Nocturnal leg cramps, night starts, and nocturnal myoclonus

INTRODUCTION

Nocturnal leg cramps, night starts, and nocturnal myoclonus are common lower extremity problems that can alter sleep. Another nighttime disorder, restless legs syndrome, is discussed separately. (See "Restless legs syndrome".)

NOCTURNAL LEG CRAMPS

Nocturnal leg cramps are common and frequently unreported to physicians [1]. They occur in all decades of life. Benign nocturnal leg and foot aches and cramps may be related to exertion and often awaken the patient.

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".)

• Leg cramps in children are common, may be familial, and require the same consideration as leg cramps in adults [2].
• Pregnancy-related leg cramps may be due in part to low serum magnesium, which may respond to magnesium supplementation [3].
• Neurologic disorders including Parkinson disease, myopathies, neuropathies, radiculopathies, motor neuron diseases, are often accompanied by leg cramps [4,5].
• Metabolic diseases including diabetes, hypoglycemia, alcoholism, hypothyroidism, and metabolic myopathies [5].
• Exercise-associated muscle cramping (EAMC) is defined as an involuntary, painful contraction of skeletal muscle during or immediately after exercise [6].
• Other unusual causes include the use of beta agonists, beta blockers with intrinsic sympathomimetic activity, inhaled bronchodilators, angiotensin II receptor antagonists, use of vasoconstrictors, beta-agonists, raloxifene, cisplatin or vincristine chemotherapy, oral contraceptives, anemia, Raynaud syndrome, nonalcoholic cirrhosis, and bariatric surgery [5,7-12].