Failed cochlear implant followed by auditory brainstem implant in a patient with Mondini malformation and uncontrolled otomastoiditis: a case report

BACKGROUND: Cochlear implant (CI) implantation is the standard intervention for children with severe-to-profound hearing loss, including those with inner ear malformations, such as Mondini malformation. Post-CI implantation infections, although uncommon, can lead to serious complications, including device failure and labyrinthine ossification (LO). CASE PRESENTATION: Here, we report the case of a 17-year-old Thai girl with bilateral Mondini malformation who underwent right-sided CI at 15 months of age. She developed recurrent otitis media that progressed to chronic otomastoiditis that was unresponsive to both antibiotics and revision mastoidectomy. Contralateral CI implantation was not feasible due to cochlear nerve aplasia. The patient then underwent auditory brainstem implant (ABI) implantation, which resulted in a modest but functionally meaningful auditory benefit with continued reliance on visual cues. This case highlights the long-term risks of post-CI infection, and emphasizes the importance of vigilance in CI patients with middle ear infection. CONCLUSION: Chronic otomastoiditis can lead to irreversible cochlear ossification and cochlear implant failure. The results of this case report support the efficacy of ABI implantation as a salvage treatment option that provides limited but functionally useful auditory benefit when CI is no longer feasible.