Value of MR imaging of the brain in children with hypoxic coma.

BACKGROUND AND PURPOSE The contribution of MR imaging to identify hypoxic-ischemic injuries has been studied mostly in neonates or adults. The purpose of this study was to describe the MR imaging findings of toddlers and older children with hypoxic coma and to analyze the prognostic value of an MR imaging scoring system. METHODS The conditions of 40 children with hypoxic coma (age range, 6 weeks to 18 years) were clinically graded according to the pediatric risk of mortality score, and MR imaging studies were performed. Sixty-four MR imaging studies were distributed in five categories according to their timing relative to the hypoxic event: days 1 through 3, 4-7, 8-15, 16-50, and after day 50. These were evaluated retrospectively by using an eight-point scoring system based on two lesion categories assessing watershed areas and basal ganglia involvement, including signal intensity and morphologic features with respect to maturation-related norms. Two age groups (< or =1 year and >1 year) were considered. The surviving children were grouped according to neurologic outcome. RESULTS The occurrence of watershed areas or basal ganglia involvement was not significantly different in association with age. Sixteen children died. Twelve children had moderate to severe sequelae resulting from neurodevelopmental disabilities, and 12 had good neurologic outcomes. There was no correlation between pediatric risk of mortality score and neurologic evolution. There was a strong correlation between first MR imaging score (P <.001) and neurologic outcome. The sensitivity of the first MR imaging score was high (96%), even when obtained during the first 3 days, with a specificity of 50% and a positive predictive value of 82%. Six patients with definite abnormal MR imaging findings experienced good neurologic outcomes. CONCLUSION The MR imaging scoring system proposed in this study can be used to establish an early prognosis in a significant proportion of children with hypoxic coma. It is helpful, even during the first 3 days after the event. However, some patients with definite abnormal MR imaging findings may experience good neurologic evolution.