Surgical technique protocol for cochlear implantation in post-meningitic ossified cochlea

Labyrinthitis ossificans is a known complication of bacterial meningitis which results in severe to profound hearing loss. Historically, labyrinthitis ossificans was considered a contraindication for cochlear implantation. However, with advances in technology, cochlear implantation is an accepted treatment for hearing loss in labyrinthitis ossificans.

17 cases with varying degrees of ossification in the cochlea were evaluated and treated at our tertiary referral hospital and cochlear implantation center out of a total of 832 profoundly deaf patients evaluated from January 2007 to June 2023. The etiology, radiology, intra-operative findings and treatment protocols followed in these patients are discussed.

15 of the 17 patients could successfully be implanted with a cochlear implant, while two were referred to another center for Auditory Brainstem Implantation. The degree/grade of ossification decided the available cochlear lumen for implantation and hence the surgical approach and choice of the electrode.

A protocol for the order of choice of electrode and site of insertion in various cases of labyrinthitis ossificans depending on the degree of ossification is proposed. In the order of preference, it would be thus: 1. Cochlear implantation with the active electrode in the scala tympani of the basal turn; 2. Electrode in the scala vestibuli of the basal turn; 3. Anterograde insertion of the implant from the second turn; 4. Retrograde insertion of the implant from the second turn; 5. Insertion of a split array electrode and finally 6. Auditory brainstem implantation.