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Auditory brainstem responses in preterm neonates: maturation and follow-up
Insights
Auditory brainstem response (ABR) screening in neonatal intensive care units (NICUs) may not be effective. Most infants failing the ABR test due to prematurity, with few confirmed cases of hearing loss.
Area of Science:
- Neonatal Medicine
- Audiology
- Neuroscience
Background:
- Neonatal intensive care units (NICUs) care for premature infants at high risk for hearing impairment.
- Auditory brainstem response (ABR) screening is commonly used to detect hearing deficits in this population.
Purpose of the Study:
- To evaluate the effectiveness of ABR screening in NICU patients.
- To determine the correlation between ABR test results and postconceptual age (PCA).
Main Methods:
- Seventy-five NICU patients underwent ABR screening at 40 dB and 70 dB.
- Presence of wave V was the criterion for passing the ABR test.
- Follow-up hearing tests or historical data were collected for infants who failed the screening.
Main Results:
- ABR test results were strongly correlated with PCA; passing at 70 dB occurred at 32 weeks PCA, and at 40 dB occurred at 40 weeks PCA.
- 44 infants failed the ABR screen before NICU discharge.
- Most failures were attributed to prematurity, with only one confirmed case of severe hearing loss among survivors.
Conclusions:
- The high failure rate of ABR screening in NICU infants appears primarily due to physiological immaturity.
- The effectiveness of routine ABR screening in the NICU setting is questionable.
- Further research is needed to refine hearing assessment protocols for premature infants.
Abstract:
Seventy-five neonatal intensive care unit patients with given auditory brainstem response screening tests at 40 db and 70 db above the normal adult hearing threshold. The presence of wave V, the criterion for pass, was strongly related to postconceptual age: It appeared at 70 db in 50% of the infants tested at 32 weeks' PCA and at 40 db in 50% of the infants tested at 40 weeks' PCA. Forty-four infants failed the last test before NICU discharge (15 at 70 db and 29 at 40 db), but most infants were discharged at a PCA of less than 40 weeks. No significant correlation appeared between ABR test failure and intraventricular hemorrhage, hyaline membrane disease, perinatal asphyxia, hyperbilirubinemia, or aminoglycoside therapy. Follow-up information was obtained in 23 of the 36 "failing" infants who survived (8 died). This consisted of definitive hearing tests in ten patients and historical information supporting normal auditory function in 13 patients. One case of severe hearing loss was confirmed. Thus, most failures of the ABR screen apparently resulted from immaturity. These data raise doubts regarding the effectiveness of ABR screening in the NICU.