What Causes Muscle Cramps?

Patient Presentation
A 10-year-old female came to clinic for her health maintenance examination. Her mother reported that she had night leg pain about 2-3 times per year over the past couple of years, but she had had one episode during the week before. The daughter would cry out and her mother would get there within 1-2 minutes. The girl would just say that her legs hurt and wanted them rubbed after which she would sleep without re-awakening. Once the mother was able to come to the bedside sooner and she was having unilateral muscle cramping. Again the mother massaged her leg and the daughter went back to sleep. She had no other sleep problems and had no problems during the day. Her mother said she didn’t seem to be restless when sleeping when she checked on her at night. She was a dancer but they were not aware of any increase in activity or changes in dietary intake on the days the episodes occurred. She and her mother denied that she sat or slept in abnormal positions. She had a good general diet and seemed to drink an appropriate amount of fluid. The past medical history showed a healthy female with some xerosis. The family history was negative for any neurological problems, sleep disorders, or leg cramping or pain. The review of systems was otherwise negative.

The pertinent physical exam showed a healthy female with normal vital signs. Her growth parameters showed a weight and height of 10-25% with normal velocities. HEENT was normal including her thyroid. Pubertal development was Tanner stage 1. Musculoskeletal examination was normal including muscle bulk. Palpation of the muscles did not produce any pain. Chvostek’s sign was negative and a Trousseau’s sign was not attempted.

The diagnosis of intermittent nocturnal leg pain possibly due to muscle cramping was made. The pediatrician discussed with the family that most leg pain and muscle cramps are idiopathic. Her history and physical examination did not reveal any other obvious causes of leg pain or muscle cramps and so the pediatrician recommended to monitor her. He recommended continuing to make sure she ate a healthy diet with calcium, potassium and magnesium foods and to drink an appropriate amount of fluid. He showed them some gentle stretching exercises that she could do before bed and told her to untuck the bedding to prevent the legs from having undue pressure put on them. They were to also keep a diary of the episodes and to call after the next one to discuss it.

Leg pain is a relatively common problem in children. Usually it is idiopathic in origin but can be the sign of organic pathology. The differential diagnosis can be found here.

Noctural legs cramps have been found to occur in about 7% of healthy children. They start after age 8 and peak at 16-18 years of age. Cramps that are idiopathic are unilateral, and those with organic causes can be uni- or bi-lateral. Most episodes last only a few minutes but those lasting longer than 10 minutes are more likely to have an organic etiology.

Learning Point
The differential diagnosis of nocturnal muscle cramping in children includes:

  • Idiopathic – most common
  • Endocrine
    • Diabetes
    • Hypothyroidism
    • Hyperthyroidism
  • Exercise
    • Myalgia due to overuse
    • Compartment syndrome
    • Myoglobinuria
  • Fluids and Electrolytes
    • Poor fluid intake
    • Hypocalcemia
    • Hypokalemia
    • Hypomagnesemia
    • Metabolic alkalosis
  • Neurological
    • Contracture
    • Neuropathy
    • Sleep disorders
      • Restless legs syndrome – causes brief sustained muscle contractions
      • Periodic limb movement disorder
  • Other
    • Growing pains
    • Medication
    • Positioning, abnormal
    • Pregnancy
    • Vascular disease

Growing pains are a common problem but do not have hard muscular contraction. Growing pains are chronic pain of both legs that occur in the evening and night with normal physical examination and laboratory testing.
The pain is in the thigh or calf muscles. The pain can occur over weeks or months.

Questions for Further Discussion
1. What are indications for a sleep study for possible sleep disorders?
2. What laboratory testing could be done for muscle cramps and why?

Related Cases

    Symptom/Presentation: Pain

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Leg Injuries and Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Leung AK, Wong BE, Chan PY, et al. Nocturnal leg cramps in children: incidence and clinical characteristics. J Natl Med Assoc. 1999;91:329-332.

Picchietti D, Allen RP, Walters AS, Davidson JE, Myers A, Ferini-Strambi L. Restless legs syndrome: prevalence and impact in children and adolescents–the Peds REST study. Pediatrics. 2007 Aug;120(2):253-66.

Guideline Development Group on Sleep Disorders in Childhood and Adolescence in Primary Care. Clinical practice guideline on sleep disorders in childhood and adolescence in primary care. Madrid (Spain): Health Technology Assessment Unit, Lain Entralgo Agency, Ministry of Health, Social Services and Equality (Spain); 2011.

Gingras JL, Gaultney JF, Picchietti DL. Pediatric periodic limb movement disorder: sleep symptom and polysomnographic correlates compared to obstructive sleep apnea. J Clin Sleep Med. 2011 Dec 15;7(6):603-9A.


Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital