INTRODUCTION

Nocturnal leg cramps, a common lower extremity condition that produces pain and can disrupt sleep, are reviewed here. Other nighttime disorders of leg movement, including restless legs syndrome and periodic limb movements of sleep, are discussed separately. (See "Restless legs syndrome" and "Restless legs syndrome", section on 'Periodic limb movements of sleep'.)

NOCTURNAL LEG CRAMPS

Nocturnal leg cramps are common and frequently unreported to clinicians [1,2]. They are present in nearly 50 percent of those over the age of 50, have an increased prevalence with age, and show no gender preference. Roughly 40 percent of those with nocturnal leg cramps report having such symptoms at least three times per week, and 5 to 10 percent report nightly cramping.

Leg cramps are characterized by sudden muscle tightness, most commonly in the foot, thigh, or calf, last from seconds to many minutes, and are relieved by forceful stretching of the affected muscles. The vast majority of individuals have such cramps only at night. Their primary morbidity is pain and sleep disturbance.

Etiology — Leg cramps can be idiopathic (the most common), associated with structural disorders or leg positioning, or related to extracellular fluid volume depletion and electrolyte disturbances.

• Structural disorders such as flat feet, genu recurvatum, and the hypermobility syndrome may predispose to leg cramps. A family history is common in these circumstances.
• Prolonged sitting, inappropriate leg position during sedentary activity, or living or working on concrete flooring may be correlated with an increased occurrence of leg cramps.
• Leg cramps may result from extracellular volume depletion (eg, due to diuretics, excessive sweating without sufficient salt replacement, or fluid removal during hemodialysis) and the dialysis disequilibrium syndrome. (See "Dialysis disequilibrium syndrome".)
• Pregnancy-related leg cramps may be due, in part, to low serum magnesium, which may respond to magnesium supplementation, although results of trials using such therapy are mixed [3-5].
• Neurologic disorders including Parkinson disease, myopathies, neuropathies, radiculopathies, and motor neuron diseases are often accompanied by leg cramps [6,7].
• Metabolic diseases associated with leg cramps include diabetes, hypoglycemia, alcoholism, hypothyroidism, and metabolic myopathies [7].
• Exercise-associated muscle cramping (EAMC) is defined as an involuntary, painful contraction of skeletal muscle during or after exercise [8].
• Other causes of leg cramps include various medications and other medical conditions [7,9-17].