Elsevier

Sleep Medicine

Volume 69, May 2020, Pages 14-18
Sleep Medicine

Original Article
Clinical characteristics of Korean pediatric patients with restless legs syndrome

https://doi.org/10.1016/j.sleep.2019.12.016Get rights and content

Highlights

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    Clinical characteristics of pediatric RLS were investigated in Korean population.

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    As opposed to adults, pediatric RLS patients did not show female predominance.

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    Pediatric RLS patients showed relatively mild to moderate RLS symptoms.

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    Children with RLS have a smaller likelihood of experiencing PLMS than adult patients.

Abstract

Objectives

Restless legs syndrome (RLS) is a common neurological disorder but it is not sufficiently recognized in children and adolescents. It often overlaps with growing pains in children, and as a result the clinical characteristics of pediatric RLS are not well studied, especially in Asia. The purpose of this study is to investigate the clinical characteristics of pediatric RLS patients in Korea and compare it to those of adult RLS patients.

Methods

We retrospectively reviewed the medical records of all pediatric RLS patients (≤18 years) from January 2015 to December 2018 in a regional tertiary hospital sleep center. We randomly selected adult primary RLS patients without comorbid medical disorders from our sleep center's dataset as controls. The number of controls was determined to be twice the number of pediatric RLS patients according to sample size calculation. The clinical and polysomnographic (PSG) characteristics of both groups were compared. The independent t-test, chi-squared test, and Fisher's exact test were used for analyzing quantitative data between the two groups and p < 0.05 was considered statistically significant.

Results

Twenty-nine primary pediatric RLS patients and 57 adult RLS patients were enrolled. Pediatric RLS patients showed equal prevalence between sexes, as opposed to adults where there is female predominance. Ferritin level was significantly lower in pediatric patients, although it remained within the normal range. Also, pediatric RLS patients showed less severe RLS symptoms and had better sleep quality than adults did in both objective and subjective measures. In addition, PLMS was shown to be less common in pediatric RLS patients compared to adults.

Conclusions

Pediatric RLS patients showed relatively mild to moderate RLS symptoms and a smaller likelihood of experiencing PLMS than adult patients, which is comparable to similar western studies. Long-term evaluation of a patient's clinical course through multicenter clinical studies is strongly suggested for the future.

Introduction

Restless legs syndrome (RLS) is a neurologic disorder that is mainly characterized by an urge to move the legs, especially during times of rest and at night. RLS has a wide variation of onset age and can be present in early childhood [1]. Previous studies have shown RLS prevalence of 2–4% in children and adolescents in the United States and Europe [[2], [3], [4], [5]]. There is very limited epidemiological data from Asian countries with one Chinese study reporting 2.8% prevalence for pediatric RLS [6].

Children may have limitations in describing their symptoms with clear language, so special considerations for age-appropriate terms are needed in diagnosing pediatric RLS. The clinical characteristics of pediatric RLS are quite different from those in adults and the symptoms often overlap with growing pains [2]. Genetic factors, dopamine dysfunction, and low iron stores are proposed as potential causes of RLS in children, as in adults. RLS is known to be associated with neurocognitive deficits in children [7]. Children with RLS are reported to have poor school performance, increased risk for depression, anxiety disorders, and attention-deficit/hyperactivity disorder (ADHD) [2]. However, the clinical characteristics of pediatric RLS are not well studied, especially in Asia.

The purpose of this study was to compare the clinical characteristics of pediatric RLS patients in Korea to those of adult RLS patients, in order to improve understanding and diagnosing pediatric RLS in the clinical realm.

Section snippets

Materials and methods

Medical records of all pediatric RLS patients from January 2015 to December 2018 were retrospectively reviewed in a regional tertiary hospital sleep center. The diagnosis of RLS in children and adolescents was made by the sleep expert during face to face interviews based on a workshop at the National Institute of Health (NIH) in 2003 [8], and the international classification of sleep disorder, third edition (ICSD-3). ICSD-3 stated that for children, they are characterized by the same symptoms

Results

In sum, 29 primary pediatric and 57 adult RLS patients were enrolled. Patient information and the blood test measurements are shown in Table 1.

The overall prevalence of pediatric RLS in our center was 2.28% of the total RLS population, but after excluding secondary RLS patients, this rate increases to 2.74%. The mean age of pediatric RLS patients was 10.97 ± 5.60 years (49.67 ± 11.64 years for adult controls). Of the pediatric RLS patients, 12 out of 29 (41.4%) were female compared to 37 out of

Discussions

In our study, pediatric RLS patients exhibited different characteristics compared to adult RLS patients. Our selection of pediatric RLS patients did not show female predominance, though the adult group did. Previous findings were consistent with our results in that gender differences in RLS are only visible after mid-late puberty, with lower serum ferritin levels [6]. BMI was much lower in the children in our study compared to the adults. Previous studies have shown that a greater BMI is

Conclusions

Pediatric RLS is not uncommon. The patients in our study showed relatively mild RLS symptoms and less likelihood of experiencing PLMS compared to adult patients, which is comparable to similar western studies.

Acknowledgements

“This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A3B03031021) and Korean Government (MSIP) (No.2014R1A5A2010008).”

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