Fixation of the anterior mallear ligament: diagnosis and consequences for hearing results in stapes surgery

Material characterization of human middle ear using machine-learning-based surrogate models

This study aims to introduce a novel non-invasive method for rapid material characterization of middle-ear structures, taking into consideration the invaluable insights provided by the mechanical properties of ear tissues. Valuable insights into various ear pathologies can be gleaned from the mechanical properties of ear tissues, yet conventional techniques for assessing these properties often entail invasive procedures that preclude their use on living patients. In this study, in the first step, we developed machine-learning models of the middle ear to predict its responses with a significantly lower computational cost in comparison to finite-element models. Leveraging findings from prior research, we focused on the most influential model parameters: the Young's modulus and thickness of the tympanic membrane and the Young's modulus of the stapedial annular ligament. The eXtreme Gradient Boosting (XGBoost) method was implemented for creating the machine-learning models. Subsequently, we combined the created machine-learning models with Bayesian optimization (BoTorch) for fast and efficient estimation of the Young's moduli of the tympanic membrane and the stapedial annular ligament. We demonstrate that the resultant surrogate models can fairly represent the vibrational responses of the umbo, stapes footplate, and vibration patterns of the tympanic membrane at most frequencies. Also, our proposed material characterization approach successfully estimated the Young's moduli of the tympanic membrane and stapedial annular ligament (separately and simultaneously) with values of mean absolute percentage error of less than 7%. The remarkable accuracy achieved through the proposed material characterization method underscores its potential for eventual clinical applications of estimating mechanical properties of the middle-ear structures for diagnostic purposes.

Use of simulated data to explore the application of optical coherence tomography for classifying middle-ear pathologies

Optical coherence tomography (OCT) vibrometry is a non-invasive tool for functional imaging of the middle ear. It provides spatially resolved vibrational responses and also anatomical images of the same ear. Our objective here was to explore the potential of OCT vibration measurements at the incus, as well as at the umbo, to distinguish among middle-ear disorders. Our approach was to build finite-element models of normal and pathological ears, generate large amounts of synthetic data, and then classify the simulated data into normal and pathological groups using a decision tree based on features extracted from simulated vibration magnitudes. We could distinguish between normal ears and ears with incudomallear joint (IMJ) disarticulation or stapes fixation, with the sensitivity and specificity both being 1.0; distinguish between stapes fixation and IMJ disarticulation with a sensitivity of 0.900 and a specificity of 0.889; and distinguish ears with ISJ disarticulation from normal ears with a sensitivity of 0.784 and a specificity of 0.872. Less extreme pathologies were also simulated. The results suggest that the vibration measurements within the middle ear that can be provided by OCT (e.g., at the incus) may be very valuable for diagnosis.

Comparison of Tympanic Membrane Perforation With and Without Calcification of Anterior Mallear Ligament Under Transcanal Endoscopic Type I Tympanoplasty

OBJECTIVES

Chronic suppurative otitis media (CSOM) induced tympanic membrane perforation (TMP) can be accompanied by anterior mallear ligament (AML) calcification. So far, comparative evaluations of TMP with and without AML calcification have rarely been reported. The aim of the current study is to compare the hearing outcomes of TMP with and without calcification of AML under transcanal endoscopic type I tympanoplasty.

METHODS

Records of 67 patients diagnosed with CSOM and receiving transcanal endoscopic type I tympanoplasty were divided into the AML calcification group (Cal group, n = 31) and the non-AML calcification group (non-Cal group, n = 36). The 31 patients in the Cal group were divided into subgroup A and B according to the severity of calcification. The operation time, closure rate, and pre- and postoperative audiometric results were retrospectively collected and analyzed.

RESULTS

Preoperatively, the Cal group had higher mean air-bone gap (ABG; P = .022), and ABGs at 250 Hz (P = .017) and 500 Hz (P = .008) compared with the non-Cal groups. The Cal group showed higher improvements of ABGs at 250 Hz (P = .039) and 500 Hz (P = .021) compared with the non-Cal groups postoperatively.

CONCLUSIONS

The TMP with AML calcification leads to higher ABGs at low frequencies. The hearing outcomes are similar for TMP both with and without AML calcification after surgery. Our results suggest that transcanal endoscopic type I tympanoplasty is an appropriate surgical method for TMP with AML calcification, if the lesion can be detected and completely eliminated.

Endoscopic Management of Malleus Head Fixation in Revision Stapes Surgery

OBJECTIVE

Malleus ankylosis is an uncommon finding during stapes surgery, which can result in functional failure if undetected during primary surgery. Its management can be difficult and different approaches and solutions have been described to date, most of which require interruption of the ossicular chain. We report the management of such condition through a transcanal endoscopic technique, with preservation of ossicular chain integrity.

PATIENTS

The procedure was carried out in a patient affected by otosclerosis with persistent hearing loss after primary stapes surgery.

INTERVENTION

Surgical treatment of malleus head fixation through a totally endoscopic transcanal approach during revision stapes surgery.

MAIN OUTCOME MEASURE

Pure tone audiometry, speech audiometry.

RESULTS

The patient experienced a complete closure of the air-bone gap. No postoperative vertigo or sensorineural hearing loss were observed.

CONCLUSIONS

The present report describes the transcanal endoscopic management of malleus ankylosis during revision stapes surgery, which has not been previously reported in the literature. Pearls related to this approach and advantages in comparison to previously described approaches of the literature are discussed as well.

