Rhythmic EEG patterns in extremely preterm infants: Classification and association with brain injury and outcome

Abstract

Objective: Classify rhythmic EEG patterns in extremely preterm infants and relate these to brain injury and outcome.

Methods: Retrospective analysis of 77 infants born <28 weeks gestational age (GA) who had a 2-channel EEG during the first 72 h after birth. Patterns detected by the BrainZ seizure detection algorithm were categorized: ictal discharges, periodic epileptiform discharges (PEDs) and other waveforms. Brain injury was assessed with sequential cranial ultrasound (cUS) and MRI at term-equivalent age. Neurodevelopmental outcome was assessed with the BSITD-III (2 years) and WPPSI-III-NL (5 years).

Results: Rhythmic patterns were observed in 62.3% (ictal 1.3%, PEDs 44%, other waveforms 86.3%) with multiple patterns in 36.4%. Ictal discharges were only observed in one and excluded from further analyses. The EEG location of the other waveforms (p<0.05), but not PEDs (p=0.238), was significantly associated with head position. No relation was found between the median total duration of each pattern and injury on cUS and MRI or cognition at 2 and 5 years.

Conclusions: Clear ictal discharges are rare in extremely preterm infants. PEDs are common but their significance is unclear. Rhythmic waveforms related to head position are likely artefacts.

Significance: Rhythmic EEG patterns may have a different significance in extremely preterm infants.

Keywords: Brain injury; EEG; Outcome; PED; Periodic epileptiform discharges; Preterm infant; Seizures.