-week treatment phase, but did not affect the intensity of cramps.
Systematic reviews found no evidence to support the use of analgesics, anti-epileptic drugs, magnesium, verapamil, or vitamin E to reduce the incidence of idiopathic nocturnal leg cramps.
The duration of nocturnal leg cramps is variable lasting anywhere from a few seconds to several minutes.
Muscle soreness may remain after the cramp ends.
Nocturnal cramps are more common in older people.
Potential contributing factors to nocturnal cramps include: dehydration, low levels of magnesium, potassium, calcium, and sodium, and reduced blood flow through muscles.
Nocturnal leg cramps common during late stages of pregnancy.
A lactic acid buildup can trigger cramps.
Medical conditions associated with leg cramps are cardiovascular disease, cirrhosis, pregnancy, and lumbar canal stenosis.
Various medications may cause nocturnal leg cramps and include: diuretics, especially potassium sparing ones, long acting adrenergic beta-agonists, and statins.
Management includes can 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.
If the cramp is in the calf muscle, pulling the big toe gently backwards will stretch the muscle and, in some cases, cause almost immediate relief.
Statins sometimes cause myalgias and cramps.
Raloxifene (Evista) is associated with a high incidence of leg cramps (10-25%).
Additional factors, which increase the probability for cramps are physical exercise, age, female gender, previous history of cramps, and hypothyroidism.
Up to 80% of athletes using statins suffer adverse muscular effects, including cramps.
Coenzyme Q10 supplementation can be helpful to avoid some statin-related adverse effects.
Skeletal muscles work as antagonistic pairs, such that contracting skeletal muscle requires the relaxation of the opposing muscle in the pair.
When muscles are unable to relax due to myosin fibers not fully detaching from actin filaments cramps may occur.
Adenosine triphosphate (ATP) must attach to the myosin in skeletal muscle to disassociate from the actin and allow relaxation.
When ATP is insufficient the myosin heads remains attached to actin and an attempt to force a muscle cramped in this way to extend can damage muscle tissue and worsen pain.
The resynthesis of muscle ATP allows the muscle to relax.
Stretching, massage and fluid intake, such as water, may be helpful in treating simple muscle cramps.
With exertional heat cramps due to electrolyte abnormalities, fluids and sufficient salt intake improves symptoms.
Quinine is effective for management but due to side effects, is considered if other treatments have failed.
Vitamin B complex, naftidrofuryl, lidocaine, and calcium channel blockers may be effective for muscle cramps.
Other treatments that may be effective for cramps include: Vitamin B, naftidrofuryl, lidocaine, calcium channel blockers, and pickle juice based on its high sodium and electrolyte levels.
Cyclobenzaprine (Flexeril) has proven effective in preventing muscle cramps.
Muscle cramp prevention includes: conditioning, stretching, and preservation of adequate fluid/electrolyte balance.