Endoscopic Stapes Surgery: Pearls and Pitfalls

The endoscopic approach to stapes surgery affords unique advantages but is not without its specific challenges. The following reviews the equipment and surgical steps required to perform endoscopic stapes surgery safely and effectively, highlighting tips and potential points of failure through a series of case examples.

Outcomes Following Revision Stapes Surgery in Children: A Single-Surgeon, Single-Center 15-Year Experience

OBJECTIVE

To review a single surgeon experience with revision pediatric stapes surgery for congenital stapes fixation (CSF) and tympanosclerosis (TS). Secondly, to determine whether hearing outcomes following revision surgery may be predicted by a thorough work-up aimed at assessing whether an extruded or malpositioned prosthesis is likely to be encountered intraoperatively.

SETTING

Tertiary referral center.

STUDY DESIGN

Retrospective chart review.

PATIENTS

Fifteen patients having revision surgery for fixation of the stapes footplate over a 15-year period.

MAIN OUTCOME MEASURES

Hearing results based on pre- and post-revision pure-tone average air-bone gap (PTA-ABG) and speech recognition threshold testing (SRT).

RESULTS

Overall, the mean improvement of PTA-ABG following revision surgery was 11.9 dB (standard deviation [SD] 15.2) while SRTs improved by a mean of 12.3 (SD 19.9). Outcomes were significantly better in patients who reported a history of trauma following their initial surgery, when there was otoscopic evidence of an extruding or extruded prosthesis and/or a pre-revision CT (where performed) suggested an extruded or malpositioned prosthesis. No patients had a significant postoperative sensorineural hearing loss.

CONCLUSION

Revision stapes surgery in children is a safe procedure in experienced hands which nonetheless should only be contemplated in patients in whom preoperative work-up suggests an extruded or malpositioned prosthesis is likely to be encountered intraoperatively.

Finite element analysis of round-window stimulation of the cochlea in patients with stapedial otosclerosis

An active actuator coupled to the round window (RW) can transmit mechanical vibrations into the cochlea and has become a therapeutic option of hearing rehabilitation for patients with stapedial otosclerosis. A finite-element model of the human ear that includes sound transmission effects of the vestibular and cochlear aqueducts of the inner ear is adopted in this study for investigating the cochlear response to RW stimulation under stapes fixation. There are two effects due to otosclerosis of the stapes: the fixation of the stapedial annular ligament (SAL) and the increase of the stapes mass. The frequency responses of the middle ear and cochlea with normal and otosclerotic stapes are calculated under sound and RW stimulations. The results show that changes in the material property of the stapes have different effects on the cochlear responses under sound and RW stimulations. Because of the vestibuli aqueduct, the reduction in the low-frequency magnitude of the pressure difference across the cochlear partition due to SAL fixation is much smaller under RW stimulation than under sound stimulation. The results of this study help understand sound transmission during RW stimulation in patients with stapedial otosclerosis.

Isolated malleus fixation: A pediatric case series

OBJECTIVES

The goal of this review was to review our series of isolated malleus fixation in pediatric patients, a rare entity causing conductive hearing loss. Malleolar fixation is poorly described in this patient population.

METHODS

A retrospective review of pediatric tympanoplasties by the senior author over a four-year period was performed. Only cases with isolated fixation of the malleus were reviewed. Primary outcome of interest was post-operative hearing. Paired t-tests were used to calculate pre- and post-operative hearing outcomes.

RESULTS

Five cases were analyzed. Mean age at time of surgery was 9.1 years (range 4.4-16.0 years). Average follow-up after surgery was 13.9 months (range 4.4-31.2 months). Patients were otherwise healthy and typically presented after a failed school hearing test despite previously good hearing. Three out of five cases showed radiographic evidence of bony fixation (60%) on computerized tomography (CT). Otoscopy was unremarkable in all cases. Average procedure time was 41.2 min and consisted of transcanal tympanoplasty with excision of fixed bony segment. A significant improvement in both pre- and post-operative air bone gaps was observed (p = 0.005)., with average ABG of 14.75 dB.

CONCLUSIONS

Isolated pediatric malleolar fixation is an uncommon cause of pediatric conductive hearing loss. CT scan is useful for identifying this abnormality, and surgical correction results in improved post-operative hearing outcomes, potentially obviating the need for hearing amplification.

A study on the effect of ligament and tendon detachment on human middle ear sound transfer using mathematic model

The objective of this study is to investigate the effects of ligament and tendon detachment on human middle ear sound transfer. For this purpose, a geometric human middle ear model was reconstructed based on the computed tomography scanning data of the temporal bones from healthy adult volunteers. For the ear model, pars tensa was assumed to be fit for a 5-parameter Maxwell model and inverse method was used to obtain the necessary coefficients. Furthermore, frequency response method was implemented to investigate the vibration behaviors of tympanic membrane umbo and stapes footplate under an acoustic stimulus of 90 dB within 0.2-8 kHz. Meanwhile, nine patterns of fractured ligaments and tendons, whose effects on the middle ear sound transfer function were simulated by setting free the nodes of the ligaments and tendons of interest. The results indicate that the displacement of tympanic membrane umbo and stapes footplate as well as the velocity transfer function lies within the bounds of the published experimental data. The detachments of ligaments or tendons except for lateral mallear ligament may incur both gains as much as 15 dB and losses of -8 dB in the velocity of stapes footplate at low frequencies (f≤ 1 kHz), while no significant changes were observed at high frequencies (f > 1 kHz). However, detachment of the ligaments or tendons induces tiny changes in the displacement of stapes footplate at the frequencies of 0.2-8 kHz.

