Scoring of pediatric polysomnograms
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- Scholle, S. Somnologie (2017) 21(Suppl 1): 9. doi:10.1007/s11818-016-0071-7
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In 2007, the American Association of Sleep Medicine (AASM) published recommendations for recording and scoring polysomnograms. These were revised in 2014 and 2015, and the given rules should be applied to polysomnography in both adults and children.
The scoring of pediatric polysomnograms is complicated by development-dependent alterations in specific patterns. The present article aims to demonstrate that in particular situations, the AASM rules for scoring and evaluation of sleep and associated events in children are worthy of further discussion.
Materials and methods
The problems associated with performing and evaluating results of sleep studies are illustrated using individual examples. Polysomnography was performed according to AASM rules.
Results and conclusion
This article highlights the problems associated with recording and scoring pediatric polysomnograms according to AASM rules with respect to the number of necessary electrodes, study over one or two nights, scoring of sleep stages (specific patterns for scoring sleep stages and the delta wave amplitude criterion), arousal definition, scoring movements and movement times, and scoring the respiratory pattern. Individual examples are discussed in each case. Beyond the fundamental aspects laid down in the AASM rules, recording and scoring polysomnograms in children necessitates additional understanding of development-specific characteristics.
Auswertung von Polysomnographien im Kindesalter
2007 wurden von der American Association of Sleep Medicine (AASM) Empfehlungen zur Durchführung und Bewertung von Polysomnographien veröffentlicht, die 2014 und 2015 überarbeitet wurden und sowohl im Erwachsenen- als auch im Kindesalter angewendet werden sollen.
Ziel der Arbeit
Die Bewertung von Polysomnographien ist im Kindesalter durch die entwicklungsbedingte Veränderung von spezifischen Mustern erschwert. Die Arbeit soll zeigen, dass im Einzelfall die Empfehlungen der AASM bezüglich der Mustererkennung und -bewertung im Kindesalter diskussionswürdig sind.
Material und Methoden
In Einzelbeispielen wird auf Probleme bei der Durchführung und Bewertung von Untersuchungen im Schlaf hingewiesen. Die Ableitungen wurden entsprechend der AASM-Regeln durchgeführt.
Ergebnisse und Diskussion
Hinweise zur Problematik der Ableitung und Auswertung von Polysomnographien im Kindesalter nach den AASM-Regeln wurden bezüglich der Anzahl von Messwertaufnehmern, der Untersuchung in 1 oder 2 Nächten, der Bewertung der Schlafstadien (spezifische Muster zur Schlafstadienerkennung und Amplitudenkriterium Deltawellen), der Arousaldefinition, der Bewertung von Bewegungen und Bewegungszeiten und der Bewertung des Atemmusters gegeben. Einzelbeispiele werden jeweils erläutert. Über die AASM-Regeln hinaus erfordert die Durchführung und Auswertung von Polysomnographien im Kindesalter ein zusätzliches Wissen über entwicklungsspezifische Besonderheiten.
The rules on scoring of sleep and associated events published in 2007 by the American Association of Sleep Medicine (AASM)  have become widely accepted during recent years. These rules are also applicable to children, providing the development-dependent changes in certain specific patterns are considered.
In 2014 and 2015, the AASM recommendations for scoring of sleep stage in children were revised, and morphologic criteria of the infant sleep electroencephalogram (EEG) were described in detail [2, 3].
Although there are rules governing scoring of sleep, ambiguity—caused by inter- and intraindividual pattern divergence and age-dependent characteristics—is frequently encountered in practice. The current article aims to indicate such pitfalls.
Using individual examples, potential problems associated with the application of AASM rules for analysis of pediatric sleep are illustrated. Each of the figures depicts the derivations recommended by the AASM . In order to improve comprehensibility, single channels have been blended out in isolated cases.
Regarding polysomnographic montage: the technical specifications for the EEG (derivations F3-M2, F4-M1, C3-M2, C4-M1, O1-M2, O2-M1), electrooculogram (EOG), and the chin electromyogram (EMG) given for adults were observed. In infants and young children, the distance between the EOG and chin EMG electrodes was reduced according to the size of the head.
To record respiration, an oronasal thermal sensor and a nasal pressure sensor were used. Oxygen saturation was measured by pulse oximetry, as specified by AASM rules. Respiratory effort was assessed using respiratory inductance plethysmography (chest and abdomen).
