Cochlear wall erosion after cochlear implantation

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.

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-microm sections and stained.

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.

Trauma may provoke an inflammatory reaction due to the presence of the foreign body after violation of the endosteum.