Maximum length sequence brainstem auditory evoked response in low-risk late preterm babies

Objectives. Recent research indicates that there is delayed development in the more central part of the auditory brainstem in very preterm babies. We aimed to study whether this is also the case for late preterm babies. Methods. The maximum length sequence brainstem auditory evoked response (MLS BAER) was used to study functional status of the auditory brainstem. Babies born at 33--36 week gestation and without any major perinatal complications were recruited. MLS BAER was recorded and analyzed at term age. Results. No significant correlation was found between most MLS BAER variables and physiological factors (gender, postconceptional age, bodyweight, and head circumference obtained at time of testing). Wave latencies and amplitudes, and I--V and I--III intervals in the preterm babies were essentially similar to those in the term controls at all click rates. However, III--V interval increased significantly at 227--910/s clicks (p < 0.05--0.01). All latencies, amplitudes and intervals correlated significantly with click rates (all p < 0.001). No differences were found in the slopes of MLS BAER variables--rate functions between the later preterm babies and term controls. Conclusions. Babies born at 33--36 weeks gestation without major complications had an increased III--V interval at high-rate stimulation. This suggests that late preterm babies have a mild delay in neural conduction in the more central part of the auditory brainstem.