Abstracts

Rationale: Hypoxic-ischemic (HI) encephalopathy is a major cause of neonatal seizures and long-term epilepsy. Extensive brain injury is usually associated with an increased risk. The objectives of this study were to determine the association between the patterns of HI brain injury and specific anatomical lesion, and the subsequent development of longer childhood epilepsy. Methods: This retrospective study included term newborns (>36 weeks gestation) with encephalopathy (n=197) seen between 2004 and 2012 at BC Children s and Women s Hospital. These neonates had standardized MR imaging performed between 3 and 5 days of life. The predominant pattern of HI brain injury on MRI was recorded by a pediatric neuroradiologist, who was blinded to the clinical information, and classified as follows: Normal, Watershed, Basal Ganglia, Total, Focal-Multifocal. Specific attention was directed to lesions in the hippocampus, motor cortex and occipital cortex. Clinical information, including demographics, use of systemic hypothermia, and occurrence of neonatal seizures, developmental outcome and incidence of childhood epilepsy, was collected by systematic chart reviews. Fisher exact test and Kruskal-Wallis analysis of variance were used for categorical and continuous variables respectively. Logistic regression was performed to examine the relationships between specific brain injury and long-term epilepsy. . Results: Of the 197 newborns, 132 (67%) had long-term clinical followed-up (median 24 months; interquartile range: 12 43 months of age) by a pediatric neurologist or pediatrician. Epilepsy diagnosed clinically and confirmed by an EEG was documented in 18 children. Review of clinical data demonstrated that children with epilepsy were sicker at birth, required more support during the immediate postnatal period and were more disabled at follow-up. A significantly higher proportion of newborns with Basal Ganglia or Total patterns developed epilepsy (P<0.001). Specific injury in the motor cortex and hippocampus (both P<0.001) and occipital cortex (P=0.005) was strongly associated with the development of epilepsy. In a logistic regression model adjusting for the predominant pattern of HI injury, all 3 anatomical structures persisted as an independent risk factor for long term epilepsy. However, when they were added to the model at the same time, only involvement of the motor cortex remained as an independent risk factor for epilepsy. Cooling did not affect these associations.Conclusions: In term newborns with hypoxic-ischemic encephalopathy, injury to the motor cortex on neonatal MRI is the best predictor of long term epilepsy, which is independent of the predominant pattern of hypoxic-ischemic brain injury.