Isolated Traumatic Dislocation of the Malleus into the External Auditory Canal

We report a rare case of isolated malleus dislocation into the external auditory canal with lateralized intact tympanic membrane following a head trauma. The patient was a 63-year-old woman who presented at the outpatient department of our institute with hearing loss of 10 years' duration after a bicycle accident. During physical examination of the patient, total dislocation of the malleus-like bony structure into the external auditory canal on the right side was observed. In the computed tomography scan, an isolated malleus dislocation with intact incus-stapes articulation was identified. The patient was successfully treated with endoscopic exploratory tympanotomy and partial ossicular replacement prosthesis. The isolated malleus dislocation can rarely occur after trauma. A careful diagnostic step through history, physical examination, and temporal bone computed tomography scan are needed to confirm this rare condition.

Neuroimaging findings in Emanuel Syndrome

Emanuel syndrome is a rare inherited chromosomal abnormality caused by an unbalanced translocation of chromosomes 11 and 22. Clinically, Emanuel syndrome is characterized by a wide spectrum of congenital anomalies, dysmorphisms, and developmental disability often confused with other similar syndromes. Outside of genetic testing, diagnosis remains challenging and current literature on typical radiologic findings is limited. We present classic neuroimaging findings of Emanuel syndrome consistent with prior literature including microcephaly, microretrognathia, external auditory canal stenosis, and cleft palate; and also introduce the additional maxillofacial anomaly of dysplastic middle ear ossicles, to our knowledge not previously described in the literature. Recognition of findings leading to earlier diagnosis of Emanuel syndrome may improve outcomes and quality of life for patients and their families.

Conductive hearing loss with a "dry middle ear cleft"-A comprehensive pictorial review with CT

Conductive hearing loss (CHL) commonly results from middle ear fluid and inflammation (otitis media). Less commonly in patients with CHL, the middle ear cleft is well aerated or 'dry' with absence of soft tissue or fluid clinically and on imaging. There are numerous causes for this but they can be clinically challenging to diagnose. This pictorial review aims to illustrate and discuss the CT features of both common and less common causes of CHL in patients with a "dry middle ear cavity".

The extent of inferior displacement of the mastoid tegmen is related to the severity of congenital aural atresia

CONCLUSION

The extent of inferior displacement of the mastoid tegmen is related to the severity of congenital aural atresia (CAA).

OBJECTIVE

To analyze anatomic variations observed on high-resolution temporal bone computed tomography (TBCT) in patients with CAA, the extent of inferior displacement of the mastoid tegmen and the size of the incudo-stapedial (IS) joint angle were compared with surgical parameters for atresiaplasty, such as Jahrsdoerfer score and hearing acuity.

METHODS

Sixty-one patients with unilateral CAA underwent high-resolution TBCT and hearing tests. We evaluated TBCTs in terms of Jahrsdoerfer criteria and analyzed the relationships among the inferior displacement of the mastoid tegmen, size of the IS joint angle, hearing acuity, and the Jahrsdoerfer score on the atretic side.

RESULTS

IS joint angle on the atretic side was found to be 120.6 ± 11°, which was significantly greater than the corresponding value of 103.4 ± 5.4° on the normal side. Cholesteatoma occurred significantly more often in CAA patients with narrow external auditory canals (EACs) (9/27; 33.3%), compared with CAA patients with no EAC opening (2/34; 5.9%). There was a significant relation between the extent of inferior displacement of the mastoid tegmen (28.9% in the atretic side and 17.3% in the normal side) and the Jahrsdoerfer score (p < 0.0001).

