Histopathologic assessment of fibrosis and new bone formation in implanted human temporal bones using 3D reconstruction

Abstract

Objective To evaluate new bone formation and fibrosis in implanted human temporal bones and relate that to neurosensory elements preservation. Study Design Human temporal bone histopathology study. Setting Temporal bone laboratory. Subjects and Methods Ten human temporal bones from eight patients with multichannel cochlear implants and one single-electrode implant were examined under light microscopy and reconstructed with AMIRA 4.1 3D reconstruction software. Volumes of new bone formation, fibrosis, and patent area were calculated in each bone. Results The amount of fibrosis and new bone formation postimplantation varied among bones. There were no statistically significant relationships between age at implantation or duration of implantation and the overall amount of new tissue in the implanted ear. There was a relationship between total amount of new tissue and preservation of neurosensory elements only in segment I of the cochlea (Rho = – 0.75, P ≤ 0.013). Most of the new tissue was located in segments I and II, segment III had little to no new tissue formation, and segment IV was clear in all of the subjects. Conclusion New tissue formation postimplantation was related to preservation of neurosensory elements primarily in segment I of the cochlea. In an era of hearing preservation surgery and hybrid cochlear implants, soft surgical techniques are advocated as a means to decrease surgical trauma.