Pars tensa and tympanicomalleal joint: proposal for a new anatomic classification

PURPOSE

The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to clarify the nature of TM, tympanic bone and malleus to propose a new anatomic classification.

METHODS

This cadaveric study was performed in two human heads and six fresh temporal bones. A study of the temporomandibular joint, external acoustic meatus (EAM), TM and middle ear structures was conducted. A medical literature review englobing anatomy, embryology, histology and phylogeny of the ear was performed and the results were compared with the results of the dissection.

RESULTS

The external ear is constituted by the auricle and the EAM. This last segment is made by a cartilaginous and an osseous portion. The osseous portion of the EAM is constituted mainly by tympanic bone. The external ear is separated from the middle ear by the TM. Inside the middle ear, there are three ossicles: malleus, incus and stapes, which allow the conduction of sound to the cochlea. Based on the anatomic dissection and medical literature review of the tympanic bone, malleus and TM, we propose that these structures are interconnected like a joint, and named it "Tympanicomalleal joint".

CONCLUSIONS

It seems that the TM can be part of a joint that evolved to improve sound transmission and middle ear protection. Thinking TM has part of a joint may help in the development of more efficient reconstructive surgical techniques.

Development of intra-operative assessment system for ossicular mobility and middle ear transfer function

Objective measurements of the ossicular mobility have not been commonly performed during the surgery, and the assessment of ossicular mobility is made by palpation in most cases. Palpation is inherently subjective and may not always be reliable, especially in milder degrees of ossicular fixation and in the case of multiple fixation. Although several devices have been developed to quantitatively measure the ossicular mobility during surgery, they have not been widely used. In this study, a new system with a hand-held probe which enables intraoperative quantitative measurements of ossicular mobility has been developed. This system not only measures the ossicular mobility, but also investigates "local" transmission characteristics of the middle ear by directly applying vibration to the ossicles and measuring cochlear microphonic. The basic performance of this system was confirmed by measuring the mobility of artificial ossicles and cochlear microphonics in an animal experiment. Our system may contribute to selection of a better surgical method and reducing the risks of revision surgery.

Review of a single surgeon's stapedotomy cases performed with a nickel titanium prosthesis over a 14-year period

CONCLUSION

Stapes surgery with a nickel titanium prosthesis is a safe and well-tolerated procedure that leads to a significant improvement in hearing outcomes.

OBJECTIVE

To identify the efficacy and safety of stapedotomy procedures performed with a nickel titanium prosthesis for patients with otosclerosis.

METHODS

A review of 431 unique stapedotomies performed over 14 years by a single surgeon at an academic tertiary care center yielded 312 cases with nickel titanium prosthesis that met inclusion criteria of otosclerosis diagnosis, initial surgery in operative ear, and presence of pre-operative and post-operative audiograms. Pure-tone averages (PTA) at baseline and 8 weeks after surgery were calculated over four frequencies; 0.5, 1, 2, and 4 kHz. Average air-bone gaps (ABG) were calculated from pre-operative and post-operative audiograms.

RESULTS

Average pre-operative baseline PTA was 56.7 dB in the affected ear. Post-operative PTA was 30.1 dB, a 26.6 dB improvement. Initial average ABG was 29.7 dB, while post-operative ABG averaged 5.4 dB, a 24.2 dB improvement. Surgical success (closure of ABG within 10 dB) was achieved in 263 (84%) patients. Rate of surgical success was not correlated with age, gender, race, or affected ear. Complications included recurrent conductive hearing loss (14), progressive SNHL (4), and post-operative BPPV (3).

Finite element modelling of sound transmission from outer to inner ear

The ear is one of the most complex organs in the human body. Sound is a sequence of pressure waves, which propagates through a compressible media such as air. The pinna concentrates the sound waves into the external auditory meatus. In this canal, the sound is conducted to the tympanic membrane. The tympanic membrane transforms the pressure variations into mechanical displacements, which are then transmitted to the ossicles. The vibration of the stapes footplate creates pressure waves in the fluid inside the cochlea; these pressure waves stimulate the hair cells, generating electrical signals which are sent to the brain through the cochlear nerve, where they are decoded. In this work, a three-dimensional finite element model of the human ear is developed. The model incorporates the tympanic membrane, ossicular bones, part of temporal bone (external auditory meatus and tympanic cavity), middle ear ligaments and tendons, cochlear fluid, skin, ear cartilage, jaw and the air in external auditory meatus and tympanic cavity. Using the finite element method, the magnitude and the phase angle of the umbo and stapes footplate displacement are calculated. Two slightly different models are used: one model takes into consideration the presence of air in the external auditory meatus while the other does not. The middle ear sound transfer function is determined for a stimulus of 60 dB SPL, applied to the outer surface of the air in the external auditory meatus. The obtained results are compared with previously published data in the literature. This study highlights the importance of external auditory meatus in the sound transmission. The pressure gain is calculated for the external auditory meatus.

Objective Measurements of Ossicular Chain Mobility Using a Palpating Instrument Intraoperatively

BACKGROUND

The judgment of a normal or impaired mobility of middle ear ossicles is based on palpation and depends highly on the surgeon's subjective experience. The aim of this study was to develop and test a palpating instrument recording force and vector and allowing to support the surgeon's subjective impression with objective measurement results.

STUDY DESIGN

Prospective recordings at surgery.

SETTING

Tertiary referral center.

