Utility of machine learning for identifying stapes fixation on ultra-high-resolution CT

PURPOSE

Imaging diagnosis of stapes fixation (SF) is challenging owing to a lack of definite evidence. We developed a comprehensive machine learning (ML) model to identify SF on ultra-high-resolution CT.

MATERIALS AND METHODS

We retrospectively enrolled 109 participants (143 ears) and divided them into the training set (115 ears) and test set (28 ears). Stapes mobility (SF or non-SF) was determined by surgical inspection. In the ML analysis, rectangular regions of interest were placed on consecutive axial slices in the training set. Radiomic features were extracted and fed into the training session. The test set was analyzed using 7 ML models (support vector machine, k nearest neighbor, decision tree, random forest, extra trees, eXtreme Gradient Boosting, and Light Gradient Boosting Machine) and by 2 dedicated neuroradiologists. Diagnostic performance (sensitivity, specificity and accuracy, with surgical findings as the reference) was compared between the radiologists and the optimal ML model by using the McNemar test.

RESULTS

The mean age of the participants was 42.3 ± 17.5 years. The Light Gradient Boosting Machine (LightGBM) model showed the highest sensitivity (0.83), specificity (0.81), accuracy (0.82) and area under the curve (0.88) for detecting SF among the 7 ML models. The neuroradiologists achieved good sensitivities (0.75 and 0.67), moderate-to-good specificities (0.63 and 0.56) and good accuracies (0.68 and 0.61). This model showed no statistical differences with the neuroradiologists (P values 0.289-1.000).

CONCLUSIONS

Compared to the neuroradiologists, the LightGBM model achieved competitive diagnostic performance in identifying SF, and has the potential to be a supportive tool in clinical practice.

Assessment of the ability of the radiological incudo-stapedial angle to predict the stapedotomy technique type: a prospective case-series study

PURPOSE

This study aimed to propose a radiological classification of the incudo-stapedial angle by preoperative high-resolution computed tomography (HRCT) images and to highlight its importance for predicting the use of reversal-steps stapedotomy (RSS) rather than the traditional non-reversal technique.

METHODS

We included 83 candidates for stapedotomy operation. Two physicians measured the radiological incudo-stapedial joint angle in the preoperative HRCT. According to this measurement, the radiological incudo-stapedial joint was classified into three types: obtuse, right, and acute. In addition, this radiological classification was correlated with the intraoperative use of the stapedotomy technique, either reversal or non-reversal.

RESULTS

The RSS technique was used in forty-two (97.7%) cases with an obtuse angle and twenty-six (89.7%) with a right angle. At the same time, the traditional non-reversal technique was used in all patients with an acute angle. The three groups differed significantly regarding the method used for stapedotomy (P value < 0.001). Moreover, Spearman's correlation coefficient revealed a significant correlation between the used technique and the radiological type of the incudo-stapedial angle (P value < 0.001).

CONCLUSIONS

This prospective study proposed a preoperative radiological classification of the incudo-stapedial angle. This classification was significantly correlated with the type of stapedotomy technique. The RSS technique was feasible in most cases with an obtuse and right radiological incudo-stapedial angle. In contrast, the non-reversal method was used in all patients with an acute radiological incudo-stapedial angle. This radiological classification could predict the choice for the stapedotomy technique with an accuracy of 95.18%, a sensitivity of 73.33%, and a specificity of 100%.

Absent Stapedial Tendon: Imaging Features of an Underrecognized Entity : Clinical Neuroradiology

PURPOSE

Congenital absence of the stapedial tendon is a rare entity with characteristic imaging findings, which can go unrecognized due the scarcity of the diagnosis and limited previous description in the imaging literature. We aim to characterize the imaging features of this entity.

METHODS

A series of 9 cases with surgical confirmation of stapedial tendon absence were retrospectively reviewed and the most common abnormalities on high resolution computed tomography (CT) of the temporal bone described.

RESULTS

Congenital fixation of the stapes footplate was present in nearly all cases of stapedial tendon absence (n = 8, 89%), a clinically important association because the stapes footplate abnormality was not detectable on preoperative CT. Absence or hypoplasia of the pyramidal eminence and aperture was identified in almost all cases (n = 8, 89%), which may be the sole imaging finding to suggest stapedial tendon absence and associated stapes footplate fixation prior to surgery.

CONCLUSION

The most reliable indicator of stapedial muscle absence on temporal bone CT is the absence or hypoplasia of the pyramidal eminence and aperture. Importantly, most patients had congenital stapes footplate fixation confirmed intraoperatively with a normal stapes footplate on CT, meaning the pyramidal eminence/aperture abnormality was the only preoperative imaging finding that could have suggested the footplate fixation.

Microcomputed tomography of the stapes: Wide-ranging dimensions

Although human stapes are known to have varied dimensions and the footplate is considered to be oval (fitting as it does into the oval window), few studies of high-resolution imaging of these structures have been performed. No study appears to have addressed the bilateral symmetry of stapes dimensions or to have determined if an association exists between the size of the stapes and the size of mastoid pneumatization; a small mastoid pneumatization is an indicator of childhood otitis media. We obtained 41 ear-normal cadaver crania specimens for study in our temporal bone laboratory and isolated 10 for further analysis: the 5 with the largest areas of mastoid pneumatization and the 5 with the smallest. Microcomputed tomography of tissue blocks was performed on the in situ stapes. Using ImageJ software, we created a three-dimensional model of each stapes. The mean height of these stapes was 3.43 mm (range: 3.20 to 3.80), the mean length of the footplates was 2.71 mm (range: 2.52 to 2.97), and the mean width of the footplates was 1.23 mm (range: 1.12 to 1.46). Qualitatively, the footplate was shaped like a human footprint in moist sand, as Eysell described in 1870. The dimensions of the stapes were found to be bilaterally symmetrical in general, but there was no correlation between these dimensions and the size of mastoid pneumatization. The distribution of footplate widths may be bimodal, which is consistent with the observation of Sim et al that men have wider footplates than do women.

