Restless Legs Syndrome and Other Sleep-Related Leg Disorders

Description

Alternative Names

Risk Factors

Restless legs syndrome is estimated to affect between 2.5% and 15% of the general population. It is more common in women than in men, and its prevalence increases with age. An estimated 10% to 28% of those older than 65 are affected by the disorder.In about 40% of patients, RLS begins in adolescence, though it is uncommon in young children.

Family History

Up to two thirds of people with RLS have a family history of the disorder. In such cases, it is more likely to occur before age 40. (A family history of RLS is less likely in people who develop it as older adults.) It is also more common in populations from northern and western Europe, giving added support for a genetic basis for some cases of the disorder.

Attention Deficit Activity Disorder (ADHD)

RLS and periodic limb movement disorder in children are strongly associated with inattention and hyperactivity. One study suggested that a quarter of children diagnosed with attention-deficit hyperactivity disorder (ADHD) also has RLS or PLMD, and this may actually contribute to inattentiveness and hyperactivity. The disorders have much in common, including poor sleep habits, twitching, and the need to get up suddenly and walk about frequently. A 2001 study also reported an associated between adult attention deficit disorder and RLS. More research is needed to determine if RLS is a cause of some cases of ADHD or if it simply aggravates it. Some evidence suggests that the link between the diseases may be a deficiency in the brain chemical dopamine, which has been observed in both conditions.

Pregnancy

About 20% of pregnant women report RLS, which in most cases goes away after delivery. RLS in this population has been strongly associated with deficiencies in iron and with B vitamin folate (which in turn reduce iron levels). Symptoms typically disappear within a month after delivery.

Dialysis

Between 20% and 62% of people undergoing dialysis report restless legs syndrome. Symptoms often dissipate after a kidney transplant.

Anxiety Disorders

Anxiety can cause restlessness and agitation at night that can cause or strongly resemble restless legs syndrome.

Other Conditions Associated with RLS

The following medical conditions are also associated with RLS, although the relationships are not clear. In some cases, these conditions may contribute to RLS or they may have a common cause. In some cases, they may simply often coexist because of other risk factors:

• Osteoarthritis. About 72% of RLS patients have osteoarthritis.
• Varicose veins occur in 14% of RLS sufferers. Sclerotherapy treatments, in which medications are injected into affected veins, may relieve symptoms in such cases.
• Obesity.
• Diabetes.
• Hypertension.
• Hypothyroidism.
• Fibromyalgia.
• Rheumatoid arthritis.
• Emphysema.
• Chronic alcoholism.
• Sleep apnea and snoring.
• Chronic headaches.
• Brain or spinal injuries.
• Many muscle and nerve disorders. Hereditary ataxia, a group of genetic diseases that affect the central nervous system and cause loss of motor control, is of particular interest. Some experts believe that hereditary ataxia may supply clues for genetic causes of RLS.

is a chronic disease of the joint cartilage and bone, often thought to result from "wear and tear" on a joint, although there are other causes such as congenital defects, trauma and metabolic disorders. Joints appear larger, are stiff and painful and usually feel worse the more they are used throughout the day.

Click the icon to see an image of hypothyroidism.

Click the icon to see an image of fibromyalgia.

Click the icon to see an image of rheumatoid arthritis.

Click the icon to see an image of emphysema.

Environmental and Dietary Factors

A number environmental and dietary factors can worsen or provoke RLS:

• Iron deficiencies. People who are deficient in iron are at risk for restless legs syndrome even if they don't have anemia.
• Folic acid or magnesium deficiencies.
• Smoking.
• Alcohol abuse.
• Caffeine. (Coffee drinking is specifically associated with PLMD.)
• Stress.
• Fatigue.
• Prolonged exposure to cold.

Medications

Drugs that worsen or provoke the condition include:

• Antidepressants.
• Antipsychotic drugs.
• Anti-nausea drugs
• Beta blockers.
• Antihistamines.
• Oral decongestants.
• Diuretics.
• Asthma drugs.
• Spinal anesthesia. Anesthesia-induced RLS typically resolves on its own within several months.

Risk Factors for Periodic Limb Movement Disorder (PLMD)

About 6% of the population has periodic limb movement disorder; they are usually elderly. As with RLS, a number of conditions may occur with PLMD. They include sleep apnea, spinal cord injuries, stroke, narcolepsy, and degenerative neurologic diseases. Certain medications, including some antidepressants and anti-seizure medications, may also contribute to PLMD.