PATIENTS AND METHODS

A fiberoptic force-sensing element allowing force measures in three orthogonal directions was integrated into a handheld 45 degree hook and tested in temporal bones. Clinical data series from patients with a functionally normal chain (e.g., cochlear implants (CI)) and impaired ossicles (otosclerosis) were collected. The ossicles were palpated until their first movements out of the resting stage were visualized, the applied force, and vector were recorded by an independent observer.

RESULTS

Four CI and 19 otosclerosis patients were further evaluated. The minimum detectable force change of the sensor was 0.2 gF (2 mN). In the otosclerosis patients the average force applied to move the malleus was 9.5 gF, on the incus 8.7 gF. These values were slightly lower after separation of the incudostapedial joint, reaching 8.5 gF and 6.9 gF, respectively. The fixed stapes showed a rigidity of 14.7 gF or higher. The values were lower in the CI group measuring 4.4 gF, 4.1 gF, and 3.3 gF on the three ossicles, respectively.

CONCLUSIONS

We were able to produce a disposable, easy-to-handle palpating probe that enables the otologist to record continuously tip contact forces in three dimensions during his standard palpation of each ossicle. Normative values were reproduced for each ossicle, as well as increased rates for stapes fixation in otosclerosis.

Evaluation of Round Window Stimulation Performance in Otosclerosis Using Finite Element Modeling

Round window (RW) stimulation is a new type of middle ear implant's application for treating patients with middle ear disease, such as otosclerosis. However, clinical outcomes show a substantial degree of variability. One source of variability is the variation in the material properties of the ear components caused by the disease. To investigate the influence of the otosclerosis on the performance of the RW stimulation, a human ear finite element model including middle ear and cochlea was established based on a set of microcomputerized tomography section images of a human temporal bone. Three characteristic changes of the otosclerosis in the auditory system were simulated in the FE model: stapedial annular ligament stiffness enlargement, stapedial abnormal bone growth, and partial fixation of the malleus. The FE model was verified by comparing the model-predicted results with published experimental measurements. The equivalent sound pressure (ESP) of RW stimulation was calculated via comparing the differential intracochlear pressure produced by the RW stimulation and the normal eardrum sound stimulation. The results show that the increase of stapedial annular ligament and partial fixation of the malleus decreases RW stimulation's ESP prominently at lower frequencies. In contrast, the stapedial abnormal bone growth deteriorates RW stimulation's ESP severely at higher frequencies.

Predictions of middle-ear and passive cochlear mechanics using a finite element model of the pediatric ear

A finite element (FE) model was developed based on histological sections of a temporal bone of a 4-year-old child to simulate middle-ear and cochlear function in ears with normal hearing and otitis media. This pediatric model of the normal ear, consisting of an ear canal, middle ear, and spiral cochlea, was first validated with published energy absorbance (EA) measurements in young children with normal ears. The model was used to simulate EA in an ear with middle-ear effusion, whose results were compared to clinical EA measurements. The spiral cochlea component of the model was constructed under the assumption that the mechanics were passive. The FE model predicted middle-ear transfer functions between the ear canal and cochlea. Effects of ear structure and mechanical properties of soft tissues were compared in model predictions for the pediatric and adult ears. EA responses are predicted to differ between adult and pediatric ears due to differences in the stiffness and damping of soft tissues within the ear, and any residual geometrical differences between the adult ear and pediatric ear at age 4 years. The results have significance for predicting effects of otitis media in children.

Elastic Properties of the Annular Ligament of the Human Stapes--AFM Measurement

Elastic properties of the human stapes annular ligament were determined in the physiological range of the ligament deflection using atomic force microscopy and temporal bone specimens. The annular ligament stiffness was determined based on the experimental load-deflection curves. The elastic modulus (Young's modulus) for a simplified geometry was calculated using the Kirchhoff-Love theory for thin plates. The results obtained in this study showed that the annular ligament is a linear elastic material up to deflections of about 100 nm, with a stiffness of about 120 N/m and a calculated elastic modulus of about 1.1 MPa. These parameters can be used in numerical and physical models of the middle and/or inner ear.

Revision surgery for otosclerosis: An overview

Stapes surgery for otosclerosis has been proved to be a very satisfying procedure. However, the condition is difficult for the patients with no or little hearing gain after surgery and for those who had sudden or gradual hearing loss after a successful air-bone gap closure in the follow-up period. The issue of re-exploring the middle ear is challenging. A general review of this subject from several points of view remains lacking. In this study, articles related with the revision surgery for otosclerosis have been reviewed after a PubMed research and common and/or contradictory points were documented. The aim of this study is to give an insight to diagnostic and therapeutic approaches for the clinicians in patients who need a revision surgery. In conclusion, prosthesis problems, loose prosthesis in stapedotomy and migrated prosthesis in stapedectomy are the most common causes for revision surgery. Most important indicators which effect better hearing outcome following revision surgery are those ears with the presence of incus, with no obliteration of oval window, with small fenestra stapedotomy and the experience of surgeon. The risk of neurosensorial hearing loss in revision cases is not high but the hearing gain is limited as compared to primary cases. The rate of 10 dB air-bone gap closure is around 60%-70% at most and even less promising results have been reported. Patient’s demands and expectations have to be clarified in a realistic way.