[The diagnostics and surgical treatment of the patients presenting with otosclerosis in the Primorye Territory]

The objective of the present study was to characterize the effectiveness of the audiological and radiological diagnostic techniques as well as the results of the surgical treatment of the patients presenting with otosclerosis based at the hospital clinic of the Pacific State Medical University. The analysis included 49 surgical interventions for stapedoplasty carried out on 42 patients during the period from 2015 to 2017. The tympanic form of the disorder was diagnosed in 51.02% of the cases, the mixed form I in 16.28%, and the mixed form II in 32.7%. The excellent results within two months after surgery were obtained in 87.2% of the treated patients, the good and satisfactory results in 8.72% and 4.08% of them respectively.

Tympanometry and isolated fracture of the stapes

INTRODUCTION

Temporal bone fractures are frequently associated with ossicular dislocations or fractures, most commonly involving the incus. To our knowledge, isolated fracture of the posterior crus of the stapes has not been previously reported.

CASE REPORT

A 20-year-old man consulted for persistent left hypoacusis several months after a head injury. Initial computed tomography of the temporal bone showed a simple temporal bone fracture with no other associated abnormalities. The diagnosis of stapes fracture was suggested by increased compliance on tympanometry, leading to a second thin-section temporal bone computed tomography, which suggested a fracture of the posterior crus of the stapes. Endaural surgical exploration confirmed the diagnosis and allowed placement of ionomer cement in the posterior crus.

DISCUSSION

The possibility of ossicular dislocation or fracture must be considered in patients with persistent conductive hearing loss associated with increased compliance on tympanometry, even when computed tomography of the temporal bone does not show dislocation of the ossicular chain or ossicular fracture. Hearing rehabilitation can be performed by hearing aid or surgical reconstruction of the ossicles.

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.

Middle ear osteoma: a rare cause of conductive hearing loss with normal tympanic membrane

Osteomas of the temporal bone are benign osseous tumors usually located to the external auditory canal. Osteomas involving the middle ear are very rare. We report the case of a patient presenting with a progressive hearing loss caused by a middle ear osteoma involving the incus and contiguous to the tympanic segment of the facial nerve. This report highlights the value of CT scan in the work-up of conductive or mixed hearing loss with normal tympanic membrane. The management of middle ear osteoma is discussed.

A preliminary investigation of four-dimensional ultrasound for evaluation of middle ear ossicles: an in vitro study

OBJECTIVE

Temporal bone imaging in children has several inherent limitations. Computed tomography has the disadvantage of ionizing radiation, possible sedation, cost and accessibility. Magnetic resonance imaging has most of these disadvantages, with the exception of radiation, and provides bone images of limited resolution. Recent advances in ultrasound have led to its increased application in numerous medical fields. The purpose of this study was to investigate the ability of four-dimensional ultrasound (4DUS) to image middle ear ossicles in vitro and determine if this technology should be adapted for future clinical use.

METHODS

Thirty cadaveric ossicles (10 malleus, 10 incus, and 10 stapes) were randomized and measured by two evaluators under a microscope. The ossicles were then immersed in a cold water bath and imaged, randomized, and measured using four-dimensional ultrasound by the same two evaluators. A separate cadaveric temporal bone, modified to allow the ultrasound probe to rest on the tympanic membrane, was imaged to visualize the ossicles in situ and evaluate whether or not the tympanic membrane and malleus would impede visualization of more medial structures.

RESULTS

Microscopic measurements were: malleus (h=8.0 mm+/-0.32, w=2.7 mm+/-0.20), incus (h=6.8 mm+/-0.41, w=5.3 mm+/-0.46), stapes (h=3.5 mm+/-0.34, w=2.4 mm+/-0.17). Inter-rater reliability was 0.8. Measurements were in agreement with previously published values. Ultrasound measurements were: malleus (h=8.0 mm+/-0.51, w=2.9 mm+/-0.27), incus (h=6.8 mm+/-0.49, w=5.5 mm+/-0.42), stapes (h=3.6 mm+/-0.41, w=2.5 mm+/-0.19). Inter-rater reliability was 0.7. Mean intra-class correlation coefficient for microscopic and ultrasound measurements was 0.7. Images of the ossicular chain in continuity in the temporal bone specimen were not as clear as images of individual ossicles that were disarticulated and imaged under water.

CONCLUSIONS

4DUS provides reasonable images of ossicles disarticulated and mounted in underwater medium. However, images of the intact ossicular chain in a modified cadaveric temporal bone were not as clear, making interpretation difficult. Further investigation into the development of a thinner ultrasound probe that can pass through the external auditory canal and into overcoming limitations of air in the middle ear cleft are warranted. This could allow for a clinically relevant, faster, lower cost and lower risk alternative to current imaging techniques.

