Restless Legs Syndrome Defies Description, Resists Cure

For those who've never experienced the condition, restless legs syndrome can sound downright bizarre. The sensations are variously described as aching, burning, creeping, throbbing, tingling or "like insects crawling inside my legs." For those of us who experience these symptoms on a regular basis, it's hard to convey the frustration (and fatigue) caused by the need to move one's legs almost constantly.

Restless legs syndrome (RLS) is a neurological disorder characterized by these unpleasant sensations and a nearly uncontrollable urge to move the legs in an effort to relieve them. Also referred to as 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 - and certainly one of the most exasperating - 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 jobs, personal relations, and everyday activities are strongly affected as a result of their exhaustion. They are unable to concentrate, have impaired memory and sometimes can't even accomplish the most basic 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 under-diagnosed 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. And 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. The syndrome can begin at any age, even as early as infancy, but 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% of people with RLS also experience a more common condition known as periodic limb movement disorder (PLMD), 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.

Symptoms
As described above, people with RLS feel uncomfortable sensations in their legs, especially when sitting or lying down, accompanied by an irresistible urge to move. These sensations usually occur deep inside the leg, between the knee and ankle; more rarely, they occur in the feet, thighs, arms, and hands. 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.

Most people find the symptoms to be less noticeable during the day and more pronounced in the evening or at night, especially during the onset of sleep. For many people, the symptoms disappear by 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.

The symptoms of RLS vary in severity and duration from person to person. Mild RLS occurs episodically, with only mild disruption of sleep onset, and causes little distress. 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.

Symptoms may begin at any stage of life, although the disorder is more common with increasing age. Some people experience spontaneous improvement over a period of weeks, months, or years. If these improvements occur, it is 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 condition tend to develop more severe symptoms rapidly. In contrast, those whose RLS is not related to any other medical condition and whose onset is at an early age show a very slow progression of the disorder and many years may pass before symptoms occur regularly.

Causes Unknown
In most cases, the cause of RLS is unknown (referred to as "idiopathic"). A family history of the condition is seen in about 50% 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 the iron deficiency or anemia is corrected, patients might 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 - can 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.

Diagnosis
There is no single diagnostic test for RLS. The 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 under-diagnosed. 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% 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 or other leg-related movement disorders. Negative results from tests may indicate a diagnosis of 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.

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.

Treatment
Since movement brings only temporary (if any) relief to those with RLS, treatment is directed toward relieving symptoms (after underlying disorders have been ruled out). For some people with mild to moderate symptoms, certain lifestyle changes and activities might reduce or eliminate symptoms. Decreased use of caffeine, alcohol, and tobacco might provide some relief. Physicians may suggest taking supplements to correct deficiencies in iron, folate and magnesium. Studies also have shown that maintaining a regular sleep pattern can reduce symptoms.

Some individuals, finding that RLS symptoms are minimized in the early morning, change their sleep patterns. Others have found that regular moderate exercise helps them sleep better; on the other hand, excessive exercise has been reported by some patients to aggravate RLS symptoms. Taking a hot bath, massaging the legs, or using a heating pad or ice pack can help relieve symptoms in some patients. Although many patients find some relief with such measures, rarely do these efforts completely eliminate symptoms.

Physicians also may suggest a variety of medications to treat RLS. Generally, physicians choose from among the following:

• Dopaminergic agents, largely used to treat Parkinson's disease, have been shown to reduce RLS symptoms and PLMD and are considered the initial treatment of choice. Good short-term results of treatment with levodopa plus carbidopa have been reported, although most patients eventually will develop augmentation, meaning that symptoms are reduced at night but begin to develop earlier in the day than usual. Dopamine agonists such as pergolide mesylate, pramipexole, and ropinirole hydrochloride may be effective in some patients and are less likely to cause augmentation.
• Benzodiazepines (central nervous system depressants such as clonazepam and diazepam) may be prescribed for patients who have mild or intermittent symptoms. These drugs help patients obtain a more restful sleep but they do not fully alleviate RLS symptoms and can cause daytime sleepiness. Because these depressants also may induce or aggravate sleep apnea in some cases, they should not be used in people with this condition.
• Opioids such as codeine, propoxyphene, or oxycodone may be prescribed for more severe symptoms, because of their ability to induce relaxation and diminish pain. Side effects include dizziness, nausea, vomiting, and the risk of addiction.
• Anticonvulsants such as carbamazepine and gabapentin are also useful for some patients, as they decrease the sensory disturbances (creeping and crawling sensations). Dizziness, fatigue, and sleepiness are among the possible side effects.

Unfortunately, no one drug is effective for everyone with RLS. What may be helpful to one person could actually worsen symptoms for another. In addition, medications taken regularly may lose their effect, making it necessary to change medications periodically.

Prognosis
RLS is generally a lifelong condition for which there is no cure. Symptoms may gradually worsen with age, though more slowly for those with the idiopathic form of RLS than for patients who also suffer from an associated medical condition. Nevertheless, current therapies can control the disorder, minimizing symptoms and increasing periods of restful sleep. In addition, some patients 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.

Research
The National Institute of Neurological Disorders and Stroke (NINDS), one of the National Institutes of Health, has primary responsibility for conducting and supporting research on RLS. The goal of this research is to increase scientific understanding of RLS, find improved methods of diagnosing and treating the syndrome, and discover ways to prevent it.

Currently, NINDS-supported researchers are investigating the possible role of dopamine function in RLS. Dopamine is a chemical messenger responsible for transmitting signals between one area of the brain, the substantia nigra, and the next relay station of the brain, the corpus striatum, to produce smooth, purposeful muscle activity. Researchers suspect that impaired transmission of dopamine signals may play a role in RLS. Additional research should provide new information about how RLS occurs and may help investigators identify more successful treatment options.

This article is based primarily on information from the National Heart, Lung, and Blood Institute

For more information on restless legs syndrome and other sleep disorders, visit the websites of the Restless Legs Syndrome Foundation, Worldwide Education & Awareness for Movement Disorders, and the National Sleep Foundation.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.