Biocompatibility of the central electroauditory prosthesis and the human cochlear nuclei

Previous studies from the House Ear Institute have reported the possibility of sound sensation from the central electroauditory prosthesis (CEP) implanted in patients during removal of bilateral acoustic neuromas. This study describes histologic features of tissues formed around a CEP that was removed due to infection in the area of the electrical plug on the external surface of the skull. We found a layer of compact collagen tissue around the CEP. The tissue penetrated spaces of the Dacron mesh matrix, preventing our determination of the precise place of the electrode-tissue interface. We also found a layer of connective tissue on the Silastic covering on the CEP leads. Histopathologic analysis showed no unusual pathologic changes around the CEP except for degeneration of the abdominal fat used for placement and stabilization of the CEP on the surface of the cochlear nuclei.