[Measurement study of MDCT 3D reconstruction and microanatomy related to individual piston shaping on malleostapedotomy]

OBJECTIVE

To study the management of basic parameters related to individual piston shaping on malleostapedotomy by MDST 3D reconstruction and microanatomy and to assess the accuracy of MDST method.

METHOD

Ten Chinese temporal bones without ear diseases were numbered randomly and scanned by GE Light Speed Ultra 64 rows of spiral CT. 3D structure of ossicular chain were reconstructed by MPR and VR methods in AW4. 1 workstation. Then measurements of distances between stapes head to stapes footplate (A line), and manubrium to stapes head (B line), and manubrium to stapes footplate (C line), angle between line A and line B (angle AB) are completed. After that, all samples of temporal bone were undergone canal wall down mastoidectomy under microscope and the relevant measurements were completed.

RESULT

The MPR and VR technique of MDCT reconstructed ossicular chain clearly, and revealed the spatial relationship between every structure stereoscopically. Respectively, lengths of A, B, C line by MDST and microanatomy are (3.42 +/- 0.86) mm and (3.60 +/- 0.94) mm, (3.42 +/- 0.80) mm and (2.96 +/- 0.42) mm, (5.86 +/- 0.60) mm and (6.22 +/- 1.10) mm, while angle AB (141.05 +/- 30.07) degrees and (144.57 +/- 41.86) degrees. There are no statistically significant differences between two groups (P>0.05).

CONCLUSION

The MPR and VR technique of MDCT can clearly reconstructed the 3D shapes of the temporal bone and finish the exactly managements on A, B, C lines and AB angel which is crucial for shaping a individual piston on malleus-to-oval window surgery.

Quantitative morphology of facial nerve based on three-dimensional reconstruction of temporal bone

Objective

To investigate an effective method of quantitative analysis of the facial nerve and its adjacent structures on the basis of three-dimensional (3D) CT image reconstruction of the temporal bone.

Methods

The inner structures of the temporal bone from CT images of 34 healthy adults were reconstructed. Precise measurement of the facial nerve and its adjacent structures were accomplished by using Able Software 3D-DOCTOR.

Results

3D images of temporal bone structures, including facial nerve, tympanic annulus, cochleariform process, cochlea, semicircular canals, jugular fossa, and carotid artery, were reconstructed. Quantitative data of the facial nerve and its adjacent structures were analyzed, especially the detailed spatial relationships between the facial nerve and the surface of the mastoid process or tympanomastoid fissure.

Conclusion

3D reconstruction of CT images clearly displayed the detailed structures of the temporal bone. Quantitative data of the facial nerve and its adjacent structures are very useful for temporal bone surgery.

Stapediovestibular dislocation with pneumolabyrinth

Traumatic luxation of the stapes into the vestibule is a rare entity, and the disease complicated with pneumolabyrinth is extremely rare. We report the case of a 72-year-old woman with pneumolabyrinth associated with a stapediovestibular dislocation. The patient presented with vertigo and nystagmus following penetrating trauma to the middle ear. High resolution computed tomography scans demonstrated air in the vestibule and dislocation of the stapes. Exploratory tympanotomy demonstrated oozing of the perilymph from the oval window and depression of the stapes into the vestibule. Pneumolabyrinth and stapes luxation detected by high resolution computed tomography should be predictive of a perilymphatic fistula.

CT scans and 3D reconstructions of Florida manatee (Trichechus manatus latirostris) heads and ear bones

The auditory anatomy of the Florida manatee (Trichechus manatus latirostris) was investigated using computerized tomography (CT), three-dimensional reconstructions, and traditional dissection of heads removed during necropsy. The densities (kg/m3) of the soft tissues of the head were measured directly using the displacement method and those of the soft tissues and bone were calculated from CT measurements (Hounsfield units). The manatee's fatty tissue was significantly less dense than the other soft tissues within the head (p<0.05). The squamosal bone was significantly less dense than the other bones of the head (p<0.05). Measurements of the ear bones (tympanic, periotic, malleus, incus, and stapes) collected during dissection revealed that the ossicular chain was overly massive for the mass of the tympanoperiotic complex.

Unusual middle-ear mischief: trans-tympanic trauma from a hair grip resulting in ossicular, facial nerve and oval window disruption

A case of piercing of the tympanic membrane, resulting in unusual consequences, is described. This is the first reported case of the long process of a dislocated incus resulting in trauma to the horizontal portion of a dehiscent facial nerve. Simultaneous depression of the stapes footplate resulted in a perilymph leak, but with delayed presentation.

Current multiplanar imaging of the stapes

PURPOSE

CT analysis of the stapes is difficult in the axial plane (AP), because of its oblique orientation. Oblique axial reformations could provide a more precise analysis of the stapes in normal and pathologic conditions.

MATERIALS AND METHODS

CT of the temporal bone was performed in 31 patients. Only the normal side was examined in the AP and oblique axial plane (OAP), in the plane of the stapes superstructure. Conspicuousness of each stapes component was evaluated in both planes by 2 independent readers. Reproducibility between the 2 readers (R1 and R2) and comparison of conspicuousness between the AP and the OAP in the analysis of the stapes crura were evaluated. The normal position of the stapes arch in relationship to the footplate was determined in the OAP by using biometric landmarks.

