NEONATAL, AUDITORY BRAIN-STEM RESPONSES RECORDED FROM 4 ELECTRODE MONTAGES

Simultaneous auditory brainstem responses (ABRs) to click stimuli at 3 0 and 60 dB nHL were recorded from 16 full term neonates with four ele ctrode arrays: vertical (Cz-Nape of neck), ipsilateral (Cz-Mi), contra lateral (Cz-Me), and horizontal (Mc-Mi). Results indicated that ABR wa veforms were morphologically similar to those recorded in adults: Wave s I, III, and V were clearly identifiable and of the same polarity in 15 of 16 subjects 60 dB nHL and Wave V was clearly identifiable in 14 of 16 subjects at 30 dB nHL. Although ABR waves were identified in mos t cases, waveforms expression was variable with different electrode re cording montages. It is suggested that if a clinician must choose one montage array for recording neonatal ABRs at high intensity levels for neurodiagnostic evaluations, the ipsilateral recording array is indic ated since it displays the highest expression of wave components. For screening applications or threshold searching at lower stimulus levels , however, either the ipsilateral or vertical montage would be justifi ed. Further, caution should be employed when interpreting ABR results in neonates recorded with unconventional montages due to the variable expression of wave components.