Auditory-evoked cerebral oxygenation changes in hypoxic-ischemic encephalopathy of newborn infants monitored by near infrared spectroscopy.

Recent neuronal activation studies have demonstrated the presence of regional cerebral blood flow (rCBF) increases in response to neuronal activation in normal newborns. In the present study, using near infrared spectroscopy (NIRS), we evaluated the evoked cerebral blood oxygenation (CBO) changes in hypoxic-ischemic encephalopathy (HIE) of newborns. We studied 20 normal newborns and 22 HIE newborns; mild HIE (n=9), moderate HIE (n=7), and severe HIE (n=6). The babies were from 1 to 3 days postdelivery. We measured the concentration changes of deoxyhemoglobin (Deoxy-Hb), oxyhemoglobin (Oxy-Hb), and total hemoglobin (Total-Hb) induced by auditory stimulation in the frontal lobes. The normal and HIE groups showed different Oxy-Hb and Total-Hb responses. In normal newborns, 19 out of 20 normal subjects showed increases of Oxy-Hb and Total-Hb, whereas 14 out of 22 subjects showed decreases of Oxy-Hb and Total-Hb during the stimulation (chi(2)=19.95, p<0.001). In addition, there was a strong negative correlation between HIE severity and changes of Total-Hb (r=-0.73, p<0.001). These results suggest that infants with HIE have decreased rCBF in the frontal lobes during auditory stimulation.