Restless Legs Syndrome (RLS) is a disorder that causes individuals to experience uncomfortable sensations in their legs. This experience is difficult to describe, and RLS patients have referred to the sensation as tingling, itching, creeping, crawling, aching, and burning along with many other descriptions. Usually, the sensation causes individuals to have a strong urge to move their legs. A key to recognizing RLS is that the sensation is made worse by rest and partially improved by walking and movement.
RLS makes it very hard for some people to rest or go to sleep and is a recognized cause of insomnia. With decreased sleep, daytime function is impaired, and individuals feel very tired during the day.
A related problem is periodic limb movements that happen while awake or asleep and are described as repetitive twitching or jerking of the limbs. During sleep, Periodic Limb Movements of Sleep or PLMS, can wake one up and make it harder to go back to sleep. This fragmentation of sleep makes it even worse to function the next day. The combination of disruptive PLMS and daytime symptoms is recognized as Periodic Limb Movement Disorder (PLMD).
About 80-90% of patients with RLS also have PLMS. Although RLS may be intermittent, the symptoms tend to become more intense and last longer over time. It normally starts in the legs but may progress to involve the rest of the body. The intensity of the symptoms may vary from day to day. It is worse after prolonged inactivity such as long plane or car rides, or sitting in a theater or meeting. RLS is more prevalant in women than in men. It can occur at any age, from early childhood to late adult life. In children, RLS can be wrongly called "growing pains." Some think that RLS in children may be related to Attention Deficit Hyperactivity Disorder or ADHD.
Secondary RLS is caused by other disorders or medical conditions including:
Iron deficiency and all conditions that produce low iron;
Spinal and other nervous system disorders;
Kidney disease and dialysis;
Peripheral neuropathy; and
Some medications such as antidepressants, antinausea medication, and some antihistamines can cause RLS as well.
Primary RLS is not directly caused by another sleep disorder or medical condition.
RLS may show up slowly and get worse over time.
Familial patterns may be present in 50% of people with RLS.
A positive family history increases the risk for RLS
The diagnosis of RLS is a clinical diagnosis and is based on the history given by the individual or the bed partner. Since it frequently coexists with PLMS, and especially in cases where daytime sleepiness is present, additional testing, and overnight studies may be indicated. Other tests to determine the presence of causative conditions may also be needed.