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Elizabeth S. Olson - One of the best experts on this subject based on the ideXlab platform.
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Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Hideko Heidi Nakajima, Elizabeth S. Olson, Saumil N. Merchant, Michael E. Ravicz, Wei Dong, John J. RosowskiAbstract:We present the first simultaneous sound pressure measurements in Scala vestibuli and Scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in Scala vestibuli ( P _SV) was much greater than Scala tympani pressure ( P _ST), except for very low and high frequencies where P _ST significantly affected the input to the cochlea. The differential pressure ( P _SV − P _ST) is a superior measure of ossicular transduction of sound compared to P _SV alone: ( P _SV− P _ST) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P _SV was not reduced as much. The middle ear gain P _SV/ P _EC and the differential pressure normalized to ear canal pressure ( P _SV − P _ST)/ P _EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)—situations that cannot be completely quantified by measurements of stapes velocity or Scala vestibuli pressure by themselves.
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Scala vestibuli pressure and three-dimensional stapes velocity measured in direct succession in gerbil.
The Journal of the Acoustical Society of America, 2007Co-Authors: Willem F. Decraemer, Wei Dong, O. De La Rochefoucauld, Shyam M. Khanna, Joris J.j. Dirckx, Elizabeth S. OlsonAbstract:It was shown that the mode of vibration of the stapes has a predominant piston component but rotations producing tilt of the footplate are also present. Tilt and piston components vary with frequency. Separately it was shown that the pressure gain between ear canal and Scala vestibuli was a remarkably flat and smooth function of frequency. Is tilt functional contributing to the pressure in the Scala vestibuli and helping in smoothing the pressure gain? In experiments on gerbil the pressure in the Scala vestibuli directly behind the footplate was measured while recording simultaneously the pressure produced by the sound source in the ear canal. Successively the three-dimensional motion of the stapes was measured in the same animal. Combining the vibration measurements with an anatomical shape measurement from a micro-CT (CT: computed tomography) scan the piston-like motion and the tilt of the footplate was calculated and correlated to the corresponding Scala vestibuli pressure curves. No evidence was found...
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Do non-piston components contribute to Scala vestibuli pressure behind the footplate in gerbils?
Middle Ear Mechanics in Research and Otology, 2007Co-Authors: Willem F. Decraemer, Wei Dong, O. De La Rochefoucauld, Shyam M. Khanna, Joris J.j. Dirckx, Elizabeth S. OlsonAbstract:Abstract: In recent papers we have shown that the mode of vibration of the ossicular chain in cat and human temporal bones is more complex than a simple rotation about a fixed axis and that it also changes with frequency. For the stapes e.g. it was shown that rotations of the footplate about its long and short axis are present besides the predominant piston-like velocity component. As the footplate motion gives rise to the pressure wave set up in the cochlea, we investigated whether the non-piston components contribute to the pressure produced in the gerbil cochlea: 3-D vibration velocity of the stapes along with the Scala vestibuli pressure were measured in the same animals. We found no correlation between non-piston components and Scala vestibuli pressure
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Observing middle and inner ear mechanics with novel intracochlear pressure sensors
The Journal of the Acoustical Society of America, 1998Co-Authors: Elizabeth S. OlsonAbstract:Intracochlear pressure was measured in vivo in the base of the gerbil cochlea. The measurements were made over a wide range of frequencies simultaneously in Scalae vestibuli and tympani. Pressure was measured just adjacent to the stapes in Scala vestibuli and at a number of positions spaced by tens of micrometers, including a position within several micrometers of the basilar membrane, in Scala tympani. Two findings emerged from the basic results. First, the spatial variation in Scala tympani pressure indicated that the pressure is composed of two modes, which can be identified with fast and slow waves. Second, at frequencies between 2 and 46 kHz (the upper frequency limit of the measurements) the Scala vestibuli pressure adjacent to the stapes had a gain of approximately 30 dB with respect to the pressure in the ear canal, and a phase which decreased linearly with frequency. Thus, over these frequencies the middle ear and its termination in the cochlea operate as a frequency independent transmission line...
John J. Rosowski - One of the best experts on this subject based on the ideXlab platform.
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Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Hideko Heidi Nakajima, Elizabeth S. Olson, Saumil N. Merchant, Michael E. Ravicz, Wei Dong, John J. RosowskiAbstract:We present the first simultaneous sound pressure measurements in Scala vestibuli and Scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in Scala vestibuli ( P _SV) was much greater than Scala tympani pressure ( P _ST), except for very low and high frequencies where P _ST significantly affected the input to the cochlea. The differential pressure ( P _SV − P _ST) is a superior measure of ossicular transduction of sound compared to P _SV alone: ( P _SV− P _ST) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P _SV was not reduced as much. The middle ear gain P _SV/ P _EC and the differential pressure normalized to ear canal pressure ( P _SV − P _ST)/ P _EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)—situations that cannot be completely quantified by measurements of stapes velocity or Scala vestibuli pressure by themselves.
