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mise à jour du
20 novembre 2003
Pediatric research
1984; 18; 1; 58-63
lexique
A scoring system for states of sleep and wakefulness in term and preterm infants
M Stefanski et al
Development of behaviors in preterm infants: relation to sleeping and waking
Bâillements du foetus: la naissance d'un comportementrévélée par l'échographie 4D Dr O.Walusinski

Chat-logomini

Descriptions of neonatatal behavior and studies on the ontogeny and organization of sleep have shown that infants exhibit several discrete and cyclic patterns of sleep and wakefulness called states. Other studies have shown that changes in physiologic variables such as heart rate, minute ventilation, oxygen consumption, transcutantous PO2, and cerebral blood flow accompany changes in state. These findings suggest that the results of physiologic research in newborn infants may be misinterpreted if the effects of an infant's state are not taken into account.
States are usually designated by observing recurring patterns of an infant's behavior, the EEG, and certain physiologic variables. Although guidelines for coding states of sleep and wakefulness of term infants have become widely accepted, no comparable guidelines exist for preterm infants whose behavioral, neuroelectric, and physiologic patterns are less discrete and less consistently interrelated. Furthermore, the primary focus of most scoring systems is on infant sleep per se, and these systems are net always conveniently applicable te other areas of neonatal research.
The purpose of this paper is to explain the design and validation of a simple, practical, and reliable system for determining the state of sleep or wakefulness in both term and preterm infants. Experience with this system indicates that it is a useful tool for relating state of sleep and wakefulness to physiologic variables during experimental studies of newborn infants.
 
DESCRIPTION OF THE SYSTEM
The scoring system, is based on independent assessments of behavioral and EEG patterns. Behavioral observations include the quality of body and eye movements. Code numbers are assigned te the behavioral and EEG patterns according to the systems given below. Designation of the infant's state of sleep or wakefulness is then made by combining concurrent behavioral and EEG scores into a single two number code. Because many physiologic variables are conventionally measured on a minute-by-minute basis, the epoch length for coding state with this system is 1 mn.
 
Coding of behavior. The following system for coding infant behavior is bàsèd upon observations made in our laboratory and by others.
Pattern 1. Eyes closed with predominantly flaccid "rag doll" appearance. Body movements are limited to startles (sudden contractions of many muscles lasting a few seconds with an immediate return to a relaxed posture). Occasionally increased muscle tone reflected in antigravity posturing of the extremities is observed. Rhythmicj aw jerks lasting 1 to 2 sec are also seen.
Pattern 2. Small body movements are seen. Motor activity includes slow intermittent writhing movements, jerky startles, small movements of an extremity or its parts, frowns, smiles, chewing and sucking movements, grimaces, and other facial activity, grunts, and occasional whimpers.
Pattern 3. REMs observed. Body movements are limited to those seen in Patterns 1 and 2. Eyes may occasionally open and close or remain briefly half-open.
Pattern 4. Wakeful behavior. Apparent nonreflex movements of limbs with prolonged startles and gross stretching and writhing. The infant may be intermittently motionless and appear alert. Facial activity is usually prescrit and the eyes may be open or closed. No crying is observed.
Pattern 5. Crying. The features of Pattern 4 are also observed.
Pattern 6. Recovery period after crying. Deep rapid respirations are prominent with little extremity movement. Eyes are usually closed.
 
Recording and coding the EEG. Widely accepted guidelines for recording the EEG have been published. We record the EEG, EOG, ECG, and other physiologic measurements on a Grass Model 6 16-channel EEG. A minimum of two EEG channels is recorded (C4-O2 and C4-A1), and EEG scoring is performed retrospectively. We extended the system widely used for coding EEGs of term infants so that it could be applied to preterm infants as well. When two or more patterns are observed in a single epoch, the pattern that predominates is assigned to the epoch.
Pattern 1. Trace alternant. Bursts of 50- 100 µV slow waves (0.53 Hz) with occasional superimposition of rapid low voltage waves. These bursts, lasting 3-8 sec, are separated by 4-8 sec of low voltage or mixed activity. or . Tracé discontinu. Bursts of high voltage (>100 µV) 0.5-2 Hz waves lasting 3-10 sec, separated by periods of attenuated activity (typically less than 5 µV) lasting 10-40 sec.
Pattern 2. High voltage slow. Continuous medium to high voltage activity (mostly 75 µV, occasionally 100-150 µV) comprised of frequencies of 0.5-4 Hz. The slow waves are often rhythmic.
Pattern 3. Mixed. Predominantly continuous polymorphic activity of 4-7 Hz, averaging 50 µV in amplitude, intermingled with slower waves (2-4 Hz) of slightly higher voltage.
Pattern 4. Immature rhythmic slowing. Monomorphic high voltage (>100 µV) waves of 0.3-2 Hz which often occur in extended sequences lasting longer than 10 sec. They are particularly prominent over the temporal and occipital areas and are often associated with superimposed 10-20 Hz activity ("brushes"). Other activity includes moderate voltage 2-8 Hz waveforms.
Pattern 5. Low voltage. Continuous 4-7 Hz activity, sometimes rhythmic, with voltages predominantly 20-30 µV.
Artifact time, a minute of poor quality that is uninterpretable due to excessive muscle activity, crying, or handling, is coded.
[...]
DISCUSSION

