Restless legs syndrome
more common than thought
BY MITCH LESLIE
Imagine that a platoon of
furry spiders is slinking up your legs and you'll get a
sense of what a person with restless legs syndrome
endures every night as she tries to sleep. This
sleep-robbing disorder may be much more common than
previously recognized, affecting nearly 30 percent of the
population, Stanford researchers report.
The hallmark of restless
legs syndrome (RLS) is an "itching, creeping,
crawling feeling in the legs that is relieved by leg
movements," said Clete Kushida, MD, PhD, director of
the Stanford Center for Human Sleep Research and
co-author of the study. Sometimes patients notice a
burning or painful sensation, while some feel nothing but
still have a powerful urge to move their legs.
RLS is more than an
annoyance. It steals sleep. The frequent leg movements
needed to relieve discomfort prevent sufferers from
dozing off, Kushida said. To make matters worse, people
with RLS often have a related problem called periodic
limb movement disorder, characterized by violent
contractions of the limbs during sleep. These episodes
can be extreme enough to wake the sleeper. Kushida said
that because sleep is "chopped up," periodic
limb movement disorder contributes to daytime fatigue.
The cause of RLS is
unknown, but it appears to become more common with age,
Kushida said. Previous studies have indicated that the
incidence of the syndrome in adults lies somewhere
between 2 percent and 15 percent. But last year Kushida
and colleagues reported that 368 out of 1,254 patients
(nearly 30 percent) surveyed at a primary care clinic in
Moscow, Idaho, showed symptoms of RLS.
However, the diagnosis of
RLS came not from sleep experts but from questionnaire
data collected from all the patients who visited the
clinic during a one-year period. So Kushida and
colleagues decided to recheck the findings with a random
sample of the patients. They had 15 patients fill out
further questionnaires, undergo a structured RLS
interview conducted by the primary care physicians,
complete a sleep log and undergo sleep monitoring for two
nights while hooked up to instruments that measure the
number of leg movements. After the primary care
physicians made their judgment, a sleep specialist who
was unaware of the doctors' decision examined each case
file and made an independent diagnosis.
As the researchers told a
meeting of the Associated Professional Sleep Societies in
Las Vegas on June 14, the expert and the primary care
physicians using questionnaires reached the same
diagnosis 87 percent of the time. The current sample is
up to 76 patients, with a similar agreement rate. Though
the sample size is small, Kushida said that the results
suggest that the questionnaires provide an accurate way
for non-experts to diagnose RLS. The results support the
group's previous conclusion that the syndrome may be much
more prevalent than even sleep experts imagined.
Doctors and patients need
more education about the symptoms and treatments of RLS,
Kushida said. In most cases, dopaminergic drugs like
carbidopa/levodopa and pramipexole relieve symptoms,
Kushida said. Side effects of these drugs, which elevate
the levels of the neurotransmitter dopamine in the brain,
are rare and usually consist of nausea or upset stomach.
He recommends that people with symptoms of RLS contact
their primary care physician or a sleep expert.
Kushida's Stanford
collaborators are professor of psychiatry William Dement,
MD, PhD, director of the Stanford Sleep Disorders
Research Center; and Pam Hyde, administrative director of
the Center. The primary co-author of the study is Deborah
Nichols, the project director in Moscow, Idaho. The other
participants in the study are Richard Allen of Johns
Hopkins University; Terry Young of the University of
Wisconsin-Madison; Richard Simon of the Kathryn Severyns
Dement Sleep Disorders Center in Walla Walla, Washington;
and John Grauke, J.B. Britzmann and John Brown of the
Moscow Clinic. Pharmacia and Upjohn funded the research.
SR
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