A Novel MRI Scoring System for Brain Injury After Pediatric Out-of-Hospital Cardiac Arrest: A Two-Center, Retrospective Cohort, 2016–2020

OBJECTIVES: To create a simple scoring system to evaluate the extent of brain injury on MRI after pediatric out-of-hospital cardiac arrest (OHCA). DESIGN: Two-center retrospective cohort from 2016 to 2020. SETTING: Two tertiary care children's hospital serving northern California. PATIENTS: Children older than 48 hours and younger than 18 years old at admission who experienced OHCA within 24 hours before admission and underwent brain MRI within 8 days following arrest. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Brain abnormalities on diffusion-weighted and T2/fluid-attenuated inversion recovery MRI in six brain regions were summed to quantify severity of injury (0/1 point for each region) in: deep structures (basal ganglia, thalamus, and/or posterior limb of the internal capsule), cortex, white matter, brainstem, hippocampus, and cerebellum. Unfavorable neurologic outcome was defined using Pediatric Cerebral Performance Category (PCPC) score greater than or equal to 1 point above baseline resulting in a hospital discharge PCPC score greater than or equal to 3. There were 58 children included and 41 (71%) had unfavorable outcome. In those with unfavorable outcome, four of 41 had no evidence of injury (MRI score 0), whereas 15 of 17 with favorable outcome had a MRI score of 0 ( p < 0.001). No patient with favorable outcome had evidence of injury in deep structures ( p < 0.001), brainstem ( p = 0.003), cerebellum ( p = 0.024), or hippocampus ( p < 0.001). There were 28 of 41 unfavorable outcome patients who had a MRI score greater than or equal to 3, whereas no children (0/17) with favorable outcome had a MRI score greater than or equal to 3. After adjusting for presence of bystander cardiopulmonary resuscitation, witnessed arrest, and estimated time to return of spontaneous circulation, the pre- to post-test probability of unfavorable outcome with a MRI score greater than or equal to 3 went from 71% to greater than 99% (0.996 [95% CI, 0.8-1.0]). CONCLUSIONS: Our simple six-point MRI scoring system developed in a 2016-2020 cohort of pediatric OHCA cases managed in two centers shows an association with outcome, with a post-test probability of unfavorable outcome greater than 99% with a MRI score greater than or equal to 3.