Does clinical status 1 week after therapeutic hypothermia predict brain MRI abnormalities?

Abstract

Hypothermia improves clinical outcomes and brain magnetic resonance imaging (MRI) findings in infants with hypoxic-ischemic encephalopathy. We hypothesized that clinical status following hypothermia predicts brain MRI abnormalities, and helps determine which infants need an early MRI evaluation before discharge. The objective of this study was to determine whether the clinical evaluation 1 week after completion of 72 h of hypothermia treatment predicts the presence of brain MRI abnormalities related to hypoxia-ischemia. The medical records of 83 consecutively cooled infants who underwent brain MRI were reviewed. Clinical evaluation by day 10 of life consisted of assessment of oral feeding ability, spontaneous activity, need for mechanical ventilation and a history of clinical seizures. Logistic regression analysis was performed using all four covariates, with an abnormal MRI as the primary outcome. Brain MRI with lesions in both the basal nuclei and the cortex was considered to be severely abnormal. MRI was abnormal in 46 (55%) infants. Univariate analysis identified all of the criteria as being significantly associated with an abnormal MRI. On multivariate analysis, only feeding difficulty (P<0.001, OR 9.5, 95% confidence interval (CI) 3 to 29.8) and a history of clinical seizures (P<0.001, OR 12, 95% CI 3 to 46.5) were significantly associated with an abnormal MRI. The areas under the receiver operating characteristic curve for feeding ability and seizure activity combined (0.86, 95% CI 0.77 to 0.94) indicated good accuracy with respect to the primary outcome. The negative predictive values of feeding difficulty and seizure activity for a severely abnormal MRI were 91% and 96%, respectively. Infants who do not have a history of clinical seizures and who attained full oral feeding by 1 week after hypothermia are unlikely to have an abnormal brain MRI. This simple assessment provides significant prognostic information that can be useful in parental counseling, and may allow selective use of pre-discharge MRI.