Normal continuity, tracé discontinu, and tracé alternant

Criteria & assessment

• Continuous activity has no interruption and <2 seconds of attenuation below 25 µV peak-to-peak.
• An interburst interval (IBI) is attenuation below an age-dependent level described broadly as <25-50 µV peak-to-peak for >=2 seconds; Table 1 supplies the age bins.
• Normal maximum IBI/voltage by PMA: <30 weeks, 35 seconds and <25 µV; 30-33 weeks, 20 seconds and <25 µV; 34-36 weeks, 10 seconds and approximately 25 µV; 37-40 weeks, 6 seconds and >25 µV.
• Tracé discontinu contains 50-300 µV bursts with low-voltage IBIs and age-appropriate graphoelements; it is developmentally expected mainly from 26-40 weeks PMA and becomes confined to quiet sleep with maturation.
• Tracé alternant occurs only in quiet sleep: 50-150 µV delta bursts lasting roughly 4-10 seconds alternate with 25-50 µV mixed theta-delta periods that never fall below 25 µV; it appears around 34-36 weeks, is minimal by 42 weeks, and is absent by 46 weeks PMA.