Introduction:

Restless legs syndrome (RLS) is an unsettling and poorly understood movement disorder affecting 3 - 15% of the general population. RLS can affect both children and adults. Although effective treatments are available, the condition often remains undiagnosed.

Symptoms of RLS. The core symptom of RLS is an irresistible urge to move the legs (medically known as akathisia). Some people describe this symptom as a sense of unease and weariness in the lower leg, which is aggravated by rest and relieved by movement. Specific characteristics of RLS include:

• "Pulling, searing, drawing, tingling, bubbling, or crawling" beneath the skin, usually in the calf area, causing an irresistible urge to move the legs. These sensations can occur mostly in the lower legs, but they can sometimes affect the thighs, feet, and even the upper body. RLS-type symptoms may also occur in the arms. This may be the first symptom of RLS in some people.
• About 80% of patients with RLS also experience semi-rhythmic movements during sleep called periodic limb movement disorder (PLMD).
• Itching and pain, particularly aching pain, may be present.
• Patients experience symptoms when they feel most relaxed and their legs are at rest. (Movement, however, brings relief.) Symptoms usually occur at night when lying down, or sometimes during the day while sitting.
• Episodes of RLS usually develop between 10 p.m. and 4 a.m. Symptoms are often most severe shortly after midnight. They usually resolve by morning. If the condition becomes more severe, people may begin to have symptoms during the day. These symptoms are always worse at night, however.
• At night, the unpleasant sensations and the resulting uncontrollable urge to move the legs can often disturb sleep. Ignoring the need to move the legs usually only builds up tension until they jerk uncontrollably. If patients experience symptoms during the day, they usually feel compelled to move their legs in order to relieve the symptoms, making it difficult to sit during air or car travel or through classes or meetings.

Late-onset and Early-onset Forms. There appear to be two forms of RLS, early-onset and late-onset. Each form may have different characteristics:

• People with early-onset RLS (occurring in the teenage years or earlier) tend to have a family history of the disorder. They also usually have RLS without accompanying pain.
• Those with late-onset RLS usually do not have a family history of RLS. Their condition is more likely the result of a problem with the nervous system, and symptoms may include pain in the lower legs.

Periodic Limb Movement Disorder

The medical term for periodic limb movement disorder (PLMD) is nocturnal myoclonus. PLMD symptoms include:

• Episodes that usually occur during the night, peaking near midnight, as they do in restless legs syndrome (RLS).
• Leg muscles contract and jerk every 20 - 40 seconds during sleep. Such movements may last less than 1 second, or as long as 10 seconds.
• Unlike RLS, contractions in PLMD usually do not wake patients. PLMD is distinct from the brief and sudden movements that occur just as people are falling asleep, jolting them awake.

Although 80% of RLS sufferers have PLMD, only about 30% of people with PLMD also have RLS. While treatments for the two conditions are similar, PLMD is a separate syndrome. PLMD is also very common in narcolepsy, a sleep disorder that causes people to fall asleep suddenly and uncontrollably.

Nocturnal Leg Cramps

Cramps that awaken people during sleep are very common, and they are not part of restless legs syndrome or periodic limb movement disorder. They can be very painful and may cause a person jump out of bed in the middle of the night. They typically affect a specific area of the calf or the sole of the foot.

What Are Nocturnal Leg Cramps?

Benign nocturnal leg cramps, sometimes known as a charley horse, are muscle spasms in the calf that can occur one or many times during the night. Cramping may also occur in the soles of the feet. They typically last from a few seconds to a few minutes. Some people experience them regularly, others only on isolated occurrences.

Causes of Nocturnal Leg Cramps. In most cases, the cause of nocturnal leg cramps remains unknown. Among the conditions that might cause leg cramps are:

• Calcium and phosphorus imbalances, particularly during pregnancy
• Low potassium or sodium (salt) levels
• Overexertion, standing on concrete for long periods, or prolonged sitting (especially with the legs contorted)
• Having structural disorders in the legs or feet (such as flat feet)
• Medical causes of muscle cramping include hypothyroidism, Addison's disease, uremia, hypoglycemia, anemia, and certain medications. Various diseases that affect nerves and muscles, such as Parkinson's, cause leg cramps. Peripheral neuropathy, a complication of diabetes, can cause cramp-like pain, numbness, or tingling in the legs. Patients with kidney disease undergoing dialysis are also prone to leg cramps.

Individuals at Higher Risk for Nocturnal Leg Cramps. Nocturnal leg cramps occur at all ages but peak at different times. They are particularly common in adolescence, during pregnancy, and in older age, affecting up to 70% of adults over age 50 at some point.

Pregnant women and those taking diuretics are also at risk for leg cramps because of low calcium levels and an imbalance in calcium and phosphorus.

Consequences of Nocturnal Leg Cramps. Nocturnal leg cramps, like restless legs syndrome, rarely have any serious consequences. However, they can be extremely painful and long lasting. In some cases, severe and persistent symptoms can cause chronic insomnia and considerable mental distress.