RESULTS

Conspicuousness of the stapes crura was increased by using OAP. The conspicuousness of the anterior crus was enhanced in 38% with the OAP according to R1 (P < .05) and 32% according to R2 (P < .05). The conspicuousness of the posterior crus was enhanced in 35% with the OAP according to R1 (P < .05), but not significantly enhanced in 22% with the OAP according to R2 (P = .095). Analysis of conspicuousness of the stapes crura was reproducible according to the kappa test. A perpendicular line to the footplate intersecting its midportion crosses the stapes head and the long process of the incus in the OAP in normal patients.

CONCLUSION

OAP could enhance the CT analysis of the stapes and provide useful biometric landmarks in pathologic conditions.

Optical and tomographic imaging of a middle ear malformation in the bullfrog (Rana catesbeiana)

Using a combination of in vivo computerized tomography and histological staining, a middle ear anomaly in two wild-caught American bullfrogs (Rana catesbeiana) is characterized. In these animals, the tympanic membrane, extrastapes, and pars media (shaft) of the stapes are absent on one side of the head, with the other side exhibiting normal morphology. The pars interna (footplate) of the stapes and the operculum are present in their normal positions at the entrance of the otic capsule on both the affected and unaffected sides. The pattern of deformity suggests a partial failure of development of tympanic pathway tissues, but with a preservation of the opercularis pathway. While a definitive proximate cause of the condition could not be determined, the anomalies show similarities to developmental defects in mammalian middle ear formation.

High-resolution X-ray computed tomographic scanning of the human stapes footplate

OBJECTIVES

The mechanical behaviour of the footplate and its annular ligament depends critically on their shape and orientation in the oval window, but accurate measurements have been difficult to make owing to their small size. Our aims are to visualize the footplate at high resolution and understand its dynamics.

METHODS

The human cadaver stapes footplate was dissected, and very high-resolution x-ray computed tomographic (CT) scans, with voxel sizes from 4 to 8 pm, were performed. Locally developed software was used to reconstruct the images.

RESULTS

The data permit us to explore minor details of shape and orientation. The footplate looks like a footprint, and the annular ligament has variable thickness, with a cleft (groove) in its anterior attachment to the oval window. The CT data also permit us to create a three-dimensional finite-element model that can simulate footplate motion.

CONCLUSIONS

The results obtained lead to further understanding of the mechanical behaviour of the footplate and the annular ligament.

[Indications of HR-CT in the early postoperative phase of stapedotomy]

PURPOSE

This is an analysis of high-resolution computed tomography (HR-CT) performed in patients with and without symptoms after stapes surgery during the early postoperative phase.

MATERIALS AND METHODS

We examined 37 patients who underwent stapes surgery between January 1995 and December 2000. HR-CT of the temporal bone was performed in axial and coronal planes with 1-mm-slice thickness and table feed. A reoperation was performed in 7 patients. CT findings were compared with clinical follow up and surgical findings.

RESULTS

All patients showed postoperative opacification of the tympanic cavity and external auditory canal as well as partial opacification of the mastoid on CT scans. A dislocation of the prosthesis was found in 11 cases and air bubbles were seen in the vestibule of 5 patients. In one case, small bone fragments were detected in the vestibule. In 6 of 7 cases, CT results were confirmed by retympanotomy.

CONCLUSIONS

Due to overlapping of normal and pathological findings in the early postoperative period, indications for HR-CT are limited in this period.

[CT multiplan reconstruction images of disorder of stapes]

OBJECTIVE

To evaluate the clinical application of multi-planar reformation (MPR) for the stapes with multi-slice spinal thin-section CT in the patients with disorder of stapes before prosthetic ossicular reconstruction and their impact on surgical decision.

METHODS

Axial CT scanning of temporal bone was undergone in 50 volunteers. Multiplan reformatted images included coronal, sagittal and oblique MPR, were made. All the MPR images were compared with each other in order to show which one could reveal the whole structures of stapes better. The height of stapes was measured with the oblique MPR. CT findings were evaluated in 102 cases with disorder of stapes. Prosthetic ossicular reconstruction was made in 65 cases.

RESULTS

The full stapes cannot be shown in axial, coronal and sagittal MPR images, however, it was shown in oblique MPR in all the cases. The highness of stapes was (3.3 +/- 0.4) mm in the abnormal group. There was chronic otitis media in 69 cases (90 ears) and congenital abnormalities of the stapes in 33 cases (47 ears) which included the dispart of incudostapedial joint in 5 cases (7 ears), defect of head and crus of stapes in 9 cases (13 ears), defect of one side of crus in 3 cases (4 ears) and absence of the oval window in 16 cases (23 ears).

CONCLUSIONS

Coronal and oblique MPR images from Axial Spiral CT Data are essential for the pre-operative planning of prosthetic ossicular reconstruction. The ship, structure or defect of stapes can be shown in the oblique MPR images. It is important for the patient to choose the type of operation.

[Failure of regain full function after surgery for otosclerosis: causes, diagnosis and treatment]

OBJECTIVE

The aim of this study was to evaluate the causes, the diagnosis, the treatment and the results obtained by revision surgery, in cases of stapedectomy failures.

MATERIALS AND METHODS

Retrospective study of 50 recent cases operated on between January 1997 and December 2001. DIAGNOSIS OF THE FAILURE: All reoperated patients had clinical and audiological assessment; CT scan with virtual endoscopy.

