Diagnosis:

A diagnosis of restless legs syndrome 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 you describe your sleep problem?
• How long have you had this sleep problem?
• How long does it take you to fall asleep?
• How many times a week does the problem occur?
• How restful is your sleep?
• What are the leg problems like (cramps, twitching, crawling feelings)?
• What is your sleep environment like? Noisy? Not dark enough?
• What medications are you taking (including the use of antidepressants and self-medications -- such as herbs, alcohol, and over-the-counter or prescription drugs)?
• Are you taking or withdrawing from stimulants, such as coffee or tobacco?
• How much alcohol do you drink per day?
• What stresses or emotional factors may be present in your life?
• Have you experienced any significant life changes?
• Do you snore or gasp during sleep? (This may be an indication of sleep apnea. Sleep apnea is a condition in which breathing stops for short periods many times during the night. It may worsen symptoms of restless legs syndrome or insomnia.)
• If you have a bed partner, does he or she notice that you have jerking legs, interrupted breathing, or thrashing while you sleep?
• Are you 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 their observations of the patient's sleep behavior.

Sleep Disorders Centers

Some high-risk patients may need to consult a sleep specialist or go to a sleep disorders center before their sleep problem can be diagnosed. At most centers, patients undergo an in-depth analysis, usually supervised by a team of consultants from various specialties, 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)

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 restless legs syndrome (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 (such as Actiwatch) to monitor sleep quality in people with suspected restless legs syndrome (RLS), periodic leg movement disorder (PLMD), insomnia, sleep apnea, and other sleep-related conditions. Patients can wear the device on their wrists or ankles. It measures and records muscle movements during sleep. For example, with PLMD, actigraphy can provide information on the total duration of movements, the number of occurrences, whether PLMD occurs simultaneously in both legs, and its effects on sleep.

Actigraphy is not as accurate as polysomnography because it cannot measure all the biological 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.

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 workup in restless legs syndrome (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, but they can also appear in anemia resulting from chronic disease, and in thalassemia.
• Hemoglobin and iron levels are low. These findings further suggest iron deficiency, but they can also occur in cases of anemia due to chronic disease.
• Ferritin levels are low. Ferritin is a protein that binds to iron, and low levels typically mean the patient does not have enough iron in their body. However, high levels of ferritin in the blood do not always mean a patient has enough iron. For example, pregnant women in their third trimester or patients with a chronic disease may not have enough iron even with normal or high ferritin levels.
• A test that measures a factor called serum transferrin receptor (TfR) is proving to be very sensitive in identifying iron deficiency in some patients, including the elderly with chronic diseases and possibly pregnant women.

When iron deficiency anemia is diagnosed, the next step is to determine what causes the iron deficiency itself. [See In-Depth Report #57: Anemia.]

Other Laboratory Tests

Certain laboratory tests may be helpful in determining causes of restless legs syndrome (RLS) or conditions that rule it out. They include:

• Blood glucose tests for diabetes
• Tests for kidney problems
• In certain cases, tests for thyroid hormone, 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 legs syndrome (RLS). The doctor will need to consider these disorders in making a diagnosis.

Peripheral Neuropathies. Peripheral neuropathies are nerve disorders in the hands or feet. Several conditions can cause these disorders, and they can produce pain, burning, tingling, or shooting sensations in the arms and legs. 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, movement does not relieve the discomfort, and they do not worsen at bedtime.

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. Drugs used to treat schizophrenia and other psychoses can cause akathisia, as can anti-nausea drugs. The condition also occurs 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 gets worse with activity and usually stops during sleep. Usually, 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 treatments that may help include orthotics for the shoes and transcutaneous electrical nerve stimulation (TENS).

Meralgia Paresthetica. An uncommon nerve condition, meralgia paresthetica causes numbness, pain, tingling, or burning on the front and side of the thigh. It usually occurs on one side of the body, and the cause may be compression of the thigh nerve as it passes through the pelvis. It typically occurs in people aged 30 - 60 years, but it can affect people of all ages. It often goes away on its own.