Effect of Hyperbilirubinemia on Medial Olivocochlear System in Newborns – A Study
J Int Adv Otol 2019; DOI: 10.5152/iao.2019.5723
Burak Karabulut, Mehmet Sürmeli, Şenol Bozdağ, İldem Deveci, Rıza Doğan, Çağatay Oysu
To evaluate medial olivocochlear efferent system of babies with hyperbilirubinemia with normal auditory brain stem responses.
MATERIALS AND METHODS:
This was a prospective study in a tertiary referral hospital. The study involved 40 hyperbilirubinemic and 44 healthy newborns. Cochlear and auditory activity of participants was evaluated by transient otoacoustic emissions (TOAEs) and brainstem auditory evoked response components (BAER). Medial olivocochlear (MOC) reflex was evoked with contralateral acoustic stimulation and recorded with TOAEs.
A comparison of the MOC reflex activity between two groups with Mann Whitney U test revealed that MOC reflex activity were significantly decreased in the hyberbilirubinemic group for both ears (p<.05). This difference was significant for all frequencies in both ears. There was no significant relation between total serum bilirubin level and MOC reflex activity.
Hyperbilirubinemic newborns had decreased MOC reflex activity. This may be indicative of future problems in speech discrimination and effective hearing in noisy background. Additional long cohort studies are needed to evaluate the clinical importance of MOC reflex measurements in this group. MOC reflex measurement has the potential to form part of the audiologic evaluation of newborns with hyperbilirubinemia in the future.
Excerpt from Material and Methods
“All infants included in the study underwent BAER (K-500 BDT; Vivosonic Inc., Ontario, Canada) using the monaural method. The test was conducted in a soundproof room reserved for this purpose within the audiology unit of the otolaryngology department, with the child in physiological sleep in a regular bed. The stimulus was introduced by the insertion of headphones (ER3). A bicannal electrode (inverting electrode on the mastoid, non inverting electrode on the forehead, and ground electrode on the cheek) was used to record signals. Test parameters were as follows: clicks with a repetition rate of 29.9/s, average response of 2000 times, and stimulus intensity of 90 dBnHL, with the stimulus intensity lowered to 20 dB intervals to confirm the hearing threshold levels for wave V. The latencies of BAER wave I, III, V, and I-V interpeak intervals were measured. The criterion for normal hearing was the presence of wave V with a stimulus intensity of 20 dBnHL.”
“Transient-evoked OAEs were documented in linear mode, and test frequencies were at 1, 2, 3, 4, and 5 kHz (Vivosonic Integrity K500; Vivosonic Inc.). Records with >70% wave reproducibility and >80% stimulus stability were included in the study, and each test was terminated with 260 sweeps. Emissions with >6 dB signal-to-noise ratio were considered valid.”
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