English translation and validation of the Zurich chronic middle ear inventory (ZCMEI-21-E) assessing quality of life in chronic otitis media: A prospective international multicentre study.

OBJECTIVES: To translate and validate the Zurich Chronic Middle Ear Inventory (ZCMEI-21) for the English language in order to provide an English instrument to assess health-related quality of life in chronic otitis media (COM). DESIGN: Pilot translation study including cognitive debriefings, prospective multicentre cross-sectional psychometric validation study. SETTING: Four tertiary referral centres in three different English-speaking countries (UK, USA and Australia). PARTICIPANTS: Adult patients suffering from COM. MAIN OUTCOME MEASURES: The English translation of the ZCMEI-21 (ZCMEI-21-E) and the five-level version of the EQ-5D questionnaire. The EQ-5D, which constitutes a generic measure of health-related quality of life, consists of a descriptive system score and a visual analogue scale. Statistical outcomes included single-item descriptive statistics, internal consistency (Cronbach's α) as an indicator of reliability, as well as construct validity. RESULTS: A total of 124 patients suffering from COM were included. The mean age was 50.1 years (SD 16.9 years), and 72 (58.1%) were males. The Cronbach's α of the ZCMEI-21-E was 0.91, suggesting an excellent internal consistency. The Spearman's correlation coefficient of the ZCMEI-21-E total score was 0.55 (P < 0.0001) for convergent construct validity with EQ-5D descriptive system score and 0.57 (P < 0.0001) with the EQ-5D visual analogue scale. CONCLUSIONS: The ZCMEI-21-E is a new validated questionnaire that provides clinicians with a short, comprehensive and reliable instrument to quantify health-related quality of life in patients suffering from COM. The ZCMEI-21-E may be of use in clinical routine as well as in outcome research and monitoring.

Three-dimensional quasi-static displacement of human middle-ear ossicles under static pressure loads: Measurement using a stereo camera system.

The time delay and/or malfunctioning of the Eustachian tube may cause pressure differences across the tympanic membrane, resulting in quasi-static movements of the middle-ear ossicles. While quasi-static displacements of the human middle-ear ossicles have been measured one- or two-dimensionally in previous studies, this study presents an approach to trace three-dimensional movements of the human middle-ear ossicles under static pressure loads in the ear canal (EC). The three-dimensional quasi-static movements of the middle-ear ossicles were measured using a custom-made stereo camera system. Two cameras were assembled with a relative angle of 7° and then mounted onto a robot arm. Red fluorescent beads of a 106-125 µm diameter were placed on the middle-ear ossicles, and quasi-static position changes of the fluorescent beads under static pressure loads were traced by the stereo camera system. All the position changes of the ossicles were registered to the anatomical intrinsic frame based on the stapes footplate, which was obtained from µ-CT imaging. Under negative ear-canal pressures, a rotational movement around the anterior-posterior axis was dominant for the malleus-incus complex, with small relative movements between the two ossicles. The stapes showed translation toward the lateral direction and rotation around the long axis of the stapes footplate. Under positive EC pressures, relative motion between the malleus and the incus at the IMJ became larger, reducing movements of the incus and stapes considerably and thus performing a protection function for the inner-ear structures. Three-dimensional tracing of the middle-ear ossicular chain provides a better understanding of the protection function of the human middle ear under static pressured loads as immediate responses without time delay.

Assessment of a direct acoustic cochlear stimulator.

This study aimed to assess the functional results of a new, active, acoustic-mechanical hearing implant, the Direct Acoustic Cochlear Stimulation Partial Implant (DACS PI), in a preclinical study. The DACS PI is an electromagnetic device fixed to the mastoid by screws and coupled to a standard stapes prosthesis by an artificial incus (AI). The function of the DACS PI-aided reconstruction was assessed by determining: (1) the maximum equivalent sound pressure level (SPL) of the implant, which was obtained from measurements of the volume displacement at the round window in normal and implanted ears, and (2) the quality at the coupling interface between the AI of the DACS and the stapes prosthesis, which was quantified from measurements of relative motions between the AI and the prosthesis. Both measurements were performed with fresh temporal bones using a scanning laser Doppler interferometry system. The expected maximum equivalent SPL with a typical driving voltage of 0.3 V was about 115-125 dB SPL up to 1.5 kHz in reconstruction with the DACS PI, and decreased with a roll-off slope of about 65 dB/decade, reaching 90 dB SPL at 8 kHz. The large roll-off relative to a normal ear was presumed to be a relatively high inductive impedance of the coil of the DACS PI actuator at higher frequencies. Good coupling quality between the AI and the prosthesis was achieved below the resonance (∼1.5 kHz) of the DACS PI for all tested stapes prostheses. Above the resonance, the SMart Piston, which is composed of a shape-memory alloy, had the best coupling quality.

