Insula Injury and State Change Predict Outcome in Cooled Neonatal Hypoxic Ischemic Encephalopathy Patients: A Pilot Study.

BACKGROUND

To determine early electroencephalography (EEG) and magnetic resonance imaging (MRI) features significantly associated with functional outcome in infants with hypoxic ischemic encephalopathy (HIE). To identify specific brain injury patterns associated with poor outcome and compare their prognostic efficacy to specific brain injury patterns.

METHODS

EEG characteristics, MRI injury patterns, and outcomes were evaluated in 23 term neonates (mean gestational age: 38 weeks) who underwent cooling and were confirmed to develop HIE. EEG features were extracted from recordings between 24 and 26 hours of life during therapeutic hypothermia. MRIs were scored for injury within the first 1.5 weeks of life. Functional outcomes were graded from 0 (best) to 5 (worst). The relationships between EEG or MRI features and outcomes were evaluated using ordinal logistic regression analysis.

RESULTS

Of the features assessed, lack of EEG state change at 24 hours of life and insula injury on MRI were most associated with poor functional outcome. When combined in a multivariate model, regression analysis suggested both features were independently associated with poor outcomes. Injury to the insula, rather than injury to the basal ganglia as previously suggested, was the strongest predictor of poor outcomes.

CONCLUSIONS

MRI evidence of insular injury within the first 1.5 weeks of life and lack of EEG state change at 24 hours predict poorer outcomes in HIE. These findings suggest that insular injury may be a more sensitive indicator of overall injury burden associated with poor outcomes than deep gray matter or other cortical involvement.