Nocturnal Leg Cramps
Posted by Canadian health care on May 6th, 2009
Nocturnal leg cramps are caused by unopposed foot flexion while in bed, placing the muscles of the calves and feet in their most shortened and therefore most vulnerable position. Without modulation by opposing muscles, the sustained contraction produces the painful cramp, which is experienced as sudden severe calf pain, often with a palpable or visibly hardened muscle. In many instances, a voluntary contraction triggers the cramp. Passive stretching relieves it.
Clinical Evaluation
History.
A detailed description of the cramping is essential and should include the setting in which the episodes occur. Those that develop at night or in the context of hemodialysis, hypoglycemia, or heavy sweating from prolonged exertion are likely to be true cramps, as are those coincident with use of calcium channel blockers or beta-agonists. Dystonic cramping is suggested by onset with occupation-related fine motor activity, and contracture by a lifelong onset with exercise. Associated symptoms should be reviewed for the paresthesias and carpopedal spasm of tetany, the weakness and fasciculations of lower motor neuron disease, and the cold or heat intolerance, skin changes, and related symptoms of thyroid disease. Location of the cramping is a less specific finding, but if calf pain is reported, one should include intermittent claudication in the differential diagnosis, particularly if pain is brought on by walking. Review of medications is always useful, but use of a potassium-wasting diuretic is not tantamount to an etiologic diagnosis, because hypokalemia is rarely responsible for true cramps (although it should be considered in the differential diagnosis of tetany). Also potentially pertinent in suspected tetany is any distant history of thyroidectomy (with coincident removal of the parathyroid glands).
Physical Examination.
The skin is examined for signs of thyroid disease, the neck for evidence of thyroidectomy, the lower extremities for diminished or absent pulses, muscle wasting, and fasciculations, and the nervous system for focal weakness and absent or abnormal deep tendon reflexes. If tetany is a consideration, one can try to elicit the facial spasm of Trousseau’s sign by tapping the facial nerve or the carpal spasm of Chvostek’s sign by inflating the arm cuff above systolic pressure.
Laboratory
For the majority of people who present with a clinical story of nocturnal muscle cramps, laboratory testing is unlikely to provide additional information. Other situations do require a few simple tests. If the patient with ordinary cramps is diabetic and taking insulin, then testing for hypoglycemia is indicated. If severe dehydration and hyponatremia are suspected, then determinations of serum sodium, blood urea nitrogen (BUN), and creatinine can guide assessment and treatment. The patient with possible tetany needs a check of sodium, potassium, calcium, albumin (to interpret the calcium level), and magnesium. Consideration of thyroid disease is best pursued by obtaining a serum thyrotropin (TSH) determination. The patient with fasciculations and possible lower motor neuron disease may need a nerve conduction study.
Tags: Nocturnal Leg Cramps