Cochlear wall titanium implants for auditory nerve stimulation.
Genetically deaf dalmatian dogs and ototoxically deafened macaque monkeys were implanted with electrodes housed in cochlear wall titanium implants to assess long-term stability, tolerance, and performance. Short-term human implantation, followed by trials of stimulation, was performed in 4 unilaterally deaf patients. In the dog experiments, cochlear wall electrode stimulation produced consistent electrophysiologic thresholds that were higher, by approximately 6 dB, than those obtained with bipolar scala tympani stimulation. Clinical testing revealed electrically evoked middle latency response, auditory brain stem response, and/or behavioral detection responses in 3 of 4 patients, at levels below those for facial nerve activation and pain sensation. Electrode place discrimination studies, with controls for loudness cues, revealed near-perfect discrimination in a monkey subject. Eleven of the 12 animal implants were found to be rigidly fixed in the cochlear bone, with direct contract between bone and implant over 8% to 23% of the implant surface for the 6 implants examined in detail. These results suggest that long-term fixation of titanium cochlear wall implants occurs by virtue of intimate implant-bone contact in restricted areas. This approach to prosthetic stimulation demonstrates encouraging performance characteristics in achieving auditory activation.
Department of Otolaryngology--Head and Neck Surgery, University of Michigan, Ann Arbor.
J K
JK
Niparko
B E
BE
Pfingst
C
C
Johansson
P R
PR
Kileny
J L
JL
Kemink
A
A
Tjellström
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000368:Aged; D000818:Animals; D003054:Cochlear Implants; D003638:Deafness / Q000151:congenital / Q000628:therapy*; D004285:Dogs; D004567:Electrodes, Implanted; D004867:Equipment Design; D005260:Female; D034381:Hearing Loss / Q000628:therapy*; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D008875:Middle Aged; D014025:Titanium
D014025:Titanium