Manohar Bance

A piezoelectric bone-conduction bending hearing actuator

A prototype of a novel bone-conduction hearing actuator based on a piezoelectric bending actuator is presented. The device lies flat against the skull which would allow it to form the basis of a subcutaneous bone-anchored hearing aid. The actuator excites bending in bone through a local bending moment rather than the application of a point force as with conventional bone-anchored hearing aids. Through measurements of the cochlear velocity created by the actuator in embalmed human heads, the device is shown to exhibit high efficiency, making it a possible alternative to present-day electromagnetic bone-vibration actuators.

Clinical Doppler-mode optical coherence tomography of the middle ear

We present results from an ongoing clinical trial examining the use of structural and Doppler-mode optical coherence tomography (OCT) for imaging the middle ear. Based on our preliminary findings, Doppler-mode OCT appears to offer a highly sensitive and specific method for diagnosing otosclerosis. More generally, it provides useful diagnostic information about the mechanics of the middle ear unavailable with competing modalities that can inform clinical decision making.

New Imaging Modalities in Otology

Despite steady improvements in cross-sectional imaging of the ear, current technologies still have limitations in terms of resolution, diagnosis, functional assessment and safety. In this chapter, state-of-the-art imaging techniques in current clinical practice are presented including cone-beam computerized tomography, non-echo planar imaging magnetic resonance imaging, imaging for labyrinthine hydrops and imaging of the central auditory pathways. Potential future imaging modalities are also presented, including optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) of the ear. These experimental modalities offer new opportunities for the assessment of ear structure and function. For example, middle ear structures can be visualized through the tympanic membrane, basilar membrane vibrations can be assessed through the round window and the passage of cochlear implants can be assessed in decalcified cochlear. Functional assessment of the middle ear using Doppler techniques are also discussed, including measurement of tympanic membrane and middle ear vibration amplitudes, visualization of dynamic changes, such as tensor tympani movements and movement of the tympanic membrane with breathing. These new modalities currently have limitations that preclude mainstream clinical use. For example, OCT is limited by the optical scattering of the thickened tympanic membrane and HFUS needs a coupling medium such as gel or fluid from the transducer to the imaged structure although it can visualize through thicker tissues. Nevertheless, further development of these novel techniques may provide an enhanced ability to assess the ear in conjunction with current technologies.

The 678 Hz acoustic immittance probe tone: a more definitive indicator of PET than the traditional 226 Hz method

BackgroundThe accurate diagnosis of Eustachian tube (ET) dysfunction can be very difficult. Our aim is to determine whether a 678xa0Hz probe tone is a more accurate indicator of Patulous ET (PET) than the 226xa0Hz probe tone when used in compliance over time (COT) testing.MethodsTwenty subjects (11 normal ET ears and 7 PET ears) were individually seated in an examination room and connected to a GSI TympStar Middle Ear Analyzer. The order of probe tone frequency (678 or 226xa0Hz) was randomized. Baseline “testing” COT recordings for each ear undergoing testing were completed. Subjects were instructed to occlude their contralateral nostril and to breathe forcefully in and out through their ipsilateral nostril until the test had run to completion. This process was repeated with the probe tone that had not been previously run. For the control group, each subject had one random ear tested. For the experimental group, only the affected ear(s) was tested. Wilcoxon rank rum tests were performed to determine statistical significance.ResultsThe baseline COT measurements for the control group and PET group were similar, 0.86xa0mL (SDu2009=u20090.34) and 0.74 (SDu2009=u20090.33) respectively. Comparing the 226xa0Hz tone between groups revealed that PET patients had a median COT difference 0.19xa0mL higher than healthy ET patients, and for the 678xa0Hz tone, PET patients had a median COT difference of 0.57xa0mL higher than healthy ET patients. Both were deemed to be statistically significant (pu2009=u20090.002, pu2009=u20090.004 respectively). The was a statistically significant median COT difference between the 678xa0Hz and 226xa0Hz of 0.61xa0mL (pu2009=u20090.034) for the PET group, while the same comparison for the control group of 0.05xa0mL was not significant (pu2009=u20090.262), suggesting that the 678xa0Hz tone yields a larger response for PET than the 226xa0Hz tone, and no difference for the control group, thus making it less prone to artifact noise interference.ConclusionThe 678xa0Hz probe tone is a more reliable indicator of ET patency, and should be preferably used over the 226xa0Hz tone for future COT testing.

