Electrophysiological Threshold Evaluation in Infants with and Without Risk Indicators for Hearing Loss

Introduction: The brainstem auditory evoked potential is used to determine the electrophysiological threshold and assessing the integrity of the auditory system. This test is sensitive to the auditory nerve maturation and brainstem; therefore, the electrophysiological threshold may change throughout child development. Objective: to evaluate the changes in the electrophysilogical threshold of brainstem auditory evoked potential in two months of follow-up. Methods: A single non-concurrent cohort study was performed in a public hospital during January 2013 to January 2015. The brainstem auditory evoked potential was performed in all neonates in two moments with electrophysiological thresholds measured in the both ears, whose results were categorized into degree: mild, moderate, severe and profound. Results: Forty-three infants of both genders, 11 with prematurity and 14 with risk indicators for hearing loss participated in the study. In the first brainstem auditory evoked potential, with an average age of two months, 34 infants had abnormal results in the right ear and 31 in the left ear. In the second brainstem auditory evoked potential, with na average age of four months, normalization was observed in 38% of the results obtained in the right ear and in 42% on the left ear. This significant change in brainstem auditory evoked potential thresholds was found in those with mild and moderate degrees. Conclusion: There were changes in the electrophysiological brainstem auditory evoked potential thresholds in infants with a mild and moderate degree, while those with a severe and profound degree the results were permanet at two months of follow-up.