Assistant Professor of Radiology University of California San Francisco University of California San Francisco Corte Madera, California, United States
Background: Mild HIE is increasingly linked to adverse outcomes. Whether therapeutic hypothermia (TH) is an effective treatment, and which clinical factors confer risk for brain injury, remain unclear.
Objective:
Design/Methods: At 9 U.S. hospitals in 2017-18, we prospectively diagnosed mild HIE defined as ≥ 1 Sarnat abnormality (consciousness, activity, tone, posture, primitive reflexes, autonomic) at 1-6 hours but not meeting criteria for mod/severe HIE; and neonatal acidosis or low Apgar. Brain MRIs were scored independently by 2 reviewers using a validated system1 with discrepancies resolved by consensus. We examined how MRI varied by clinical factors including TH. All subjects who did not receive TH were enrolled at a single site where TH is not used for mild HIE given lack of established evidence.
Results: Of 114 newborns with mild HIE (mean 39.3 weeks GA; pH 7.01; 5-min Apgar 4.7), 93 (82%) received TH. 67 (59%) had brain lesions on MRI at mean age 4.7 (SD 1.4) days. Median brain injury score was 4 (IQR 2-10, range 0-84). Mild injury (42%) was more common than moderate (12%) or severe (4%). Among 108 (95%) MRIs done at <11 days, timing of injury was acute (reduced diffusion, 32%), subacute (no reduced diffusion, 34%) or chronic (volume loss, 1%). Injury of different ages occurred in 14%. Parenchymal injury patterns (Table) were peripheral watershed (20%), punctate white matter (17%), central gray (16%), focal lesion (9%), arterial ischemic stroke (4%), hippocampal (2%) and atypical (18%). 21 (18%) had >1 injury pattern. 19 (17%) had mod/severe intraparenchymal, intraventricular or extra-axial hemorrhage. Clinical chorioamnionitis, seen in 38%, was associated with higher injury score (median 10.2 vs. 6.4, p=0.04) and demonstrated a trend toward higher rate of acute injury (42% vs 25%, p=0.07). Sentinel event, lowest pH and Apgar were not associated with severity or acuity of brain injury. An abnormal MRI was equally common in those with ≥1, ≥2 and ≥5 Sarnat findings (57-59%). Subjects treated with TH did not differ significantly from the untreated group in rate of abnormal MRI (56% vs. 71%, p=0.19), median injury score (4 vs. 6, p=0.95) or injury severity (Table). Peripheral watershed injury was less common in those who received TH (14% vs. 48%, p=0.001). Conclusion(s): Chorioamnionitis may be associated with more severe and acute brain injury in mild HIE. Subacute lesions are common. Future neuroprotective treatments for mild HIE will ideally target both acute and subacute injury mechanisms.
Authors/Institutions: Yi Li, University of California San Francisco, Corte Madera, California, United States; Jessica L. Wisnowski, Children's Hospital Los Angeles, Los Angeles, California, United States; Lina F. Chalak, ut southwestern medical center, Dallas, Texas, United States; Amit Mathur, Saint Louis University School of Medicine, St. Louis, Missouri, United States; Robert C. McKinstry, Washington University, Saint Louis, Missouri, United States; Genesis Licona, Vanderbilt University Medical Center, Nashville, Tennessee, United States; Dennis E. Mayock, University of Washington, Seattle, Washington, United States; Taeun Chang, Children's National Medical Center, Washington, District of Columbia, United States; Krisa P. Van Meurs, Stanford University, Palo Alto, California, United States; Tai-Wei Wu, Children's Hospital Los Angeles, Los Angeles, California, United States; Kaashif A. Ahmad, Pediatrix Medical Group & Baylor College of Medicine, San Antonio, Texas, United States; Amy Goodman, University of California, San Francisco, San Francisco, California, United States; Yvonne W. Wu, UCSF, San Francisco, California, United States
