Post-meningitis deafness and cochlear implantation

Objective: The objective of this paper is to review and discuss the role, indications, beneficial effects and outcomes of cochlear implantation in patients with post-meningitis deafness. Methods: A search in the PubMed, Lilacs and SciELO databases was performed. The keywords used were ("Cochlear implant" OR "Cochlear implants" OR "Cochlear implantation") AND ("meningitis"). Results: The complications of hearing impairment following bacterial meningitis are many, and not only regarding to the deafness itself. There is a risk of cochlear fibrosis and subsequent obliteration of the cochlear lumen, which may occur within weeks after the onset of meningitis. The streptococcus pneumoniae is the commonest identified organism and the one that more commonly leads to labyrinthitis ossificans. The prompt administration of dexamethasone, even prior to the antibiotics, reduces the neurologic complications and risk of hearing loss. All children recovering from meningitis should have a hearing assessment before and 4 to 6 weeks after hospital discharge to allow early identification of hearing impairment. Early implantation is essential before obliteration has occurred, and if imaging shows that it is developing, there is a very high degree of urgency. For all implant candidates, the imaging evaluation of the cochlea and inner ear is mandatory, and it should include a high-resolution computerized tomography and a magnetic resonance imaging regarding cochlear patency. Patients with cochlear ossification achieved worse auditory results than patients without ossification, and implantees with other causes of deafness achieved best performances than the ones deafened by bacterial meningitis Discussion: Early identification of hearing disorders in patients with meningitis is essential to prevent future complications. All patients should have a reliable assessment of their hearing as soon as the patient is capable or at the discharge. Several studies show that the performance of implantees deafened by meningitis is directly related to the duration of deafness, and children implanted within 6 months after the meningitis achieve best results. The cochlear osteoneogenesis should be soon recognized, and early implantation is essential before obliteration has occurred. The surgical options for patients with cochlear ossification varies accordingly to the degree of ossification; if the obliteration is partial and does not extend further than the anterior end of the basal turn, it is possible to drill past it to a clear lumen and insert an implant to its full extent; if the cochlea is completely obstructed, the auditory brainstem implant is an option. The reasons why post-meningitis deafened patients usually achieve worse results than patients with other causes of deafness is because meningitis may damage parts of the central auditory pathways and compromise the patient's cognitive abilities. Conclusion: Post-meningitis deafness should be soon recognized and treated in order to prevent cochlear ossification and to allow a safe surgery for cochlear implantation.