NUMERICAL ANALYSIS OF TYMPANOSCLEROSIS AND TREATMENT EFFECT

Tympanosclerosis is a typical middle ear disease, which is one of the main causes of conduction deafness. We investigate the effects of tympanosclerosis and lesion excision on sound transmission of the human ear by using finite element technique. Based on CT scan images from Zhongshan Hospital of Fudan University on the normal human middle ear, numerical values of the CT scans were obtained by further processing of the images using a self-compiled program. The CT data of the right ear from a healthy volunteer were digitalized and imported into PATRAN software to reconstruct the finite element model of the ear by a self-compiling program. A frequency response analysis was made for the model, and comparative analysis was made between the calculated results and experimental data, which validated the model in this paper. The results show that the sclerosis of the ligaments and tensor muscle in the middle ear caused by force on the ossicles is larger than the normal ear and the amplitude of the stapes footplate is larger than the normal ear. This leads to a decrease of the final conductive hearing function. Furthermore, the excision of the stapes ligament and tensor tympani is good for the restoration of normal hearing. This paper provides new research perspective for clinical treatment.

The atretic plate--a conduit for drill vibration to the inner ear?

CONCLUSION

In the presence of simulated congenital aural atresia with fixation of the ossicular chain to the surrounding bone, access to the chain for placement of a middle ear prosthesis using the rotating burr is not associated with significant stapes movement that would cause vibrational trauma to the cochlea.

OBJECTIVES

To determine the energy transmitted to the cochlea while drilling the mastoid in an ear with simulated congenital aural atresia and fixation of the ossicular chain to the surrounding bone.

METHODS

Eight human cadaveric temporal bones were used. Cement was placed in the external auditory canal and on the incudomalleolar joint and surrounding epitympanum, to simulate congenital aural atresia and ossicular fixation, respectively. Stapes vibration was measured with the Laser Doppler Vibrometer using acoustic then drill stimulation by touching the wall of the epitympanum with a running burr.

RESULTS

Using acoustic stimulation, all bones showed frequency-specific reduction of stapes motion of up to 17 dB with fixation of the ossicular chain to the surrounding bone. There was no measurable stapes motion when the external auditory canal was filled with cement. On drill stimulation, there was no difference in stapes velocity between the normal bone and the bone with simulated congenital aural atresia.

A three-dimensional finite element model of round window membrane vibration before and after stapedotomy surgery

Piston stapes prostheses are implanted in patients with refractory conductive or mixed hearing loss due to stapes otosclerosis to stimulate the perilymph with varying degrees of success. The overclosure effect described by the majority of researchers affects mainly low and medium frequencies, and a large number of patients report a lack of satisfactory results for frequencies above 2 kHz. The mechanics of perilymph stimulation with the piston have not been studied in a systematic manner. The objective of this study was to assess the influence of stapedotomy surgery on round window membrane vibration and to estimate the postoperative outcomes using the finite element (FE) method. The study hypothesis is that the three-dimensional FE model developed of the human inner ear, which simulates the round window (RW) membrane vibration, can be used to assess the influence of stapedotomy on auditory outcomes achieved after the surgical procedure. An additional objective of the study was to enable the simulation of RW membrane vibration after stapedotomy using a new type of stapes prosthesis currently under investigation at Warsaw University of Technology. A three-dimensional finite element (FE) model of the human inner ear was developed and validated using experimental data. The model was then used to simulate the round window membrane vibration before and after stapedotomy surgery. Functional alterations of the RW membrane vibration were derived from the model and compared with the results of experimental measurements from temporal bones of a human cadaver. Piston stapes prosthesis implantation causes an approximately fivefold (14 dB) lower amplitude of the RW membrane vibrations compared with normal anatomical conditions. A satisfactory agreement between the FE model and the experimental data was found. The new prosthesis caused an increase of 20–30 dB in the RW displacement amplitude compared with the 0.4-mm piston prosthesis. In all frequencies, the FE model predicted a RW displacement curve that was above the experimental curves for the normal ear. The stapedotomy can be well simulated by the FE model to predict the auditory outcomes achieved following this otosurgery procedure. The 3D FE model developed in this study may be used to optimize the geometry of a new type of stapes prosthesis in order to achieve a similar sound transmission through the inner ear as for a normal middle ear. This should provide better auditory outcomes for patients with stapedial otosclerosis.

Self-Crimping Superelastic Nitinol Prosthesis and Malleostapedotomy

Objective

The aim of this study was to compare the results of application of 2 types of superelastic nitinol prostheses.

Study Design

Temporal bones study with planned data collection.

Setting

Tertiary referral center.

Subjects and Methods

Malleostapedotomy was performed in 15 human temporal bones implanting 3 different prostheses: manually crimping polytetrafluoroethylene (MC-PTFE) piston, nitinol self-crimping polytetrafluoroethylene (SC-PTFE) piston, and a modified nitinol self-crimping polytetrafluoroethylene (mSC-PTFE) piston. The first 2 have a diameter of 0.4 mm and length of 7 mm, whereas the mSC-PTFE piston has a diameter of 0.4 mm but a length of 7.75 mm. We evaluated various parameters of prosthesis attachment—that is, the time for implantation of SC and mSC nitinol loop pistons and the MC platinum loop piston, the quality of attachment of the prostheses to the malleus, their positions with respect to the center of the stapes footplate, and the protrusion of the piston into the vestibule.

Results

The mSC-PTFE superelastic nitinol prosthesis showed a statistically significant difference in mean operation time (mSC vs SC, P < .0001; SC vs MC, P < .0001; mSC vs MC, P < .0001). The protrusion of the piston into the vestibule was highly reproducible in all 3 prostheses.

Conclusion

Because of its greater length, the mSC-PTFE allows for management of the most varied anatomical conditions. At the same time, its self-crimping nature prevents the risk of distortion of the prosthesis by the crimping process and reduces the operation time in combination with standardized bending of the prosthesis shaft.

