What is restless legs syndrome?
Restless legs syndrome (RLS) is a neurological disorder characterized by throbbing, pulling, creeping, or other unpleasant sensations in the legs and an uncontrollable, and sometimes overwhelming, urge to move them. Symptoms occur primarily at night when a person is relaxing or at rest and can increase in severity during the night. Moving the legs relieves the discomfort. Often called paresthesias (abnormal sensations) or dysesthesias (unpleasant abnormal sensations), the sensations range in severity from uncomfortable to irritating to painful.
The most distinctive or unusual aspect of the condition is that lying down and trying to relax activates the symptoms. Most people with RLS have difficulty falling asleep and staying asleep. Left untreated, the condition causes exhaustion and daytime fatigue. Many people with RLS report that their job, personal relations, and activities of daily living are strongly affected as a result of their sleep deprivation. They are often unable to concentrate, have impaired memory, or fail to accomplish daily tasks. It also can make traveling difficult and can cause depression.
As many as 10 percent of the U.S. population may have RLS. Several studies have shown that moderate to severe RLS affects approximately 2-3 percent of adults (more than 5 million individuals). An additional 5 percent appears to be affected by a milder form. Childhood RLS is estimated to affect almost 1 million school-age children, with one-third having moderate to severe symptoms. Some people with RLS will not seek medical attention, believing that they will not be taken seriously, that their symptoms are too mild, or that their condition is not treatable. Some physicians wrongly attribute the symptoms to nervousness, insomnia, stress, arthritis, muscle cramps, or aging.
RLS occurs in both men and women, although the incidence is about twice as high in women. It may begin at any age. Many individuals who are severely affected are middle-aged or older, and the symptoms typically become more frequent and last longer with age.
RLS is classified as a movement disorder, as individuals are forced to move their legs in order to gain relief from symptoms.
More than 80 percent of people with RLS also experience a more common condition known as periodic limb movement of sleep (PLMS). PLMS is characterized by involuntary leg twitching or jerking movements during sleep that typically occur every 15 to 40 seconds, sometimes throughout the night. The symptoms cause repeated awakening and severely disrupted sleep. Although many individuals with RLS also develop PLMS, most people with PLMS do not experience RLS. People who have PLMS and do not have RLS or another cause for the PLMS may be diagnosed with periodic limb movement disorder (PLMD). PLMD may be a variant of RLS and thus respond to similar treatments.
What are common signs and symptoms of restless legs?
People with RLS feel uncomfortable sensations in their legs, especially when sitting or lying down, accompanied by an irresistible urge to move the affected limb. These sensations less commonly affect the arms, trunk, or head. Although the sensations can occur on just one side of the body, they most often affect both sides.
Because moving the legs (or other affected parts of the body) relieves the discomfort, people with RLS often keep their legs in motion to minimize or prevent the sensations. They may pace the floor, constantly move their legs while sitting, and toss and turn in bed.
A classic feature of RLS is that the symptoms are worse at night with a distinct symptom-free period in the early morning, allowing for more refreshing sleep at that time. Other triggering situations are periods of inactivity such as long car trips, sitting in a movie theater, long-distance flights, immobilization in a cast, or relaxation exercises. Many individuals also note a worsening of symptoms if their sleep is further reduced by events or activity.
RLS symptoms may vary from day to day and in severity and frequency from person to person. Individuals with mild RLS may have some disruption of sleep onset and minor interference in daytime activities. In moderately severe cases, symptoms occur only once or twice a week but result in significant delay of sleep onset, with some disruption of daytime function. In severe cases of RLS, the symptoms occur more than twice a week and result in burdensome interruption of sleep and impairment of daytime function.
Individuals with RLS can sometimes experience remissions—spontaneous improvement over a period of weeks or months before symptoms reappear—usually during the early stages of the disorder. In general, however, symptoms become more severe over time.
People who have both RLS and an associated medical condition tend to develop more severe symptoms rapidly. In contrast, those who have RLS that is not related to any other condition and experience onset at an early age show a very slow progression of the disorder; many years may pass before symptoms occur regularly.
What causes restless legs syndrome?
In most cases, the cause of RLS is unknown. However, it may have a genetic component; RLS is often found in families where the onset of symptoms is before age 40. Specific gene variants have been associated with RLS. Evidence indicates that low levels of iron in the brain also may be responsible for RLS.
