Computer-Aided Three-Dimensional Reconstruction in Human Cochlear Maps: Measurement of the Lengths of Organ of Corti, Outer Wall, Inner Wall, and Rosenthal's Canal

Kawano, Atsushi; Seldon, H. Lee; Clark, Graeme M.

doi:10.1177/000348949610500906

Cited by 141 publications

(152 citation statements)

References 17 publications

(3 reference statements)

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“…This finding is consistent with numerous prior reports indicating a large extent of variation in human cochlear length (Bredberg 1968;Ulehlova et al 1987;Wright et al 1987;Hardy 1968;Kawano et al 1996;Ketten et al 1998: Skinner et al 2002. We did not observe a significant difference between female and male OC length as reported by Sato et al (1991), who found OC lengths of 32.3 T 1.8 mm for females and 37.1 T 1.6 mm for males (total n = 18).…”

Section: Measurements Of Oc Sg and Mw And Implications For CIsupporting

confidence: 93%

“…Our data showed a significant correlation between total length of OC and SG, which suggests that if OC length is known (e.g., from high-resolution CT images), it can be used to estimate the length of the SG. Kawano et al (1996) reported a longer mean value of 15.98 mm for Rosenthal_s canal in the human cochlea. The cochlear reconstructions in that study were made with a computer-aided 3D technique, and the authors also reported a systematic difference between the 2D and 3D reconstructions, with the larger values obtained with the 3D reconstructions.…”

Section: Measurements Of Oc Sg and Mw And Implications For CImentioning

confidence: 93%

“…The relationship between OC and SG frequency maps also must change in different coils due to the change in radius of curvature along the spiral. It has been reported previously that Rosenthal_s canal is not linearly related to the OC (Kawano et al 1996), but the relationship between corresponding frequencymatched points along the OC and SG has never been studied.…”

Section: Introductionmentioning

confidence: 96%

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Frequency Map for the Human Cochlear Spiral Ganglion: Implications for Cochlear Implants

Stakhovskaya

Sridhar

Bonham

et al. 2007

JARO

347

357

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The goals of this study were to derive a frequencyposition function for the human cochlear spiral ganglion (SG) to correlate represented frequency along the organ of Corti (OC) to location along the SG, to determine the range of individual variability, and to calculate an Baverage^frequency map (based on the trajectories of the dendrites of the SG cells). For both OC and SG frequency maps, a potentially important limitation is that accurate estimates of cochlear place frequency based upon the Greenwood function require knowledge of the total OC or SG length, which cannot be determined in most temporal bone and imaging studies. Therefore, an additional goal of this study was to evaluate a simple metric, basal coil diameter that might be utilized to estimate OC and SG length. Cadaver cochleae (n = 9) were fixed G24 h postmortem, stained with osmium tetroxide, microdissected, decalcified briefly, embedded in epoxy resin, and examined in surface preparations. In digital images, the OC and SG were measured, and the radial nerve fiber trajectories were traced to define a series of frequency-matched coordinates along the two structures. Images of the cochlear turns were reconstructed and measurements of basal turn diameter were made and correlated with OC and SG measurements. The data obtained provide a mathematical function for relating represented frequency along the OC to that of the SG.Results showed that whereas the distance along the OC that corresponds to a critical bandwidth is assumed to be constant throughout the cochlea, estimated critical band distance in the SG varies significantly along the spiral. Additional findings suggest that measurements of basal coil diameter in preoperative images may allow prediction of OC/SG length and estimation of the insertion depth required to reach specific angles of rotation and frequencies. Results also indicate that OC and SG percentage length expressed as a function of rotation angle from the round window is fairly constant across subjects. The implications of these findings for the design and surgical insertion of cochlear implants are discussed.

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Section: Measurements Of Oc Sg and Mw And Implications For CIsupporting

confidence: 93%

Section: Measurements Of Oc Sg and Mw And Implications For CImentioning

confidence: 93%

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Frequency Map for the Human Cochlear Spiral Ganglion: Implications for Cochlear Implants

Stakhovskaya

Sridhar

Bonham

et al. 2007

JARO

347

357

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“…However, hair cells are usually absent in implant patients after conventional implant surgery. The remaining neural targets, dendrites and cell bodies in the spiral ganglion, do not have the same relationship to distance along the cochlear partition as hair cells (Kawano et al 1996;Sridhar et al 2006). Thus, the Greenwood frequency-place (or frequency to distance along the cochlea) map is not likely to be appropriate for cochlear implant patients.…”

mentioning

confidence: 99%

An Electric Frequency-to-place Map for a Cochlear Implant Patient with Hearing in the Nonimplanted Ear

