Merck Manual

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Periodic Limb Movement Disorder (PLMD) and Restless Legs Syndrome (RLS)

By

Richard J. Schwab

, MD, University of Pennsylvania, Division of Sleep Medicine

Last full review/revision Jun 2020| Content last modified Jun 2020
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NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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Periodic limb movement disorder involves repetitive movements of the arms, legs, or both during sleep. Restless legs syndrome involves an irresistible urge to move and usually abnormal sensations in the legs, arms, or both when people sit still or lie down.

  • In people with periodic limb movement disorders, the legs, arms, or both twitch and jerk, disrupting sleep, but people are usually not aware of the movements.

  • People with restless legs syndrome have trouble relaxing and sleeping because they feel an irresistible urge to move their legs or arms.

  • Doctors may diagnose restless legs syndrome based on symptoms, but testing in a sleep laboratory is needed to diagnose periodic limb movement disorder.

  • There is no cure, but drugs used to treat Parkinson disease and other drugs may help control symptoms.

These sleep disorders are more common during middle and older age.

In the United States, restless legs syndrome may affect 5 to 15% of people, but only about 2 to 3% have significant symptoms. It is particularly common among people older than 50. Most people with restless legs syndrome also have symptoms of periodic limb movement disorder, but most people with periodic limb movement disorder do not have restless legs syndrome.

What causes restless legs syndrome and periodic limb movement disorder is unknown. But one third or more of people with restless legs syndrome have family members with the syndrome. Risk factors include the following:

  • A sedentary lifestyle

  • Smoking

  • Obesity

Periodic limb movement disorder commonly occurs in people with narcolepsy or rapid eye movement (REM) sleep behavior disorder.

Both restless legs syndrome and periodic limb movement disorder are more likely in people who have or do the following:

  • Stop taking certain drugs (including benzodiazepines such as diazepam)

  • Take stimulants (such as caffeine or stimulant drugs) or certain antidepressants

  • Have iron deficiency

  • Have anemia

  • Are pregnant

  • Have a severe chronic kidney or liver disorder

  • Have diabetes

  • Have a neurologic disorder, such as multiple sclerosis or Parkinson disease

Symptoms

Both periodic limb movement disorder and restless legs syndrome interrupt sleep. As a result, people feel tired and sleepy during the day.

Symptoms of periodic limb movement disorder

The legs or arms typically twitch and jerk every 20 to 40 seconds during sleep. People are usually unaware of these movements and the brief awakenings that follow, but they may complain of sleeping poorly, waking up several times during the night, or feeling sleepy during the day. People do not have any abnormal sensations in their legs or arms.

Symptoms of restless legs syndrome

Typically, people with restless legs syndrome have an irresistible urge to move their legs when they are sitting still or lying down. People also often feel vague but intense strange sensations in their legs, sometimes accompanied by pain. The sensations may be described as burning, creeping, or tugging or like insects crawling inside the legs.

Walking or moving or stretching the legs can relieve the sensations. People may pace, constantly move their legs while they are sitting, and toss and turn in bed. Thus, people have difficulty relaxing and falling asleep. During sleep, the legs may move spontaneously and uncontrollably, often awakening the sleeper.

Symptoms are more likely to occur when people are under stress. Episodes may occur occasionally, causing few problems, or several times a week, depriving people of sleep and making it difficult to concentrate and function.

Diagnosis

  • For restless legs syndrome, a doctor's evaluation

  • For periodic limb movement disorder, polysomnography

  • For either disorder, tests to check for a cause

Doctors can often diagnose restless legs syndrome based on symptoms reported by the person or the person’s bed partner. Doctors may suspect periodic limb movement disorder based on symptoms, such as insomnia, excessive daytime sleepiness, and/or excessive twitching just before going to sleep or during sleep.

Polysomnography, including electromyography (EMG), is always done to diagnose periodic limb movement disorder. These tests are done overnight in a sleep laboratory and are not done at home. In polysomnography, brain activity, heart rate, breathing, muscle activity, and eye movements are monitored while people sleep. People may also be videotaped during an entire night's sleep to document limb movements. These tests may also be done after restless legs syndrome is diagnosed to determine whether people also have periodic limb movement disorder.

If either disorder is diagnosed, blood and urine tests are done to check for disorders that can contribute, such as anemia, iron deficiency, and kidney and liver disorders.

Treatment

  • Changes in the diet

  • Drugs used to treat Parkinson disease and other drugs

Avoiding caffeine, which can make symptoms worse, is recommended. If people are deficient in iron, the primary treatment is iron supplements.

The same drugs are used to treat periodic limb movement disorder and restless legs syndrome. These drugs include

  • Drugs typically used to treat Parkinson disease: Pramipexole, ropinirole, or rotigotine (used as a patch) may help. These drugs imitate the actions of dopamine—a chemical that transmits messages from nerve cells to other cells (neurotransmitter). They increase nerve impulses to muscles. Sometimes these drugs cause symptoms to worsen. They can also cause nausea, an excessive decrease in blood pressure when a person stands (orthostatic hypotension), compulsive behaviors, and insomnia.

  • Antiseizure drugs: An antiseizure drug that is also used to treat pain is effective in some people. These drugs include gabapentin or pregabalin.

  • Opioids: An opioid such as oxycodone may be used. However, doctors use them cautiously because they can have serious side effects, including the possibility of addiction.

Gabapentin enacarbil is the main treatment for people with periodic limb movement disorder or restless leg syndrome. This drug relieves symptoms of restless legs syndrome and does not cause symptoms to worsen.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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