Wei Dong - One of the best experts on this subject based on the ideXlab platform.
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Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Hideko Heidi Nakajima, Elizabeth S. Olson, Saumil N. Merchant, Michael E. Ravicz, Wei Dong, John J. RosowskiAbstract:We present the first simultaneous sound pressure measurements in Scala vestibuli and Scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in Scala vestibuli ( P _SV) was much greater than Scala tympani pressure ( P _ST), except for very low and high frequencies where P _ST significantly affected the input to the cochlea. The differential pressure ( P _SV − P _ST) is a superior measure of ossicular transduction of sound compared to P _SV alone: ( P _SV− P _ST) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P _SV was not reduced as much. The middle ear gain P _SV/ P _EC and the differential pressure normalized to ear canal pressure ( P _SV − P _ST)/ P _EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)—situations that cannot be completely quantified by measurements of stapes velocity or Scala vestibuli pressure by themselves.
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Scala vestibuli pressure and three-dimensional stapes velocity measured in direct succession in gerbil.
The Journal of the Acoustical Society of America, 2007Co-Authors: Willem F. Decraemer, Wei Dong, O. De La Rochefoucauld, Shyam M. Khanna, Joris J.j. Dirckx, Elizabeth S. OlsonAbstract:It was shown that the mode of vibration of the stapes has a predominant piston component but rotations producing tilt of the footplate are also present. Tilt and piston components vary with frequency. Separately it was shown that the pressure gain between ear canal and Scala vestibuli was a remarkably flat and smooth function of frequency. Is tilt functional contributing to the pressure in the Scala vestibuli and helping in smoothing the pressure gain? In experiments on gerbil the pressure in the Scala vestibuli directly behind the footplate was measured while recording simultaneously the pressure produced by the sound source in the ear canal. Successively the three-dimensional motion of the stapes was measured in the same animal. Combining the vibration measurements with an anatomical shape measurement from a micro-CT (CT: computed tomography) scan the piston-like motion and the tilt of the footplate was calculated and correlated to the corresponding Scala vestibuli pressure curves. No evidence was found...
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Do non-piston components contribute to Scala vestibuli pressure behind the footplate in gerbils?
Middle Ear Mechanics in Research and Otology, 2007Co-Authors: Willem F. Decraemer, Wei Dong, O. De La Rochefoucauld, Shyam M. Khanna, Joris J.j. Dirckx, Elizabeth S. OlsonAbstract:Abstract: In recent papers we have shown that the mode of vibration of the ossicular chain in cat and human temporal bones is more complex than a simple rotation about a fixed axis and that it also changes with frequency. For the stapes e.g. it was shown that rotations of the footplate about its long and short axis are present besides the predominant piston-like velocity component. As the footplate motion gives rise to the pressure wave set up in the cochlea, we investigated whether the non-piston components contribute to the pressure produced in the gerbil cochlea: 3-D vibration velocity of the stapes along with the Scala vestibuli pressure were measured in the same animals. We found no correlation between non-piston components and Scala vestibuli pressure
Hideko Heidi Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Impedances of the ear estimated with intracochlear pressures in normal human temporal bones
2018Co-Authors: Darcy L. Frear, Xiying Guan, Christof Stieger, Hideko Heidi NakajimaAbstract:We have measured intracochlear pressures and velocities of stapes and round window (RW) evoked by air conduction (AC) stimulation in many fresh human cadaveric specimens. Our techniques have improved through the years to ensure reliable pressure sensor measurements in the Scala vestibuli and Scala tympani. Using these measurements, we have calculated impedances of the middle and inner ear (cochlear partition, RW, and physiological leakage impedance in Scala vestibuli) to create a lumped element model. Our model simulates our data and allows us to understand the mechanisms involved in air-conducted sound transmission. In the future this model will be used as a tool to understand transmission mechanisms of various stimuli and to help create more sophisticated models of the ear.
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Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Hideko Heidi Nakajima, Elizabeth S. Olson, Saumil N. Merchant, Michael E. Ravicz, Wei Dong, John J. RosowskiAbstract:We present the first simultaneous sound pressure measurements in Scala vestibuli and Scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in Scala vestibuli ( P _SV) was much greater than Scala tympani pressure ( P _ST), except for very low and high frequencies where P _ST significantly affected the input to the cochlea. The differential pressure ( P _SV − P _ST) is a superior measure of ossicular transduction of sound compared to P _SV alone: ( P _SV− P _ST) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P _SV was not reduced as much. The middle ear gain P _SV/ P _EC and the differential pressure normalized to ear canal pressure ( P _SV − P _ST)/ P _EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)—situations that cannot be completely quantified by measurements of stapes velocity or Scala vestibuli pressure by themselves.
