Materials and Methods
Ethical approval was provided by the ethical review board of China
Medical University Hospital (CMUH103-REC2-082). Patient consent was not
required for this research. The data for children (< 18 years
old) with sleep problems who came to the outpatient department (OPD) of
China Medical University Children’s Hospital for help and underwent PSG
from April 2015 to May 2017 were collected and analyzed retrospectively.
However, data for those who underwent follow-up PSG studies after
adenotonsillectomy or for other reasons were excluded in this study.
The indications for PSG include snoring, sleep apnea, other
sleep-related breathing disorders, excessive daytime sleepiness, limb
movements while sleeping, bruxism, enuresis, sleep walking, insomnia,
difficulty falling sleeping, and others.
A level 1 PSG study is performed in our sleep laboratory with a sleep
technologist present, and 12 channels are recorded, including eight
channels of electroencephalography (EEG), 2 channels of
electrooculography (EOG), 1 channel of submentalis (chin)
electromyography (EMG), and 1 channel of
electrocardiogram (ECG)/heart rate, and 1 channel of pulse oximetry
(SpO2). A multiple sleep latency test (MSLT) was also
arranged for the day after any PSG study for those children who had a
history of more than 3 months of excessive daytime sleepiness.
Obstructive sleep apnea syndrome (OSAS) was diagnosed based on the PSG
data when obstructive events were noted and the apnea-hypopnea index
(AHI) was one or more per hour, with 1< AHI ≤5 taken to
indicate mild OSA, 5< AHI ≤10 taken to indicate moderate OSAS,
and an AHI >10/hr of total sleep time (TST) taken to
indicate severe OSAS.
The periodic limb movements (PLMs) during sleep were scored if there
were at least four movements of 0.5–5/sec’ duration that occurred
between 5 and 90s apart. A PLM index of >5 per hour of
sleep is generally considered to be rare in normal children, and
therefore this threshold was used to define the presence of periodic
limb movement disorder (PLMD).
Central sleep apnea (CSA) was defined as the absence of both inspiratory
effort and chest wall movement lasting longer than 20 seconds when
accompanied by a central apnea index greater than 1.
Furthermore, the presence of two or more sleep-onset rapid eye movement
(REM) periods (SOREMPs) and a mean sleep latency of <8 minutes
on the MSLT was regarded as being diagnostic of narcolepsy.