RLS is a sensory-motor disorder affecting five to ten percent of the population that can produce difficulty falling asleep or returning to sleep after an awakening. The symptoms are a "crawly," "achy," or painful sensation, usually in the lower legs (or less commonly in the arms), and a need to move (restlessness) that may temporarily relieve the sensory symptoms. At times, involuntary twitches or "jumps" of the limb may occur. Once this disorder begins, it often continues to progress with advancing age.
Heredity accounts for about thirty percent of cases. The remaining seventy percent of cases have no identifiable cause, although neuropathy, renal failure, alcohol or caffeine use, iron deficiency, or certain medications may contribute to the problem.
If the underlying causes of RLS cannot be determined, first-line treatment is with low doses of dopaminergic agents (e.g., L-Dopa). Other options include benzodiazepines, opiates, and anticonvulsants.
Like RLS, Periodic Limb Movement Disorder (PLMD), also known as nocturnal myoclonus, is a movement disorder that disturbs sleep. Unlike RLS, PLMD involves involuntary movements that occur when the person is sleeping. Patients with RLS usually have PLMD, but most people with PLMD do not have RLS. Restlessness and nonrestorative sleep may be the only recognized symptoms in a patient with PLMD.The treatment of PLMD is similar to that of RLS.