Considerable evidence suggests that RLS is related to a dysfunction in the brain’s basal ganglia circuits that use the neurotransmitter dopamine, which is needed to produce smooth, purposeful muscle activity and movement. Disruption of these pathways frequently results in involuntary movements. Individuals with Parkinson’s disease, another disorder of the basal ganglia’s dopamine pathways, often have RLS as well.
RLS also appears to be related to the following factors or conditions, although researchers do not yet know if these factors actually cause RLS:
- Chronic diseases such as kidney failure, diabetes, and peripheral neuropathy. Treating the underlying condition often provides relief from RLS symptoms.
- Certain medications that may aggravate symptoms. These medications include antinausea drugs (prochlorperazine or metoclopramide), antipsychotic drugs (haloperidol or phenothiazine derivatives), antidepressants that increase serotonin, and some cold and allergy medications-that contain sedating antihistamines.
- Pregnancy, especially in the last trimester. In most cases, symptoms usually disappear within 4 weeks after delivery.
- Alcohol and sleep deprivation also may aggravate or trigger symptoms in some individuals. Reducing or completely eliminating these factors may relieve symptoms, but it is unclear if this can prevent RLS symptoms from occurring at all.
How is restless legs syndrome diagnosed?
There is no specific test for RLS. The four basic criteria for diagnosing the disorder are:
Symptoms that are worse at night and are absent or negligible in the morning;
- A strong and often overwhelming need or urge to move the affected limb(s), often associated with paresthesias or dysesthesias;
- Sensory symptoms that are triggered by rest, relaxation, or sleep; and
- Sensory symptoms that are relieved with movement and the relief persists as long as the movement continues.
Physicians should focus largely on the individual’s descriptions of symptoms, their triggers and relieving factors, as well as the presence or absence of symptoms throughout the day. A neurological and physical exam, plus information from the individual’s medical and family history and list of current medications, may be helpful. Individuals may be asked about frequency, duration, and intensity of symptoms as well as their tendency toward daytime sleep patterns and sleepiness, disturbance of sleep, or daytime function.
Laboratory tests may be performed to rule out other conditions. Blood tests can identify iron and vitamin deficiencies as well as other medical disorders associated with RLS. In some cases, sleep studies such as polysomnography (a test that records the individual’s brain waves, heartbeat, breathing, and leg movements during an entire night) may identify the presence of other causes of sleep disruption (e.g., sleep apnea), which may impact management of the disorder.
Diagnosing RLS in children may be especially difficult, since it may be hard for a child to describe where it hurts, when and how often the symptoms occur, and how long symptoms last. Pediatric RLS can sometimes be misdiagnosed as "growing pains" or attention deficit disorder.
How is restless legs syndrome treated?
RLS can be treated, with care directed toward relieving symptoms. Moving the affected limb(s) may provide temporary relief. Sometimes RLS symptoms can be controlled by finding and treating an associated medical condition, such as peripheral neuropathy or diabetes.
Certain lifestyle changes and activities that may reduce symptoms in persons with mild to moderate symptoms include decreased use of caffeine, alcohol, and tobacco; supplements to correct deficiencies in iron, folate, and magnesium; changing or maintaining a regular sleep pattern; a program of moderate exercise; and massaging the legs, taking a hot bath, or using a heating pad or ice pack. A trial of iron supplements is recommended only for individuals with low iron levels. Although many people find some relief with such measures, rarely do these efforts completely eliminate symptoms.
Medications are usually helpful but no single medication effectively manages RLS for all individuals. Trials of different drugs may be necessary. In addition, medications taken regularly may lose their effect over time, making it necessary to change medications periodically.
What is the prognosis of people with restless legs?
RLS is generally a lifelong condition for which there is no cure. Nevertheless, current therapies can control the disorder, minimizing symptoms and increasing periods of restful sleep. Symptoms may gradually worsen with age, although the decline may be somewhat faster for individuals who also suffer from an associated medical condition. In addition, some individuals have remissions—periods in which symptoms decrease or disappear for days, weeks, or months—although symptoms usually eventually reappear. A diagnosis of RLS does not indicate the onset of another neurological disease, such as Parkinson’s disease.