RESULTS

The mean time of onset of failure was 23 months. The mean preoperative air bone gap was 25.5 dB. Otoscopy revealed a retraction pocket caused by poor eustachian tube function in 9 cases. CT scan proved to be very effective at differentiating the cause of the failure.

OPERATIVE FINDINGS

In 11 cases the prosthesis was too short, in 8 cases the prosthesis had migrated out of the hole of stapedotomy and in 6 cases the piston was fixed in the stapedotomy hole. A partial or complete lysis of the long process of the incus was frequently associated, but in 9 cases it was the only cause of the failure. In all the cases when the piston was displaced, the stapedotomy was found to be covered by a thin mucous membrane, avoiding labyrinthine fistula. In 3 cases, the failure was due to recurrent otosclerosis. In 5 cases the failure was due to a local anomaly at the level of the oval window niche, 2 cases of failure were due to a malleus ankylosis. In 5 cases fibrous adhesion was found between the incus and the mucosa of the promontory. In one case a reparative granuloma was found at the level of the oval window.

TREATMENT

In cases of partial lysis of the long process of the incus, a new prosthesis was placed in a 0.4 mm diameter stapedotomy, performed using a KTP laser. A 0.4 mm diameter piston was extended 0.2 mm below stapedotomy to avoid a new extrusion. Indeed some prosthesis extrusion could be due to increased movements of the ossicular chain in cases of eustachian tube dysfunction. In cases of complete lysis of the long process of the incus, or in cases of a very short long process of the incus, a piston was put in the stapedotomy and attached to the malleus manubrium. The results of revision stapedotomy were favorable in the absence of associated fibrous tissue adhesion or local malformation. The air bone gap was found to be less than 10 dB in 40 cases and between 10 and 20 dB in 8 cases. An impairment of the air bone gap was found in 2 cases. No case of bone conduction impairment was found in this series.

Ectopic stapes: a case report with embryologic correlations

A case report of unilateral congenital stapes misplacement revealed by computed tomography is presented. In addition to this malformation, the malleus was synostosed to the middle ear roof. This kind of stapes ectopia has not been described previously. We have analyzed the malformative pattern in the light of normal and teratologic development of the stapes. In a teratologic model in which retinoic acid is administered to pregnant mice, we have observed an ectopic stapes primordium independent of the otic capsule. We discuss the possible pathogenesis of this abnormality in terms of the genetic events of middle ear development, which can be perturbed by retinoic acid administration.

Imaging of a congenital perilymphatic fistula

A 7-year-old boy with a history of purulent meningitis and watery rhinorrhea was studied using computed tomography (CT) and magnetic resonance imaging (MRI). He had a common cavity in the left inner ear. With high-resolution heavily T2-weighted MRI, leakage of the inner ear fluid into the middle ear at the oval window area through a congenital perilymphatic fistula could be visualized. Surgery to close the fistula showed a perforation in the stapes footplate.

Characterization of a stapes ankylosis family with a NOG mutation

OBJECTIVE

To characterize the otologic phenotype in a family with autosomal dominant stapes ankylosis, hyperopia, and skeletal abnormalities caused by a mutation in the noggin gene (NOG).

STUDY DESIGN

Case series.

SETTING

Academic tertiary care center.

PATIENTS

Eight affected and 3 unaffected family members.

MAIN OUTCOME MEASURES

History, physical and radiologic examination, and surgical outcomes.

RESULTS

Although affected members were initially presumed to have typical nonsyndromic otosclerosis, the clinical data were most consistent with an autosomal dominant congenital stapes ankylosis syndrome. Eight of eight affected family members had bilateral low-frequency conductive hearing loss. Six of eight underwent fenestration procedures and/or stapedectomies. All members with initial postoperative closure of the air-bone gap returned to their baseline conductive loss within 2 years. Two affected family members had documented maximal conductive hearing loss by age 4, and two members without previous otologic surgery have not experienced sensorineural hearing loss. High-resolution temporal bone computed tomography showed stapes ankylosis and indistinction of the incudomalleal junction bilaterally and bony regrowth over the stapedotomy for those with stapedectomies. Detailed physical and radiologic examination identified multiple other skeletal abnormalities.

CONCLUSIONS

Although this phenotype may present as classic otosclerosis to the otolaryngologist, detailed investigation revealed a congenital stapes ankylosis syndrome. Because is essential in regulating normal bone development and maturation, mutations in this gene may be associated with excessive bony overgrowth and refixation of the stapes footplate after initial successful surgery. Patients with hereditary conductive hearing loss should be assessed to rule out subtle features of a skeletal syndrome.

CT and MR imaging after middle ear surgery

This article describes the current value of imaging in patients after stapes surgery and surgery after chronic otitis media including cholesteatoma. Possibilities and limits of computed tomography (CT) and MRI are described and most important investigation parameters are mentioned. After otosclerosis surgery, CT is the method of first choice in detection of reasons for vertigo and/or recurrent hearing loss in the later postoperative phase. CT may show the position and condition of prosthesis, scarring around the prosthesis and otospongiotic foci. Sometimes, it gives indirect hints for perilymphatic fistulas and incus necrosis. MRI is able to document inner ear complications. CT has a high negative predictive value in cases with a free cavity after mastoidectomy. Localized opacities or total occlusion are difficult to distinguish by CT alone. MRI provides important additional information in the differentiation of cholesterol granuloma, cholesteatoma, effusion, granulation and scar tissue.

