Sleep-related leg cramps are a sleep-related movement disorder whereby painful contractions of the calf or foot muscles arise during time in bed and may interrupt sleep, and they may be associated with muscle cramps during daytime wakefulness. Sleep-related leg cramps are encountered at all ages, but they are especially prevalent among the elderly. They may result from a variety of pathologies, metabolic muscle and nerve disorders, electrolyte disturbances, vascular diseases, neurologic disorders such as Parkinson disease, and toxic and drug side effects. Sleep-related leg cramps may sometimes mimic and need to be differentiated from other sleep-related movement disorders, especially the manifestations of restless legs syndrome.
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• Sleep-related leg cramps represent a common sleep-related movement disorder characterized by painful contractions of the muscles of the lower limbs during sleep.
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• This disorder can be either idiopathic or secondary to metabolic, vascular, or neurologic diseases or medications.
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• Diagnosis is clinical and requires exclusion of secondary forms; polysomnography may be helpful to rule out other conditions.
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• Treatment comprises nonpharmacological and pharmacological therapies.
Historical note and terminology
According to the American Academy of Sleep Medicine International Classification of Sleep Disorders, sleep-related leg cramps, previously classified within the parasomnias and precisely as a wake-sleep transition disorder, fall within the category of the sleep-related movement disorders (03). Within this category, sleep-related leg cramps are grouped together with restless legs syndrome, periodic limb movement disorder, sleep-related bruxism, sleep-related rhythmic movement disorder, benign sleep myoclonus of infancy, propriospinal myoclonus at sleep onset, and sleep-related movement disorder either unspecified, due to drug or substance, or to a medical condition. Sleep-related movement disorders are conditions that are primarily characterized by relatively simple, usually stereotyped movements that disturb sleep or by other sleep-related monophasic movement disorders such as sleep-related leg cramps. Leg cramps may be sleep related when they occur solely or predominantly during sleep and idiopathic when they remain unassociated with any other disturbance. On the other hand, sleep-related leg cramps may be secondary to several systemic or focal pathologic conditions.