Diagnostic Timeliness and Pre-implant Nonverbal Development in Thai Children with Severe-to-profound Sensorineural Hearing Loss: A 2017–2024 Retrospective Review

Background: Congenital severe-to-profound sensorineural hearing loss (SNHL) may compromise early development, and timely cochlear implantation (CI) is essential; however, data from low- and middle-income countries, where universal newborn hearing screening is limited and referral is delayed, remain scarce. This study describes diagnostic timeliness and CI referral in Thai children with congenital severe-to-profound SNHL, and reports age-stratified pre-implant nonverbal developmental profiles as secondary contextual descriptive data. Methods: A retrospective chart review was conducted at Siriraj Hospital, Bangkok, Thailand. Children with congenital severe-to-profound SNHL who underwent pre-CI developmental or non-verbal cognitive assessments between January 2017 and December 2024 were enrolled. Data on age at diagnosis, age at CI evaluation and surgery, comorbidities, and performance on age-appropriate tools (Bayley-III, Mullen Scales of Early Learning, and TONI-4) were analyzed descriptively. No inferential statistical testing was performed. Results: Ninety-nine children were included (48.5% male); 14.1% had genetic syndromes and 22.2% had global developmental delay or intellectual disability. Median age at diagnosis was 1.83 years (IQR 0.75–2.50), and median age at CI evaluation was 2.75 years (IQR 1.82–3.92); 62.6% received CI at median age 3.00 years (IQR 2.00–3.77). Among infants <1 year, 72.7% scored at/above average on Bayley-III cognitive and fine motor scales; among children 1–6 years, 52.7% and 50.5% scored at/above average on MSEL visual reception and fine motor, respectively; among those ≥6 years, 66.7% achieved TONI-4 index scores ≥85. Conclusion: Diagnosis and CI referral in Thailand occurred well beyond internationally recommended ages, and age-group differences in non-verbal performance were observed, underscoring the need to strengthen early hearing detection and referral systems.