Objective assessment of stapedotomy surgery from round window motion measurement.

OBJECTIVES: As prostheses and techniques related to stapes surgery develop and improve, there is a need to assess the functional outcomes of the surgery objectively. This study provides a bench test method to assess the functional results of stapes surgery by measuring volume displacement at the round window (RW), which is closely related to pressure propagation of the travelling wave inside the cochlea and thus to hearing. DESIGN: Motion of the RW membrane in fresh temporal bones was measured using a scanning laser Doppler interferometry system for normal and reconstructed conditions, and the performance of the reconstruction with stapes surgery was quantitatively assessed by comparison of the volume displacements at the RW between the two conditions. To obtain optimal measurements, reflectivity of the laser beam of the scanning laser Doppler interferometry system was improved by retroreflective beads coated onto the surface of the RW, and orientation of the RW membrane relative to the laser beam was obtained using micro-computed tomography imaging. RESULTS: From measurements in 12 temporal bones, difference in the RW volume displacement between normal ears and ears reconstructed with stapes surgery was approximately 15 dB below 2 kHz and approximately 10 dB above 4 kHz, which was comparable with air-bone gaps in patients after stapes surgery. Two different sizes of the stapes prostheses were also tested (n = 3), and a tendency toward a better outcome with a larger diameter was found. CONCLUSION: The method developed in this study can be used to assess various prostheses and surgical conditions objectively in controlled laboratory environments. It may also have potential for providing ways to assess other middle- and inner-ear surgeries, and to study other aspects of hearing science.

Contribution of the flexible incudo-malleal joint to middle-ear sound transmission under static pressure loads.

The incudo-malleal joint (IMJ) in the human middle ear is a true diarthrodial joint and it has been known that the flexibility of this joint does not contribute to better middle-ear sound transmission. Previous studies have proposed that a gliding motion between the malleus and the incus at this joint prevents the transmission of large displacements of the malleus to the incus and stapes and thus contributes to the protection of the inner ear as an immediate response against large static pressure changes. However, dynamic behavior of this joint under static pressure changes has not been fully revealed. In this study, effects of the flexibility of the IMJ on middle-ear sound transmission under static pressure difference between the middle-ear cavity and the environment were investigated. Experiments were performed in human cadaveric temporal bones with static pressures in the range of +/- 2 kPa being applied to the ear canal (relative to middle-ear cavity). Vibrational motions of the umbo and the stapes footplate center in response to acoustic stimulation (0.2-8 kHz) were measured using a 3D-Laser Doppler vibrometer for (1) the natural IMJ and (2) the IMJ with experimentally-reduced flexibility. With the natural condition of the IMJ, vibrations of the umbo and the stapes footplate center under static pressure loads were attenuated at low frequencies below the middle-ear resonance frequency as observed in previous studies. After the flexibility of the IMJ was reduced, additional attenuations of vibrational motion were observed for the umbo under positive static pressures in the ear canal (EC) and the stapes footplate center under both positive and negative static EC pressures. The additional attenuation of vibration reached 4~7 dB for the umbo under positive static EC pressures and the stapes footplate center under negative EC pressures, and 7~11 dB for the stapes footplate center under positive EC pressures. The results of this study indicate an adaptive mechanism of the flexible IMJ in the human middle ear to changes of static EC pressure by reducing the attenuation of the middle-ear sound transmission. Such results are expected to be used for diagnosis of the IMJ stiffening and to be applied to design of middle-ear prostheses.

Multiphoton imaging for morphometry of the sandwich-beam structure of the human stapedial annular ligament.

