Rarely is a candidate eliminated from consideration for an implant based on medical history.
Almost all diseases and disorders that induce profound deafness primarily affect the cochlear hair cells, which are responsible for transducing acoustical signals into electrical responses. This has enabled candidates with almost all causes of profound deafness to be candidates for cochlear implantation. Exceptions to this are those who have had tumors removed from their hearing and balance nerves and those with severe trauma severing the auditory nerve. Studies have failed to identify any etiology except meningitis with severe labyrinthine ossification with obliteration of the cochlea as a disadvantage for cochlear implantation (Gantz, Woodworth, Abbas, Knutson, and Tyler, 1993).
Radiographic imaging of the cochlea is essential to determine the presence of a congenital inner ear deformity. Absence of the cochlea (Michele deformity) or a small internal auditory canal (similar to the fallopian canal) are contraindications for implantation on that side. Congenital malformations, such as Mondini deformities, are not contraindications for implantation, but they should alert the implant team that complications may be encountered during implantation and the candidate must be carefully counseled as to possible limited hearing outcome (Jackler, Luxford, and House, 1987; Miyamoto, Robbins, Myres, and Pope, 1986).
Recurrent acute or chronic ear disease must be controlled prior to placing a cochlear implant. If acute otitis media occurs following implantation, it should be treated with appropriate antibiotics.
In the recent past it has been recognized that there may be an increased risk of meningitis associated with cochlear implantation. Because of this, the Centers for Disease Control and Prevention (2003), the FDA (2003), and the American Academy of Pediatrics (2004) have recommended that all young children who receive a cochlear implant, as well as adults at high risk of invasive pneumococcal disease, be vaccinated against meningitis. It is recommended that vaccination take place prior to implantation in children and the elderly.
Finally, a history of a congenitally deafened ear should be noted. The congenitally deafened ear in a postlingual deaf adult should not be implanted. Case reports indicate that these ears perform similarly to implants in prelingually deafened adults, in that a sensation of sound may not be perceived in a prelingually deafened ear.
The characteristics of an individual cochlear implant user play a large role in the communication outcomes he or she achieves (Wilson, Lawson, Finley, and Wolford, 1993). Two important factors are age at implantation