High postnatal oxidative stress in neonatal cystic periventricular leukomalacia

Oxidative stress plays an important role in cystic periventricular leukomalacia (PVL). We performed a case-control study of preterm infants delivered at <35 weeks of gestation between January 2003 and December 2006. Patients were stratified into three groups, according to age at which cysts were initially identified: 10 days old (early cystic PVL; n=10), >10 days old (late cystic PVL; n=12); and no cystic PVL (controls; n=22). Serum total hydroperoxide, biological antioxidant potential and oxidative stress index (calculated as total hydroperoxide/biological antioxidant potential) were measured within 3h after birth. Frequencies of preterm rupture of membrane and chorioamnionitis were significant higher in early cystic PVL than in late cystic PVL or controls. Duration of oxygen treatment and mechanical ventilation and frequency of apnea were significantly higher in late cystic PVL than in controls or early cystic PVL. Serum total hydroperoxide levels and oxidative stress index were significantly higher in early cystic PVL than in late cystic PVL or controls (p<0.05, respectively). Postnatal duration until cyst identification displayed a significant negative correlation with oxidative stress index and total hydroperoxide level (r=-0.497, p<0.05; r=-0.50, p<0.05, respectively). These findings suggest that early onset of cystic PVL might be due to either antenatal or intrapartum factors, but late onset might be due to postnatal factors. In the pathophysiology and therapy of cystic PVL, oxidative stress and onset timing appear crucial. This is the first study to reveal that neonates experiencing much more oxidative stress at birth show earlier onset of cystic PVL.