Periodic Limb Movements and Restless Legs

Millions of Americans have serious sleep problems and their lives could be vastly improved by getting a reliable night’s sleep. It is estimated that one-third or 80 million people either sleep too little, too much or fitfully. The failure to get a good night’s sleep has become a problem of epidemic proportions. Two disorders that are somewhat similar in nature — and either cause fitful sleep or the inability to get to sleep — are periodic leg movement disorder (PLMD) and restless leg syndrome (RLS).

What is periodic leg movement disorder (PLMD)?

This disorder usually occurs while a person sleeps. The unaware sleeper has a repetitive series of leg jerks in combination with the extension of the big toe and partial bending of the ankle, knee and sometimes hip. PLMD can result in fragmented, restless sleep and complaints of insomnia or excessive daytime sleepiness. In addition, for serious sufferers the disorder can produce anxiety and depression.

What causes PLMD?

PLMD can be associated with, or evoked by, a variety of medical conditions, such as chronic uremia (kidney disease) and other metabolic disorders. Taking antidepressants can induce or aggravate this disorder as can the withdrawals from a variety of drugs. This disorder is rare in children and progresses with advancing age to become a common finding in up to 34% of patients over the age of 60 years. PLMD can accompany sleep apnea (refer to Part 2 in this series) and narcolepsy (look for Part 4 in this series) — and has been reported in up to 15% of people suffering with insomnia.

How is restless leg syndrome (RLS) different from PLMD?

Many who suffer from RLS has described the feeling in their legs usually between the ankle and the knee as an “aching,” “discomforting,” “creeping,” “crawling,” “pulling,” “prickling,” “tingling,” or “itching” sensation. These sensations and associated leg movements begin just before falling asleep and can usually be relieved by getting up and walking around, but returns again once in bed and just before falling asleep. RLS can delay sleep onset for hours, whereas PLMD may occur during sleep with the sleeper unaware of their partial awakenings throughout the night.

What causes RLS?

More common in females, RLS can be associated with pregnancy, anemia (blood disorder), uremia (kidney disease) and rheumatoid arthritis. Most, if not all, patients with RLS show periodic leg movements during sleep. Unlike those with PLMD only, people who suffer with both conditions may show involuntary limb movements even while awake. This condition can produce severe insomnia, psychological disturbance and depression.

How are PLMD and RLS diagnosed?

Any person who suspects they may have PLMD or RLS should ask their family doctor for a referral to a doctor who specializes in sleep disorders. If referred to a sleep specialist, the doctor will obtain a medical history and ask sleep-related questions, may perform a physical examination, and may ask to interview the patient’s bed partner. If the sleep specialist feels an overnight sleep study is indicated, the patient may be referred to a sleep lab at the nearest hospital. In the sleep lab, the patient’s leg movements, brain waves, muscle activity, arm movements, heart rhythms, and other body functions will be monitored during sleep. With this information, the doctor can properly diagnose the patient’s condition and begin the patient on an appropriate treatment plan.

How are these disorders treated?

A variety of medications and sedative drugs are available for the treatment of movement disorders. Also, treatment of associated conditions can prove to be effective. When this condition develops with pregnant women, the symptoms usually disappear after delivery. Studies also have shown that the condition may result from a shortage of Vitamin E, iron or calcium. As a result, vitamin and mineral supplements are often prescribed. Sometime leg exercises will produce a satisfactory outcome.