PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 8512272

Cochlear wall titanium implants for auditory nerve stimulation.

J K Niparko·B E Pfingst·C Johansson·P R Kileny·J L Kemink·A Tjellström
View original source ↗Export metadata ↓

Abstract

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.

Explore related subjects

Acoustic StimulationAdultAgedAnimalsCochlear ImplantsDeafnessDogsElectrodes, ImplantedEquipment DesignFemaleHearing LossHumansMacaca mulattaMaleMiddle AgedTitaniumCase ReportsJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J K Niparko, B E Pfingst, C Johansson, P R Kileny, J L Kemink, A Tjellström. 1993. Cochlear wall titanium implants for auditory nerve stimulation.. https://doi.org/10.1177/000348949310200608

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1999

Characterization of progressive motor deficits in mice transgenic for the human Huntington's disease mutation.

Transgenic mice expressing exon 1 of the human Huntington's disease (HD) gene carrying a 141-157 CAG repeat (line R6/2) develop a progressive neurological phenotype with motor symptoms resembling those seen in HD. We have characterized the motor deficits in R6/2 mice using a battery of behavioral tests selected to measure motor aspects of swimming, fore- and hindlimb coordination, balance, and sensorimotor gating [swimming tank, rotarod, raised beam, fore- and hindpaw footprinting, and acoustic startle/prepulse inhibition (PPI)]. Behavioral testing was performed on female hemizygotic R6/2 transgenic mice (n = 9) and female wild-type littermates (n = 22) between 5 and 14 weeks of age. Transgenic mice did not show an overt behavioral phenotype until around 8 weeks of age. However, as early as 5-6 weeks of age they had significant difficulty swimming, traversing the narrowest square (5 mm) raised beam, and maintaining balance on the rotarod at rotation speeds of 33-44 rpm. Furthermore, they showed significant impairment in prepulse inhibition (an impairment also seen in patients with HD). Between 8 and 15 weeks, R6/2 transgenic mice showed a progressive deterioration in performance on all of the motor tests. Thus R6/2 mice show measurable deficits in motor behavior that begin subtly and increase progressively until death. Our data support the use of R6/2 mice as a model of HD and indicate that they may be useful for evaluating therapeutic strategies for HD, particularly those aimed at reducing the severity of motor symptoms or slowing the course of the disease.

Acoustic Stimulation↗
PubMed1999

The magnitude and phase of temporal modulation transfer functions in cat auditory cortex.

Temporal modulation transfer functions (tMTFs) in response to periodic click trains are presented for simultaneous recordings from primary auditory cortex, anterior auditory field, and secondary auditory cortex in 21 cats. The multiunit records could be separated in to 215 single-unit spike trains that allowed a reliable estimate of a group delay, which represents the cumulative delay for responses to repetitive stimuli. For approximately two-thirds of the 215 single units the group delay was within 7.5 msec of the response latency to the first clicks in the trains. For the remaining units, the group delay was on average approximately 14 msec higher, and this may result from differences in synaptic properties. These findings were similar in the three cortical areas studied. The findings are modeled based on presynaptic facilitation and depression and pyramidal cell calcium kinetics, and a quantitative description of the magnitude of the tMTF was obtained that resulted in substantially shorter depression time constants (20 msec) than reported for visual cortex (300 msec). A small amount (0-5.5%) of facilitation that decayed with a time constant of 60 msec was obtained. Auditory cortical cells apparently have much faster recovery mechanisms than visual cortical cells. This allows for the ability of the auditory cortex to reliably track the rhythms that occur in natural sounds.

Acoustic Stimulation↗
PubMed1999

Gene disruption of p27(Kip1) allows cell proliferation in the postnatal and adult organ of corti.

Hearing loss is most often the result of hair-cell degeneration due to genetic abnormalities or ototoxic and traumatic insults. In the postembryonic and adult mammalian auditory sensory epithelium, the organ of Corti, no hair-cell regeneration has ever been observed. However, nonmammalian hair-cell epithelia are capable of regenerating sensory hair cells as a consequence of nonsensory supporting-cell proliferation. The supporting cells of the organ of Corti are highly specialized, terminally differentiated cell types that apparently are incapable of proliferation. At the molecular level terminally differentiated cells have been shown to express high levels of cell-cycle inhibitors, in particular, cyclin-dependent kinase inhibitors [Parker, S. B., et al. (1995) Science 267, 1024-1027], which are thought to be responsible for preventing these cells from reentering the cell cycle. Here we report that the cyclin-dependent kinase inhibitor p27(Kip1) is selectively expressed in the supporting-cell population of the organ of Corti. Effects of p27(Kip1)-gene disruption include ongoing cell proliferation in postnatal and adult mouse organ of Corti at time points well after mitosis normally has ceased during embryonic development. This suggests that release from p27(Kip1)-induced cell-cycle arrest is sufficient to allow supporting-cell proliferation to occur. This finding may provide an important pathway for inducing hair-cell regeneration in the mammalian hearing organ.

Acoustic Stimulation↗