ENO2 and periventricular leukomalacia: However, in the present study, IVH cases had a higher grade of NBI in comparison to those with PVL, and this difference in severity of NBI was represented in the levels of NSE in the different sub-group analyses we performed, where neonates with IVH had a higher concentration of serum NSE compared to controls and neonates with PVL on the third day of life.