Chapter 3: Newborn

Tracé Discontinu. EEG of a 27-week CA infant with severe HIE. Tracé discontinu (TD) is the earliest EEG activity that appears in viable neonate at 22–23 weeks of gestational age (GA). The waves are described as short bursts, consisting of slow and fast rhythm, interspersed against a flat or quiescent background of less than 25 μV.¹ At a very early age of 22–24 weeks GA may vary from 5 sec to 8 min.² As age increases, the periods of inactivity shorten. The longest acceptable single interburst interval (IBI) duration has been reported to be 26 weeks CA, 46 sec; 27 weeks CA, 36 sec; 28 weeks CA, 27 sec³; less than 30 weeks CA, 35 sec; 31–33 weeks CA, 20 sec; 34–36 weeks CA, 10 sec; and 37–40 weeks CA, 6 sec.^4–6

The TD is also the first EEG pattern occurring during quiet sleep that differentiates wakefulness from sleep in the premature infant at around 30–32 weeks CA.

Infants less than 30 weeks CA show interhemispheric hypersynchrony whereby the majority of bursts arising within the two hemispheres appear at the same time.⁵

Interhemispheric Hypersynchrony. EEG of an infant 28 weeks CA with apnea. The tracing is discontinuous. Infants at less than 30 weeks CA have “paradoxical hypersynchrony” whereby bursts of cerebral electrical activities are well synchronized and appear simultaneously between the two hemispheres. The pathophysiology of this phenomenon is unknown. After 30 weeks CA, bursts of cerebral activities appear to be more asynchronous. The bursts of cerebral activities during quiet sleep are synchronized in approximately 70% at 31–32 weeks CA, 80% at 33–34 weeks CA, and 100% after 37 weeks CA.

In infants less than 30 weeks CA, the average interburst interval (IBI) or quiescence is about 6–12 sec. The longest acceptable IBI is 30–35 sec.

Tracé Discontinu. EEG of a 28-week CA infant with severe HIE. Tracé discontinu (TD) is the earliest EEG activity that appears in the viable neaonate at 22–23 weeks of gestational age (GA). It is described as short bursts, consisting of slow and fast rhythm, interspersed against a flat or quiescent background of less than 25 μV.¹ At a very early age of 22–24 weeks GA, it may vary from 5 sec to 8 min.² As age increases, the periods of inactivity shorten. The longest acceptable single interburst interval (IBI) duration has been reported to be 26 weeks CA, 46 sec; 27 weeks CA, 36 sec; 28 weeks, 27 sec³; less than 30 weeks CA, 35 sec; 31–33 weeks CA, 20 sec; 34–36 weeks CA, 10 sec; and 37–40 weeks CA, 6 sec.^4–6

The TD ...