Cramp

For the heraldic device, see Cramp (heraldry). For the band, see The Cramps

Cramp

ICD-10	R25.2
ICD-9	729.82
DiseasesDB	3151
MedlinePlus	003193
MeSH	D009120

Cramps are unpleasant, often painful sensations caused by muscle contraction or over shortening. Common causes of skeletal muscle cramps include muscle fatigue, low sodium, and low potassium. Smooth muscle cramps may be due to menstruation or gastroenteritis.

Differential diagnosis

Causes of cramping include^[1] hyperflexion, hypoxia, exposure to large changes in temperature, dehydration, or low blood salt. Muscle cramps may also be a symptom or complication of pregnancy, kidney disease, thyroid disease, hypokalemia, hypomagnesemia or hypocalcemia (as conditions), restless-leg syndrome, varicose veins,^[2] and multiple sclerosis.^[3]

Electrolyte disturbance may cause cramping and muscle tetany, particularly hypokalaemia and hypocalcaemia. This disturbance arises as the body loses large amounts of interstitial fluid through sweat. This interstitial fluid comprises mostly water and table salt (sodium chloride). The loss of osmotically active particles outside of muscle cells leads to a disturbance of the osmotic balance and therefore shrinking of muscle cells, as these contain more osmotically active particles. This causes the calcium pump between the muscle lumen and sarcoplasmic reticulum to short circuit; the calcium ions remain bound to the troponin, continuing muscle contraction. This may occur when lactic acid is high in the cells.^{[citation needed]}

As early as 1965, researchers observed that leg cramps and restless-leg syndrome result from excess insulin, sometimes called hyperinsulinemia.^[4] Hypoglycemia and reactive hypoglycemia are associated with excess insulin (or insufficient glucagon), and avoidance of low blood glucose concentration may help to avoid cramps.

Smooth muscle cramps

Smooth muscle contractions lie at treatment may be symptomatic of endometriosis or other health problems. Menstrual cramps may also occur before a female menstrual cycle.

Skeletal muscle cramps

Skeletal muscles can be voluntarily controlled. Skeletal muscles that cramp the most often are the calves, thighs, and arches of the foot. A so-called Charley horse, this kind of cramp is associated with strenuous activity and can be intensely painful—though skeletal cramps can occur while relaxing. Around 40% of people who experience skeletal cramps are likely to endure extreme muscle pain, and may be unable to use the affected limb. It may take up to seven days for the muscle to return to a pain-free state.

Nocturnal leg cramps

Nocturnal leg cramps are involuntary muscle contractions that occur in the calves, soles of the feet, or other muscles in the body during the night or (less commonly) while resting. Only a few fibers of a muscle may be in spasm.^[5] 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.^[6] They happen quite frequently in teenagers and in some people while exercising at night. Usually, putting some pressure on the affected leg by walking some distance will end the cramp.^[7]

The precise cause of these cramps is unclear. Potential contributing factors include dehydration, low levels of certain minerals (magnesium, potassium, calcium, and sodium), and reduced blood flow through muscles attendant in prolonged sitting or lying down. Less common causes include more serious conditions or drug use.^{[citation needed]}

Nocturnal leg cramps may also sometimes be relieved by stretching the affected leg and pointing the toes upward. ^[7]

Nocturnal leg cramps (almost exclusively calf cramps) are considered 'normal' during the late stages of pregnancy. They can, however, vary in intensity from mild to extremely painful.

Besides being painful, a nocturnal leg cramp can cause much distress and anxiety.^[8]

Iatrogenic causes

Statins cause myalgia and cramps among other possible side effects, including substantially lowering blood glucose concentration.^[9] Additional factors, which increase the probability for these side effects, are physical exercise, age, female gender, history of cramps, and hypothyroidism. Up to 80% of athletes using statins suffer significant adverse muscular effects, including cramps;^[10] the rate appears to be approximately 10–25% in a typical statin-using population.^[11][12] 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.^[13]

Pathophysiology

Main article: Muscle contraction

Skeletal muscles work as antagonistic pairs. Contracting one skeletal muscle requires the relaxation of the opposing muscle in the pair. Cramps can occur when muscles are unable to relax properly due to myosin fibers not fully detaching from actin filaments. In skeletal muscle, both ATP (energy) and magnesium must attach to the myosin fibers for them to disassociate from the muscle and allow relaxation — the absence of either of these in sufficient quantities means that the myosin remains attached to actin.^[14] An attempt to force a muscle cramped in this way to extend (by contracting the opposing muscle) can tear muscle tissue and worsen the pain. The muscle must be allowed to recover (take in Mg and resynthesize ATP), before the myosin fibres can detach and allow the muscle to relax.

