Hearing assessment of infants with congenital syphilis

Purpose  To evaluate the presence of hearing loss in the first months of life in infants treated for congenital syphilis at birth.

Methods  Prospective study including all neonates born in a University public hospital in South Brazil, who needed treatment for congenital syphilis after birth in the Neonatal Unit, between 2021 and 2022. Otorhinolaryngologic and audiologic evaluations were performed at a mean age of 3.3 months, concomitantly with the first post-discharge appointment in the congenital syphilis outpatient clinic, through frequency-specific auditory brainstem response.

Results  Sixty-five patients were included in the study. All subjects underwent Neonatal Hearing Screening before being discharged from the hospital, consisting of transient evoked otoacoustic emission and automated auditory brainstem response tests. Sixty-one patients (93.8%) passed both screening tests and four (6.2%) failed both tests. Concerning the 4 newborns who failed, 2 returned for retesting and had normal results, 1 patient did not show up for retesting, and 1 patient failed both retests. Follow-up was concluded by 23 infants (35.4% of the initial sample) who underwent Frequency-Specific Auditory Brainstem Response testing. The other patients did not attend to the appointments. Regarding the 23 patients that concluded the follow-up, no interaural response asymmetries suggestive of retrocochlear involvement were observed. Additionally, no changes were found in the absolute latencies of waves I, III, and V, or in the interpeak intervals I–III, III–V, and I–V. The Frequency-Specific Auditory Brainstem Response evaluation did not present any abnormalities in the electrophysiological thresholds at the tested frequencies.

Conclusion  No signs of hearing loss were found in patients treated for congenital syphilis during neonatal period, either in the Neonatal Hearing Screening or in the Frequency-Specific Auditory Brainstem Response during follow-up.

Keywords:
Hearing Loss; Congenital Syphilis; Auditory Evoked Potentials; Neonatal Hearing Screening; Audiologic Diagnosis