A study of effect of aminoglycoside therapy on auditory brainstem evoked responses in preterm and term neonates

Background: Aminoglycosides are widely used drugs in neonates with associated ototoxic side effects, that can be diagnosed with auditory brainstem evoked responses, which is the recommended screening technique in neonatal intensive care unit infants. This study was conducted to evaluate the effect of aminoglycoside therapy on auditory brainstem evoked responses in term and preterm neonates.Methods: A cross-sectional case control study. Two groups of 26 term and 22 preterm neonates who received aminoglycosides, with no other known risk factors for ototoxicity, were compared with suitable matched control group of 10 neonates in each. ABER was done after at least 5 days of aminoglycoside therapy and results were compared to suitable matched controls.Results: Mean latency of wave I in term neonates at 90 dB and 60 dB and mean interwave latencies of I-V waves in preterm neonates at 30 dB was higher in study group and statistically significant. No statistically significant difference in any of ABER parameters was observed in any group, at all other intensities.Conclusions: Wave I latency was prolonged in study group of term neonates at two intensities which indicates effect of aminoglycoside therapy on distal portion of acoustic nerve. But as there were no such findings at other intensities in term study group and in preterm study group and moreover no other ABER abnormalities were observed, it was concluded that the aminoglycoside therapy has low potential for ototoxicity. Authors support the ABER screening for early detection of hearing abnormalities, and recommend study on larger group of neonates and meta-analysis for final conclusion for evidence-based recommendations to use aminoglycosides in neonates, in view of audiometric and neurological abnormalities.

Implantation of the Auditory Nerve via the Middle Ear Cavity in Rats with Partial Hearing Preservation

The aim of this study was to evaluate the residual hearing function and cochlear morphology after auditory nerve implantation via middle ear spaces in rats. A titanium rod (1.5 mm long and 0.3 mm thick) coated with Parylene was inserted in the cochlear apex in the direction of the modiolus in 9 Wistar rats. Auditory brainstem-evoked responses to tone bursts at 2, 8, 12 and 32 kHz were recorded before surgery and on postoperative days 0, 2, 15 and 30. Eight cochleas were examined microscopically. The rod was inside the modiolus in 4, and partly or totally outside the modiolus in 4 animals. Residual hearing was present in all cases. The average threshold shift in cochleas with modiolar implant was 39 ± 11.2, 54 ± 9.7, 48 ± 20.3 and 43 ± 21.3 dB SPL on postoperative days 0, 2, 15 and 30, respectively. The transmodiolar approach allows a minimally invasive cochlear implantation and a partial hearing preservation.

Auditory brainstem evoked responses in hyperlipidaemia: effect of various lipid fractions on auditory function

Objective:To evaluate the effect of different lipid fractions on auditory brainstem evoked responses in hyperlipidaemia.Method:We conducted a single institution (medical college), prospective, cross-sectional study of 25 hyperlipidaemic patients and 25 normolipidaemic controls, all with a normal hearing threshold on pure tone audiometry. Brainstem evoked response audiometry results were recorded in both groups. The hyperlipidaemic group were further divided into two subgroups, based on the serum value of each lipid fraction: those with less than and those with greater than the mean serum value. These two subgroups were further compared with the control group.Results:The hyperlipidaemic and normolipidaemic groups had statistically significant differences for all audiometry waves apart from the wave I and the III–V interpeak latencies. The subgroups had a statistically significant difference in brainstem evoked responses. We found a statistically significant association between low-density lipoproteins and many waveforms in the hyperlipidaemic group.Conclusion:We found that low-density lipoproteins were significantly associated with many waveforms in hyperlipidaemic patients. Thus, low-density lipoproteins may be important in auditory dysfunction.

Auditory Brainstem Evoked Responses in Newborns With Down Syndrome

Auditory brainstem evoked responses (ABRs) were compared in 15 newborns with Down syndrome and 15 sex-, age-, and weight-matched control newborns. Participants had normal ABRs based upon values specific to 32- to 42-weeks postconceptional age. Although Wave III and Wave V component latencies and the Wave I–III interpeak latency (IPL) were shorter in ABRs of infants with Down syndrome, the Wave III–V IPL was not, pointing to anomalies in the lower rather than upper brainstem auditory pathways. Shorter Down syndrome ABR latencies have been reported at many ages. Extending these findings to newborns suggests that the underlying basis for this develops prenatally. ABR patterns in infants with Down syndrome were similar to reports for intrauterine growth restricted newborns.