Abnormal auditory brainstem response among infants with prenatal cocaine exposure.

OBJECTIVE: To determine the auditory brainstem response (ABR) patterns in infants with prenatal cocaine exposure as detected by meconium analysis.

METHODS: Meconium drug analysis was done on term infants who were at risk for antenatal illicit drug exposure. Infants who tested positive for cocaine served as the exposed group; those who tested negative served as control subjects. An ABR was done on the infants within 6 days of life. Absolute latencies at 40 and 70 decibels (dB) of waves I, III, and V and interpeak latencies between I and III, III and V, and I and V were measured.

RESULTS: Among 58 infants in the study, 21 (35.6%) were positive, by meconium analysis, for cocaine and 5 (8.5%) were positive for cannabinoids. Four infants tested positive for cocaine, although their mothers denied illicit drug use. There was a significant difference in mean maternal age, gravidity, parity, birth weight, and head circumference among cocaine-exposed versus nonexposed infants. The ABR from cocaine-positive infants showed significantly prolonged mean absolute latencies in both ears as compared with nonexposed infants: right ear at 40 dB III (4.823 vs 4.447 milliseconds), 40 dB V (7.400 vs 6.968 milliseconds), 70 dB I (2.111 vs 1.631 milliseconds), and 70 dB III (4.122 vs 3.821 milliseconds); left ear at 40 dB III (4.820 vs 4.444 milliseconds), 40 dB V (7.460 vs 6.860 milliseconds), 70 dB I (2.063 vs 1.741 milliseconds), 70 dB III (4.026 vs 3.656 milliseconds), and 70 dB V (6.568 vs 6.258 milliseconds). The interpeak latency was not significantly different except in 1 cocaine-positive infant: left ear at 40 dB III to V (2.667 vs 2.417 milliseconds).

CONCLUSION: The ABR in neonates who are exposed prenatally to cocaine shows prolonged absolute peak latencies compared with nonexposed neonates and may indicate compromise of the auditory system from gestational exposure to cocaine that will need additional audiologic follow-up. Meconium analysis can more accurately detect the infants who are at risk.