How are sleep-state transitions identified in the visual analysis of neonatal electroencephalogram (EEG)?

Updated: Nov 08, 2018
  • Author: Samuel Koszer, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Sleep-state transitions: While observation of sleep-state changes provides the electroencephalographer with a considerable amount of information regarding the status of the infant's brain, those interpreting neonatal EEGs must be cautioned that considerable variation occurs during a routine 1-hour EEG, not only in different neonates but also in the same infant when tested at intervals of a few days. These marked individual fluctuations often overlap with those observed in impaired newborns. Care must be taken in interpreting an abnormal record solely based on sleep features. As with other abnormalities, persistence of the abnormality on serial records adds to the strength of the predictive value of the EEG.

  • Records in which no recognizable sleep states exist, despite lengthy recordings, are abnormal. In infants older than 30 weeks' postconceptional age, the lack of sleep-state differentiation usually is readily apparent (continuous activity typically appears in active sleep by 30 weeks' postconceptional age). In addition to the lack of cyclical states, the EEGs often contain other abnormalities such as persistent low voltage or excessive discontinuity, monotonous moderate theta or alpha range frequencies, and even interictal or ictal discharges. Disruption in the ability to develop cyclic states often is observed in infants in a coma state due to a variety of causes. In these patients, the following factors should be ruled out: reversible toxic factors, hypothermia, and the use of drugs for controlling seizures or minimizing brain damage due to anoxic-ischemic insults. Lack of distinct sleep states is associated with poor outcomes.

  • Transitional or indeterminate sleep is used by some to indicate periods of sleep in which a lack of concordance between criteria does not allow their classification as either REM or NREM. An excessive amount of transient sleep is considered abnormal. A similar pattern, excessive labile sleep states, refers to rapid changes of sleep state, with the infant spending only a few minutes or even seconds in one sleep state before entering another state.

  • Both excessive transient sleep state and excessive labile sleep state have been observed in infants born to mothers on drugs such as alcohol.


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