[An experimental study for qualitatively diagnosing stapes lesions by helical 3-dimensional CT]

To evaluate qualitative diagnosis of stapes lesions by 3-dimensional computed tomography (3D-CT) combined with superselective image processing (3D-SS) of stapes, we studied helical 3D-CT on a phantom model of the temporal bone. Two stapes models were used-1 made from the bone filler, Celatite, consistent in bone density but changing in cross sectional area, and the other made from an apacerum rod used in quantitative computed tomography (QCT), consistent in cross sectional area but changing in bone density. These stapes models were put into a skull phantom and analyzed by helical 3D-CT. The influence of the tympanic cavity conditions on CT images of stapes was evaluated by filling the phantom model with Vaseline following 3D selective reconstruction. In all stapes models, lowering the lower CT window width threshold resulted in an enlarged cross-sectional area of the model. The higher the bone density, the lower the increase in cross-sectional area in the image. The stapes model with lower density had greater influence on the imaging by tympanic cavity conditions and was likely to be misdiagnosed as showing higher bone density. Based on the experimental study, 3D-SS by helical 3D-CT appears to be a useful measure for qualitatively diagnosing stapes lesions.

Imaging of the windows of the temporal bone

Imaging of the window of the temporal bone has became an important tool in the analysis of hearing loss, vertigo, tinnitus in a context of trauma, malformation, otosclerosis, and chronic otitis media. A good knowledge of the anatomy and a good technical procedure are necessary for making an efficient diagnosis. The increased thickness of the footplate may be delineated in otosclerosis, chronic otitis media, malformation, when it is measured at 0.7 mm or more in horizontal computed tomography (CT) sections. The traumatic displacement of the stapes, particularly within the labyrinths, is easily diagnosed in horizontal CT section. Imaging of the round window is now very important for the detection of otosclerotic foci, congenital stenosis, and perilymphatic fistula with or without fracture. Magnetic resonance imaging (MRI) with the high-resolution T2 plays an important role in the detection of a small amount of fluid in the round window recess, confirming the traumatic perilymphatic fistula without fracture.

Scanning electron microscopy images and energy-dispersive X-ray microanalysis of the stapes in otosclerosis and Van der Hoeve syndrome

OBJECTIVE/HYPOTHESIS

The objective of this study was to evaluate the morphological and microchemical changes that affect sclerotic stapes in otospongiosis and van der Hoeve syndrome.

METHODS

A scanning electron microscope equipped with an energy-dispersive x-ray analyzer was used in the experiments.

RESULTS

In otosclerosis, focal lesions are poorly mineralized, with low calcium salt and reduced calcium-to-phosphorus (Ca/P) ratio (1.9:1). This finding correlates with a spongiotic type of lesion and indicates unstable mineralization with possible change from hydroxyapatite to calcium triphosphate. In van der Hoeve syndrome the presence of magnesium in stapes suggests osteoclastic function stimulation. The osteoclasts secrete many protons, causing an acidified microenvironment. Brushite is formed, and Ca/P ratio decreases in comparison with that of control patients (2.0:1 vs. 2.6:1).

Congenital absence of the oval window: radiologic diagnosis and associated anomalies

BACKGROUND AND PURPOSE

In most children with conductive hearing loss, acquired otitis media and/or middle ear effusion are ultimately diagnosed. Congenital conductive hearing loss is a rare condition; absence of the oval window is an unusual pathogenesis for this type of hearing impairment and can be associated with an anomalous horizontal facial nerve canal. Our goal was to describe the imaging features of congenital absence of the oval window, to determine the frequency with which anomalous development of the horizontal facial nerve canal occurs, and to review the developmental error responsible for this malformation.

METHODS

Nine temporal bones in seven patients (5 to 36 years old) were found to have an inadequately formed oval window on high-resolution CT scans; seven ears showed complete lack of oval window formation, and two showed partial absence of the oval window. Records were reviewed for clinical information, and images were examined for associated anomalies.

RESULTS

Six of nine ears with abnormal oval window formation showed malposition of the horizontal facial nerve canal. In each of these, the canal was abnormally low, overlying the expected location of the oval window; three of the canals lacked a visible bony covering. Seven of the nine ears were found to have a dysplastic or absent stapes.

CONCLUSION

Congenital absence of the oval window can be diagnosed on CT studies. In the present series, this anomaly was associated with a grossly aberrant horizontal facial nerve canal in six of nine involved ears. Familiarity with the developmental sequence of oval window formation fosters an understanding of these anomalies. Preoperative recognition is important clinically, as a low facial nerve will block surgical access to the oval window and its presence will alter patient management.

Three-dimensional reconstruction of the incudostapedial joint with helical computed tomography

Three-dimensional images of the incudostapedial joint (I-S joint) were reconstructed using helical computed tomography (CT). The images of the joint were most often reconstructed when threshold values were selected at -500 to -700 Hounsfield Units. These shapes were changed by choosing various threshold values. Histological examinations of the cadaver specimen indicate that these changes are due to structure of the I-S joints. We conclude that these 3-D images may be useful in assessing pathology of the I-S joint.

Round window atresia in association with congenital stapes fixation

OBJECTIVE

To document an association of round window atresia with congenital stapes fixation, discuss the diagnostic role of computed tomography, and implicate the clinical significance of these anomalies.

