Changes in Neonatal Intraoperative Electroencephalogram Alpha: Delta Ratios Precede Neurologic Injury

Background: Unrecognized intraoperative cerebral ischemia during neonatal aortic arch reconstruction may precede neurologic injury. Electroencephalogram (EEG) alpha:delta ratio (A:D) changes predict cerebral ischemia; however, if A:D differences can identify ischemia during neonatal antegrade cerebral perfusion (ACP) and aortic arch reconstruction is unknown. We hypothesized that A:D changes would precede neurologic injury. Methods: Simultaneous EEG derived left versus right: hemispheric and anterior cerebral A:Ds were retrospectively measured at baseline and every 5 min during arterial cannulation, cooling, ACP, and the rewarming phases of the operation. A paired left versus right A:D difference >25% was considered significant for ischemia, and the duration of a significant and continuous A:D difference was quantified in minutes. Neonates were divided into two groups: (1) new neurologic injury (stroke or seizure) and (2) no known neurologic injury. Results: From 72 neonates, there were no significant differences in the baseline A:Ds. Seven neonates (9.7%) developed a new neurologic injury (seizure = 3, stroke = 2, seizure and stroke = 2). Male gender and longer ACP times were significantly associated with neurologic injury. In neonates with a neurologic injury, the duration of a significant and continuous A:D difference was longer within the hemispheric and anterior regions. Multivariable analysis demonstrated that a significant and continuous anterior A:D difference (odds ratio: 1.345, 95% CI 1.058-1.712; P = .01) was independently associated with neurologic injury. Conclusions: A longer continuous anterior A:D difference > 25% was independently associated with neurologic injury. Intraoperative EEG monitoring could be considered during neonatal arch reconstruction.