Additional Findings Associated with Restless Legs Syndrome

Other features associated with restless legs syndrome may include periodic limb movements in sleep (PLMS) characterized by repeated stereotypic movements of the legs. These movements typically consist of upward extension of the great toe and foot as well as flexion of the ankle, knee, or hip. They occur every 15 to 40 seconds and last for one half of a second up to 6 seconds, usually during periods of lighter sleep (non-REM or NREM sleep). Patients who experience at least five periodic limb movements per hour are said to have PLMS. The number of periodic limb movements seems to increase along with the severity of RLS symptoms. Most people with RLS also have PLMS; however, a specialized sleep study is usually required to confirm PLMS. Large movements associated with PLMS contribute, in some measure, to repeated arousals and awakenings.

Almost all patients with RLS also experience sleep disturbances including difficulty falling asleep as well as problems remaining asleep. Difficulty with sleep onset (sleep latency) may be due to the activation of symptoms upon relaxation. PLMS may also be an important contributing factor to sleep disturbances during the night (sleep maintenance). Fifty percent of patients report that discomfort in the leg(s) prevents them from getting a good night's sleep. Those with severe symptoms may sleep for only a few hours each night and, as a result, experience excessive daytime sleepiness (EDS). Increasing difficulty falling asleep and maintaining sleep is usually associated with a worsening of RLS symptoms.

While awake and at rest, patients may also experience uncontrolled, sporadic movements of the legs (and, in some cases, the arms). These movements, which may occur during the day or night, may be very rapid (myoclonic) or quite slow and prolonged (dystonic); they usually disappear upon voluntary action. Some researchers think that these movements, which are known as dyskinesias while awake (DWA), may represent a wakeful form of PLMS. About 50% of individuals who seek medical attention for RLS experience DWA.

The symptoms of RLS progress with increasing age; however, medical attention is usually not sought until middle age or later. In addition, a family history of RLS is often noted by patients with primary or idiopathic RLS; about 50% to 60% (or higher in some studies) report close relatives with the disease.

	What Causes Restless Legs Syndrome?