Malleus fixation: clinical and histopathologic findings

Stochastic modeling of the human middle ear dynamics under pathological conditions

BACKGROUND

Although the dynamics of the middle ear (ME) have been modeled since the mid-twentieth century, only recently stochastic approaches started to be applied. In this study, a stochastic model of the ME was utilized to predict the ME dynamics under both healthy and pathological conditions.

METHODS

The deterministic ME model is based on a lumped-parameter representation, while the stochastic model was developed using a probabilistic non-parametric approach that randomizes the deterministic model. Subsequently, the ME model was modified to represent the ME under pathological conditions. Furthermore, the simulated data was used to develop a classifier model of the ME condition based on a machine learning algorithm.

RESULTS

The ME model under healthy conditions exhibited good agreement with statistical experimental results. The ranges of probabilities from models under pathological conditions were qualitatively compared to individual experimental data, revealing similarities. Moreover, the classifier model presented promising results.

DISCUSSION

The results aimed to elucidate how the ME dynamics, under different conditions, can overlap across various frequency ranges. Despite the promising results, improvements in the stochastic and classifier models are necessary. Nevertheless, this study serves as a starting point that can yield valuable tools for researchers and clinicians.

Radiological and Audiological Prediction for Ossicular Fixation in Chronic Otitis Media and Tympanic Membrane Perforation

OBJECTIVES

Recurrent middle-ear infection can lead to ossicular fixation, adversely affecting post-tympanoplasty hearing outcomes. Preoperative prediction of ossicular fixation remains challenging. We aimed to investigate potential predictors of ossicular fixation in patients with chronic otitis media.

STUDY DESIGN

Retrospective.

SETTING

Tertiary academic medical center.

PATIENTS

Patients with noncholesteatomatous chronic otitis media and tympanic membrane perforation, without ossicular discontinuities.

INTERVENTIONS

Diagnostic.

MAIN OUTCOME MEASURES

The fixation of each ossicle was assessed during tympanoplasty. The impact of preoperative otoscopic findings, computed tomography (CT) features, and hearing levels on the prediction of ossicular fixation was evaluated using uni- and multivariable logistic regression analyses.

RESULTS

One hundred thirty-five patients were included. Soft-tissue density between the malleus head and the anterior wall (odds ratio, 3.789 [95% confidence interval, 1.177-12.196]; p = 0.0255) and poor development of mastoid cells (16.826 [2.015-134.520]; p = 0.0078) were independent predictors of malleus fixation. In addition, ≥50% tympanic membrane perforation (5.412 [1.908-15.353]; p = 0.0015), poor development of mastoid cells (3.386 [1.039-11.034]; p = 0.0431), and a ≥40-dB preoperative air-bone gap (ABG) at 500 Hz (4.970 [1.732-14.261]; p = 0.0029) were independent predictors of incus fixation. Soft-tissue density surrounding the stapes (18.833 [1.856-191.104]; p = 0.0119) and a ≥40-dB preoperative ABG at 500 Hz (13.452 [1.640-∞]; p = 0.0138) were correlated with stapes fixation.

CONCLUSIONS

The accurate prediction of ossicular fixation in patients with chronic otitis media based on CT features and the ABG may facilitate decision-making regarding the need for ossiculoplasty, possibly avoiding unnecessary manipulation or overlooking of fixation.

Does The Type of Ossicular Chain Lesion Affect Outcomes in Chronic Suppurative Otitis Media Without Cholesteatoma?

OBJECTIVES

We evaluated the pattern of ossicular chain (OC) lesion in chronic suppurative otitis media (CSOM) without cholesteatoma and its impact on outcomes in primary and revision surgeries.

MATERIALS AND METHODS

This was a retrospective chart review. Patients who underwent tympanoplasty due to CSOM with OC defect between 2010 and 2015 were included in the study.

RESULTS

OC lesions were found during 40 of 147 tympanoplasties performed due to CSOM. The preoperative air-bone gap (ABG) was greater in both discontinuity and fixation cases than in cases with CSOM with an intact OC (p<0.001). Twenty-nine patients were followed up postoperatively, after excluding four patients with stapes footplate fixation, in whom stapedotomy was not performed simultaneously. Among the 29 patients, the audiological results were similar in cases of discontinuity and fixation regarding gap change, residual ABG, and the rate of successful ossiculoplasty. Primary tympanoplasties provided better results according to postoperative ABG and the rate of successful ossiculoplasty than revision surgeries (p<0.05); however, similar patterns of OC lesions were found during primary and revision surgeries.

