Restless Legs Syndrome

In 1685 Thomas Willis, a 17th century English physician, published the first description
of what we now term RLS. He characterized patients with this disorder as, "…
when being a bed they betake themselves to sleep, presently in the Arms and Legs
Leapings and Contractions of the Tendons, and so great a Restlessness and Tossing of
their Members ensure, that the diseased are no more able to sleep, than if they were in a
Place of greatest Torture." In 1945 Karl Axel Ekbom, coined the term "restless legs
syndrome" and suggested a biological instead of a psychological origin to the
disorder.

Patients with RLS experience disturbing, painful sensations in the legs (and sometimes
the arms) catalogued as "…creepy-crawly, ants crawling, jittery, pulling, worms moving,
soda bubbles in veins, electric shock, pain, the gotta moves, burning, jimmy legs, hebbie
jeebies, tearing, throbbing, tight feeling, grabbing, Elvis legs, itching bones, crazy legs,
and fidgets." With pain symptoms as unusual as these, it is no wonder that early
investigators lumped patients with RLS in with patients with psychiatric conversion
(hysterical) disorders. However, clinical responses to various categories of drugs and to
iron therapy and the presence of at least two genetically identifiable phenotypes all argue
in favor of a biological origin to RLS.

RLS is a common disorder: prevalence of symptoms 5 or more nights per month were
reported in 3% of individuals 18-29 years, 10% in 30-79 years, and 19% in those 80 or
older. Age adjusted prevalence rate in this study was 10%. In a similar study,
prevalence was 11.5% with half of those reporting RLS symptoms causing moderate to
very severe pain and discomfort. RLS is more common in older individuals than
younger, and it severely affects emotional well-being in the elderly. RLS can be
early in onset (before the age of 45) with slow progression of symptoms and high family
prevalence, or it can start later in life, involve only one member of a family with rapid
development of severe symptoms.

With development of "Sleep Labs" in the 1970's, the sleep-robbing nature of RLS was
objectively characterized. In 1990 the American Sleep Disorders Association defined
RLS as (i) disagreeable touch sensations seemingly originating in the legs, that (ii) come
upon some nights and not other nights, and that (iii) are relieved almost immediately
upon standing or walking. In 1999 a task force of the American Academy of Sleep
Medicine summarized the then current understanding of RLS. Diagnostic criteria
were further expanded in 1995 and 2004 by international groups to include episodes
occurring during the daytime when drowsy.
Four criteria define RLS:
Criterion 1: An urge to move the legs accompanied by unpleasant sensations in the legs (and occasionally arms),
Criterion 2: the urge and unpleasant sensations are worse at rest and inactivity,
Criterion 3: the urge and sensations are relieved by movement, and
Criterion 4: the urge and sensations are worse in the evening and night-time.