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Restless legs syndrome and related disorders

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of RLS.

Alternative Names

Ekbom's syndrome; Nocturnal leg cramps; Periodic limb movement disorder

Diagnosis

A diagnosis of restless legs syndrome or nocturnal leg cramps often relies solely on the patient's description of symptoms. In general, the recommended approach is first to take a sleep and personal history. The doctor may conduct an interview that includes the following questions:

• How would the sleep problem be described?
• How long has the sleep problem been experienced?
• How long does it take to fall asleep?
• How many times a week does it occur?
• How restful is sleep?
• What are the leg problems like (cramps, twitching, crawling feelings)?
• What is the sleep environment like? Noisy? Not dark enough?
• What medications are being taken (including the use of antidepressants and self-medications for insomnia, such as herbs, alcohol, and over-the-counter or prescription drugs)?
• Is the patient taking or withdrawing from stimulants, such as coffee or tobacco?
• How much alcohol is consumed per day?
• What stresses or emotional factors may be present?
• Has the patient experienced any significant life changes?
• Does the patient snore or gasp during sleep (an indication of sleep apnea, a condition in which breathing stops for short periods many times during the night and which may worsen symptoms of restless legs syndrome or insomnia)?
• If there is a bed partner, is his or her behavior distressing or disturbing?
• Is the patient a shift worker?

Keeping a Record of Sleep. To help answer these questions, the patient may need to keep a sleep diary. Every day for 2 weeks, the patient should record all sleep-related information, including responses to questions listed above described on a daily basis. Recording sleep behavior using an extended-play audio or videotape can be very helpful in diagnosing sleep apnea.

A bed partner can help by adding his or her observations of the patient's sleep behavior.

Sleep Disorders Centers

In some cases of an uncertain diagnosis, high-risk patients may need to consult a sleep specialist or go to a sleep disorders center. At most centers, patients undergo an in-depth analysis, usually supervised by a multi-disciplinary team of consultants who can provide both physical and psychiatric evaluations. Centers should be accredited by the American Academy of Sleep Medicine.

Among the signs that may indicate a need for a sleep disorders center are:

• Insomnia due to psychological disorders
• Sleeping problems due to substance abuse
• Snoring and sudden awakening with gasping for breath (possible sleep apnea)
• Severe restless legs syndrome
• Persistent daytime sleepiness
• Sudden episodes of falling asleep during the day (possible narcolepsy)
• At most sleep disorders centers, patients undergo an in-depth analysis, usually supervised by a multidisciplinary team of consultants who can provide both physical and psychiatric evaluations.

Polysomnography

Overnight polysomnography involves several tests to measure different functions during sleep. It is typically performed in a sleep center and may help rule out sleep apnea or confirm the effectiveness of RLS treatments.

The patient arrives about 2 hours before bedtime without having made any changes in daily habits. Polysomnography electronically monitors the patient as he or she passes, or fails to pass, through the various sleep stages. Polysomnography tracks the following:

• Brain waves
• Body movements
• Breathing
• Heart rate
• Eye movements
• Changes in breathing and blood levels of oxygen

Actigraphy

Actigraphy uses a small wristwatch-like device (e.g., Actiwatch) to monitor sleep quality in people with suspected RLS, periodic limb movement disorder (PLMD), insomnia, sleep apnea, and other sleep-related conditions. The device can be applied to the wrists or ankles. It measures muscle movements and records them during sleep. For example, with PLMD, it can provide information on total duration of movements, the number of occurrences, whether PLMD occurs simultaneously in both legs, and the effects on sleep.

It is not as accurate as polygraphy because it cannot measure all the biologic effects of sleep. It is more accurate than a sleep log, however, and very helpful for recording long periods of sleep.

Sleepiness Scale

The Epworth sleepiness scale uses a simple questionnaire to measure excessive sleepiness during eight situations.

THE EPWORTH SLEEPINESS SCALE
SITUATION	CHANCE OF DOZING
Sitting and reading	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Watching TV	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Sitting inactive in a public place	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Riding as a passenger in a car for an hour without a break	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Lying down to rest in the afternoon when circumstances permit	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Sitting and talking to someone	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Sitting quietly after a lunch without alcohol	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Sitting in a car while stopped for a few minutes in traffic	(Indicate a score of 0 to 3) 0 = no chance of dozing 1 = slight chance of dozing 2 = moderate chance of dozing 3 = high chance of dozing
Score Results 1-6: Getting enough sleep. 4-8: Tends to be sleepy but is average. 9 and over: Very sleepy and suggestive of sleep-disordered breathing. Patient should seek medical advice.

Diagnosing Iron Deficiency Anemia and Its Causes

Because of the high association between restless legs syndrome and iron deficiency, a test for low iron stores should be part of the diagnostic work-up in RLS. There are two steps in making this diagnosis:

• The first step is to determine if a person is actually deficient in iron.
• If iron stores are low, the second step is to diagnose the cause of the iron deficiencies, which will help determine treatment.

