Editing Cramp (section)

==Causes==
Skeletal muscle cramps may be caused by [[muscle fatigue]] or a lack of [[electrolyte]]s{{Citation needed|date=March 2023}} such as [[sodium]] (a condition called [[hyponatremia]]), [[potassium]] (called [[hypokalemia]]), or [[magnesium]] (called [[Magnesium deficiency|hypomagnesemia]]<ref>{{Cite journal|last1=Gragossian|first1=Alin|last2=Bashir|first2=Khalid|last3=Friede|first3=Rotem|date=September 6, 2020|title=Hypomagnesemia|url=https://www.ncbi.nlm.nih.gov/books/NBK500003/|access-date=October 14, 2020|website=National Center for Biotechnology Information (NCBI)|pmid=29763179|quote="Hypomagnesemia is an electrolyte disturbance caused when there is a low level of serum magnesium [...] in the blood"}}</ref>). Some skeletal muscle cramps do not have a known cause.<ref name=":1" /> Motor neuron disorders (e.g., [[amyotrophic lateral sclerosis]]), [[metabolic disorder]]s (e.g., [[liver failure]]), some medications (e.g., [[diuretic]]s and inhaled [[Beta-adrenergic agonist|beta‐agonists]]), and [[Hemodialysis|haemodialysis]] may also cause muscle cramps.<ref name=":1" />

Causes of cramping include<ref>[http://www.medicinenet.com/muscle_cramps/page2.htm#2whatare Muscle Cramps Symptoms, Causes, Treatment – Do all muscle cramps fit into the above categories on MedicineNet] {{webarchive|url=https://web.archive.org/web/20080824152442/http://www.medicinenet.com/muscle_cramps/page2.htm |date=2008-08-24 }}. Medicinenet.com. Retrieved on 2011-02-13.</ref> [[hyperflexion]], [[Hypoxia (medical)|hypoxia]], exposure to large changes in temperature, dehydration, or [[Hyponatremia|low blood salt]]. Muscle cramps can also be a symptom or complication of [[pregnancy]]; [[kidney]] disease; [[thyroid]] disease; [[hypokalemia]], [[hypomagnesemia]], or [[hypocalcaemia]] (as conditions); [[restless legs syndrome]]; [[varicose veins]];<ref>Bergan J. The Vein Book, Hardcover text, Editor Bergan J, 2007. {{isbn|9780195399639}}</ref> and [[multiple sclerosis]].<ref name="test2">[http://www.webmd.com/hw-popup/Muscle-cramps Muscle Cramps at WebMD] {{webarchive|url=https://web.archive.org/web/20071015073632/http://www.webmd.com/hw-popup/muscle-cramps |date=2007-10-15 }}</ref>

As early as 1965, researchers observed that leg cramps and restless legs syndrome can result from excess [[insulin]], sometimes called [[hyperinsulinemia]].<ref>{{cite journal|last1=Roberts|first1=HJ|title=Spontaneous Leg Cramps and "restless Legs" Due to Diabetogenic Hyperinsulinism: Observations on 131 Patients|journal=Journal of the American Geriatrics Society|volume=13|issue=7|pages=602–38|year=1965|pmid=14300967|doi=10.1111/j.1532-5415.1965.tb00617.x|s2cid=28096190}}</ref>

===Skeletal muscle cramps===
{{See also|Exercise-associated muscle cramps}}

Under normal circumstances, [[skeletal muscle]]s can be voluntarily controlled. Skeletal muscles that cramp the most often are the [[Calf muscle|calves]], [[thighs]], and [[arches of the foot]], and in North America are sometimes called a "[[Charley horse]]" or a "corky". Such cramping is associated with strenuous physical activity and can be intensely painful; however, it can occur while inactive and relaxed. Around 40% of people who experience skeletal cramps are likely to endure extreme muscle pain and may be unable to use the entire limb that contains the "locked-up" muscle group. It may take up to a week for the muscle to return to a pain-free state, depending on the person's fitness level, age, and several other factors.{{citation needed|date=August 2021}}

