Managing cochlear implant patients with suspected insulation damage.

Six Nucleus® 24 Contour™ and five Nucleus® Freedom™ with Contour Advance™ cochlear implants examined at the South of England Cochlear Implant Centre have failed and were explanted because of insulation damage. Insulation damage occurs when the silicone elastomer coating surrounding the electrode array wires and electronics capsule fails, allowing fluid entry to the electrode lead bundle. In addition, four Nucleus® 24 Contour™, one Nucleus® Freedom™ with Contour Advance™, and one Nucleus® 24 devices have failed as a result of suspected insulation damage; two have been explanted but explant reports not yet been received from the device manufacturer, four have not been explanted. Sixteen other Nucleus® devices are suspected to have insulation damage but the patients have retained clinical benefit, with remapping to exclude some or all affected electrodes in 14 cases. Insulation damage does not cause a sudden loss of sound; instead, a progressive deterioration can occur, which can make management and detection challenging, particularly in young children or those with additional needs. Monitoring of both impedances and clinical benefit is recommended.