The morphological findings of malleus and incus in a case of Marfan's syndrome

In Marfan's syndrome, which is a connective tissue disorder of hereditary origin, collagenous tissue development and bone synthesis are generally altered in addition to the occurrence of many systemic deformities. External ear, stapes, and vestibular aqueduct pathologies are reported as some of the otological deformities. However, the malleus and incus pathologies of the ear are not reported in any study. In the morphometric measurements carried out, the distance between the malleus head and manubrium was found to be 9.8 mm. When similar measurements were carried out for the incus, the distance between the upper part of the incus body and tip of the long process was found to be 6.9 mm. All of these measurements were detected to be greater than in normal people. It can be concluded from this study that in Marfan's syndrome, in addition to the musculoskeletal alterations particularly in bone synthesis, the ossicular chain in the middle ear is also affected.

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.

Soft tissue morphometry of the malleus-incus complex from micro-CT imaging

The malleus-incus complex (MIC) is unique to mammalian hearing. To develop a comprehensive biomechanical MIC model for the human middle ear, measurements regarding its anatomical features are a necessity. Micro-scale X-ray computed tomography (micro-CT) imaging, which is known to be a suitable method for imaging high-density tissue such as middle-ear ossicles and surrounding bones, is used in this study to determine the three-dimensional (3-D) morphometry of the soft tissue attachments of the MIC. The MIC morphometry is based on their 3-D reconstruction from micro-CT image slices with resolutions ranging from 10 to 20 mum. The suspensory ligament and tendon attachments of the malleus and the incus as well as the incudomalleal joint (IMJ), are quantified in terms of dimensions, positions, and orientations for four human cadaver temporal bones. The malleus principal frame, the incus principal frame, and the MIC principle frame are calculated and the morphometry is reported in relation to each of these frames for the first time. The resulting values show significant variation across ear samples, suggesting that models of the MIC should be based on individual anatomy. The IMJ morphometry dimensions appear to be proportional to the ossicular mass. The micro-CT imaging modality is a nondestructive and relatively fast method for obtaining soft tissue morphometry and provides accurate anatomical features in relation to the principal axes of bones.

Otosclerosis of the incus

OBJECTIVE

To report a case of a patient with otosclerosis of the incus.

PATIENTS

A 61-year-old woman with a progressive hearing loss on her left ear and a computed tomographic scan of the temporal bone revealing an expansible lesion of the incus.

INTERVENTIONS

The ossicle was removed by using a transtympanomastoid approach; the ossicular chain was reconstructed using a titanium partial ossicular replacement prosthesis.

MAIN OUTCOME MEASURE

The diagnosis of the disease was obtained by means of histopathologic examination of the specimen.

RESULTS

The patient obtained a good postoperative hearing result. The histopathologic examination of the specimen documented an otosclerosis of the incus.

CONCLUSION

Otosclerotic involvement of the middle ear ossicles, apart from footplate, was very rarely mentioned. Most subjects were incidentally diagnosed postmortem by means of examination of specimens from temporal bone collections. The diagnosis and treatment of a patient with otosclerosis of the incus is exceptional; however, otosclerosis should be considered in the differential diagnosis of expansible lesions of the ossicles.

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.

Middle ear cholesteatoma: characteristic CT findings in 64 patients

BACKGROUND

High resolution computerized tomography (HRCT) is valuable for detection of early erosive changes suggestive of cholesteatoma. The aim of our study was to determine characteristic CT findings in patients with middle ear cholesteatoma.

METHODS

We conducted a retrospective review of CT scans and surgical and histopathological reports in 64 patients with middle ear cholesteatoma (35 male, 29 female; age range, 7-80 years, median age, 22 years). CT scans were evaluated for the presence of intra-tympanic non-dependent soft tissue density, the extent of middle ear involvement, bone expansion and thinning, and bone erosions involving the ossicles and adjacent structures.

RESULTS

Middle ear cholesteatoma was more common in male patients and in patients aged 20-35 years. All patients had soft tissue density in the middle ear. Fifty-nine (92%) had expansion of the aditus and mastoid antrum, 59 (92%) had erosions of the ossicles, with involvement of the long process of the incus in 48 (75%), 55 (86%) had an eroded scutum, 55 (86%) an eroded facial nerve canal, 57 (89%) an eroded Koerner's septum, which was totally destroyed in 19 (27%), 48 (75%) had tegmen erosion, and 63 (98%) had erosions of the antral walls. The correlation of pre-operative CT with surgical and histopathological findings was 97%.