====Nocturnal leg cramps====
{{see also|Charley horse}}
[[Nocturnal]] leg cramps are involuntary muscle contractions that occur in the [[Gastrocnemius muscle|calves]], [[Sole (foot)|soles]] of the feet, or other muscles in the body during the night or (less commonly) while resting. The duration of nocturnal leg cramps is variable, with cramps lasting anywhere from a few seconds to several minutes. Muscle soreness may remain after the cramp itself ends. These cramps are more common in older people.<ref name="mayo">[http://www.mayoclinic.com/health/night-leg-cramps/MY00410 Night leg cramps - Mayo Clinic] {{webarchive|url=https://web.archive.org/web/20110923231142/http://www.mayoclinic.com/health/night-leg-cramps/MY00410 |date=2011-09-23 }}</ref> They happen quite frequently in teenagers and some people while exercising at night. Besides being painful, a nocturnal leg cramp can cause much [[Distress (medicine)|distress]] and [[anxiety]].<ref>{{cite journal|last=Weiner|first=Israel H|title=Nocturnal Leg Muscle Cramps|year=1980|volume=244|issue=20|pages=2332–3|url=http://jama.ama-assn.org/content/244/20/2332.short|journal=JAMA|doi=10.1001/jama.1980.03310200066033|pmid=7431559|access-date=26 October 2011|url-status=live|archive-url=https://web.archive.org/web/20101228162905/http://jama.ama-assn.org/content/244/20/2332.short|archive-date=28 December 2010|url-access=subscription}}</ref> The precise cause of these cramps is unclear. Potential contributing factors include [[dehydration]], low levels of certain minerals ([[magnesium]], [[potassium]], [[calcium]], and [[sodium]], although the evidence has been mixed),<ref>{{cite journal |vauthors=Schwellnus MP, Nicol J, Laubscher R, Noakes TD |title=Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners |journal=Br J Sports Med |year=2004 |volume=38 |issue=4 |pages=488–492 |doi=10.1136/bjsm.2003.007021|pmid=15273192 |pmc=1724901 }}</ref><ref name="pmid16015122">{{cite journal | vauthors = Sulzer NU, Schwellnus MP, Noakes TD | title = Serum electrolytes in Ironman triathletes with exercise-associated muscle cramping | journal = Med Sci Sports Exerc | volume = 37 | issue = 7 | pages = 1081–5 | date = July 2005 | pmid = 16015122 | doi = 10.1249/01.mss.0000169723.79558.cf| s2cid = 12582883 | doi-access = free }}</ref><ref name=":0"/> and reduced blood flow through muscles attendant in prolonged sitting or lying down. Nocturnal leg cramps (almost exclusively calf cramps) are considered "normal" during the late stages of pregnancy.<ref>{{cite web |url=https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/leg-cramps-during-pregnancy/faq-20057766 |title=What causes leg cramps during pregnancy, and can they be prevented? |vauthors = Wick M  |website=Mayo Clinic |access-date=2018-04-03 }}</ref>

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.<ref name=":0">{{cite journal |url=http://www.aafp.org/afp/2012/0815/p350.html |title=Nocturnal Leg Cramps |journal=American Family Physician |vauthors=Allen RE, Kirby KA |year=2012 |volume=86 |issue=4 |pages=350–355 |pmid=22963024 |url-status=live |archive-url=https://web.archive.org/web/20160329134250/http://www.aafp.org/afp/2012/0815/p350.html |archive-date=2016-03-29 }}</ref>

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.<ref name="nytimes-ray">{{cite news|url=https://www.nytimes.com/2009/06/09/health/09qna.html|title=Q & A – A Charley Horse in Bed|last=Ray|first=C. Claiborne|date=2009-06-09|work=[[The New York Times]]|access-date=2009-06-09|url-status=live|archive-url=https://web.archive.org/web/20130407063441/http://www.nytimes.com/2009/06/09/health/09qna.html|archive-date=2013-04-07}}</ref> 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 blocker]]s, [[carisoprodol]], and [[vitamin B12|vitamin B<sub>12</sub>]].<ref name=":0"/>

[[Quinine]] is no longer recommended for the treatment of nocturnal leg cramps due to potential fatal hypersensitivity reactions and [[thrombocytopenia]]. [[Cardiac arrhythmia|Arrhythmias]], [[cinchonism]], and [[Hemolytic-uremic syndrome|hemolytic uremic syndrome]] can also occur at higher dosages.<ref name=":0"/>

===Cramps caused by treatments===
Various medications may cause nocturnal leg cramps:<ref name=":0"/><ref name="pmid22157068">{{cite journal | vauthors = Garrison SR, Dormuth CR, Morrow RL, Carney GA, Khan KM | title = Nocturnal leg cramps and prescription use that precedes them: a sequence symmetry analysis | journal = Arch. Intern. Med. | volume = 172 | issue = 2 | pages = 120–6 | date = January 2012 | pmid = 22157068 | doi = 10.1001/archinternmed.2011.1029 | doi-access =  }}</ref>
* [[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]])

[[Statin]]s 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, that increase the probability of 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;<ref>
{{cite journal |vauthors=Sinzinger H, O'Grady J |title=Professional athletes suffering from familial hypercholesterolaemia rarely tolerate statin treatment because of muscular problems |journal=Br J Clin Pharmacol |volume=57 |issue=4 |pages=525–8 |year=2004 |pmid=15025753 |doi=10.1111/j.1365-2125.2003.02044.x |pmc=1884475}}</ref> the rate appears to be approximately 10–25% in a typical statin-using population.<ref>
{{cite journal |vauthors=Bruckert E, Hayem G, Dejager S, Yau C, Bégaud B |title=Mild to moderate muscular symptoms with high-dosage statin therapy in hyperlipidemic patients—the PRIMO study |journal=Cardiovasc Drugs Ther |volume=19 |issue=6 |pages=403–14 |year=2005 |pmid=16453090 |doi=10.1007/s10557-005-5686-z|s2cid=24525127 }}</ref><ref>
{{cite journal |title=Statin-induced apoptosis and skeletal myopathy |journal=Am. J. Physiol., Cell Physiol. |volume=291 |issue=6 |pages=C1208–12 |year=2006 |pmid=16885396 |doi=10.1152/ajpcell.00226.2006 |author=Dirks, A. J. |last2=Jones |first2=KM|s2cid=13313618 }}</ref> 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 help avoid some statin-related adverse effects, but currently, there is not enough evidence to prove its effectiveness in avoiding myopathy or myalgia.<ref>{{cite journal |vauthors=Lamperti C, Naini AB, Lucchini V |title=Muscle coenzyme Q10 level in statin-related myopathy |journal=Arch. Neurol. |volume=62 |issue=11 |pages=1709–12 |year=2005 |pmid=16286544 |doi=10.1001/archneur.62.11.1709|display-authors=etal|doi-access= }}</ref>