Assessment of hearing organ activity in a group of neonates with central nervous system impairment

ObjectiveHypoxic-ischemic encephalopathy, primary subarachnoid hemorrhage in term newborns as well as periventricular leukomalacia and intraventricular hemorrhage in premature newborns are the major consequences of perinatal asphyxia. Intrauterine hypoxia and labor prolongation can also affect the hearing organ in newborns causing reversible or irreversible changes in the cochlea, brainstem or cortex.The aim of the study was to carry out the objective assessment of the cochlea and hearing pathway activity using CEOAEs and ABR; to find relationships between hearing status and parameters effecting on nervous system in neonates with central nervous system impairment occurring following perinatal asphyxia.MethodsTo the investigation 36 newborns with hypoxic-ischemic encephalopathy, periventricular leukomalacia or intraventricular hemorrhage were included. The control group encompassed 32 health newborns matched as to the age. In all newborns otoscopic examination, CEOAEs after birth and CEOAEs with ABR 3 months later were performed. Perinatal anamnesis, general pediatric status, results of trans-fontanel ultrasonography and biochemical test results were taken into account in statistical analyses.ResultsThe mean amplitudes of CEOAEs in the first days of life were significantly reduced in investigation group comparing to control babies. 3 months later the recorded responses significantly increased but did not reach values of control group. No differences were found between latencies of waves I and II. ABR latencies of waves III, IV, V and interpeak latencies I-III, III-V, I-V were delayed in investigation group when compared to control patients. Also morphology of ABR recordings in investigation group has slightly changed. Perinatal aspyxia leading to hypercapnia, low gestational age, prolonged artificial ventilation and meningitis were the main risk factors related to disturbances in ABR recordings.ConclusionsThe combined use of CEOAEs and ABR in neonates with central nervous system impairment involvement revealed the existence of abnormalities in cochlear micromechanics and retrocochlear auditory pathway. Etiology seems to be multifactoral.