Electrophysiological and behavioral methods in early detection of hearing impairment

Background. Recent advances in neonatal life-support systems have contribut ed to the survival of high-risk newborns. However, protection of the audito ry system and the pre vention of sequelae is still paramount in neonatal ne urology. The aim of this study was to compare auditory-evoked responses wit h a toy test and acoustic reflex in the early detection of hearing loss in infants. Methods. Three groups were studied. The first was composed of infants showi ng less than a 30 dB biaural threshold in the neurophysiological test. The second group was made up of infants showing peripheral alterations on one s ide or both ears. The third group was comprised of infants who showed no re sponses at 95 dB HL in both ears after neurophysi ological testing. The neu rophysiological test, toy test, and acoustic reflex were performed on the s ame day, with masked results given to each investigator. Sensitivity and sp ecificity for each toy test and acoustic reflex were calculated afterward. Results. Forty-five controls, 44 peripheral alterations, and 8 non-response infants were studied. Most patients studied were born prior to the 37(th) week of gestation with a birthweight of less than 2,250 g, received require d administration of potential ototoxic drugs and mechanical ventilation, an d showed hyperbilirubinemia and hypoxia. Sensitivity for each toy was as fo llows: drum 0.54; wooden rattle 1.0, and metallic ratle 0.88. Specificity w as 0.95, 1.0, and 1.0, respectively. Acoustic reflex sensitivity was 0.38 a nd specificity was 0.97. Conclusions. Results suggest that the wooden and the metallic rattles of th e toy test can be useful tools in the study of hearing in the high-risk inf ant and deserve more attention in future studies. (C)2000 IMSS. Published b y Elsevier Science Inc.