Brain Immaturity on MRI is Associated with Pre- and Postoperative Brain Injury in Neonates Undergoing Cardiac Surgery

  • Dr Dean Andropoulos, Texas Children's Hospital/Baylor College of Medicine, United States
  • Dr Jill Hunter, Texas Children's Hospital/Baylor College of Medicine, United States
  • Dr David Nelson, Texas Children's Hospital/Baylor College of Medicine, United States
  • Dr Stephen Stayer, Texas Children's Hospital/Baylor College of Medicine, United States
  • Dr Ann Stark, Texas Children's Hospital/Baylor College of Medicine, United States
  • Dr Emmitt McKenzie, Texas Children's Hospital/Baylor College of Medicine, United States
  • Dr Jefrey Heinle, Texas Children's Hospital/Baylor College of Medicine, United States

    • Introduction: Full-term neonates with CHD have brain immaturity on MRI scans.(1,2) This may explain the vulnerability of these neonates to injury. We hypothesized that neonates with brain immaturity are more likely to have both pre- and postoperative brain injury.

    Methods: 68 neonates with CHD, 35+ weeks gestational age, had pre-, and 7-day postoperative MRI. Brain abnormality score was calculated, including white matter injury (WMI), infarction, and hemorrhage. Brain maturity was assessed from T1 and T2-weighted MRI using the Total Maturity Score of Childs(3) scoring 4 features: myelination, cortical infolding, germinal matrix, and bands of migrating glial cells.

    Results: Birthweight was lower in single ventricle patients, but there was no difference in gestational age, head circumference, or TMS for the entire group. (Table).

    Seven of 13 patients with TMS ≤ 10 (equal to brain maturity of 35 weeks gestational age or less) had postoperative brain injury score ≥6(moderate injury), vs. only 10 of 54 with TMS > 10. (p=0.01). Preoperative WMI was more likely with TMS <10 (5/13 vs. 6/55, p=0.03), as was postoperative WMI (6/13 vs. 9/54, p=0.05).

    Discussion: Neonates with CHD who have a structurally immature brain are more likely to have both pre- and postoperative WMI, and moderate or severe postoperative brain injury score. This could explain the high rate of WMI in these patients, as the brain in CHD shares features with the premature neonates, who also has a high rate of WMI.

    References:
    1. Licht DJ. JTCVS 2008; in press.
    2. NEJM 2007;357:1928
    3. AJNR 2001;22:1577

    Parameter Single Ventricle, n=36 Two Ventricle, n=32
    Birthweight (kg) 3.01 ± 0.33 3.27 ± 0.56*
    Gestational age (weeks) 38.3 ± 1.3 38.8 ± 1.4
    Head circumference (cm.) 33.2 ± 1.7 33.9± 1.3
    MRI Total Maturity Score (TMS) 11.8 ± 1.5 11.8 ± 1.0
    Patients with TMS ≤ 10, no., (%) 8 (22) 6(19)
    Preoperative total MRI abnormality score 1.8± 2.6 2.3± 2.8
    7-day postoperative total MRI abnormality score 3.8± 4.2 3.2± 3.7