CONCLUSION

Both OC discontinuity and fixation occur in CSOM in a similar distribution in primary tympanoplasties and revision surgeries. The type of OC lesion does not affect outcomes. Primary surgeries provide better results, but that is not due to a difference in the character of the OC lesion.

Ossicular chain mobilisation versus reconstruction in surgery for isolated malleus and/or incus fixation: systematic review and meta-analysis

OBJECTIVE

To compare post-operative audiometric outcomes for the two prevailing surgical approaches for isolated malleus and/or incus fixation: ossicular mobilisation with preservation of the ossicular chain, and disruption and reconstruction of the ossicular chain.

METHODS

A search was conducted, in December 2016, of PubMed, Scopus, and Cumulative Index to Nursing and Allied Health Literature articles written in English. Papers presenting original data regarding post-operative audiometric outcomes in patients who underwent surgical treatment for malleus and/or incus fixation with a mobile and intact stapes were included. A risk of bias assessment was performed on the 14 selected papers and a tier system was developed. Meta-analysis was accomplished by comparing pooled rates of surgical success by chi-square test and calculating odds ratios by logistical regression. Analysis was performed using Revman5 and R software.Results and conclusionAnalysis of the literature revealed no differences in audiometric outcomes between ossicular chain mobilisation and ossicular chain reconstruction in patients with isolated malleus and/or incus fixation. A large, prospective study comparing both short- and long-term hearing results for ossicular chain mobilisation and ossicular chain reconstruction in this population may identify whether a difference in outcomes exists between the two approaches.

Congenital Familial Fixation of the Malleus

We present a familial association of radiographically and surgically demonstrated mallear fixation with concurrent stapedial abnormality and dehiscence of the facial nerve in a father and son, including history, physical findings, surgical findings, radiologic analyses, and a literature review. A 12-year-old boy presented with long-term left-sided conductive hearing loss, and was found to have mallear fixation and a dehiscent facial nerve on a computed tomographic (CT) scan of the temporal bone. Release of the malleus was performed at surgery, revealing hypermobility of the remaining ossicular chain. A repeat CT scan of the temporal bone showed successful release of the mallear head. The patient's father later presented with bilateral hearing loss, and a CT scan of the temporal bones showed bilateral osseous fixation of the mallear head to the tegmen and bilateral facial nerve dehiscences. He underwent right middle ear exploration, but release of the malleus was not performed because of the risk to the dehiscent facial nerve. The stapes crurae were found to be filiform at surgery. This is the first reported familial association of mallear fixation. Mallear fixation with facial nerve dehiscence and an abnormal stapes occurring in a parent and his child is interesting embryologically, and suggests that these anomalies may be genetically linked.

Surgery of isolated malleus fixation due to tympanosclerosis

The aim of the present study was to describe our surgical approach for isolated malleus fixation in patients with tympanosclerosis and to analyze the postoperative results. A total of 30 patients presented with isolated malleus fixation were operated. The fixation was reached via canalplasty. Fixated areas were cleaned without damaging the ossicle. Pre- and postoperative audiometric results were evaluated for each patient. Improvement of the pure-tone average (PTA) by at least 10 dB and an air-bone gap (ABG) of less than 20 dB after 12 months of follow-up was accepted to indicate success. The recovery of the postoperative PTA and ABG measurements was significant. Pre- and postoperative PTA was 48.00 ± 11.86 and 24.90 ± 12.45 dB, respectively (p < 0.001). According to PTA measurements, 40-50 dB recovery was achieved in four (13.3 %) patients, 31-40 dB in six (20 %) patients, 21-30 dB in ten (33.3 %) patients, and 11-20 dB in five (16.6 %) patients, with a total success rate of 25/30 (83.2 %). Pre- and postoperative ABG levels were 38.95 ± 9.92 and 16.10 ± 7.79 dB (p < 0.001), respectively. The ABG level was between 0 and 10 dB for 8 (26.6 %) patients, and 11-20 dB for 16 (53.3 %), with a total success rate of 24/30 (80 %). In cases of isolated malleus fixation with tympanosclerosis, performing a canalplasty to clean the sclerotic plaques without damaging the normal anatomy of the ossicle system using a diamond burr is a safe surgical option that provides significant recovery in hearing levels.