Treatment

Conservative

Stretching and massage are widely considered to reduce muscle cramps due to fatigue,^[15] but the quality of evidence for both is poor.^[16] With exertional heat cramps due to electrolyte abnormalities (primarily sodium loss and not calcium, magnesium, and potassium ) appropriate fluids and sufficient salt improves symptoms.^[15]

Medication

Vitamin B complex, naftidrofuryl, lidocaine, and calcium channel blockers may be effective for muscle cramps.^[17] Quinine is likely effective, however, due to side effects its use should only be considered if other treatments have failed and in light of these concerns.^[17]

References

1. ^ Muscle Cramps Symptoms, Causes, Treatment – Do all muscle cramps fit into the above categories on MedicineNet. Medicinenet.com. Retrieved on 2011-02-13.
2. ^ Bergin J. The Vein Book, Hardcover text, Editor Bergin J , 2007.
3. ^ Muscle Cramps at WebMD
4. ^ Roberts, HJ (1965). "Spontaneous Leg Cramps and "restless Legs" Due to Diabetogenic Hyperinsulinism: Observations on 131 Patients". Journal of the American Geriatrics Society 13: 602–38. PMID 14300967. 
5. ^ Muscle Cramps Causes, Cramping Prevention and Treatment Information by. Medicinenet.com. Retrieved on 2011-02-13.
6. ^ Night leg cramps - Mayo Clinic
7. ^ ^{a b} Ray, C. Claiborne (2009-06-09). "Q & A – A Charley Horse in Bed". New York Times. http://www.nytimes.com/2009/06/09/health/09qna.html. Retrieved 2009-06-09. 
8. ^ Weiner, Israel H. "Nocturnal Leg Muscle Cramps". JAMA. http://jama.ama-assn.org/content/244/20/2332.short. Retrieved 26 October 2011. 
9. ^ Prabhakar, Vijay; Krishna Kishore, P.V.; Balaji, Madhuri; Balaji, V.; Seshaiah, V. (2005). "Can Statins Be Considered as a Tertiary Level Agent in Patients with Failure of Conventional Oral Hypoglycemic Agents?". Heart Drug 5 (4): 183. doi:10.1159/000089597. 
10. ^ Sinzinger H, O'Grady J (2004). "Professional athletes suffering from familial hypercholesterolaemia rarely tolerate statin treatment because of muscular problems". Br J Clin Pharmacol 57 (4): 525–8. doi:10.1111/j.1365-2125.2003.02044.x. PMC 1884475. PMID 15025753. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1884475. 
11. ^ Bruckert E, Hayem G, Dejager S, Yau C, Bégaud B (2005). "Mild to moderate muscular symptoms with high-dosage statin therapy in hyperlipidemic patients—the PRIMO study". Cardiovasc Drugs Ther 19 (6): 403–14. doi:10.1007/s10557-005-5686-z. PMID 16453090. 
12. ^ Dirks, A. J.; Jones, KM (2006). "Statin-induced apoptosis and skeletal myopathy". Am. J. Physiol., Cell Physiol. 291 (6): C1208–12. doi:10.1152/ajpcell.00226.2006. PMID 16885396. 
13. ^ Lamperti C, Naini AB, Lucchini V, et al. (2005). "Muscle coenzyme Q10 level in statin-related myopathy". Arch. Neurol. 62 (11): 1709–12. doi:10.1001/archneur.62.11.1709. PMID 16286544. 
14. ^ Magnesium Mucle Relaxation. Members.upnaway.com. Retrieved on 2011-02-13.
15. ^ ^{a b} Bergeron, Michael F.. Muscle Cramps during Exercise-Is It Fatigue or Electrolyte Deficit?. doi:10.1249/JSR.0b013e31817f476a. 
16. ^ patient.co.uk > Muscle Cramps By Dr Chloe Borton. Last Updated: 1 Jun 2009
17. ^ ^{a b} Katzberg HD, Khan AH, So YT (2010). "Assessment: Symptomatic treatment for muscle cramps (an evidence-based review): Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology". Neurology 74 (8): 691–6. doi:10.1212/WNL.0b013e3181d0ccca. PMID 20177124. 

External links

• What are Cramps?
• Cramps at Patient UK
• Muscle Cramps (Of Skeletal Muscles)