Risk Factors for Severe-To-Profound Sensorineural Hearing Loss in Cochlear Implant Recipients: Consanguinity, Bacterial Meningitis and The Perinatal Cluster in 369 Patients

Abstract

Background and Objective: The risk factor profile of severe-to-profound sensorineural hearing loss (SNHL) differs markedly between populations, and it determines which preventive measures are worth deploying. In settings where consanguineous marriage is common and bacterial meningitis is still frequent, that profile has rarely been characterised in a large cohort. We analysed the prevalence of recognised risk factors in 369 cochlear implant recipients and their association with the clinical phenotype of the hearing loss.

Methods: All patients implanted in a single tertiary referral department between January 2010 and December 2024 were reviewed. Sixteen predefined risk factors - familial, perinatal and acquired were abstracted from a standardized institutional registry, together with the type of hearing loss (congenital, genetic/familial, acquired), its period of onset relative to language acquisition, and its laterality. Prevalences were compared between phenotypic groups using the chi-square or Fisher exact test; odds ratios (OR) with 95% confidence intervals (CI) were estimated with the Haldane Anscombe correction.

Results: Parental consanguinity was the single most prevalent risk factor (123 patients; 33.3%), followed by a family history of deafness (108; 29.3%) and bacterial meningitis (43; 11.7%). The two familial factors were tightly linked: a family history of deafness was present in 69.1% of consanguineous families versus 9.0% of non-consanguineous ones (OR 22.6, 95% CI 12.6–40.4; p < 0.001). Consanguinity and family history were both associated with congenital or genetic hearing loss (OR 3.69 and 4.42; p < 0.001) and with prelingual onset (OR 2.73 and 3.31; p < 0.001), whereas meningitis, neonatal distress, prematurity, neonatal hospitalisation, recurrent chronic otitis media and head trauma were all associated with acquired, later-onset disease. Perinatal factors clustered in 62 patients (16.8%). No identifiable risk factor was found in 137 patients (37.1%). Maternal rubella and cytomegalovirus infection were recorded in no patient.

Conclusions: The risk factor profile of this cohort is dominated by a familial axis, driven by consanguinity, and by a residual burden of bacterial meningitis that has largely disappeared from high-income series. These two axes call for different interventions: genetic counselling and targeted molecular diagnosis for the first, and completion of pneumococcal and Haemophilus influenzae type b vaccination coverage with systematic post-meningitis audiological assessment for the second. The absence of any documented congenital cytomegalovirus infection, in a cohort where 37.1% of patients had no identifiable risk factor, almost certainly reflects under-testing rather than true absence.