STUDY DESIGN

Retrospective chart review and review of the literature.

RESULTS

The authors report three pediatric cases of round window atresia. All cases presented with hearing loss of a conductive nature (two cases bilateral, one unilateral). Two patients underwent middle ear exploration, demonstrating stapes fixation and the absence of a round window. Stapedectomy was performed in both cases without postoperative hearing improvement. Subsequent revision stapedectomy was also unsuccessful in one of these cases. The unoperated case represents the fraternal twin of one patient. In all cases, computed tomography scanning demonstrated findings consistent with atresia of the round window niche without cochlear anomaly.

CONCLUSIONS

An association of round window atresia and congenital stapes fixation is apparent. The mechanism of the conductive hearing loss following stapedectomy remains poorly understood. Computed tomography imaging and surgical confirmation are probably both necessary to establish the diagnosis of round window atresia.

[Isotopic studies on the regeneration of stapedial bone in otosclerosis]

The aim of the study was determining the bone rebuilding activity in stapes and otosclerotic focus and comparison the relation between bone rebuilding activity with some clinical features such as the patient's sex and age, duration of the disease and the degree of hearing impairment. The study covered 98 patients aged from 18 to 68 years (X = 37 years) in whom, due to otosclerosis, stapedectomy was performed at the Clinic of Otolaryngology--PAM in Szczecin. The rebuilding activity was estimated in bone fragments having been removed during the operation, i.e. in 98 specimens of canal wall bone, 97 specimens of stapedial crura, 88 fragments from posterior and 18 fragments from anterior parts of footplate as well as in 15 otosclerotic foci, using isotopic method implementing a complex of pyrophosphate labelled with technetium Tc-99m. The degree of bone rebuilding activity was defined by the amount of absorbed isotopic index. The "control group" was made up of 9 cases, in which stapedectomy was carried out for therapeutical purpose in consequence of other ailments, namely: in 3 cases of congenital stapedial ankylosis, 5 cases of stapedial tympanosclerosis, and 1 case of Menier's disease. It has been disclosed that otosclerosis is an active pathological process, involving the bone of the entire stapes with the strongest manifestation in the disease focus. An essential fact was linked with the very low bone rebuilding activity in the stapedial footplate and crura in the "control group". The bone rebuilding activity in otosclerotic foci and footplate of stapes was somewhat higher in males than in females. It was the highest in patients whose disease duration was the longest. In general the bone rebuilding activity didn't influence the degree of hearing impairment.

Normal and opacified middle ears: CT appearance of the stapes and incudostapedial joint

PURPOSE

To establish the computed tomographic (CT) visibility of the incudostapedial joint and of the stapes superstructure in normal and opacified middle ears.

MATERIALS AND METHODS

Two independent observers reviewed CT studies with 1-mm section thickness of the temporal bone in 75 normal ears and in 33 opacified middle ears (13 of which had definitive proof of disease) to establish the rate of visualization of the stapes and incudostapedial joint.

RESULTS

In normal ears, both the stapes crura and the continuity between the incus and stapes were seen in almost 100% of cases, whereas the actual incudostapedial joint was identified in 86% (86 observations) and 67% (67 observations) of cases in the axial and coronal planes, respectively. The position of the incudostapedial joint was below footplate level on the axial images and mostly at or anterior to the midportion of the foot-plate on the coronal images. In 13 clinically confirmed diseased middle ears, the status of the stapes superstructure in all cases and that of the incus in 11 cases was correctly predicted with CT.

CONCLUSION

It is now possible to visualize routinely the incudostapedial joint and stapes superstructure at CT. Absence of these structures in an opacified middle ear strongly indicates abnormality.

Traumatic luxation of the stapes evidenced by high-resolution CT

We encountered a case of acquired perilymphatic fistula in which the origin of the disease, namely, the stapes begin medially displaced into the vestibule, was shown by thin-section CT. Accordingly, we recommend that every patient with suspected perilymphatic fistula of traumatic origin undergo high-resolution CT of the petrous bone.

Computed tomographic image analysis of ears with otosclerosis

To evaluate the usefulness of quantitative analysis of computed tomographic images in diagnosing stapedial otosclerosis, high-resolution temporal bone computed tomography (CT) of 32 ears with otosclerosis and 19 control ears was used. The images on the section containing the oval window were digitized using a scanner, and the ratio of the mean gray scale value of 5 areas in the optic capsule including the area anterior to the oval window to that of the cortical bone was calculated. The mean value of the ratio of the area anterior to the oval window was significantly lower in the otosclerosis group (0.85 +/- 0.10) than in the control group (1.03 +/- 0.03; Student t test: t = 7.94, p < 0.0001). In 30 of 32 (93.7%) otosclerotic ears, the values were lower than the normal range calculated in the control group. This method of quantitative CT image analysis comparing the area anterior to the oval window was considered useful in diagnosing stapedial otosclerosis.

CT cisternography in congenital perilymphatic fistula of the inner ear

Perilymphatic fistulas of the inner ear constitute abnormal leaks of perilymphatic fluid into the middle ear or mastoid air cell system and represent a rare cause of otorrhea. We report the case of a 5-month-old child presenting with sudden otorrhea. High resolution CT cisternography showed a malformation of the middle ear and a passage of contrast-enhanced CSF into the tympanic cavity through the left oval window. Surgery confirmed a tear of the tympanic membrane as well as a stapes malformation with aplasia of the crura and an associated perilymphatic fistula through a defect in the stapes footplate. The fistula was closed with adipose tissue from the ear lobe.