Dorman

Spahr

Gifford

et al. 2007

JARO

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The aim of this study was to relate the pitch of high-rate electrical stimulation delivered to individual cochlear implant electrodes to electrode insertion depth and insertion angle. The patient (CH1) was able to provide pitch matches between electric and acoustic stimulation because he had auditory thresholds in his nonimplanted ear ranging between 30 and 60 dB HL over the range, 250 Hz to 8 kHz. Electrode depth and insertion angle were measured from high-resolution computed tomography (CT) scans of the patient_s temporal bones. The scans were used to create a 3D image volume reconstruction of the cochlea, which allowed visualization of electrode position within the scala. The method of limits was used to establish pitch matches between acoustic pure tones and electric stimulation (a 1,652-pps, unmodulated, pulse train). The pitch matching data demonstrated that, for insertion angles of greater than 450 degrees or greater than approximately 20 mm insertion depth, pitch saturated at approximately 420 Hz. From 20 to 15 mm insertion depth pitch estimates were about one-half octave lower than the Greenwood function. From 13 to 3 mm insertion depth the pitch estimates were approximately one octave lower than the Greenwood function. The pitch match for an electrode only 3.4 mm into the cochlea was 3,447 Hz. These data are consistent with other reports, e.g., Boëx et al. (2006), of a frequency-to-place map for the electrically stimulated cochlea in which perceived pitches for stimulation on individual electrodes are significantly lower than those predicted by the Greenwood function for stimulation at the level of the hair cell.

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“…Furthermore, the auditory-nerve fibers do not maintain the same relationship of frequency map to distance along the electrode array as inner hair cells (Kawano et al 1996;Sridhar et al 2006). It is fortunate, however, that CI users are partially able to adapt to distorted frequency-to-place maps (e.g., Fu and Galvin 2003;Faulkner 2006;Smith and Faulkner 2006).…”

Section: Introductionmentioning

confidence: 99%

Spectral and Temporal Analysis of Simulated Dead Regions in Cochlear Implants

Won

Jones

Moon

et al. 2015

JARO

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A cochlear implant (CI) electrode in a Bcochlear dead region^will excite neighboring neural populations. In previous research that simulated such dead regions, stimulus information in the simulated dead region was either added to the immediately adjacent frequency regions or dropped entirely. There was little difference in speech perception ability between the two conditions. This may imply that there may be little benefit of ensuring that stimulus information on an electrode in a suspected cochlear dead region is transmitted. Alternatively, performance may be enhanced by a broader frequency redistribution, rather than adding stimuli from the dead region to the edges. In the current experiments, cochlear dead regions were introduced by excluding selected CI electrodes or vocoder noise-bands. Participants were assessed for speech understanding as well as spectral and temporal sensitivities as a function of the size of simulated dead regions. In one set of tests, the normal input frequency range of the sound processor was distributed among the active electrodes in bands with approximately logarithmic spacing (Bredistributedm aps); in the remaining tests, information in simulated dead regions was dropped (Bdropped^maps). Word recognition and Schroeder-phase discrimination performance, which require both spectral and temporal sensitivities, decreased as the size of simulated dead regions increased, but the redistributed and dropped remappings showed similar performance in these two tasks. Psychoacoustic experiments showed that the near match in word scores may reflect a tradeoff between spectral and temporal sensitivity: spectral-ripple discrimination was substantially degraded in the redistributed condition relative to the dropped condition while performance in a temporal modulation detection task degraded in the dropped condition but remained constant in the redistributed condition.

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Computer-Aided Three-Dimensional Reconstruction in Human Cochlear Maps: Measurement of the Lengths of Organ of Corti, Outer Wall, Inner Wall, and Rosenthal's Canal

Cited by 141 publications

References 17 publications

Frequency Map for the Human Cochlear Spiral Ganglion: Implications for Cochlear Implants

Frequency Map for the Human Cochlear Spiral Ganglion: Implications for Cochlear Implants

An Electric Frequency-to-place Map for a Cochlear Implant Patient with Hearing in the Nonimplanted Ear

Spectral and Temporal Analysis of Simulated Dead Regions in Cochlear Implants

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