Repeated courses of antenatal corticosteroids: Are there effects on the infant's auditory brainstem responses?

Abstract

Our objective was to assess the effects of repeated antenatal corticosteroid treatments on the neonatal auditory brainstem response (ABR), a sensitive measure of neonatal brain maturity and auditory function. To achieve this, we performed and blindly evaluated neonatal ABRs on a subset of infants delivering within a multicenter randomized placebo-controlled clinical trial comparing single versus repeated courses of antenatal corticosteroid treatments for women at 23–31 weeks gestation who remained at increased risk for preterm birth. The women were randomly assigned to either the single or the repeated antenatal corticosteroid treatment group. Women in the repeated antenatal corticosteroid group received weekly antenatal corticosteroid treatments until 34 weeks gestation or until they reached a study-determined limited number of courses, whereas women in the single antenatal corticosteroid group received an initial course of corticosteroid followed by weekly placebo injections. We performed ABR testing on their infants prior to discharge. The latencies of waves I, III and V and the peak-to-trough amplitudes of waves I and V were compared between those in the single (n=27) and repeated antenatal corticosteroid treatment (n=24) groups. The majority of repeated antenatal corticosteroid infants (20 of 24) were exposed to ≥4 antenatal corticosteroid treatments. Even though gestational age was similar between our subset of single and repeated antenatal corticosteroid treatment groups, infant birth weight and length and head circumference were significantly smaller in the repeated antenatal corticosteroid group (p<0.05). Despite these differences in birth sizes, there were no significant group differences in the ABR wave latencies or amplitudes. We concluded that our repeated antenatal corticosteroid treatments, in comparison to a single treatment, did not significantly benefit or harm the neonatal ABR despite significant effects on birth size.

Antenatal factors modulate hearing screen failure risk in preterm infants

“…According to Waters et al ,29 antenatal steroid exposure did not affect hearing screen outcomes in VLBW infants. Multiple courses compared with a single course of betamethasone did not impact ABRs in exposed infants30 31 or hearing outcomes at age 5 years 32. However, Lee et al 33 observed that prenatal betamethasone reduced the risk for hearing impairment, but prenatal dexamethasone increased the risk for hearing impairment at 18–22 months’ adjusted age in extremely low birthweight infants.…”

Repeated antenatal corticosteroid treatments adversely affect neural transmission time and auditory thresholds in laboratory rats

“…In one regimen, AC therapy is given only once; whereas in the others, AC therapy is repeated weekly [19,95,96], biweekly [1] or twice [3] from as early as 23 weeks to as late as 32 weeks of gestation. Some pregnant women have received as many as 9 treatment courses of 2 injections per course for a total of 18 AC injections [19,95,96]. Yet, there is concern that repeated AC treatment harms infant development if too much is given [67].…”

“…Yet, there is concern that repeated AC treatment harms infant development if too much is given [67]. For example, human studies found that repeated AC treatments reduced birth weights and/or head circumferences [19,35,95,96], reduced brain cortex convolutions [65], decreased placental growth [83], increased the incidence of cerebral palsy [95], and caused attention problems at 2 years of age [25]. One study reported that merely two AC courses perturbed respiratory adaptation in preterm infants [70].…”

“…Similarly, repeated courses of postnatal corticosteroids can cause brain pathology, cerebral palsy and/or neurodevelopmental problems in children [8,57,66,69,86,99]. In contrast, some human studies on repeated AC treatment found no significant effects on birth weights and/or head circumferences [31,88], neurodevelopmental behavior [57] or neural transmission time as evidenced by the auditory brainstem response (ABR) [4,5,19]. …”

“…The ABR is a sensitive measure of brain development and sensory function that is used to assess hearing and neurological function [13,16-19,21]. It is also an indirect measure of brain myelination [82].…”