BACKGROUND: The annular ligament of the human stapes constitutes a compliant connection between the stapes footplate and the peripheral cochlear wall at the oval window. The cross section of the human annular ligament is characterized by a three-layered structure, which resembles a sandwich-shaped composite structure. As accurate and precise descriptions of the middle-ear behavior are constrained by lack of information on the complex geometry of the annular ligament, this study aims to obtain comprehensive geometrical data of the annular ligament via multiphoton imaging. METHODS: The region of interest containing the stapes and annular ligament was harvested from a fresh-frozen human temporal bone of a 46-years old female. Multiphoton imaging of the unstained sample was performed by detecting the second-harmonic generation of collagen and the autofluorescence of elastin, which are constituents of the annular ligament. The multiphoton scans were conducted on the middle-ear side and cochlear side of the annular ligament to obtain accurate images of the face layers on both sides. The face layers of the annular ligament were manually segmented on both multiphoton scans, and then registered to high-resolution µCT images. RESULTS: Multiphoton scans of the annular ligament revealed 1) relatively large thickness of the core layer compared to the face layers, 2) asymmetric geometry of the face layers between the middle-ear side and cochlear side, and variation of their thickness and width along the footplate boundary, 3) divergent relative alignment of the two face layers, and 4) different fiber composition of the face layers along the boundary with a collagen-reinforcement near the anterior pole on the middle-ear side. CONCLUSION AND OUTLOOK: Multiphoton microscopy is a feasible approach to obtain the detailed three-dimensional features of the human stapedial annular ligament along its full boundary. The detailed description of the sandwich-shaped structures of the annular ligament is expected to contribute to modeling of the human middle ear for precise simulation of middle-ear behavior. Further, established methodology in this study may be applicable to imaging of other middle-ear structures.

Characterization of stapes anatomy: investigation of human and guinea pig.

The accuracy of any stapes model relies on the accuracy of the anatomical information upon which it is based. In many previous models and measurements of the stapes, the shape of the stapes has been considered as symmetric with respect to the long and short axes of the footplate. Therefore, the reference frame has been built based upon this assumption. This study aimed to provide detailed anatomical information on the dimensions of the stapes, including its asymmetries. High-resolution microcomputed tomography data from 53 human stapes and 11 guinea pig stapes were collected, and their anatomical features were analyzed. Global dimensions of the stapes, such as the size of the footplate, height, and volume, were compared between human and guinea pig specimens, and asymmetric features of the stapes were quantitatively examined. Further, dependence of the stapes dimensions on demographic characteristics of the subjects was explored. The height of the stapes relative to the footplate size in the human stapes was found to be larger than the corresponding value in guinea pig. The stapes showed asymmetry of the footplate with respect to the long axis and offset of the stapes head from the centroid of the medial surface of the footplate for both humans and guinea pigs. The medial surface of the footplate was curved, and the longitudinal arches of the medial surface along the long axis of the footplate were shaped differently between humans and guinea pigs. The dimension of the footplate was gender-dependent, with the size greater in men than in women.

Contribution of complex stapes motion to cochlea activation.

Classic theories of hearing have considered only a translational component (piston-like component) of the stapes motion as being the effective stimulus for cochlear activation and thus the sensation of hearing. Our previous study (Huber et al., 2008) qualitatively showed that rotational components around the long and short axes of the footplate (rocking-like components) lead to cochlear activation as well. In this study, the contribution of the piston-like and rocking-like components of the stapes motion to cochlea activation was quantitatively investigated with measurements in live guinea pigs and a related mathematical description. The isolated stapes in anesthetized guinea pigs was stimulated by a three-axis piezoelectric actuator, and 3-D motions of the stapes and compound action potential (CAP) of the cochlea were measured simultaneously. The measured values were used to fit a hypothesis of the CAP as a linear combination of the logarithms of the piston-like and rocking-like components. Both the piston-like and rocking-like components activate cochlear responses when they exceed certain thresholds. These thresholds as well as the relation between CAP and intensity of the motion component were different for piston-like and rocking-like components. The threshold was found to be higher and the sensitivity lower for the rocking-like component than the corresponding values for the piston-like component. The influence of the rocking-like component was secondary in cases of piston-dominant motions of the stapes although it may become significant for low amplitudes of the piston-like component.

Experimental study on admissible forces at the incudomalleolar joint.