CONCLUSION

Middle ear cholesteatoma is a distinct clinical entity with characteristic findings that may be suggested by CT imaging. These findings should alert the clinician to the possibility of cholesteatoma, which will guide in the surgical approach and treatment plan.

CT findings of bilateral congenital absence of the long process of the incus

Bilateral conductive deafness due to congenital absence of the long process of the incus (CALPI) is rare. The authors present the case of a patient with bilateral CALPI. To the best of our knowledge, this is the first reported case preoperatively diagnosed as bilateral CALPI by computed tomography. Multislice computed tomography is very useful for the diagnosis of minute abnormalities of the ossicles.

Dislocation of the incus into the external auditory canal after mountain-biking accident

We report a rare case of incus dislocation to the external auditory canal after a mountain-biking accident. Otoscopy showed ossicular protrusion in the upper part of the left external auditory canal. CT indicated the disappearance of the incus, and an incus-like bone was found in the left external auditory canal. There was another bony and board-like structure in the attic. During the surgery, a square-shaped bony plate (1 x 1 cm) was found in the attic. It was determined that the bony plate had fallen from the tegmen of the attic. The fracture line in the posterosuperior auditory canal extending to the fossa incudis was identified. According to these findings, it was considered that the incus was pushed into the external auditory canal by the impact of skull injury through the fractured posterosuperior auditory canal, which opened widely enough for incus dislocation.

The anatomic relationship between the second genu of the facial nerve and the incus: a high-resolution computed tomography study

OBJECTIVE

This study defines the three-dimensional location of the posterior-most point of the tympanic segment of the facial nerve (TSFN) relative to the posterior-most point of the short process of the incus, using ultrahigh-resolution computed tomography (CT) of the temporal bone.

STUDY DESIGN, SETTING, AND PATIENTS

Included were patients who had been referred for CT of the temporal bone for various reasons other than suspected pathologic conditions of the middle ear. The decision whether to include a patient in the study was based on the referring physician's referral note for the examination.

INTERVENTION

All of the patients underwent axial CT of the temporal bone, with consecutive slices of 1.1 mm width and 0.5-mm increments.

MAIN OUTCOME MEASURES

The posterior-most point of the short process of the incus was identified on axial CT and was superimposed onto a lower axial slice in which the posterior-most point of the TSFN was identified. Its shortest distance to the TSFN was measured. Afterward, the length of the TSFN that remained posterior to the perpendicular of the posterior-most point of the short process of the incus was measured by measuring the length of TSFN that could be seen posterior to the point of bisection of the line marking the shortest distance between the posterior-most point of the short process of the incus and the FN in the previous measurement. The measurements were performed on 30 normal temporal bones.

RESULTS

The shortest distance measured between the posterior-most point of the short process of the incus and the TSFN was, on average, 3.31 mm for all 30 ears (range 2-4.8 mm). The length of TSFN that could be seen posterior to the perpendicular of the most posterior point of the short process of the incus was, on average, 2.70 mm (range 1.80-3.90 mm).

CONCLUSIONS

In addition to defining the spatial location of the posterior-most point of the TSFN, this study also offers a practical method by which the surgeon can evaluate, preoperatively, how far medial to the incus and how much posterior to the posterior-most point of the short process of the incus the facial nerve is located.

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.

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.

Three-dimensional CT-imaging of the ossicular chain

In eight patients, with a known air-conduction hearing loss, three-dimensional images of the ossicular chain were constructed based on heavily overlapping high resolution CT-slices, obtained from a spiral CT data set. High quality three-dimensional images could be obtained in all eight patients. Supplementary information was derived from these three-dimensional images in three patients; in one, this supplementary information had therapeutic importance. The slight image quality loss in spiral-CT of the temporal bone, compared with conventional CT, is in some cases largely compensated by the possibility of rendering high quality secondary reconstructions.