From incus bypass to malleostapedotomy: technical improvements and results

Objective:

To assess results of malleostapedotomy using a Fisch Storz titanium piston with at least 10 months’ follow up.

Methods:

Using a prospective database, the indications, surgical technique, and pre- and post-operative audiometric data for 60 patients undergoing malleostapedotomy between 2002 and 2010 were evaluated. Diagnoses and primary and revision surgeries were compared with reference to the literature.

Results:

Sixty endaural malleostapedotomies were performed, 28 as a primary intervention and 32 as revision surgery. In 68 per cent, the underlying pathology was otosclerosis. The most common reason for revision surgery (i.e. in 59 per cent) was prosthesis dysfunction. Overall, the mean air–bone gap (0.5–3 kHz) for the primary intervention and revision surgery groups was 9.4 and 11.3 dB, respectively; an air–bone gap of less than 20 dB was obtained in 100 and 81 per cent of patients, respectively. There was no significant audiological difference between the primary and revision surgeries groups, and no deafness.

Conclusion:

Malleostapedotomy shows comparable results to standard incus-stapedotomy and may be preferable in the presented situations.

Effect of anterior tympanomeatal angle blunting on the middle ear transfer function using a finite element ear model

The anterior tympanomeatal angle (ATA) blunting is clinically defined as a certain degree of the ATA obliteration due to excessive fibrous tissue formation, which is a relatively common complication of external auditory canal (EAC) related operations. The aim of this study was to examine the effect of ATA blunting on the middle ear transfer function using a finite element (FE) model. Results showed that the displacements at the tympanic membrane (TM), at the manubrium and at the stapes footplate, and also the ratio of stapes footplate velocity to the sound pressure in the EAC were decreased to various degrees from ATA blunting of Grades 1-4. This was more significant with TM thickening at the frequencies below 3.2kHz, particularly in Grades 3 and 4 when analyzing the anterior region of the TM. The phase differences of TM and stapes footplate increased with the ATA blunting from Grades 1 to 4 in relation to normal ATA. It is noteworthy that the vibration mode of the malleus does not show obvious change, compared to the displacement reduction at the TM with ATA blunting Grades 1-4. These results suggest that FE analysis of ATA blunting effect appears to be effective.

Morphology of the malleus handle and the comparison of different prostheses for malleostapedotomy

OBJECTIVES

To assess malleus morphology to characterize optimal sites for prosthesis attachment in malleostapedotomy and to examine attachment, position, and depth of penetration in the vestibule of the 3 most used prostheses.

METHODS

Ten mallei were processed for histologic examination with the light microscope. Using digitized video images of the histologic slices, the diameters, circumference, and shape of the specimen were determined. Implantation of 3 prostheses (Gyrus Nitinol piston, Storz titanium stapes piston, and Kurz malleovestibulopexy piston), was performed in 3 temporal bones for a total of 27 implantations.

RESULTS

The cross-section of the malleus just distal to the lateral process shows an inclined oval shape with a mean minimum diameter of 0.84 +/- 0.10 mm, a mean maximum diameter of 1.02 +/- 0.23 mm, and a mean circumference of 3.23 +/- 0.49 mm. The quality of attachment to the malleus, the position of the prosthesis piston, and the depth of penetration were reliable for the Storz titanium stapes piston, satisfactory though variable for the Gyrus Nitinol piston and poor for the Kurz malleovestibulopexy piston as judged by contact with the malleus surface and predictability of insertion depth into the vestibule.

CONCLUSION

The oval and inferoanteriorly inclined shape of the malleus distal to the lateral process requires the use of a prosthesis capable of molding itself to its surface for reliable attachment. To achieve the correct perpendicular position of the piston as it relates to the stapedotomy opening, individualized adaptation of the prosthesis shaft and loop to the anterior position of the malleus should be made in situ.

[Laser Doppler vibrometric measurements of DPOAE in humans. Eardrum vibrations reflect middle- and inner-ear characteristics]

BACKGROUND

Up to now, laser interferometric vibration measurements of the human eardrum have not provided any information about cochlear function, because the measurement devices have not been sufficiently sensitive.

METHODS

After designing a new type of laser Doppler vibrometer (LDV) that allows detection of displacement amplitudes down to about 1 pm, we used this device in 20 subjects to measure growth functions of the distortion products of otoacoustic emissions (DPOAE) as vibrations of the umbo. For comparison, DPOAE growth functions were also measured conventionally with an acoustic probe in the closed external auditory meatus. Hearing thresholds were estimated from both sets of measurements and compared with Békésy thresholds.

RESULTS

The standard deviation of the threshold estimate obtained from the vibration DPOAEs was 8.6 dB, which is significantly smaller than that of the threshold estimate (16.7 dB) obtained from the acoustic DPOAEs. We attribute the smaller standard deviation for the LDV data to the fact that these measurements are made in an open sound field and are therefore less susceptible to pressure calibration errors.

CONCLUSIONS

Being relatively free of sound-field measurement artefacts, the LDV method allows precise estimation of the hearing threshold. Vibration measurements of the umbo have, therefore, considerable potential for the differential diagnosis of mechanical dysfunction of the middle and inner ear.

