What Is the Optimal Timing for Cochlear Implantation in a Post‐Meningitic Infant With Sensorineural Hearing Loss?

Profound sensorineural hearing loss (pSNHL) occurs in up to 4%–5% of bacterial meningitis cases, with Streptococcus pneumoniae infection carrying the highest risk [1-3]. Direct spread through the cochlear aqueduct and internal auditory canal can lead to labyrinthitis ossificans (LO), resulting in bony obliteration of the cochlea. Ossification develops in up to 90% of post-meningitic pSNHL patients and has been identified as early as 21 days after infection [1]. The presence of LO can preclude cochlear implantation (CI), permanently limiting access to sound and speech. The workup of post-meningitic pSNHL is time-sensitive, and current recommendations are to perform implantation within 6 months of infection [4]. When meningitis occurs within the first weeks of life, both definitively confirming pSNHL and subsequently performing implantation are intrinsically challenging. Delays can risk development and progression of cochlear ossification. Currently, clinicians must navigate this complex clinical dilemma with limited expert consensus or established guidelines. The 2022 American Cochlear Implant Alliance Task Force Guidelines [5] provide a global overview of pediatric CI candidacy. Off-label implantation in infants under 9 months of age is considered when medically appropriate. The single mention of meningitis in the guidelines advocates for implantations “as soon as possible” due to the risk of LO and loss of the window of opportunity for successful CI outcomes. However, no standardized timeline or formal recommendation is given regarding management of a post-meningitic newborn or young infant. Singhal et al. [1] performed a systematic review of 610 post-meningitic CI outcomes across 12 retrospective cohort studies, three retrospective case series, three prospective cohort studies, and one retrospective case control study, published between 1993 and 2019. At least 200 patients had evidence of LO at the time of implantation with inconsistent reports of complete electrode insertion. The presence of LO at the time of implantation was related to poorer hearing outcomes. High-resolution CT (HRCT) could appear normal in early fibrosis, so T2-weighted MRI was recommended to detect early fluid signal loss. Importantly, this study acknowledged that the “wait and see” approach with serial imaging should be cautiously applied, as delays beyond 3 weeks risk fibrosis progression and reduced surgical success. A second systematic review by Ahmadian et al. [4] in 2024 discussed 376 patients across 11 articles focused on pediatric post-meningitic CI hearing outcomes. Factors associated with superior audiometric outcomes included shorter time to implantation (< 6 months) and absence of ossification. A shorter duration of deafness was associated with superior meaningful use of speech scale and open-set test scores. Patients with LO had inferior speech perception on monosyllabic word tests; however, the mean CAP-II scores were not significantly different (LO = 5.27 vs. non-LO = 5.42, p = 0.709). Patients with LO had higher impedances and more frequent programming adjustments due to the microelectrical environment destruction and limits of devices. Interestingly, data indicated partial electrode insertion did not affect hearing outcomes, contrary to historical studies. The literature is limited regarding CI specifically in post-meningitic infants less than 9 months of age. In 2011, Roukema et al. [2] reported a single institutional retrospective review of four male infants implanted between 3 and 7 months of age after pneumococcal meningitis between February 2005 and March 2010. Formal audiologic testing was performed as soon as medically feasible. Following the Dutch Consensus Protocol on Post-Meningitic Hearing Evaluation, MRI was performed within 14 days after the identification of SNHL with auditory brainstem response (ABR). It should be noted that reliable audiometry in infants < 6 months depends on developmental age. The auditory system is often not fully mature in infants younger than 6 months of age, and adjunctive measures, such as auditory steady state responses, tone burst ABR, and electrocochleography, should be considered if there are inconsistencies. The authors assessed for LO with signal loss on T2-weighted MRI or active cochlear inflammation on contrast-enhanced T1-weighted MRI, which often precedes cochlear signal loss. All patients were implanted within a month of pSNHL diagnosis (range, 15–31 days) with a mean age of implantation of 6.5 months (range, 4–8 months). This paper included a list of surgical considerations in the very young CI recipient, summarized in Table 1. More recently, Swartz et al. [3] described CI in a post-meningitic ex-38-week female infant at 10 weeks of age, the youngest reported in the literature. She was diagnosed with pneumococcal meningitis on day of life 3, complicated by hydrocephalus requiring a ventriculoperitoneal shunt. Unsedated ABR and MRI suggested right pSNHL and early cochlear changes. A second confirmatory ABR was performed. The patient received her 2-month vaccinations early, with surgery then scheduled 2 weeks later. Intraoperatively, fibrosis encountered in the scala tympani necessitated a cochleostomy. The implant was placed via a subperiosteal tight pocket, and the Cochlear CI612 electrode was utilized with the stylet left in place to prevent migration. An incomplete insertion was achieved (14/22 electrodes). Given the thin, fragile soft tissue of the scalp, the device was not formally activated until age 5 months to prevent skin breakdown. Special surgical considerations from this paper are also included in Table 1. Bilateral SNHL necessitates prompt management, while unilateral hearing loss may require a thorough discussion of expectations, noting the potential for delayed hearing loss on the contralateral side. Surgery should ideally be performed as quickly as possible after hearing loss confirmation, ideally within 3–4 weeks, to minimize labyrinthitis. This review includes two systematic reviews (Level 3), one retrospective case series (Level 4), one case report (Level 5), and one consensus guideline (Level 5). The authors have nothing to report. The authors declare no conflicts of interest.