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Saturday, 1st January 2005
The study examined 538 cases registered in
the pediatric sleep disorders program at Mayo Clinic between 2000 and 2004.
ROCHESTER, Minn. -- A new Mayo Clinic study has for the
first time established rates of restless legs syndrome in
children, finding that almost 6 percent of children seen in
Mayo"s sleep clinic have the disease. The study, published
in this month's issue of Annals of Neurology, also notes
that the most common risk factors for the disease in kids
are family history of restless legs syndrome and iron
"Restless legs syndrome is underdiagnosed in kids," says Suresh
Kotagal, M.D., chair of Mayo Clinic pediatric neurology and a sleep
specialist. "If you look at children with difficulty falling asleep,
you'll see a fair number have restless legs. Thus far, there have
been sporadic case reports, but nobody has studied a larger group of
children, looking at children with insomnia complaints as a whole to
see how many had restless legs syndrome."
Dr. Kotagal and his colleague Michael Silber, M.B.Ch.B., Mayo
Clinic neurologist and sleep specialist, indicate that restless legs
syndrome may account for some of the age-old notion of "growing
"It's been known for decades that children have 'growing pains,'"
says Dr. Kotagal. "Studies by other investigators have now shown
that growing pains in some children may actually be restless legs
Dr. Kotagal says that while infrequent "growing pains" may be
immaterial, parents and children should be alert for a habitual
pattern of discomfort in the limbs around bedtime.
"Occasional growing pains are nothing to worry about, but growing
pains every night may be restless legs syndrome," he says. "It's
like the fact that somebody might snore one or two days a month, but
if it happens every night, it may be something that needs medical
The study examined the records of 538 children who had been seen
in the pediatric sleep disorders program at Mayo Clinic between Jan.
2000 and March 2004. New, rigidly defined diagnostic criteria
established by a consensus conference of the National Institutes of
Health and the International Restless Legs Syndrome Foundation in
2003 allowed the Mayo Clinic researchers to classify their 32
patients as having probable restless legs in nine cases and definite
restless legs syndrome in 23 cases. Those in the probable restless
legs syndrome group were more likely to be younger. The most common
symptoms were trouble getting to sleep or staying asleep, which
affected 87.5 percent. One commonality in the restless legs syndrome
patients was a low iron level in the blood (as measured by serum
ferritin) seen in 83 percent of the patients, the explanation for
which is unknown, according to Dr. Kotagal.
"With regard to the iron deficiency, we don't know if it's the
diet or a genetic predisposition to low iron levels," says Dr.
Kotagal. Drs. Kotagal and Silber also found family history of
restless legs syndrome in 23 out of 32 patients identified to have
restless legs syndrome in the study, or 72 percent. The child's
mother was three times more likely to be the parent affected with
restless legs syndrome.
"There seems to be a strong genetic component in restless legs
syndrome," says Dr. Kotagal. "Very often when taking the medical
history with the child, the parents say they have a similar
An additional characteristic seen in 25 percent of the patients
The researchers note that the symptoms of restless legs occur
most often in the evening or around bedtime. Symptoms include
discomfort or needing to move the legs, which is alleviated by
"Children very often describe it as 'creepy crawlies,' as 'ouchies'
or 'owies,'" says Dr. Kotagal. "It feels like bugs crawling on the
legs. One child described it as feeling like he was walking though
snow. There is also an uncontrollable urge to move the legs."
Dr. Kotagal believes that it is important to recognize and treat
this condition, as it hampers a child's lifestyle. "If affects the
quality of life," he says. "They wake up frequently in the night.
They wake up tired. They may also be inattentive during the day."
The long-term outcome of childhood restless legs syndrome is not
known, according to Dr. Kotagal, but it is treatable using
medications that increase the levels of dopamine in the central
nervous system. Dr. Kotagal notes that there is evidence that iron
seems to be very important to the synthesis of dopamine in the body.
He says that there is not yet sufficient evidence, however, that
treatment with iron helps relieve restless legs syndrome in
Dr. Kotagal indicates that there may be connections between
restless legs syndrome and attention deficit hyperactivity disorder.
The treatments for both conditions address somewhat the same
chemical imbalance, he notes.
"When we look at kids who have decreased attention span, over
one-third of them will have sleep apnea or restless legs syndrome,"
he says. "We can say that it goes to further affirm the fact that
inattentiveness is multifactorial -- due to depression, anxiety,
stressors in the child's life, obstruction of breathing passageways,
sleep apnea or restless legs. We need to look at all of these
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