Restless legs syndrome

Clinical features

The term “restless legs” has been applied to a number of conditions. originally applied this term to unpleasant crawling sensations in the legs, particularly when sitting and relaxing in the evening, which disappeared on walking. The syndrome was probably first described by Thomas Willis in 1685. In honor of these two physicians, and to indicate that the syndrome is a disease, some now refer to restless legs syndrome as Willis-Ekbom disease (WED) ( ). “Restlessness” is also a characteristic feature of akathisia, but here the feeling is of inner restlessness not specifically referred to the legs, although this inner feeling can be dissipated by activity. “Inner tension” is also a feature of the urge preceding tics, relieved by the involuntary movement..

The restless legs syndrome (RLS) is characterized by a deep, ill-defined discomfort or dysesthesia in the legs that arises during prolonged rest or when the patient is drowsy and trying to fall asleep, especially at night ( ; ; ; ; ; ; ; ). The disorder is truly diurnal; the symptoms are worse during the night, even when the person tries to stay awake for long periods. The discomfort may be difficult to describe—terms such as crawling, creeping, pulling, itching, drawing, or stretching are used, and the feeling usually is felt in the muscles or bones. The most frequent words and phrases used are tabulated in several large series ( ; ) and the most common anatomic sites diagrammed ( Fig. 25.1 ) ( ; ). These intolerable sensations are relieved by movement of the legs or by walking. The feeling usually is bilateral and symmetrical in the legs. The arms are occasionally involved, and a restless arms syndrome variant has been described ( ). Standardized criteria have been put forward by the International Restless Legs Syndrome Study Group ( Table 25.1 ) ( ) that have been integrated with considerations for the diagnosis of pediatric RLS ( ). Symptoms in children are similar to those in adults, but children often choose different words to describe them ( ). In some patients there is overt pain ( ).

Complaints of restless legs are common, with an estimated prevalence of 3% to 10% ( ; ; ). A large population study (over 16,000 adults) showed a prevalence of any restless symptoms to be 7.2% and moderately or severely distressing symptoms to be 2.7% ( ). RLS is generally a condition of middle to old age, but at least one-third of patients experience their first symptoms before the age of 20 years ( ). There may be increased mortality among men with RLS ( ). Most patients have mild symptoms to begin with, but these worsen with time, so that they seek aid in middle life. Remission is uncommon, occurring in about 15% ( ). RLS can even affect a phantom limb ( ; ). The differential diagnosis conditions for RLS are called mimics, and it is necessary to rule them out specifically to make the diagnosis ( ; ). Specifically noted in the criteria are myalgia, venous stasis, leg edema, arthritis, leg cramps, positional discomfort, and habitual foot tapping.

The majority of those with RLS also exhibit periodic leg movements of sleep (PLMS) ( ) ( Table 25.2 ). These consist of brief (1–2 seconds) jerks of one or both legs, consisting of, at its simplest, dorsiflexion of the big toe and foot. Initially there is a jerk, but subsequently there is sustained tonic spasm. Such events tend to occur in runs every 20 seconds or so for minutes or hours, and there should be more than five per hour to be considered significant. Sometimes the whole leg or both legs may flex ( Fig. 25.2 ). The movement resembles a flexion reflex ( ). Such periodic movements can wake the sleeping partner. There also may be arousals in the affected individual, in which case there may be excessive daytime drowsiness. The arousals often appear to be related to the PLMs ( ), but there is some evidence that they are not directly associated with the PLMs, but instead with an electroencephalography phenomenon called the cyclic alternating pattern ( ). Generally, they appear during periods of arousal during sleep in stages I and II, and decrease during deep sleep during stages III and IV; they are unusual during rapid eye movement (REM) sleep. Sometimes such flexion movements of one or both legs can occur in the waking subject, particularly when drowsy ( ) ( Video 25.1 ). Note should be made that some patients with RLS have propriospinal myoclonus just before falling asleep ( ).

Video 25.1 Periodic limb movements.

Although most people with restless legs have PLMS (at least in the sleep laboratory), a proportion do not complain of restless legs. The combined syndrome of restless legs and PLMS is an age-related condition; its incidence increases in adult and late life. It usually manifests after the age of 30, and it is said to affect 5% of those between the ages of 30 and 50 years and as many as 30% of those over the age of 50. However, in a large proportion of cases, the PLMS do not cause complaints and are found incidentally during sleep studies. In many with restless legs, the condition is not disabling. A revised scoring system for PLMs has been developed, increasing the sensitivity of measurement. ( ).

There is an indication that RLS may adversely affect the cardiovascular system through sympathetic activiation, leading to autonomic instability an increased risk of cardiovascular events ( ; ).