The effect of stimulus level on click evoked oto-acoustic emissions and brainstem responses in neonates under intensive care.
Click evoked oto-acoustic emissions (EOAE) at a range of stimulus levels and the auditory brainstem response (ABR) threshold have been measured in 40 infants admitted to a neonatal intensive care unit (NICU). The stimulus levels at which the emissions were first observed had a similar mean value and distribution to those found in previous studies on normal newborns and young adult volunteers. The difference was in the proportion who had no detectable emissions, 16.7% as against 3.9% in the normal newborns and 2.6% in young adult volunteers. The distribution of thresholds for the ABR was again similar to those measured on normal newborns but 8.1% of the ears of the NICU infants had a threshold worse than 53 dBnHL compared with 0% for the normal newborns. A combined screening method starting with the click evoked oto-acoustic emission is proposed. A comparison of the mean ABR thresholds for those in whom an EOAE was recorded to those with no EOAE showed a group effect. The stimulus latency relationship of the NV peak showed too much variation between individual results to consider its use to define accurately the degree of conductive hearing loss.
Stevens
J C
JC
Department of Medical Physics and Clinical Engineering, Royal Hallamshire Hospital, Sheffield, UK.
Webb
H D
HD
Smith
M F
MF
Buffin
J T
JT
D000161:Acoustic Stimulation; D001309:Auditory Threshold; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006311:Hearing Disorders / Q000175:diagnosis; D006801:Humans; D007231:Infant, Newborn; D015931:Intensive Care, Neonatal; D008297:Male; D011446:Prospective Studies