To detect leg movements, the EMG of the left and right tibialis anterior muscle was recorded. According to AASM cardiologic rules, a modified electrocardiograph lead II using torso electrode placement was employed. An audiovisual recording was generally made throughout the PSG. In addition, the behavior was observed by trained personnel.
Results and discussion
Number of electrodes
Compared to polysomnography in adults, polysomnographic evaluation of infants, children, and adolescents is considerably more complicated. Subjects are frequently highly unsettled by the unknown environment and the recoding, such that placement of the electrodes can prove problematic, particularly in infants and small children.
In versions 2.1 and 2.2 [2, 3], the AASM recommends placement of additional electrodes in 2‑year-old children, i. e., F4-M1, C4-M1, O2-M1, F3-M2, C3-M2, O1-M2, C4-Cz, C3-Cz, since sleep spindles often occur asynchronously at this age and are particularly detectable in central derivations C3-Cz, C4-Cz and C3-M2, C4-M1. However, in our experience, the number of electrodes applied to the head should be reduced for routine recordings (e. g., for routine recordings up to the age of 2 years, only C3-M2 and C4-M1) in order to minimize stress. Since high-amplitude delta waves are particularly detectable frontally and centrally from 2 months after birth, as are sleep spindles and K complexes from 3–6 months, a frontal derivation would be recommendable in addition to the central derivation. The occipital derivation provides little additional information in infants and small children . Placing sensors to record oral and nasal respiration is also extremely disturbing for infants; therefore, only an oronasal thermistor or a nasal pressure measurement system should be employed, whereby a nasal pressure sensor is preferred for detection of hypopnea .
Study over one or two nights
Due to the well-known first-night effect, the intention should be to evaluate children during the second night. However, if a clear statement on diagnosis can already be made after the first night, the second night may be omitted .
Scoring sleep stages
Specific patterns for scoring sleep stages and the delta wave amplitude criterion
Typical electroencephalogram patterns during sleep and their maturation (table modified from )
31–44 weeks conceptional age (cA)
First year postpartum
1–3 years of age
3–5 years of age
5–12 years of age
12–20 years of age
Dominant posterior rhythm
Starting at 2–4 months with 2–4 Hz; at 5–6 months, 5–6 Hz
5–6 to 9.5 Hz
6–8 to 7–9.5 Hz
8–10 to 9–11 Hz
10 Hz (8–13 Hz)
At 6 months rhythmic theta activity, increasing amplitude in comparison to wakefulness
Rhythmic theta activity at 4–6 Hz, so-called “hypnagogic hypersynchrony” until 4 years, increasing amplitude in comparison to wakefulness
Rhythmic theta becomes slower and rare, hypnagogic rhythms
Decreasing alpha activity, hypnagogic rhythms (seldom)
Decreasing alpha activity, hypnagogic rhythms more seldom
Trace alternant (TA)
During quiet sleep, after 36 weeks mature pattern
Vanishes in the 1st/2nd month
Starting at 6 weeks to 3 months, 12–15 Hz; before 10 weeks: “pre-spindles”: rounded negative, sharp positive component
Progressive increase of inter-spindle intervals with age
Increasing spindle density from 3 years, typical maximum at vertex
From 18–24 months: mature spindles without rounded component; from 2 years: central 14 Hz, anterior 12 Hz
From the 3rd to 6th month
High, fully developed with 2 years
High, with increasing steep component
High, with marked steep component
Smaller, steep component less prominent
Vertex sharp waves
From 4 to 6 months onwards
Most prominent at 3–10 years
Burst pattern after 28 (33–36) weeks cA
High-density bursts with interburst intervals <1 s decrease with age
Stage N2 is scored “when at least one sleep spindle or one K complex occurs in the 30-second epoch” . N2 is also scored in the following epochs if a low-amplitude EEG with mixed frequencies is present in the absence sleep spindles or K complexes . It is particularly important to observe this rule between the ages of 1 and 3 years, when sleep spindles are rare  and only few typical K complexes are found.
The designation of rapid eye movement sleep (REM) is based, among other things, on eye movements. Particularly in infants, although these movements are visible under the closed eyelids, it is often not possible to reproduce them in the derivations. Eye movements are recorded by electrodes (diagonal derivation E1-M2 and E2-M2) that register changes in the potential between cornea (positive) and retina (negative). If the distance between cornea and retina is very small, the changes in potential are also small, and the typical picture of rapid eye movements is less recognizable. In this instance, stage R should also be scored if the EEG pattern (low-amplitude mixed-frequency, no sleep spindles or trace alternate patterns) and the chin EMG pattern (low tone) are indicative of this stage and no eye movements are present [2, 3].
