MR imaging was performed preoperatively on a 3T magnet (General Electric, Milwaukee, WI). Sequences obtained included conventional T1- and T2-weighted imaging, diffusion-tensor imaging (DTI), and gradient-echo (GRE) sequences, as well as MR spectroscopy of the basal ganglia. Our neuroradiologist (JM) reviewed postnatal, pre-operative brain MRI and scored MRIs according to the Magnetic Resonance Imaging Abnormality Scoring System used by Andropoulos et al.33 (link) This scoring system categorizes brain MRI abnormalities as (i) white matter injury (WMI) , (ii) infarction (INF), (iii) intraparenchymal hemorrhage (IPH), (iv) punctate lesions (PL), (v) lactate peak on MRS (lactate), (vi) intraventricular hemorrhage (IVH), (vii) subdural hemorrhage (SDH), or (viii) deep venous sinus thrombosis (DVST). Abnormalities in each category are given a score of 0-3 (0=none, 1=mild, 2=moderate, 3=severe) and weighted by a significance multiplier.33 (link) For WMI, INF, and IPH the significance multiplier is 3, for PL and lactate the significance multiplier is 2, and for IVH, SDH, and DVST the significance multiplier is 1. Scores used in the analysis are derived from summated scores of all categories after application of the significance multiplier.