For purposes of physiologic investigation, this scoring system has several important advantages. First, it may be applied to preterm as well as term infants, thus allowing the investigator to code sleep and wakefulness in a consistent, practical way while following developmental changes in physiology. Second, it uses a simplified scheme aflowing important behavioral and neurophysiologic criteria to be grouped so that designation of sleep and wakefulness is expressed by a 2-number code. In addition, the system retains its usefulness when epoch lengths other than 1 min are desired. For example, we bave successfülly applied the system in analyzing 3-min values of heart rate, minute ventilation, and oxygen consumption.

The designation of state with separate scores for behavioral and EEG patterns preserves valuable information, especially regarding indeterminate sleep. For example, an infant with REMs who shows EEG criteria of quiet sleep wouId be scored EEG 1, B3. Similarly, constant small body movements without REMs but with a discontinuous EEG would be registered EEG 1, B2.

The criteria selected to define individual behavioral and EEG patterns are based on extensive observations in our nursery as well as on the work of others. Chin myogram and the rates and variabilities of pulse and respiration are excluded. The chin myogram is highly variable, particularly in preterm infants and, therefore, is not consistently applicable as a criterion for state designation. Heart rate and respiration are excluded because they are often dependent variables in physiologic studies. These variables require a framework for interpretation that does not presuppose their occurrence in a particular state of sleep or wakefulness.

Selection and grouping of criteria is, to a certain degree, arbitrary in any system of state assignment, and the designation of an infant's state will sometimes differ according to the system used. Monod and Guidasci coded records of 10 normal terrn neonates according to four different systems and found large discrepancies, particularly in the distribution of active and indeterminate sleep. Parmelee et al. coded records of both term and preterm, infants according to two different methods and found similar discrepancies. The present system produces rends in the distribution of sleep and wakefulness within the range of previous findings.

No consensus exists that it is possible or advisable to determine states in preterm infants. We emphasize, however, that physioogic measurements that do not control for state variability are often misleading; thus, physiologic studies of preterm infants cannot proceed optimally without a system for the designation of state. Results of validation studies with the present system how that good agreement between observers exists in recognizng behavioral and EEG patterns in both term and preterm nfants. Our data indicate that the criteria of body movements, eye movements, and EEG activity are in fact as applicable to the designation of states in preterin infants as in term subjects.

Furthermore, studies using this scoring system show that consistent changes in multiple physiologic measurements accompany changes in state. Use by other investigators is needed to confirm the practicality and reliability of the system.

 
fetal yawn 
 
Sleep-wake states and their regulatory mechanisms throughout early human development
Peirano P, Algarin C, Uauy R
Journal Of Pediatrics 2003; 143; 4S; S70-9
 
The emergence of sleep states is one of the most significant aspects of development. Descriptions of both neonatal and late fetal behavior and studies on the organization of sleep have shown that fetus and newborns exhibit spontaneously discrete and cyclic patterns of active sleep (AS) and quiet sleep (QS).
 
Human fetuses and neonates sleep most of their life, and AS is the prevailing state even during the first postnatal months. Several hypotheses to explain central nervous system development consider that AS is the expression of a basic activation program for the central nervous system that increases the functional competence of neurons, circuits, and complex patterns before the organism is called on to use them.
 
Current results indicate the maturation of QS not only coincides with the formation of thalamocortical and intracortical patterns of innervation and periods of heightened synaptogenesis, since this sleep state is also associated with important processes in synaptic remodeling. In fact, several studies suggest that the information acquired during wakefulness is further processed during AS and QS.
 
This article reviews the processes involved in the timing of both AS/QS and sleep/wake alternating patterns throughout early human development. A growing body of evidence indicates that the duration of unmodulated parental care and noncircadian environmental conditions may be detrimental for the establishment of these basic rhythmicities. As a consequence, alterations in parental/environmental entraining factors may well contribute to disturb sleep and feeding commonly experienced by preterm infants. Further knowledge on the early establishment of sleep-wake states regulatory mechanisms is needed to improve modalities for appropriate stimulation in the developing human being.