Determining if Iron Stores are Low: The following findings are important in determining that a person is iron deficient:

• Blood cells viewed under the microscope are pale ( hypochromic ) and abnormally small ( microcytic ). They are also mostly uneven in shape. (These findings suggest iron deficiency, they but can also appear in anemia of chronic disease and thalassemia.)
• Hemoglobin and iron levels are low. (These findings further suggest iron deficiency, but they can also occur in cases due to anemia due to chronic disease.)
• Ferritin levels are low. Ferritin is a protein that binds to iron and low levels typically mean reduced iron stores. (However, high levels in the blood do not always mean sufficient iron stores. For example, pregnant women may have high ferritin levels into their third trimester but still be iron deficient. Ferritin levels may also be normal or even elevated in patients with inflammation from anemia of chronic disease, even if they also have low iron stores.)
• A test that measures a factor called serum transferrin receptor (TfR) is proving to be very sensitive in identifying iron deficiency in problematic patients, including the elderly with chronic diseases and possibly pregnant women.

Determining Causes of Iron Deficiency. When iron deficiency anemia is diagnosed, the next step is to determine what causes the iron deficiency itself.

• Dietary iron deficiency is most common in children and infants. It is rare in adults.
• Heavy menstrual or abnormal uterine bleeding is usually the cause of iron deficiencies in young women. Increased need for iron during pregnancy is also a common cause in this population.
• If internal bleeding is suspected as the cause, the gastrointestinal tract is usually the first suspect as the source. A diagnosis in such cases can be often be made if the patient has noticed blood in the stools, which can be black and tarry or red-streaked. Often, however, bleeding may be present but not visible. In such cases, stool tests for this hidden ( occult ) blood are required. Additional tests may then be needed to diagnose the precipitating condition. Endoscopy, in which a fiber optic tube is used to view into the gastrointestinal tract, may be used, particularly when the source of bleeding is unclear.

If the patient's diet suggests low iron intake and other causes cannot be established, then a monthly trial of iron supplements may be given. If the patient fails to respond, further evaluation is needed.

Other Laboratory Tests

Certainly laboratory tests may be helpful in determining causes of RLS or conditions that rule it out. They include:

• Blood glucose tests for diabetes
• Tests for kidney problems
• Possibly tests for thyroid hormone and magnesium and folate levels

Ruling Out Other Leg Disorders

In addition to other sleep-related leg disorders, a number of other medical conditions may have features that resemble restless leg syndrome. The doctor will need to consider these disorders in making a diagnosis.

Peripheral Neuropathies. Peripheral neuropathies are nerve disorders in the legs or feet. They can be caused by several conditions and can produce pain, burning, tingling, or shooting sensations in the extremities. Diabetes is a very common cause of painful peripheral neuropathies. Other causes include alcoholism, rheumatoid arthritis, systemic lupus erythematosus, amyloidosis, HIV infection, kidney failure, and certain vitamin deficiencies. Symptoms of peripheral neuropathies may mimic RLS. However, unlike RLS they are not usually associated with restlessness, nor are they relieved by movement, and they do not worsen at bedtime.

Deep Vein Thrombosis. Deep vein thrombosis is caused by a blood clot deep in the leg, usually in the thigh or calf. It may cause pain, swelling and aching in the leg where the clot has developed. It can occur in people with heart disease, with varicose veins, during pregnancy, in women from hormonal treatments, from injury to the leg, or from inactivity (such as after surgery or during long flights). Left untreated, this can be a very serious and even life-threatening condition.

Intermittent Claudication and Peripheral Artery Disease. Peripheral artery disease (PAD) occurs when atherosclerosis (commonly called hardening of the arteries) affects the feet and legs. In such cases, the arteries become blocked, obstructing oxygen-rich blood flow. Intermittent claudication is an important symptom of PAD and occurs in between a third and half of these patients. Claudication is taken from the Latin word "to limp". The name is used to describe the pain that occurs in PAD patients when they exercise, particularly during walking. In intermittent claudication, blood flow is sufficient to meet the needs of the person at rest. The result is leg pain during exercise, which is relieved by rest.

Akathisia. Akathisia is a state of restlessness or agitation and feelings of muscle quivering. A condition called hypotensive akathisia is caused by failure in the autonomic nervous system. Unlike RLS, it occurs at any time of the day and usually only when the patient is sitting -- not lying down. Akathisia itself can also be caused by drugs used to treat schizophrenia and other psychoses, with anti-nausea drugs, or when drugs to treat Parkinson's disease are withdrawn.

Painful Legs and Moving Toes Syndrome. A rare disorder affecting one or both legs, painful legs and moving toes syndrome is marked by a constant deep, throbbing ache in the limbs and involuntary toe movements. The discomfort may be mild or severe. It intensifies with activity and usually ceases during sleep. In most cases the cause is unknown, though it may arise from spinal injuries or herpes zoster infection. The condition is difficult to treat, although the drug baclofen, combined with either clonazepam or carbamazepine, has shown some success. Other therapies that may help include orthotics for the shoes and transcutaneous electrical nerve stimulation (TENS).

Meralgia Paresthetica. An uncommon nerve condition, meralgia paresthetic is characterized by numbness, pain, tingling, or burning on the front and side of the thigh. It usually occurs on one side and is thought to be due to compression of the thigh nerve as it passes through the pelvis. It occurs most commonly in people ages 30 - 60 years, but it can affect people of all ages. It often goes away on its own.

• Review Date: 10/18/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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