P2.G130: Hypoxic-Ischemic Encephalopathy and Infantile Cerebral Palsy: A Comprehensive Examination of Perinatal Factors and Outcomes in an Irish Cohort

Background: Hypoxic ischemic encephalopathy (HIE) is a clinical diagnosis made when manifestations indicate brain dysfunction. HIE is a serious birth complication with limited diagnostic and therapeutic interventions and presents with clinical symptoms such as seizures, hypotonia, and depressed levels of consciousness that can last between 2-14 days. Magnetic resonance imaging (MRI) is the imaging modality of choice. The severity of HIE is quantitatively assessed using the Sarnat grading system, which categorizes the condition into three severity levels, from Grade 1 to Grade 3. The current standard of care for HIE is to apply moderate therapeutic hypothermia (TH) to maintain body temperature between 33-34 ºC. Surviving infants have an increased risk of developing cerebral palsy (CP) (2/1000). This study examines the relationship between HIE and CP in an Irish infant cohort.

Methods: We retrospectively reviewed the data of 60 neonates (50 Grade 2 HIE, 10 Grade 3 HIE) born between 2018 and 2022 in the Department of Neonatology, Rotunda Hospital, Dublin, Ireland. Perinatal factors, including gestational age, birth weight, HIE grade, cranial abnormalities, CP incidence, and age at diagnosis, were examined using medical charts, cranial ultrasounds, MRI reports, and clinical follow-up records. Data were organized in Excel and summarized in tables to analyze associations between HIE and CP.

Results: CP prevalence was 25% (15/60) with HIE grade 2 accounting for 80% (12/15) of cases. CP incidence was lower in HIE grade 2 patients receiving TH (21.3% (10/47) vs. 66.7% (2/3) without TH) (Table1). HIE grade 2 peaked in gestation week 39 (32%) and HIE grade 3 peaked in week 40 (40%). CP prevalence varied across HIE grades and years, with high rates in 2020 and 2021 returning to baseline in 2022.
In neonates with HIE, those without CP had higher average birthweights compared to those with CP. In neonates with HIE, CP prevalence was higher in those exhibiting abnormal findings on cranial ultrasound (47%) and MRI (34%), compared to neonates with normal imaging results (12% for ultrasound and 10% for MRI) (Table 2).

Conclusion: This study demonstrates a significant prevalence of CP (25%) in the studied population, primarily driven by HIE grade 2 cases, underscoring HIE's impact on CP development. TH significantly reduced CP incidence in Grade 2 HIE, highlighting its use as a critical therapeutic strategy. The variations in CP prevalence across HIE grades and years, with peaks in 2020 and 2021, pointed to external factors influencing these trends and emphasize the need for continued monitoring and intervention. Lower birth weights and imaging abnormalities associated with increased CP risk in HIE have important implications for clinical practice and future research. These findings necessitate further research into the prenatal, perinatal, and postnatal determinants of CP in HIE, to improve prevention, intervention, and neonatal care.