Potencial evocado auditivo de tronco encefálico e de estado estável com estímulo clique na triagem auditiva em lactentes

Abstract

Introduction Conventional (ABR) or automatic (AABR) auditory brain responses is an electrophysiological method used in auditory screening, mainly in newborns with hearing loss risk indicators. Studies indicate that click stimulus used in auditory steady state response (ASSR) can quickly detect the presence of response at low intensities as well as can simultaneously stimulate both ears. The procedure could then be useful in newborn auditory screening (NAS). Objective To describe and to compare the results of pass and refer as well as the duration of the hearing screening in infants by the use of ABR, AABR and ASSR with click stimulus techniques at 30 and 35dBHL intensities. Methods Once referred from public hospitals for hearing screening, 30 infants with hearing loss risk indicators aging from 10 to 97 days were evaluated. ASSR and ABR techniques were performed at 30 and 35dBHL intensities. The AABR one was held at 35dBHL. In ASSR 11 infants underwent binaural stimulation and 19 infants, the mononaural one. Those who failed could be reevaluated. The duration of each of the techniques was also analysed. Results The AABR technique showed that 28 (93.3%) infants passed in both ears and 2 (6.7%) had bilaterally failed. The meantime of test duration was nearly 1.8 minutes for right ear(RE) and 2.1 minutes for left Ear (LE). For ABR at 30dBHL , 27 (90%) subjects passed in both ears, 2 (6.7%) failed bilaterally and only 1 (3.3%) failed unilaterally. At 35dBHL, 26 (86.7%) passed in both ears, 2 (6.7%) failed unilaterally and 2 (6.7%) failed bilaterally. The meantime of test duration was nearly 2.4 minutes for each ear, at both intensities. For ASSR at 30dBHL, 26 (86.6%) infants passed in both ears and 4 (13.3%) failed unilaterally. The average test duration in monoaural evaluation was nearly 2.3 minutes in RE and 2.5 minutes in LE. In binaural evaluation the average duration was 3.1 minutes. At 35dBHL, 25 (83.3%) infants passed in both ears and 5 (16.7%) failed unilaterally. For RE evaluation the average duration was 2.2 minutes and for LE it was 2.1 minutes. When performed the binaural test, the average duration was 3.7 minutes. At 30 dBHL, results suggest agreement for both tests. As to the duration, no significant difference was detected between ABR and ASSR values. At 35dBHL most individuals showed concordant results when compared in twos. In duration assessment the lowest mean and median values were observed in AABR test and the highest in ASSR binaural. Most subjects who passed in ASSR were evaluated only once. There was no association between the results and gestational age at both intensities. Conclusion There was a clear agreement between ABR and ASSR results at 30dBHL; AABR and ABR techniques showed strong concordant results at 35dBHL and no significant differences were detected among the three techniques as to the test duration. Additional investigations on ASSR in NAS are needed so that the technique can be improvingly adjusted