Mechanical properties of anterior malleolar ligament from experimental measurement and material modeling analysis

In this paper, mechanical properties of the anterior malleolar ligament (AML) of human middle ear were studied through the uniaxial tensile, stress relaxation and failure tests. The digital image correlation (DIC) method was used to assess the boundary effect in experiments and calculate the strain on specimens. The constitutive behavior of the AML was described by a transversely isotropic hyperelastic model which consists of a first-order Ogden model augmented by a I(4)-type reinforcing term. The material parameters of the model were estimated and the viscoelasticity of the AML was illustrated by hysteresis phenomena and stress relaxation function. The mechanical strength of the AML was obtained through the failure test and the mean ultimate stress and stretch ratio were measured as 1.05 MPa and 1.51, respectively. Finally, a linear Young's modulus-stress relationship of the AML was derived based on constitutive equation of the AML within a stress range of 0-0.5 MPa.

Fixation and detachment of superior and anterior malleolar ligaments in human middle ear: experiment and modeling

The aim of this study is to investigate the function of the superior malleolar ligament (SML) and the anterior malleolar ligament (AML) in human middle ear for sound transmission through simulations of fixation and detachment of these ligaments in human temporal bones and a finite element (FE) ear model. Two laser vibrometers were used to measure the vibrations of the tympanic membrane (TM) and stapes footplate. A 3-D FE ear model was used to predict the transfer function of the middle ear with ligament fixation and detachment. The results demonstrate that fixations and detachments of the SML and AML had different effects on TM and stapes footplate movements. Fixation of the SML resulted in a reduction of displacement of the TM (umbo) and the footplate at low frequencies (f<1000 Hz), but also caused a shift of displacement peak to higher frequencies. Fixation of both SML and AML caused a reduction of 15 dB at umbo or stapes at low frequencies. Detachment of the SML had almost no effect on TM and footplate mobility, but AML detachment had a minor effect on TM and footplate movement. The FE model was able to predict the effects of SML and AML fixation and detachment.

Distortion product otoacoustic emissions measured as vibration on the eardrum of human subjects

It has previously not been possible to measure eardrum vibration of human subjects in the region of auditory threshold. It is proposed that such measurements should provide information about the status of the mechanical amplifier in the cochlea. It is this amplifier that is responsible for our extraordinary hearing sensitivity. Here, we present results from a laser Doppler vibrometer that we designed to noninvasively probe cochlear mechanics near auditory threshold. This device enables picometer-sized vibration measurements of the human eardrum in vivo. With this sensitivity, we found the eardrum frequency response to be linear down to at least a 20-dB sound pressure level (SPL). Nonlinear cochlear amplification was evaluated with the cubic distortion product of the otoacoustic emissions (DPOAEs) in response to sound stimulation with two tones. DPOAEs originate from mechanical nonlinearity in the cochlea. For stimulus frequencies, f1 and f2, with f2/f1 = 1.2 and f2 = 4-9.5 kHz, and intensities L1 and L2, with L1 = 0.4L(2) + 39 dB and L2 = 20-65 dB SPL, the DPOAE displacement amplitudes were no more than 8 pm across subjects (n = 20), with hearing loss up to 16 dB. DPOAE vibration was nonlinearly dependent on vibration at f2. The dependence allowed the hearing threshold to be estimated objectively with high accuracy; the standard deviation of the threshold estimate was only 8.6 dB SPL. This device promises to be a powerful tool for differentially characterizing the mechanical condition of the cochlea and middle ear with high accuracy.

Surgical Findings and Long-Term Hearing Results in 3,050 Stapedotomies for Primary Otosclerosis

OBJECTIVE

To evaluate with a new otologic database the results of primary stapes surgery for otosclerosis with up to 14 years of follow-up in a consecutive series of 2,525 patients operated on by the same surgeon with the same technique (stapedotomy and vein graft interposition) and to provide online access to the complete data of this study for the reviewers. To study the effect of specific operative findings (obliterative otosclerosis and simultaneous malleus ankylosis) and age at the time of surgery on the long-term outcome.

STUDY DESIGN

Prospective clinical study using a new computerized otologic database.

SETTING

: Tertiary referral center.

PATIENTS

Two thousand five hundred twenty-five patients who underwent 3,050 stapedotomies for otosclerotic stapes fixation were enrolled in this study from January 1991 to December 2004. Separate analyses were made for two unique pathologies (92 cases of obliterative otosclerosis and 19 cases of simultaneous malleus ankylosis) diagnosed during surgery and for patients in two age brackets (<or=18 yr [28 patients] and >or=65 yr [302 patients]).

INTERVENTION

Stapedotomy with vein graft interposition and reconstruction with either a Teflon piston, a bucket handle prosthesis, or a total prosthesis.

MAIN OUTCOME MEASURES

Preoperative and postoperative audiometric evaluation using conventional audiometry. Air-bone gap (ABG), bone-conduction thresholds, and air-conduction thresholds were all assessed. Postoperative audiometry was performed at 3, 6, 9, 12, 18, and 24 months and then annually for 14 years.

RESULTS

Overall, the postoperative ABG was closed to 10 dB in 94.2% of cases. The mean four-frequency postoperative ABG was 1.7 dB compared with 25.6 dB preoperatively. The mean four-frequency bone-conduction thresholds were unchanged postoperatively. A significant postoperative sensorineural hearing loss (SNHL; >15 dB) was seen in 0.5% of cases in this series. Postoperative ABG was achieved to within 10 dB in 95% of cases of obliterative otosclerosis and in 64.7% of cases of simultaneous malleus ankylosis. A significant postoperative SNHL (>15 dB) was seen in 4.8% of cases of obliterative otosclerosis and was not observed in any cases of simultaneous malleus ankylosis. Postoperative ABG was achieved to within 10 dB in 93.5% of cases in the pediatric series and in 94.5% of cases in the senior series. A significant postoperative SNHL (>15 dB) was seen in 0.7% of cases in the senior group but was not observed in the children.