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.

Surgery of idiopathic malleus fixation

OBJECTIVE

To describe and compare 2 different surgical techniques used in treatment of malleus fixation syndrome.

STUDY DESIGN

A retrospective study including 24 patients (25 ears). In 11 of them, the attical fixation was removed via a transmastoid approach without disruption of the ossicular chain. In 14 patients, an ossiculoplasty was performed via a transcanal approach; the malleus head was removed with the incus, and the ossicular chain was reconstructed either by incus interposition (9 cases) or by using a partial ossicular replacement prosthesis (5 cases). The hearing results were analyzed according to the Committee on Hearing and Equilibrium Guidelines of the American Academy of Otolaryngology.

RESULTS

In the group of attical fixation removed via a transmastoid approach, the preoperative air-bone gap (ABG) attained 25.2 dB, and the postoperative ABG at 1 year followup was 9.1 dB. In the group of ossiculoplasty, the average preoperative ABG reached 26.5 dB, and the postoperative ABG at 1-year follow-up was 8.2 dB.

CONCLUSION

There was no statistically significant difference (p = 0.79) between the 2 surgical techniques used to improve hearing in malleus head fixation.

Accuracy of velocity distortion product otoacoustic emissions for estimating mechanically based hearing loss

Distortion product otoacoustic emissions (DPOAEs) measured as vibration of the human eardrum have been successfully used to estimate hearing threshold. The estimates have proved more accurate than similar methods using sound-pressure DPOAEs. Nevertheless, the estimation accuracy of the new technique might have been influenced by endogenous noise, such as heart beat, breathing and swallowing. Here, we investigate in an animal model to what extent the accuracy of the threshold estimation technique using velocity-DPOAEs might be improved by reducing noise sources. Velocity-DPOAE I/O functions were measured in normal and hearing-impaired anaesthetized guinea pigs. Hearing loss was either conductive or induced by furosemide injection. The estimated distortion product threshold (EDPT) obtained by extrapolation of the I/O function to the abscissa was found to linearly correlate with the compound action potential threshold at the f(2) frequency, provided that furosemide data were excluded. The standard deviation of the linear regression fit was 6 dB as opposed to 8 dB in humans, suggesting that this accuracy should be achievable in humans with appropriate improvement of signal-to-noise ratio. For the furosemide animals, the CAP threshold relative to the regression line provided an estimate of the functional loss of the inner hair cell system. For mechanical losses in the middle ear and/or cochlear amplifier, DPOAEs measured as velocity of the umbo promise an accuracy of hearing threshold estimation comparable to classical audiometry.

[Verification of malleus head fixation : computed tomography as diagnosis standard]

Malleus head fixation and otosclerosis causing conductive hearing loss are often difficult to differentiate by clinical features. Up to now exploratory anterior tympanotomy was necessary to distinguish these pathologies. The case of a 22-year-old male suffering from conductive hearing loss of the right ear is presented. Otosclerosis was suspected and high-resolution CT scanning of the petrous bone was performed. The diagnosis was confirmed radiologically by the detection of an isolated malleus head fixation. Instead of explorative anterior tympanotomy, radiological and audiological controls were combined for the follow-up.

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.

Bony Sheathed Chorda Tympani

OBJECTIVE

To describe a unilateral conductive hearing loss caused by restriction of the movements of malleus and incus due to chorda tympani in a bony sheath.

PATIENT

A 23-year-old man with a stable mild conductive hearing loss in the left ear and mild sensorineural hearing loss in the right ear.

INTERVENTION

An exploratory tympanotomy was performed.

MAIN OUTCOME MEASURE

Immobility of the ossicles due to a bony structure, which was found to be chorda tympani encircled in a bony sheath. Ossicular system regained its mobility with the severance of the chorda tympani.

RESULTS

Hearing was improved both subjectively and audiographically.

CONCLUSION

This is the second case of chorda tympani with a bony sheath and the first case of this pathologic finding affecting both malleus and incus. Bony sheathed chorda tympani is considered to be a congenital anomaly of the chorda tympani that causes incudomalleolar fixation and behaves as posterior bony bars.

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.