HYPOTHESIS: The forces that cause rupture of the incudomalleolar joint during the fixation of stapedial prostheses can be determined by means of load-deflection measurements at the long process of the incus. As in other tissues, 3 ranges of forces can be defined: micro rupture, rupture, and short-term maximum. BACKGROUND: A crucial step in stapes surgery is the attachment of the stapedial prosthesis to the long process of the incus. It is unknown which forces occur during the crimping process that increase the risk of damage to the incudomalleolar joint or incus luxation. The goal of this study was to assess the admissible range of forces at the long process of the incus that would be tolerable before damaging the structures and to compare them with the forces occurring during surgery. METHODS: Load-deflection curves in the lateral-medial and anterior-posterior direction were measured in 9 freshly frozen or fresh temporal bones. The force was measured with a load cell, and displacement was taken from the encoder information of the electrically driven translation stage on which the load cell was mounted. The long process of the incus was coupled to the load cell via a customized needle. We also monitored with video recordings for visual confirmation of findings. RESULTS: The rupture force at which the middle ear was found to be severely injured was 894 (724-1018) mN in the anterior-posterior direction and 695 (574-771) mN in the lateral-medial direction. Micro-ruptures occurred at forces around 568 (469-686) mN in the anterior-posterior direction and in the lateral-medial direction at 406 (254-514) mN. Short-term maximum forces of 1,321 (1,051-1,533) mN were measured in the anterior-posterior direction and 939 (726-1,132) mN in the lateral-medial direction. CONCLUSION: Rupture forces of the incudomalleolar joint could be defined with high accuracy. These results were used to calculate risks of incus luxation or subluxation during stapes surgery. Compared with the use of clip and SMA prostheses, the risk of damage from a crimping procedure is significantly higher.

The influence of prosthesis diameter in stapes surgery: a meta-analysis and systematic review of the literature.

OBJECTIVE: To analyze the influence of stapes prosthesis diameter on postoperative hearing results after stapedotomy without interposition in otosclerotic patients. DATA SOURCES: PubMed search from 1970 to 2009 using the key words stapedotomy or stapedectomy or otosclerosis or stapesplasty. STUDY SELECTION: Inclusion criteria to select articles and patient groups for meta-analysis and statistical analyses were as follows: otosclerosis as diagnosis, clear description of technique and prosthesis size, calibrated stapedotomy, and complete report of functional results. DATA EXTRACTION: Five controlled studies were found analyzing the influence of prosthesis diameter and reporting the results in a comparable way for meta-analysis (n = 590). Sixty-two studies not analyzing the influence of prosthesis diameter contained comparable subgroups with a total of 9,536 cases. These cases were pooled according to their diameter (0.3, 0.4, 0.5, 0.6,and 0.8 mm). The results of air conduction, bone conduction, air-bone gap (ABG), and success rate (closure of the ABG within 10 dB as percentage of the total cases) for all groups and frequency-specific ABG results were gathered. Furthermore, 12 clinical and experimental studies were reviewed that did not contribute to the statistical analysis. DATA SYNTHESIS: A meta-analysis performed for success rate of the 5 controlled studies showed favorable results for 0.6-mm over 0.4-mm prostheses (success rate, 67% versus 58%, p = 0.05). In the statistical analysis of the pooled data, the 0.6-mm prosthesis showed better results compared with 0.4 mm (p < 0.001) in the postoperative air conduction threshold (29 dB versus 35 dB), postoperative ABG (7 dB versus 11 dB), ABG improvement (25 dB versus 21 dB), and success rate (81.1% versus 75.1%). The frequency-specific analysis of the postoperative ABG showed no advantage for the small prosthesis in the high frequencies. There was no difference in postoperative change of bone conduction in the 0.6- and 0.4-mm groups. Statistically significant results could not be assessed for other prosthesis diameters because of the small number of cases reported. CONCLUSION: A 0.6-mm diameter piston prosthesis is associated with significantly better results than a 0.4-mm prosthesis and should be used if the surgical conditions allow it.

Ossiculoplasty with total ossicular replacement prosthesis and Omega Connector: early clinical results and functional measurements.

OBJECTIVE: Among other difficulties, achieving a stable position of a total ossicular replacement prosthesis (TORP) is demanding because of a limited view on the TORP-footplate interface and individual angles between the footplate and tympanic membrane. The Kurz Omega Connector aims at a simplified insertion of the TORP. The performance of total ossicular reconstruction using the Omega Connector was evaluated. STUDY DESIGN: Prospective cohort study and experimental measurements with a fresh human temporal bone. SETTING: Tertiary referral center. PATIENTS: Seventeen consecutive patients receiving total ossicular reconstruction were included. Historical control group composed of 36 patients. INTERVENTIONS: Total ossicular reconstruction using the Omega Connector. MAIN OUTCOME MEASURES: (a) Handling of the TORP and Omega Connector intraoperatively, (b) functional short-term results compared with a historical control group, (c) sound transmission properties with 3 different connective positions between the TORP and the Omega Connector. RESULTS: Placing the Omega Connector on the footplate and coupling the Omega Connector to the TORP was straightforward in 65% of cases. A stable final position of the TORP was obtained in 88% of cases. Mean (SD) preoperative and postoperative air-bone gaps were 36.00 (11.05) and 25.29 (12.25) dB and were almost identical with those in the historical control group (p = 0.9). In the experimental measurements, functional outcomes with "partial connection" showed almost the same results as those with "full connection." CONCLUSION: The Omega Connector provides easy handling of the TORP. The short-term functional results were comparable to those achieved previously without the Omega Connector. The temporal bone measurement supports tolerance in connective position between the TORP and the Omega Connector.