CONCLUSION

Using a new otologic database, our series confirms that stapedotomy with vein graft interposition for otosclerotic stapes fixation is a safe and successful treatment for long-term hearing improvement. The deterioration in hearing with time after stapedotomy did not exceed the rate of hearing loss because of presbyacusis. Therefore, argon laser stapedotomy with vein graft interposition is our preferred surgical technique in the treatment of otosclerosis. Obliterative otosclerosis and simultaneous malleus ankylosis may be encountered during stapedotomy. Our study shows that reasonable success rates can still be expected in these situations. Stapedotomy results in the elderly and in children are comparable to those obtained in patients of other groups of age undergoing surgery for otosclerosis without an increased risk for complications.

Low-frequency finite-element modeling of the gerbil middle ear

The gerbil is a popular species for experimental middle-ear research. The goal of this study is to develop a 3D finite-element model to quantify the mechanics of the gerbil middle ear at low frequencies (up to about 1 kHz). The 3D reconstruction is based on a magnetic resonance imaging dataset with a voxel size of about 45 microm, and an x-ray micro-CT dataset with a voxel size of about 5.5 microm, supplemented by histological images. The eardrum model is based on moiré shape measurements. Each individual structure in the model was assumed to be homogeneous with isotropic, linear, and elastic material properties derived from a priori estimates in the literature. The behavior of the finite-element model in response to a uniform acoustic pressure on the eardrum of 1 Pa is analyzed. Sensitivity tests are done to evaluate the significance of the various parameters in the finite-element model. The Young's modulus and the thickness of the pars tensa have the most significant effect on the load transfer between the eardrum and the ossicles and, along with the Young's modulus of the pedicle and stapedial annular ligament, on the displacements of the stapes. Overall, the model demonstrates good agreement with low-frequency experimental data. For example, (1) the maximum footplate displacement is about 35 nm; (2) the umbo/stapes displacement ratio is found to be about 3.5; (3) the motion of the stapes is predominantly piston-like; and (4) the displacement pattern of the eardrum shows two points of maximum displacement, one in the posterior region and one in the anterior region. The effects of removing or stiffening the ligaments are comparable to those observed experimentally.

Otosclerosis: etiopathogenesis and histopathology

Otosclerosis is a disease of the bony labyrinth manifesting clinically as a progressive conductive hearing loss, a mixed-type hearing loss, or a sensorineural hearing loss. The age of onset of the hearing loss caused by otosclerosis is principally between 15 and 40 years. Although histopathological inner ear changes due to otosclerosis have been very well documented, the true etiopathogenesis of the disease has yet to be described despite intensive research. Both genetic and environmental factors have been implicated, however.

An apparatus for diagnosis of ossicular chain mobility in humans

Confirmation of the conditions of the ossicles is essential for tympanoplasty. However, at present, ossicular mobility is experimentally estimated with palpation by a surgeon, and the results depend on the surgeon's skill. In this study, a new apparatus for quantitatively measuring ossicular mobility was developed. With this apparatus, the ossicles were displaced and the reaction force from the ossicles, (i.e. the load applied to the ossicles) was simultaneously detected. Ossicular mobility of three patients with otosclerosis or chronic otitis media was measured to evaluate the usability of the apparatus. The apparatus can distinguish the differences in ossicular mobility between normal and fixed ossicles, and it makes estimating the change of mobility between pre- and posttreatments for ossicular fixation possible. Positive correlation was seen between ossicular mobility and hearing level.

[Malleostapedotomy in the pathology of the incudomalleolar complex combined with fixation of the stapes]

INTRODUCTION

Stapes fixation combined with disorders of the incudo-malleolar complex disorders requires a sound transmission reconstruction that often is difficult to solve. This circumstance can turn up in several pathologies and also in revision surgery for otosclerosis.

PATIENTS AND METHODS

We present our experience with four patients that underwent to malleostapedotomy with removal of the malleus anterior ligament and the malleus anterior apophysis.

RESULTS

We discuss the previous findings in each case. Two patients reached a gap closure and the other two patients obtained an auditive gain without complete gap closure.

DISCUSSION

We set out the ethiology of malleus and incus hipomobility. We do a bibliographic review on the results of this technique in revision stapedectomy.

Malleus head fixation: histopathology revisited

CONCLUSIONS

Malleus head fixation is a rare but not exceptional pathology. It may be apparently congenital or acquired, and can be associated with stapes fixation. In the acquired secondary process two histological types of malleus head fixation were found: the first corresponded to non-tympanosclerotic bone remodeling and the second to localized tympanosclerosis.

OBJECTIVE

To describe the histopathologic features of malleus head fixation and to correlate them with its clinical appearance.

MATERIAL AND METHODS

Ten patients with surgically proven malleus head fixation were included in this series. A fixed malleus head was resected via a transcanal approach in six patients, and attic bony fragments fixing the malleus head were removed via a mastoidectomy without disruption of the ossicular chain in four. Histopathologic studies were performed for both types of malleus head fixation.

RESULTS

Three types of acquired malleus head fixation were defined in accordance with the surgical and histopathological findings. Histologically, the first type presented with normal bone tissue, the second was characterized by non-tympanosclerotic bone remodeling and the third presented with a localized tympanosclerotic focus in the tympanic cavity.