Therapeutic hypothermia in preterm infants under 36 weeks: Case series on outcomes and brain MRI findings

Perinatal hypoxic-ischemic encephalopathy (HIE) is a significant cause of neonatal brain injury. Therapeutic hypothermia (TH) is the standard treatment for term neonates, but its safety and efficacy in neonates < 36 weeks gestational age (GA) remains unclear. This case series aimed to evaluate the outcomes of preterm infants with HIE treated with TH.

Retrospective analysis of preterm infants (< 36w GA) treated with TH (01/2019-06/2024). Data on demographics, clinical complications, coagulation profiles, brain magnetic resonance imaging (MRI), and neurodevelopment outcomes were analyzed.

Seventeen patients were included (range 32.5-35.5w, median 34.4; birthweight range 1556-2493 g, median 2300 g), 58.8% were male. Placental abruption was identified in 7 cases (41.2%), and 8 (47.1%) required advanced resuscitation. Thirteen patients (76.5%) presented anemia, 12 (70.6%) coagulopathy, 9 (52.9%) thrombocytopenia, and 9 (52.9%) acute liver failure. Hypofibrinogenemia (< 1 g/L) was significantly associated with severe intracranial hemorrhage (ICH), defined as extracerebral, intraventricular or parenchymal hemorrhage causing mass effect. MRI findings were classified based on the predominant lesion: I- hypoxic-ischemic injury, II- severe ICH, or III- normal/mild findings. Severe ICH was the predominant lesion in 4 cases (23.5%). White matter injury was seen in 12 (76%). Death occurred in 8 cases (47.1%). Of the 9 surviving patients, at 2 years, 6 (66.7%) had normal neurodevelopment, while 1 (11.1%) had severe disability.

Coagulation abnormalities, particularly hypofibrinogenemia, significantly increase the risk of severe ICH in < 36w infants treated with TH. The safety and efficacy of TH in this population require further investigation.