The influence of postoperative tissue formation on sound transmission after stapes surgery.

In the surgical treatment of otosclerosis, the coupling between the stapes prosthesis and the long process of the incus is critical. After surgery, connective tissue and mucosa may grow over the coupling area and thereby influence the sound transmission properties of the incus-prosthesis interface. It was the hypothesis of this study that tissue ongrowth in the incus-prosthesis interface has little influence on sound transmission following stapes surgery. The goals of the study were to: (1) investigate the extent of postoperative tissue ongrowth over the stapes prosthesis; (2) objectively evaluate intra- and postoperative sound transmission properties of revision stapes surgery and compare the findings to those from primary surgery; (3) quantify the influence of ongrown tissue on sound transmission after stapes surgery. A group of 10 patients undergoing revision stapes surgery was investigated with audiological evaluations and intraoperative laser Doppler interferometry, and with scanning electron microscopy of the explanted incus with its adherent prosthesis in 6 patients. Results were compared to a group of patients undergoing primary otosclerosis surgery and temporal bone experiments. Results indicated that tissue grows over the prosthesis, as identified in all specimens. Sound transmission properties were evaluated intraoperatively (i.e., incus mobility and prosthesis-fixation quality), and found to correlate well with the functional hearing results. Ongrowing mucosa in the incus-prosthesis interface had only a minimal effect on sound transmission properties and cannot compensate adequately for insufficient prosthesis fixation. Therefore, it is essential that the stapes prosthesis is properly fixed during primary otosclerosis surgery.

Errors in measurement of three-dimensional motions of the stapes using a laser Doppler vibrometer system.

Previous studies have suggested complex modes of physiological stapes motions based upon various measurements. The goal of this study was to analyze the detailed errors in measurement of the complex stapes motions using laser Doppler vibrometer (LDV) systems, which are highly sensitive to the stimulation intensity and the exact angulations of the stapes. Stapes motions were measured with acoustic stimuli as well as mechanical stimuli using a custom-made three-axis piezoelectric actuator, and errors in the motion components were analyzed. The ratio of error in each motion component was reduced by increasing the magnitude of the stimuli, but the improvement was limited when the motion component was small relative to other components. This problem was solved with an improved reflectivity on the measurement surface. Errors in estimating the position of the stapes also caused errors on the coordinates of the measurement points and the laser beam direction relative to the stapes footplate, thus producing errors in the 3-D motion components. This effect was small when the position error of the stapes footplate did not exceed 5 degrees.

Complex stapes motions in human ears.

It has been reported that the physiological motion of the stapes in human and several animals in response to acoustic stimulation is mainly piston-like at low frequencies. At higher frequencies, the pattern includes rocking motions around the long and short axes of the footplate in human and animal ears. Measurements of such extended stapes motions are highly sensitive to the exact angulation of the stapes in relation to the measurement devices and to measurement errors. In this study, velocity in a specific direction was measured at multiple points on the footplates of human temporal bones using a Scanning Laser Doppler Vibrometer (SLDV) system, and the elementary components of the stapes motions, which were the piston-like motion and the rocking motions about the short and long axes of the footplate, were calculated from the measurements. The angular position of a laser beam with respect to the stapes and coordinates of the measurement points on the footplate plane were calculated by correlation between the SLDV measurement frame and the footplate-fixed frame, which was obtained from micro-CT images. The ratios of the rocking motions relative to the piston-like motion increased with frequency and reached a maximum around 7 kHz.A novel method for quantitatively assessing measurements of complex stapes motions and error boundaries of the motion components is presented. In the frequency range of 0.5 to 8 kHz, the magnitudes of the piston-like and two rocking motions were larger than estimated values of the corresponding upper error bounds.