Abnormal sensations or abnormal movements of the legs can prevent restful sleep and cause excessive daytime sleepiness. Some patients experience a deep, creeping or crawling sensation in the legs whenever they are quiet or motionless. They are overcome with an irresistible urge to move the legs to combat the sensation. This has been referred to as restless leg syndrome (RLS). Other patients experience periodic movement of leg muscles during sleep. The intensity of the movements can sometimes cause people to awaken. This problem is referred to as periodic leg movement syndrome (PLMS). Most patients with RLS have associated PLMS while only a small fraction of all cases of PLMS had associated RLS.
Victims: Men and women are equally affected. It can develop at any age, but is more common in middle age and worsens with aging. Some studies estimate that as many as 35% of people >65 years of age may be affected. Symptoms can worsen during pregnancy or during periods of hormonal changes.
Cause: The cause of RLS and PLMS is unknown, however many cases run in families suggesting a genetic link. Some cases have been associated with deficiencies of iron, ferritin, folate and vitamin B 12. Other cases have been associated with diabetes mellitus, kidney disease, vascular disease, lung disease and excessive caffeine consumption.
Diagnosis: Measurements of anterior tibialis muscle electrical activity (EMG) during sleep (part of the standard polysomnogram) confirms the presence of periodic leg movements. A typical EMG burst last between 0.5 -5 seconds and recurs every 20 - 40 seconds. At least 40 bursts/8 hours of sleep is required to establish the diagnosis. The brain electrical activity component of this test confirms whether or not the leg movements disrupt sleep.
Treatment: Because no clear health consequences have been linked to PLMS, treatment is only justified if there is associated insomnia or disabling RLS. The major medications with documented effectiveness include benzodiapines, opiates and dopaminergic agents. Because benzodiapines and opiates have addicting potential, dopaminergic agents (sinemet, L-Dopa) are preferred.