Cochlear Wall Erosion after Cochlear Implantation

Abstract

Objectives: Cochlear implantation is a clinically satisfactory procedure, but it is associated with a variable degree of histologic intracochlear trauma. We report a new histologic finding in a cochlear implant specimen from the House Ear Institute collection. Methods: An analysis of 34 temporal bones with single-channel (n = 23) or multichannel (n = 11) cochlear implants was performed. All temporal bones had been fixed for a month in 10% buffered formalin, progressively decalcified in ethylenediaminetetraacetic acid, and embedded in celloidin. After electrode removal, the bones were cut into 20-μm sections and stained. Results: In 1 specimen, the implanted electrode had caused erosion of the bone through the endosteum into the marrow spaces, at the superior-anterior portion of the basal turn. This area showed an intense lymphocytic infiltration surrounded by some new bone formation. Conclusions: Trauma may provoke an inflammatory reaction due to the presence of the foreign body after violation of the endosteum.