Trajectory of the incidence of brushes on preterm electroencephalogram and its association with neurodevelopment in extremely low birth weight infants

Abstract Background Brush or delta brush is a well-known characteristic waveform in preterm electroencephalograms. However, the longitudinal trajectory of brushes and its association with neurodevelopment remain uncertain. Methods We analyzed the longitudinal incidence of brushes in 36 extremely low birth weight infants without severe brain lesions and its association with neurodevelopment and white matter abnormality. Conventional eight-channel electroencephalograms were recorded at 30, 32, 36, and 40 postmenstrual weeks (PMW). Incidence of brushes was calculated as the sum of brushes from each channel separated by active sleep and quiet sleep. A developmental delay was defined as a developmental quotient of Results The median incidence of brushes (per minute) in 36 infants at PMW 30, 32, 36, and 40 was 16.4, 20.4, 22.5, and 1.8 during active sleep and 7.5, 10.3, 11.5, and 1.7 during quiet sleep, respectively. Among the 36 infants, 14 infants were diagnosed with developmental delay. Longitudinal trajectories of the incidence of brushes were different between the normal and the delayed development groups. Brushes were observed most frequently at 36 PMW in the delayed development group. The incidence of brushes at 36 PMW was significantly correlated with the severity of white matter abnormalities and negatively correlated with the developmental quotient. Conclusion The incidence of brushes at 36 PMW can be a unique predictor of early neurodevelopment in extremely low birth weight infants without severe brain lesions.