Stability of ABR Wave V Threshold in EarlyHearing Diagnostics in Children from SelectedGroups at Risk of Congenital Hearing Loss

Introduction: Upon hearing that the "little" patient has trouble with hearing, we are mostly interested in the level of his hearing threshold. When the child is in the first year of life, results can only be achieved by means of ABR test. Subsequent control tests, especially in children from the hearing loss risk groups selected in this study, show that the obtained outcomes are subject to fluctuations. Their fluctuating nature is manifested by the instability of wave V threshold in subsequent diagnostic periods. Such variability often delays the implementation of the appropriate proceeding. Knowledge of the dissimilarity of behavior of the wave V threshold occurring in individual groups at risk of hearing loss allows for the correct interpretation of the obtained results, and thus, effective therapeutic measures. Aim: The aim of the paper is to analyze the stability of wave V threshold during the first year of life in children from selected risk groups for congenital hearing disorders. Material and methods: From the patient population of 2,114 individuals examined in 2015-2016 at a reference center participating in the Universal Neonatal Hearing Screening Program in 2015-2016, the results of 250 children were subjected to retrospective analysis. Furthermore, 4 groups of little patients were formed (children with Down syndrome; children with other diseases or damage to the nervous system; children with cleft palate or cleft lip and cleft palate; children with congenital cytomegaly) in whom diagnostic practice revealed variable results of the wave V threshold. We analyzed the results of tests obtained during the first year of the child's life divided into 4 diagnostic periods. Results: The highest percentage of instability in the established threshold of wave V between individual diagnostic periods occurred in the group of children with cleft palate or cleft lip and cleft palate. In the group of children with Down syndrome, it was observed that the instability of the ABR test results decreased over time. In the group of children with other diseases or damage of the nervous system, the highest percentage of the lack of stable ABR wave V thresholds was observed between the 1st and 2nd as well the 1st and 4th diagnostic periods. On the other hand, in the group of children with congenital CMV, there was a relatively low percentage of instability of results. Conclusions: (1) Although the ABR test is a diagnostic standard, in particular groups of patients the study is burdened with high variability of measurement results in subsequent diagnostic periods. Such a group of patients are children with cleft palate or cleft lip and cleft palate; therefore, it must receive particular attention in treatment planning; (2) in selected groups at risk of hearing loss, due to the high percentage of children with hearing impairment (70%), the validity of performing newborn hearing screening tests was confirmed.