Histologic changes in the anterior mallear ligament and the head of the malleus in otosclerosis

OBJECTIVE

To determine ossicular and anterior mallear ligament (AML) changes in otosclerosis.

STUDY DESIGN AND SETTING

Hyalinization of AML was graded as follows: none, patchy, or diffuse in 95 temporal bones (TBs) with otosclerosis: 52 with stapedial fixation (SF); 43 without fixation (NSF); and 52 age-matched controls. Fixation of the head of the malleus was noted.

RESULTS

Hyalinization with SF was 17 none, 23 patchy, and 12 diffuse; with NSF it was 16 none, 20 patchy, and 7 diffuse; and in controls, 23 none, 24 patchy, and 5 diffuse. There was no significant difference in hyalinization among groups and no correlation between degree of hyalinization and age. The malleus head was fixed in 4 TBs with SF.

CONCLUSION

Based on our findings, we do not believe that there is a relationship between hyalinization of the AML and otosclerosis; however, otosclerosis with SF seems to be a predisposing factor for fixation of the head of the malleus.

Experimental ossicular fixations and the middle ear’s response to sound: Evidence for a flexible ossicular chain

A human temporal-bone preparation was used to determine the effects of various degrees of artificial ossicular fixation on the sound-induced velocity at the input-side (the umbo of the malleus) and the output-side (the stapes) of the ossicular chain. Construction of various degrees of attachment between an ossicle and the surrounding temporal bone provided a range of reduction in ossicular mobility or "fixations". The results demonstrate different effects of the fixations on the umbo and stapes velocity: fixations of the stapes or incus produce larger reductions in sound-induced stapes velocity (as much as 40-50 dB with extensive stapes fixation), than reductions in umbo velocity (typically less than 10 dB). Fixations of the malleus produce similar-sized changes in both umbo and stapes velocity. These differential effects are consistent with significant flexibility in the ossicular joints (the incudo-malleolar joint and the incudo-stapedial joint) that permits relative motion between the coupled ossicles. The existence of flexibility in the ossicular joints indicates that joints in the ossicular chain can effect a loss of sound-induced mechanical energy between the umbo and the stapes, with a concomitant reduction in the sound-induced motion of the stapes. The introduction of such losses in sound transmission by the joints raises questions concerning the utility of three ossicles in the mammalian ear. The consequences of ossicular flexibility to ossicular-chain reconstruction is discussed. Also, as examined in a more clinically directed paper [Laryngoscope 115 (2005) 147], the different effects of the various ossicular fixations on the motion of the umbo and malleus may be useful in the diagnosis of the site of fixations in humans with conductive hearing losses caused by such pathologies.

Experimental and Clinical Studies of Malleus Fixation

OBJECTIVES/HYPOTHESIS

Preoperative clinical diagnosis of malleus fixation can be difficult. "Fixation" of the malleus can be caused by various disorders or diseases: fibrous tissue, bony spurs, and neo-osteogenesis around the malleus head or stiffening of the anterior malleal ligament. The conductive hearing loss produced by these disorders or diseases has not been well characterized. The study goals were 1) to determine the effects of various types of malleus fixation using a cadaveric temporal bone preparation and 2) to assess the clinical utility of umbo velocity measurements in preoperative differential diagnosis of malleus fixation and stapes fixation.

METHODS

Umbo and stapes velocity were measured in 18 fresh cadaveric human temporal bones with laser vibrometry before and after controlled application of adhesives to the malleus, stapes, or both ossicles.

RESULTS

Each simulated pathological condition produced a specific degree of loss in stapes velocity: stiffening of anterior malleal ligament, 0 to 8 dB; fibrous tissue around malleus head, less than 10 dB; bony bar to malleus head, 10 to 30 dB; and extensive neo-osteogenesis around malleus head, greater than 35 dB. Simulated malleus fixations generally produced similar reductions in both umbo and stapes velocity. Stapes fixation reduced stapes velocity with little change in umbo velocity. Because the change in stapes velocity would be similar to conductive hearing loss, experimental results were directly compared with clinical measurements of umbo velocity in surgically confirmed cases of malleus or stapes fixation. The effects of malleus and stapes fixations between the clinical and experimental data were similar.

CONCLUSION

The study showed that measurements of umbo velocity and air-bone gap can enable one to diagnose malleus fixation and specifies how to differentiate malleus from stapes fixation.