FACTORS ASSOCIATED WITH HEARING IMPAIRMENT IN INFANTS WHO RECEIVED THERAPEUTIC HYPOTHERMIA

Birth asphyxia and hypoxic-ischemic encephalopathy (HIE) are among the leading causes of neonatal brain injury. Therapeutic hypothermia (TH) reduces the risk of death or severe disability at 18–24 months of age in infants with severe asphyxia. However, a significant proportion of survivors remain at higher risk of long-term complications, including hearing impairment. Currently, the incidence of hearing disorders in children after TH, considering various technical modalities, remains insufficiently studied. Therefore, this study aimed to determine the frequency of hearing impairment in infants treated with TH simple cooling methods and to identify risk factors for sensorineural hearing loss (SNHL) in infants with HIE. Materials and methods. A retrospective cohort clinical study was conducted, comprising 82 infants in their first year of life (51 males [72.2%] and 31 females [37.8%]) who experienced severe birth asphyxia and underwent therapeutic hypothermia (systemic hypothermia utilizing simple cooling methods) between 2020 and 2023. Inclusion criteria were defined as follows: therapeutic hypothermia administered postnatally according to established indications (gestational age ≥35 weeks; evidence of perinatal depression [Apgar score <6 at 10 minutes postpartum or requirement for primary resuscitation lasting ≥10 minutes]; presence of moderate-to-severe hypoxic-ischemic encephalopathy [as classified by the modified Sarnat staging system] within 1-6 hours after birth). Exclusion criteria encompassed: gestational age <35 weeks, congenital malformations, confirmed genetic abnormalities, progressive obstructive ventriculomegaly, previous central nervous system infections, and neonatal hemolytic disease. A three-phase audiological screening protocol was implemented (initial two phases employing transient evoked otoacoustic emissions, followed by comprehensive diagnostic audiometry in the third phase). Statistical analyses included methods for evaluating dichotomous outcomes (two-tailed Fisher's exact test, χ² test), comparison of continuous variables between independent cohorts, and nonparametric analyses for small sample sizes (Mann-Whitney U test). The predetermined significance threshold (α-level) for all analyses was p < 0.05. This investigation was conducted as part of the Department of Pediatrics and Neonatology's research initiative entitled "Diagnostic and Therapeutic Approaches to Pediatric Disorders: A Patient Safety Perspective" (State Registration No. 0121U114304). The study protocol received ethical approval from the Dnipro State Medical University's Ethics Committee. Results. Adverse outcomes of hypoxic-ischemic injury, manifested as destructive cerebral tissue changes and diagnosis of cerebral palsy, were observed in 6 cases (7.3%). Abnormal otoacoustic emission results during the second screening phase were detected in 7 infants (8.5%). Sensorineural hearing loss (SNHL) was diagnosed in 6 patients (7.3%), with these findings demonstrating no statistically significant divergence from comparative studies where therapeutic hypothermia with simple cooling methods was not specified (p > 0.05). Among SNHL cases, 4 exhibited post-ischemic cerebral lesions while 2 demonstrated moderate lateral ventricular dilatation. Infants with SNHL required significantly prolonged respiratory support (8 (4-26; 7-14) vs. 14.5 (13-29; 13.5-22) days, p < 0.05), extended intensive care unit hospitalization (25 (9−106; 19−33) vs. 29 (15-85; 21-37) days, p < 0.05), and delayed initiation of oral feeding (7 (2-25; 5-9) vs. 19 (11-22; 19-21) days, p < 0.1). This cohort demonstrated significantly elevated incidence rates of primiparous delivery (p < 0.05), cesarean delivery requirement, cardiopulmonary resuscitation with cardiac massage and medication administration during initial stabilization, need for postpartum hemodynamic support, and neonatal sepsis occurrence. A markedly higher prevalence of short-term adverse outcomes from asphyxia and hypoxic-ischemic encephalopathy at discharge was documented (2.7% vs. 66.7%, p < 0.05). Conclusions. The incidence of auditory impairment following therapeutic hypothermia utilizing simple cooling methods demonstrated no significant variation from studies employing unspecified cooling techniques. Principal risk factors for hearing dysfunction included severity of birth asphyxia, degree of postnatal clinical compromise, extent of cerebral tissue injury, and occurrence of postnatal infectious complications.