Tobias Struffert - One of the best experts on this subject based on the ideXlab platform.
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Evaluation After Cochlear Implant Surgery
Clinical Neuroradiology, 2020Co-Authors: Annika Stock, Victoria Bozzato, Stephan P. Kloska, Alessandro Bozzato, Ulrich Hoppe, Joachim Hornung, Arnd Dörfler, Tobias StruffertAbstract:Purpose Assessment of the cochlear implant (CI) electrode array position using flat-detector computed tomography (FDCT) to test dependence of postoperative outcome on intracochlear electrode position. Methods A total of 102 patients implanted with 107 CIs underwent FDCT. Electrode position was rated as 1) Scala tympani, 2) Scala vestibuli, 3) Scalar dislocation and 4) no deconvolution. Two independent neuroradiologists rated all image data sets twice and the Scalar position was verified by a third neuroradiologist. Presurgical and postsurgical speech audiometry by the Freiburg monosyllabic test was used to evaluate auditory outcome after 6 months of speech rehabilitation. Results Electrode array position was assessed by FDCT in 107 CIs. Of the electrodes 60 were detected in the Scala tympani, 21 in the Scala vestibuli, 24 electrode arrays showed Scalar dislocation and 2 electrodes were not placed in an intracochlear position. There was no significant difference in rehabilitation outcomes between Scala tympani and Scala vestibuli inserted patients. Rehabilitation was also possible in patients with dislocated electrodes. Conclusion The use of FDCT is a reliable diagnostic method to determine the position of the electrode array. In our study cohort, the electrode position had no significant impact on postoperative outcome except for non-deconvoluted electrode arrays.
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Evaluation After Cochlear Implant Surgery
Clinical Neuroradiology, 2020Co-Authors: Annika Stock, Victoria Bozzato, Stephan P. Kloska, Alessandro Bozzato, Ulrich Hoppe, Joachim Hornung, Arnd Dörfler, Tobias StruffertAbstract:Purpose Assessment of the cochlear implant (CI) electrode array position using flat-detector computed tomography (FDCT) to test dependence of postoperative outcome on intracochlear electrode position. Methods A total of 102 patients implanted with 107 CIs underwent FDCT. Electrode position was rated as 1) Scala tympani, 2) Scala vestibuli, 3) Scalar dislocation and 4) no deconvolution. Two independent neuroradiologists rated all image data sets twice and the Scalar position was verified by a third neuroradiologist. Presurgical and postsurgical speech audiometry by the Freiburg monosyllabic test was used to evaluate auditory outcome after 6 months of speech rehabilitation. Results Electrode array position was assessed by FDCT in 107 CIs. Of the electrodes 60 were detected in the Scala tympani, 21 in the Scala vestibuli, 24 electrode arrays showed Scalar dislocation and 2 electrodes were not placed in an intracochlear position. There was no significant difference in rehabilitation outcomes between Scala tympani and Scala vestibuli inserted patients. Rehabilitation was also possible in patients with dislocated electrodes. Conclusion The use of FDCT is a reliable diagnostic method to determine the position of the electrode array. In our study cohort, the electrode position had no significant impact on postoperative outcome except for non-deconvoluted electrode arrays.
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Evaluation After Cochlear Implant Surgery : Correlation of Clinical Outcome and Imaging Findings using Flat-detector CT.
Clinical neuroradiology, 2020Co-Authors: Annika Stock, Victoria Bozzato, Stephan P. Kloska, Alessandro Bozzato, Ulrich Hoppe, Joachim Hornung, Arnd Dörfler, Tobias StruffertAbstract:PURPOSE Assessment of the cochlear implant (CI) electrode array position using flat-detector computed tomography (FDCT) to test dependence of postoperative outcome on intracochlear electrode position. METHODS A total of 102 patients implanted with 107 CIs underwent FDCT. Electrode position was rated as 1) Scala tympani, 2) Scala vestibuli, 3) Scalar dislocation and 4) no deconvolution. Two independent neuroradiologists rated all image data sets twice and the Scalar position was verified by a third neuroradiologist. Presurgical and postsurgical speech audiometry by the Freiburg monosyllabic test was used to evaluate auditory outcome after 6 months of speech rehabilitation. RESULTS Electrode array position was assessed by FDCT in 107 CIs. Of the electrodes 60 were detected in the Scala tympani, 21 in the Scala vestibuli, 24 electrode arrays showed Scalar dislocation and 2 electrodes were not placed in an intracochlear position. There was no significant difference in rehabilitation outcomes between Scala tympani and Scala vestibuli inserted patients. Rehabilitation was also possible in patients with dislocated electrodes. CONCLUSION The use of FDCT is a reliable diagnostic method to determine the position of the electrode array. In our study cohort, the electrode position had no significant impact on postoperative outcome except for non-deconvoluted electrode arrays.