[CT (high-resolution) in 60 cases of stapediovestibular otosclerosis with surgical indications]

Sixty patients with stapediovestibular otosclerosis (OEV) were studied by CT-scan (target program). These patients had stapedectomy indication because they had a conductive hearing loss in which one had an A/B gap of > 25 dB. The leading principle of this study was how to know the main indications of the CT-scan which makes it possible for morphologic and densitometric evaluation of the extension and probable activity of the stapedial, fenestral and fissural labyrinthine otosclerotic foci. A correlation between the CT pattern of otosclerosis and the pure or mixed hearing loss had been tried. The conclusion is that CT should be a routine examination of OEV clinical study.

[The value of computed tomography in persistent balance disorders following the use of stapes prostheses]

10 of 150 patients had persistent vertigo after implantation of stapes prostheses. These patients were evaluated by high-resolution CT in the axial and coronal plane. Scans showed in all cases findings which related to the symptoms. The CT findings were proved intraoperatively in 9 cases. A new indirect sign of a perilymphatic fistula is described in form of an air bulla at the end of the prosthesis. Retympanotomy could be planned better with the help of HR-CT.

Congenital perilymphatic fistula: computed tomography appearance of middle ear and inner ear anomalies

Congenital perilymphatic fistula is an abnormal communication between the inner ear and middle ear. Inner ear anomalies have been described on computed tomography scans. Middle ear anomalies have been found at surgery; the most frequent are anomalies of the stapes and round window. This retrospective study describes the appearance of the inner and middle ear on computed tomography scans, and of the middle ear at surgery, in 10 patients (15 ears) in whom perilymphatic fistula was found at surgery. Twelve of 15 stapes were abnormal at surgery; 4 of these 12 (33%) could be seen on computed tomography scans. Two stapes normal at surgery were normal on computed tomography. Three round windows were abnormal at surgery; none of these was seen on computed tomography scans. There were also four dysplastic cochleas, four dysplastic vestibules, and three dilated vestibular aqueducts. Computed tomography scans identified an abnormal inner ear, middle ear, or both in 8 (53%) of the 15 ears with perilymphatic fistula. An inner ear or middle ear anomaly on computed tomography may heighten clinical suspicion of congenital perilymphatic fistula.

Inferior mastoidectomy-hypotympanic approach for surgical removal of glomus jugulare tumors: an anatomical and radiologic study emphasizing distances between critical structures

The technique of inferior mastoidectomy-hypotympanic dissection, with preservation of the middle and inner ear structures, has been established for radical surgical removal of glomus tumors involving the skull base. In order to study the gross anatomic differences and correlate with the computed tomography (CT) scan, 20 human temporal bones were dissected and accurate measurements between vital structures were made. This study revealed a wide variation in distances between the neurovascular structures, whereas the distances between inner ear structures were not statistically different. This original study of critical distances of gross topographic anatomical structures and CT correlation is very helpful indeed in the understanding of variations found in the surgical removal of lesions involving this important and challenging area of the skull base. The inferior mastoidectomy-hypotympanic dissection has been performed in the removal of six suitable tumors involving the jugular bulb area. This technique, combined with upper cervical dissection, is very useful for the radical removal of such neoplasms with preservation of external and middle ear structures as well as the function of the facial, eighth, and other lower cranial nerves.

Diagnosis of the ossicular chain in the middle ear by high-resolution CT

This study was conducted to assess the usefulness and limitations of high-resolution CT for diagnosing the ossicular chain in the middle ear. The CT images in this study were obtained in as much detail as possible and 2 direction images. Preoperative CT findings of the ossicular chain were compared with operative findings in 26 patients with ossicular defects. Preoperative detection of the complete defect of the malleus head and the body and long process of the incus by high-resolution CT was possible in all cases, while detection of the defect of the manubrium of the malleus and superstructure of the stapes could be made in 33.3 and 60%, respectively. The defect of the incudostapedial joint (1 case) and partial defect of the stapes crus (2 cases) could not be diagnosed correctly by preoperative estimation.

[Computerized tomography in persisting stapedial artery]

About 30 cases of a persistent stapedial artery have been described in the literature so far. It is usually associated with other malformations, suggesting an inhibition of normal embryonic development. For the first time, it was possible to demonstrate this using high-resolution computed tomography.

[Apropos of a case of recurrent meningitis]

The recurrent meningitis associated with spontaneous CSF rhinorrhea in a 4-year-old boy was found to be due to simultaneous congenital defects. There was a dehiscence of the anterior fossa associated with congenital changes in the temporal bone, the petrous bone and the stapes. All these defects were visible including demineralization of the footplate stapes region. The high-resolution X-ray CT served as a clear guide to the surgeon.

Acquired disruptions of the incudostapedial articulation: diagnosis with CT

To determine the best technique for diagnosing incudostapedial joint disruption with computed tomography (CT), the authors reviewed 15 surgically proved cases. In each case, the articulation was depicted on axial but not coronal images. Disruption was due to inflammation in ten cases and trauma in five. Axial high-resolution CT is valuable in the diagnosis of traumatic and inflammatory disruption of the incudostapedial joint.