ABR latency in infants: properties and applications of various measures.

ABR latency ratios have been proposed as useful clinical tools in the assessment of infants at risk for auditory or neurologic deficits. These parameters, together with classical absolute and interwave latency measures, were examined in 131 infants with normal ABR thresholds at 48-64 weeks post-conceptional age, and with no conventional risk factor for hearing impairment or neurological abnormality. Latency of wave I is unaffected by age or gender, but that of waves III and V decreases linearly with age and is smaller in females. These effects must be accounted for in clinical evaluation. However, latency ratios V/I, V/III and III/I show no significant age or gender effects. Wave I latency and the V/I latency ratio both permitted very good discrimination between normal infants and those with presumed conductive hearing losses, but the effects of sensorineural impairment have yet to be determined. On a priori grounds it seems improbable that latency ratios will outperform classical ABR parameters, at least for the goals and age range considered in this study.