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Timothy C. Hain, MD. 
Page last modified:
March 19, 2008
An exciting recent development is an ability to provide hearing to some bilaterally deafened individuals through implantation of a device which directly stimulates the hearing nerve (actually the spiral ganglion). Although this device is not generally considered as a "hearing aid", it performs the same purpose for individuals with severe hearing impairment involving both ears. At the time of writing of this section, 12/2002, there are three companies that make implants -- Advanced Bionics, Med-El, and Cochlear Ltd. Generally an electrode is threaded into the cochlea.
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| Cochlear implant from a patient of Dr. Hain's practice in Chicago. |
Cochlear implants do not completely substitute for a normally hearing ear,and at very best, may allow someone who was previously totally deaf to understand conversation on a telephone. Cochlear implant packages, including the device, surgery, and rehabilitation are much more expensive than hearing aids (roughly $45,000), but when one is indicated, they are generally covered by insurance, unlike the situation with hearing aids. A patient-contributed history is found here. Remarkable improvements in performance have been accomplished since 1980. Further information about cochlear implants can be found at the following sites:
Cochlear implants are not without complications. Dodson reported a 9.3% overall complication rate, with 59% being due to device failure (Dodson et al, 2007).
Meningitis is a rare but serious complication.
Hearing may continue to deteriorate after the implant is inserted(Barbara et al. 2003), perhaps due to scarring or nerve degeneration.
CSF leaks are also complication, usually around the receiver/stimulator recess (Dodson et al, 2007). These are treated by operative repair.
Vertigo or imbalance occurs in 40-74% of patients who have cochlear implants (Steenerson et al, 2001). Caloric responses are not necessarily eliminated by cochlear implants, and thus the underlying process that affected hearing can continue to cause dizziness and balance. About 50 % of these patients develop positional vertigo and can be treated with vestibular rehabilitation. Although one might think that dizziness could be related to inadvertent electrical stimulation of the vestibular nerve, dizziness is not related to implant activation, (Fina et al, 2003).
Todt et al(2008) suggested that dizziness was common post implant, and that insertion through the round window decreased the risk of dizziness associated with insertion.
The BAHA (bone attached hearing aid) is an excellent implantable device for persons who have either primarily a conductive hearing loss or good hearing on the opposite ear.
There is also a device that is implanted into the middle
ear, in essence, implanting the speaker part of the hearing aid. This device, the Symphonix Vibrant Soundbridge,
is mainly used for individuals who are unable to tolerate conventional hearing
aids. It avoids the "occlusion" effect and feedback. These devices often have mechanical problems. The Vibrant Soundbridge is now available in the US through MED-EL Corporation.
The auditory brainstem implant (ABI) is mainly used for people with "nerve" deafness, such as persons with neurofibromatosis. It provides sound quality similar to a single-channel cochlear implant (i.e. sound awareness, but not speech comprehension).
| © Copyright May 22, 2008 , Timothy C. Hain, M.D. All rights reserved. Last saved on May 22, 2008 |