Particularly in infants but also in children and adolescents, consideration of heart rate is useful, which is less variable NREM (N) than in REM (R) sleep. This enables wakefulness and sleep stages N and R to be roughly determined by simply examining the heart rate pattern in the whole-night overview.
In children, arousal patterns frequently occur as paroxysmal delta bursts. These are not mentioned in the AASM guidelines , although they characterize the disruption of sleep microstructure as well as the typical age-related theta arousals .
Scoring leg movements lasting >10 s
Rules for movements in connection with respiratory events
Movements occurring prior to a central apnea can trigger a central apnea via pulmonary stretch receptors (Hering–Breuer reflex). From infancy to adolescence, the occurrence of central apneas following movements decreases with increasing age. Therefore, these are age-specific in infants and young children, but not in adolescents. If central apneas following movements occur at an increased rate in older subjects, detection of this pattern could also demonstrate abnormal development.
In the AASM rules, central apneas are however scored when an EEG arousal, a transition to wakefulness, or ≥3 % oxygen saturation follows the apnea . A movement following an apnea should be considered a motoric arousal; however, according to AASM, only cortical arousals are considered. In the author’s opinion, it would be contradictory to negate the movement (Fig. 6).
Scoring of respiratory patterns
To record the respiratory signal, the AASM  recommends using oronasal thermistors and nasal pressure sensors (for detection of hypopnea), as well as esophageal pressure measurement (invasive methods not really suitable for routine use in children) or dual thoracoabdominal belts (inductance plethysmography) for measurement of respiratory effort. To detect hypoventilation, measurement of arterial pCO2, transcutaneous pCO2, or end-tidal pCO2 is suggested.
Apnea duration is determined with reference to the respiratory rate, which changes in a development-dependent fashion .
According to AASM rules , central apneas in children are only scored from a duration of 20 s, providing they are not terminated by an arousal, an awakening, or an oxygen desaturation ≥3 %. However, if one considers that the cutoff in adults is 10 s, this 20 s duration is set very high, particularly in the case of older children and adolescents. From the age of 8 years, the average duration of central apneas is about 10 s [4, 10]. This should justify scoring central apneas <20 s from this age. In the author’s experience, 20 s apneas are also more than rare in infants with immature respiratory control [4, 10].
Other AASM rules  on scoring central apneas also appear worthy of further discussion. Movements prior to and following an apnea should not be scored. So how does one proceed when faced with a pattern such as the one shown in Fig. 7? In this case, a periodic breathing pattern would be scored; however, according to AASM rules , events preceding or following the apnea would not be considered, i. e., arousals and leg movements would be ignored. “Score periodic breathing if >3 consecutive episodes of central apnea with duration >3 s are separated by an interval of normal breathing not longer than 20 s.” Disruption of sleep due to cortical arousals and leg movements (motoric arousals) would not be detectable by such an approach.
Children with clinical symptoms of obstructive sleep apnea syndrome (OSAS), who have an abnormal respiratory pattern during sleep, do not have to exhibit apneas/hypopneas that fulfill the AASM criteria [11, 12]. In children, it is important to clarify whether increased respiratory effort is present. Observation by trained personnel cannot always be replaced by audio/video recordings.
Age-dependent changes in the patterns representative of sleep stage, in the respiratory pattern, and in the other polysomnographic parameters must be considered, since children up to the age of 14 years pass through key developmental processes [4, 7, 10, 13]. This receives less attention in the AASM rules.
The current article presents examples which are intended to facilitate scoring of pediatric polysomnograms beyond the scope of the AASM rules.
It is recommended that polysomnographic data be evaluated in their overall context, e. g., when scoring arousals, leg movements, and heart rate responses should also be included.
Compliance with ethical guidelines
Conflict of interest
S. Scholle states that she has no competing interests.
All studies on humans described in the present manuscript were carried out with the approval of the responsible ethics committee and in accordance with national law and the Helsinki Declaration of 1975 (in its current, revised form). Informed consent was obtained from all patients included in studies. Written consent was obtained from the parents of all children.