The "Y" sign of lateral dislocation of the incus

This report presents a new sign of ossicular dislocation utilizing high resolution computed tomography of the temporal bone. In the case of lateral dislocation of the incus, a "Y" shaped configuration (Y sign) of the malleoincudal complex is seen in the coronal views even though the axial views present a normal "ice cream cone" configurations.

Imaging of ossicular prostheses

The prostheses available for reconstruction of the ossicular chain have expanded to include a variety of synthetic materials. Hydroxyapatite contains the inorganic constituents found in human living bone and is currently being incorporated into many new prostheses. This study demonstrates the computed tomography and magnetic resonance image characteristics of eight middle ear prostheses, a block of dense hydroxyapatite, and a human incus. Imaging of ossicular prostheses is more informative with computed tomography.

Bone tissue kinetics in the surgically disarticulated dog incus

The incus of the right ear from 4 growing mongrel dogs was surgically disarticulated and left in the middle ear space. The external auditory canal was then filled with teflon paste and sutured. After 6 weeks (D-6 group) and 13 weeks (D-13 group) the animals were sacrificed. The right experimental incus and the left control one were embedded in methyl methacrylate and sectioned in single 50-microns-thick sections according to the principal axis of the two processes. On the microradiographs of each section we evaluated the thickness of the body and of both processes and the percentage area of the primary channels of the secondary osteons and that of the appositional bone tissue. The thickness of the body and of the two processes was more pronounced in all the experimental incuses, in which 6% (in D-6) and 8% (in D-13) of the total area were occupied by new appositional woven bone. In the body of the D-13 group, 9% of the pre-existing bone was substituted by secondary osteons. The results indicate that the incus react to the variations of mechanical stimuli.

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.

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.

Cholesteatoma of the middle ear and mastoid. A comparison of CT scan and operative findings

High-resolution CT scanning accurately depicts the status of the structures of the temporal bone, allowing delineation of pathology prior to surgical exploration of ears with cholesteatoma. It provides information concerning location and extent of disease as well as possible anatomic variations and complications that may be encountered. The main advantages of CT scanning over polytomography are superior soft-tissue contrast resolution and improved spatial detail at a reduced radiation dose for the patient.

The tympanic cavity: tomographic anatomy

This study was carried out on 100 tomograms of the petrous bone using Guillen's transorbital view of the anatomy of the middle ear. It provides basic data concerning the morphology, size and surface area of the tympanum, the epitympanum and the hypotympanum. It correlates the surface area of the epi-and hypotympanum, and suggests certain embryological interpretation. This study contributes to the diagnostic radiology of the middle ear in the following ways: I It provides basic data for the interpretation of tomograms in patients with ossicular dislocation. 2 It provides essential data for the radiology of congenital malformation and of tumors. 3 It puts in perspective certain criteria used for the diagnosis of cholesteatoma. Finally, this study justifies the use of preoperative radiological investigation.

Incudostapedial joint in health and disease

The incudostapedial joint was studied in tomograms of 370 normal and 80 diseased middle ears. The Guillen view was found to be superior to the anteroposterior view in demonstrating this joint in normal middle ears (85% and 62% visualization, respectively). In the presence of disease, visualization was markedly reduced to 19%; this lack of visualization is a nonspecific finding since early cholesteatomas, chronic otitis media, and retraction pockets could not be differentiated radiologically. Nonvisualization of the incudostapedial joint in the Guillen view is a more objective indicator of middle ear disease than such terms as "indistinct of hazy" middle ear cavities.

The inclined lateral projection: a new view in temporal bone tomography

Radiographic findings in the inclined lateral projection are presented. This view provides detail of the malleus and incus which is not provided on any other view and also preserves the visualization of temporal bone anatomy seen by routine lateral projection. The frequent occurrence of ossicular pathology in inflammatory and traumatic diseases of the ear requires the meticulous radiographic examination of the ossicles provided by this projection. Patient positioning is uncomplicated and comfortable.