Depressed brainstem auditory electrophysiology in preterm infants after perinatal hypoxia–ischaemia

Abstract

Our understanding of pathophysiology of hypoxic–ischemic brain damage in preterm infants remains very limited. We studied the amplitudes of brainstem auditory evoked response, recorded with 91–910/s clicks, at term in preterm infants after perinatal HI for functional status of the auditory brainstem. Compared with age-matched healthy preterm infants, the preterm infants after HI did not show any major abnormality in waves I and III amplitudes at any click rates. However, wave V amplitude was reduced significantly at 227 ( P < 0.05), 455 and 910/s (both P < 0.01). V/I amplitude ratio was slightly reduced at 455 and 910/s. Compared with normal term infants, waves III amplitude in the preterm infants after HI tended to be reduced at all click rates, and differed significantly the highest rate 910/s ( P < 0.05). Wave V amplitude was significantly reduced at higher click rates (455 and 910/s, P < 0.05 and 0.01). V/I amplitude ratio was slightly reduced at 455 and 910/s. The reduction of wave amplitudes generally became more significant with the increase in click rate. The slopes of III–V interval-rate function, and wave V amplitude–rate function were significantly steeper than in both the healthy preterm infants and the term infants. Thus, the major abnormality in the preterm infants after HI was a significant reduction in wave V amplitude that mainly reflects central auditory or brainstem function. Brainstem auditory electrophysiology is depressed and so brainstem auditory function is impaired in preterm infants after perinatal HI.