612 - Do neonatal respiratory morbidities influence hippocampal development in preterm-born infants?

Poster Number: 612
Publication Number: 612.1471

Background: Infants born very preterm [VPT] ( < 32 weeks gestational age [GA]) enter the extra-uterine environment with underdeveloped lungs and immature respiratory control centers, putting them at high risk for in-hospital respiratory morbidities [RM], including prolonged respiratory support [RS], prolonged oxygen therapy, and severe cardiorespiratory events [CREs] characterized by apneas, bradycardias, and/or desaturations requiring intervention. Prior animal and histological studies have highlighted the susceptibility of the hippocampus, particularly the CA1 region, to fluctuations in cerebral oxygenation. Whether RM-specific CA1 alterations can be detected in infants born VPT remains to be determined.

Objective: To fill this gap, this study aims to examine the relationships between RM and bilateral CA1 volumes at term-equivalent age [TEA] in infants born VPT using quantitative magnetic resonance imaging [MRI]. Associations between RM and remaining hippocampal subfields will also be explored as a secondary objective.

Design/Methods: In this ongoing prospective study, participants complete a brain MRI at TEA. Total duration of RS, O2 therapy, and cumulative number of severe CREs from birth until TEA were extracted from infants' medical records. Total volume from the hippocampus and from 7 subfields (i.e., subiculum, CA 1 to 4, dentate gyrus [DG], and Stratum Radiatum, Lacunosum, and Moleculare [SRLM]) were obtained using ‘Hippunfold’, a validated automatic segmentation pipeline. Multiple linear regression analyses were performed to determine the effects of each RM on bilateral CA1 volumes, while controlling for GA at birth and at MRI. Additional models were developed for the other subfield volumes.

Results: To date, a total of 36 VPT infants were analyzed, with a median GA at birth of 28.43 weeks and birth weight of 1205g. The median O2 duration was 61 hours, RS duration was 815.5 hours, and the cumulative number of CREs was 49 (Table 1). After adjusting for GA at birth and at MRI, higher number of CREs was significantly associated with smaller bilateral CA1 volumes at TEA (left: p=0.03; right: p=0.008; Fig. 1), as well as smaller right CA2/CA3 (p=0.02) and right total hippocampus volumes (p=0.02). RS duration and O2 therapy duration were not significantly associated with hippocampal volumes.

Conclusion(s): VPT infants' hippocampal development may be vulnerable to recurrent severe CREs during the neonatal period, particularly affecting bilateral CA1 region. Upcoming analyses in a larger sample size will allow the addition of more clinical variables in our models to better understand these complex associations.