Postnatal functional integrity of the brainstem auditory pathway in late preterm infants born of small-for-gestation age: how different from those born of appropriate-for-gestation.

It is unclear whether there is any postnatal abnormality in brainstem auditory function in late preterm small-for-gestational-age (SGA) infants. We investigated the functional integrity of the brainstem auditory pathway at 4 months after term in late preterm SGA infants and defined differences from appropriate-for-gestational age (AGA) infants. The maximum length sequence brainstem evoked response (MLS BAER) was recorded and analyzed in 24 SGA (birthweight < 3rd centile) infants and 28 AGA infants (birthweight > 10th centile). All infants were born at 33-36-week gestation without major perinatal and postnatal problems. We found that I-V interval in SGA infants was shorter than in AGA infants at higher click rates and significantly shorter at the highest rate of 910/s. Of the two smaller intervals, I-III interval was significantly shorter in SGA infants than in AGA infants at higher click rates of 455 and 910/s clicks, whereas III-V interval was similar in the two groups. The III-V/I-III interval ratio in SGA infants tended to be greater than in AGA infants at all rates and was significantly greater at 455 and 910/s clicks. The slope of I-III interval-rate functions in SGA infants was moderately smaller than in AGA infants.  Conclusions: The main and fundamental difference between late preterm SGA and AGA infants was a significant shortening in the MLS BAER I-III interval in SGA infants at higher click rates, suggesting moderately faster neural conduction in the caudal brainstem regions. Postnatal neural maturation in the caudal brainstem regions is moderately accelerated in late preterm SGA infants. What is Known: • At 40 weeks of postconceptional age, late preterm SGA infants manifested a mild delay in neural conduction in the auditory brainstem. What is New: • At 56 weeks of postconceptional age, late preterm SGA infants manifested moderately faster neural conduction in the caudal brainstem regions. • Postnatal neural maturation is moderately accelerated in the caudal brainstem regions of late preterm SGA infants.

Infants with neonatal Chronic Lung Disease are associated with delayed auditory conduction in the rostral brainstem after term.

AIMS: Very Low Birthweight (VLBW) infants with neonatal Chronic Lung Disease (CLD) have been found to have functional impairment of the brainstem auditory pathway at term. This study investigated the functional status of the brainstem auditory pathway in VLBW infants with CLD after term for any abnormality. METHODS: Fifty-two VLBW infants were recruited at 50 weeks of Postconceptional Age: 25 with neonatal CLD and 27 without CLD. None had any other major complications to minimize confounding effects. Brainstem Auditory Evoked Responses were studied at 21‒91/s click rates. RESULTS: Compared with those without CLD, VLBW infants with CLD had relatively shorter latencies of BAER waves I and III, associated with a slightly lower BAER threshold. Wave V latency and I‒V interpeak interval did not differ significantly between the two groups of infants. The I‒III interval in infants with CLD was shorter than in those without CLD at 91/s clicks. However, the III‒V interval was significantly longer than in those without CLD at all click rates (all p < 0.05). There were no significant differences in the amplitudes of BAER wave components between the two groups of infants. CONCLUSIONS: The main BAER abnormality in VLBW infants with CLD was a prolonged III‒V interval. Auditory conduction is delayed or impaired at more central regions of the brainstem in CLD infants. After term central auditory function is adversely affected by neonatal CLD. Monitoring post-term change is required to provide valuable information for post-term care of CLD infants.

Suboptimal postnatal function of brainstem auditory pathway in late preterm infants who do not have major perinatal and postnatal complications.

OBJECTIVES: To examine postnatal functional status of the brainstem auditory pathway in late preterm infants and detect any postnatal auditory abnormality. METHODS: Thirty preterm infants born at 33-36 weeks gestation were studied three months after term. None had major perinatal and postnatal complications to minimize confounding effects. Brainstem auditory evoked responses were recorded with 21-91/s clicks. RESULTS: Compared with postnatal age-matched normal term infants, the late preterm infants did not manifest any major abnormalities in brainstem auditory evoked responses at conventionally used 21/s clicks. At higher click rates, however, the late preterm infants manifested a moderate prolongation in BAER wave V latency. All interpeak intervals tended to be prolonged at higher click rates. The I-V interval was significantly prolonged at 51/s and particularly at 91/s clicks. Both the I-III and III-V intervals were significantly prolonged at 91/s. The late preterm infants also manifested reduced amplitudes of BAER waves III and V at most click rates. CONCLUSION: The central components of the brainstem auditory evoked responses were abnormal at higher click rates three months after term in the late preterm infants. Postnatal brainstem auditory function is suboptimal in late preterm infants without major complications. This suboptimal brainstem auditory function may not be clearly shown at term or an earlier stage, but can be shown later. Late preterm infants, although they may not have major complications, should be followed for later auditory development, providing valuable information for improving postnatal care.

Infants with neonatal Chronic Lung Disease are associated with delayed auditory conduction in the rostral brainstem after term

Abstract Aims Very Low Birthweight (VLBW) infants with neonatal Chronic Lung Disease (CLD) have been found to have functional impairment of the brainstem auditory pathway at term. This study investigated the functional status of the brainstem auditory pathway in VLBW infants with CLD after term for any abnormality. Methods Fifty-two VLBW infants were recruited at 50 weeks of Postconceptional Age: 25 with neonatal CLD and 27 without CLD. None had any other major complications to minimize confounding effects. Brainstem Auditory Evoked Responses were studied at 21‒91/s click rates. Results Compared with those without CLD, VLBW infants with CLD had relatively shorter latencies of BAER waves I and III, associated with a slightly lower BAER threshold. Wave V latency and I‒V interpeak interval did not differ significantly between the two groups of infants. The I‒III interval in infants with CLD was shorter than in those without CLD at 91/s clicks. However, the III‒V interval was significantly longer than in those without CLD at all click rates (all p < 0.05). There were no significant differences in the amplitudes of BAER wave components between the two groups of infants. Conclusions The main BAER abnormality in VLBW infants with CLD was a prolonged III‒V interval. Auditory conduction is delayed or impaired at more central regions of the brainstem in CLD infants. After term central auditory function is adversely affected by neonatal CLD. Monitoring post-term change is required to provide valuable information for post-term care of CLD infants.