Shared decision making and decisional conflict in the Management of Vestibular Schwannoma: a prospective cohort study

BackgroundPatients with vestibular schwannomas (VS) are faced with complex management decisions. Watchful waiting, surgical resection, and radiation are all viable options with associated risks and benefits. We sought to determine if patients with VS experience decisional conflict when deciding between surgery or non-surgical management, and factors influencing the degree of decisional conflict.MethodsA prospective cohort study in two tertiary ambulatory skull-base clinics was performed. Patients with newly diagnosed or newly growing vestibular schwannomas were recruited. Patients were given a demographic form and the decisional conflict scale (DCS), a validated measure to assess the degree of uncertainty when making medical decisions. The degree of shared decision making (SDM) experienced by the patient and physician were assessed via the SDM-Q-10 and SDM-Q-Doc questionnaires, respectively. Non-parametric statistics were used. Questionnaires and demographic information were correlated with DCS using Spearman correlation coefficient and Mann-Whitney U. Logistic regression was performed to determine factors independently associated with DCS scores.ResultsSeventy-seven patients participated (55% female, aged 37–81xa0years); VS ranged in size from 2xa0mm–50xa0mm. Significant decisional conflict (DCS score 25 or greater) was experienced by 17 (22%) patients. Patients reported an average SDM-Q-10 score of 86, indicating highly perceived level of SDM. Physician and patient SDM scores were weakly correlated (pu2009=u20090.045, Spearman correlation coefficient 0.234). DCS scores were significantly negatively correlated with a decision to pursue surgery, presence of a trainee, and higher SDM-Q-10 score. DCS was higher with female gender. Using logistic regression, the SDM-Q-10 score was the only variable associated with significantly reduced DCS.ConclusionsAbout one fifth of patients deciding how to manage their vestibular schwannoma experienced a significant degree of decisional conflict. Involving the patients in the process through shared decision-making significantly reduced the degree of uncertainty patients experienced.

Real-time intracochlear imaging of automated cochlear implant insertions in whole decalcified cadaver cochleas using ultrasound

Objectives: This study aimed to determine the feasibility of combining high-frequency ultrasound imaging, automated insertion, and force sensing to yield more information about cochlear implant insertion dynamics. Methods: An apparatus was developed combining these aspects along with software to control implant and imaging probe positions. Decalcified unfixed human cochleas were implanted at various speeds, insertion sites, and implant models while imaging near the implant tip throughout insertion and recording force data from the cochlea mounting stage. Ultrasound video data were also captured. Results: The basilar membrane (BM) was frequently penetrated by the implant in either the mid-basal or lower middle turn. Measurements were also performed of apical BM motion in response to upstream implant movement at varying insertion speeds. Increasing insertion speed resulted in greater BM displacement. Discussion: Multiple insertions per cochlea increase the volume of data per specimen while also reducing variability due to differences between cochleas. However, to image inside the cochlea with ultrasound, the bone had to be decalcified, which likely had a significant effect upon the response of tissue to contact by the implant. As calcified bone strongly reflects ultrasound, we also found ultrasound imaging to be an excellent method for easily assessing bone decalcification progress. Conclusion: This technique may be very useful for some studies, although the confounding effects of bone decalcification may make results of other studies too difficult to generalize. The approach could be adapted to other real-time imaging modalities, such as optical coherence tomography.

No effect of prolonged pulsed high frequency ultrasound imaging of the basilar membrane on cochlear function or hair cell survival found in an initial study

&NA; Miniature high frequency ultrasound devices show promise as tools for clinical middle ear and basal cochlea imaging and vibrometry. However, before clinical use it is important to verify that the ultrasound exposure does not damage the cochlea. In this initial study, electrophysiological responses of the cochlea were measured for a range of stimulus frequencies in both ears of anesthetized chinchillas, before and after exposing the organ of Corti region of one ear to pulsed focused ultrasound for 30 min. Measurements were again taken after an 11 day survival period. Cochlear tissue was examined with a confocal microscope for signs of damage to the cochlear hair cells. No significant change in response thresholds due to exposure was found, and no signs of ultrasound‐induced tissue damage were observed, although one animal (out of ten) did have a region of extensive tissue damage in the exposed cochlea. However, after further analysis this was concluded to be not likely a result of the ultrasound exposure. HighlightsHigh frequency ultrasound has promise for clinical imaging of middle and inner ears.Chinchilla cochleas were exposed to pulsed ultrasound to assess its safety.Cochlear responses were measured before, just after, and 11 days after exposure.Organ of Corti hair cells and peripheral neural fibers were confocal imaged.The results indicate that the ultrasound exposure was not harmful to the cochlea.

A miniature, ultrasonic transcutaneous energy transmission system for powering implantable medical devices.

We present a novel miniaturized ultrasonic transcutaneous energy transmission system (TETS) for powering implantable hearing aids. To operate, implantable hearing aids typically require 50–80 mW of electrical power, which has traditionally been delivered through a set of coupled magnetic induction coils. Because of inherent trade‐offs between size and efficiency in this design, typical devices are 50 mm diameter or larger which severely limits the implantation locations available to the surgeon, particularly when implanting infants. We have developed an ultrasonic TETS that offers comparable efficiency (>30%) to electromagnetic links in a device that, at less than 5 mm diameter, is more than an order of magnitude smaller. The ultrasonic TETS also shows a high degree of insensitivity to alignment and to separation distance of the transmit and receive transducers. We will present the results of measurements of electrical efficiency in experiments in water and tissue, and examine the theoretical limits on de...