a vocabulary that ranges between 5,000 and 26,000 words. In comparison, a deaf child of the same age usually has access to a vocabulary of about 200 words and limited ability to structure a spoken sentence.3 Given the substantial impact of deafness on development and the potential benefit of restored hearing, there are risks of underestimating the importance of potential complications associated with a device-oriented approach to deafness. Complications associated with the implantation procedure and device malfunction may arise during critical stages of language acquisition, before a child can be expected to report on their experience with an implanted device.
The cochlear implant is best characterized as a device that provides access to sound. The device enables the hearing pathway to respond to environmental and speech sounds, providing informational cues from the surroundings and from others through direct, electrical activation of auditory nerve fibers tuned to frequencies that span the spectrum of practical hearing.
In October 2004, the U.S. Food and Drug Administration (FDA) developed a website that contains general information on hearing physiology (including animated graphics), information on how a cochlear implant functions, as well as FDA regulatory approvals for these devices. The reader is referred to this website as a comprehensive resource for background information on cochlear implants: http://www.fda.gov/cdrh/cochlear/index.html.
Three different manufacturers of cochlear implant systems provide currently available devices. All three product devices consist of similar component parts
The design of the electrode array must incorporate biocompatibility, mechanical stability, practical fabrication, and minimize insertion trauma. From a surgical point of view, efforts to reduce insertion trauma must be accomplished at the materials and design levels, as well as through the surgical technique.
For the past two decades, mastoid-implantable internal devices with leads to electrical arrays placed in the basal turn of the cochlea have been applied to deaf children as an increasingly large proportion of all cochlear implants placed (Figures F.5 and F.6). As of 2003, more than half of all newly implanted devices have been placed in children under age 5. It is estimated that approximately 7,500 to 10,000 United States children have received a multichannel cochlear implant prior to the age of 5 years out of