Cochlear Implants – A Primer
Cochlear implants are electronic devices with three principal elements, a battery operated external speech processor that converts sound waves into digital signals, a magnetically attached connector that transmits the signals to the implant, and an internal implant surgically placed under the skin on the skull and linked by a wire array to the hearing nerve.
The speech processor is essentially a mini-computer that processes sound waves electronically and sends them to the implant so the sounds can be understood by the brain as speech. Multiple programs give the user flexibility to adapt to different hearing situations.
Implants come in behind-the-ear (BTE) models and body pack versions. Most wearers choose the BTE model that became available in 2000. Body packs continue to be employed because of bone structure or other special circumstances.
Who Is Eligible for Cochlear Implants?
Increasingly, implants are installed where hearing aids have failed to establish satisfactory speech thresholds. As of mid-2005, an estimated 90,000 persons have received implants worldwide, more than 30,000 in the United States. Implants are installed for infants as young as 12 months, as well as persons of all ages with a severe to profound hearing loss. Individuals in their 80s and early 90s have received implants.
The surgery costs many times more than even a pair of top-of-the-line hearing aids; however, many health insurance policies and Medicare underwrite a substantial portion under “medical necessity” coverage.
A “medical necessity” letter from a physician or audiologist is required in the U.S.A. to establish implant eligibility. In effect, the letter certifies that surgery is required to deal with the hearing needs of the patient. Strict Federal standards enforced by the Food and Drug Administration (FDA) govern eligibility for implant surgery. These standards, set up in 2005, require 60% or less sentence discrimination in the best-aided condition, with 50% or less in the ear being implanted. Medicare’s standard for expense reimbursement requires speech understanding of 40% or less.
Surgery is required on the head above the ear to insert a small disc-like device next to the skull. It is usually performed as day surgery unless there is bone structure irregularity (rare) or other special condition. The implant usually eliminates residual hearing in that ear.
The surgeon threads a wire array through the cochlea (hence the name cochlear implant) where it is linked to the hearing nerve and brain. The implanted wire array transmits the signals in their component speech frequencies.
Typically only one ear is implanted, although dual implants have been installed to meet special needs. There have been several hundred dual installations by 2005. Many implant wearers use a hearing aid in their other ear. Wearing devices in both ears helps with determining sound direction and dealing with speech interfering background noise.
Getting Used To An Implant
Auditory therapy may be required as part of the “breaking-in” process, depending on the extent and character of the hearing loss and receptivity to the implant’s new sounds. Some patients find that implants improve speech understanding in a day or two without therapy, but others may take weeks or months to reach acceptable levels, sometimes assisted with speech-language therapy. Although at first voices may resemble Donald Duck, with time and training the brain accepts the new sounds as normal. As one veteran implant audiologist put it, “That old brain continues to learn new tricks.”
Implants are produced by highly competitive worldwide manufacturers who vie in marketing instrument capabilities, design, and special features. The implants operate similarly, although they differ in their formats, appearance and features. All are subject to strict regulatory scrutiny by the U. S. Food and Drug Administration.
The three principal implant manufacturers in the American market place are Cochlear, Advanced Bionics and Med-El. Cochlear Americas uses titanium for inserts while Advanced Bionics and Med-El use ceramic.
Seattle-Area ENT and CI Surgeon
Washington Implant Centers
Children’s Hospital and Medical Center, Seattle
Puget Sound Hearing & Balance Center, Seattle
Seattle Ear Clinic, Seattle
University of Washington Otolaryngology Clinic, Seattle
Veterans Administration (VA) Medical Center, Seattle
Virginia Mason Listen for Life Center, Seattle
Tacoma Ear and Balance (counseling only), Tacoma
Madigan Army Medical Center, Tacoma
Spokane Ear, Nose & Throat, Spokane
Washington Email Contacts for Cochlear Americas
Washington Email Contact for Advanced Bionics