Restless Leg Syndrome

What Is RLS?


Restless legs syndrome (RLS) is a neurological disorder characterized by unpleasant sensations in the legs and an uncontrollable urge to move when at rest in an effort to relieve these feelings. RLS sensations are often described by people as burning, creeping, tugging, or like insects crawling inside the legs. 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. As a result, 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 exhaustion. They are often unable to concentrate, have impaired memory, or fail to accomplish daily tasks.

Some researchers estimate that RLS affects as many as 12 million Americans. However, others estimate a much higher occurrence because RLS is thought to be underdiagnosed and, in some cases, misdiagnosed. 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 genders, although the incidence may be slightly higher in women. Although the syndrome may begin at any age, even as early as infancy, most patients who are severely affected are middle-aged or older. In addition, the severity of the disorder appears to increase with age. Older patients experience symptoms more frequently and for longer periods of time.

More than 80 percent of people with RLS also experience a more common condition known as periodic limb movement disorder (PLMD). PLMD, also referred to as PLMS, is characterized by involuntary leg twitching or jerking movements during sleep that typically occur every 10 to 60 seconds, sometimes throughout the night. The symptoms cause repeated awakening and severely disrupted sleep. Unlike RLS, the movements caused by PLMD are involuntary-people have no control over them. Although many patients with RLS also develop PLMD, most people with PLMD do not experience RLS. Like RLS, the cause of PLMD is unknown.


What Causes RLS?


In most cases, the cause of RLS is unknown (referred to as idiopathic). A family history of the condition is seen in approximately 50 percent of such cases, suggesting a genetic form of the disorder. People with familial RLS tend to be younger when symptoms start and have a slower progression of the condition. In other cases, RLS appears to be related to the following factors or conditions, although researchers do not yet know if these factors actually cause RLS.
  • People with low iron levels or anemia may be prone to developing RLS. Once iron levels or anemia is corrected, patients may see a reduction in symptoms.
  • Chronic diseases such as kidney failure, diabetes, Parkinson's disease, and peripheral neuropathy are associated with RLS. Treating the underlying condition often provides relief from RLS symptoms.
  • Some pregnant women experience RLS, especially in their last trimester. For most of these women, symptoms usually disappear within 4 weeks after delivery.
  • Certain medications-such as antinausea drugs (prochlorperazine or metoclopramide), antiseizure drugs (phenytoin or droperidol), antipsychotic drugs (haloperidol or phenothiazine derivatives), and some cold and allergy medications-may aggravate symptoms. Patients can talk with their physicians about the possibility of changing medications.
Researchers also have found that caffeine, alcohol, and tobacco may aggravate or trigger symptoms in patients who are predisposed to develop RLS. Some studies have shown that a reduction or complete elimination of such substances may relieve symptoms, although it remains unclear whether elimination of such substances can prevent RLS symptoms from occurring at all.

Medications for other conditions can often worsen the symptoms of Restless Leg Syndrome. The following are some of the medications implicated in the development of the disorder.

  • Fluoxetine (Prozac)
  • Paroxetine (Paxil)
  • Sertraline (Zoloft)
  • Mirtazapine (Remeron)
  • Olanzapine
  • Risperdone
  • Beta-blockers
  • Phenytoin (Dilantin)
  • Lithium

In some cases, it may be possible to change medications and lessen the sympotms of RLS. If you feel you are suffering from RLS and are taking one or more of these drugs, you are encouraged to speak with your prescriber about the possibility of RLS complications and potential substitute meds.


The Diagnosis Of RLS


This disorder is diagnosed clinically by evaluating the patient's history and symptoms. Despite a clear description of clinical features, the condition is often misdiagnosed or underdiagnosed. In 1995, the International Restless Legs Syndrome Study Group identified four basic criteria for diagnosing RLS: (1) a desire to move the limbs, often associated with paresthesias or dysesthesias, (2) symptoms that are worse or present only during rest and are partially or temporarily relieved by activity, (3) motor restlessness, and (4) nocturnal worsening of symptoms. Although about 80 percent of those with RLS also experience PLMD, it is not necessary for a diagnosis of RLS. In more severe cases, patients may experience dyskinesia (uncontrolled, often continuous movements) while awake, and some experience symptoms in one or both of their arms as well as their legs. Most people with RLS have sleep disturbances, largely because of the limb discomfort and jerking. The result is excessive daytime sleepiness and fatigue. Despite these efforts to establish standard criteria, the clinical diagnosis of RLS is difficult to make. Physicians must rely largely on patients' descriptions of symptoms and information from their medical history, including past medical problems, family history, and current medications. Patients 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. If a patient's history is suggestive of RLS, laboratory tests may be performed to rule out other conditions and support the diagnosis of RLS. Blood tests to exclude anemia, decreased iron stores, diabetes, and renal dysfunction should be performed. Electromyography and nerve conduction studies may also be recommended to measure electrical activity in muscles and nerves, and Doppler sonography may be used to evaluate muscle activity in the legs. Such tests can document any accompanying damage or disease in nerves and nerve roots (such as peripheral neuropathy and radiculopathy) or other leg-related movement disorders. Negative results from tests may indicate that the diagnosis is RLS. In some cases, sleep studies such as polysomnography (a test that records the patient's brain waves, heartbeat, and breathing during an entire night) are undertaken to identify the presence of PLMD. The diagnosis is especially difficult with children because the physician relies heavily on the patient's explanations of symptoms, which, given the nature of the symptoms of RLS, can be difficult for a child to describe. The syndrome can sometimes be misdiagnosed as "growing pains" or attention deficit disorder.

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