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Objective: To determine the feasibility of using temporal bone computed tomography (CT) scans to identify malleal ligaments and the prevalence of calcification in malleal ligaments., Study Design: Retrospective case review. CT scans were blindly and retrospectively reviewed by two physicians (a radiologist and a nonradiologist). Scans differed by slice thickness, and included both conventional CT and cone beam CT (CBCT)., Setting: Ambulatory tertiary referral center., Patients: One hundred fifty-one temporal bone CT scans, obtained between the years 2014 and 2017, were initially screened, which included 302 ears. Patients with previous tympanomastoid surgery or middle ear opacification were excluded, leaving 187 ears in the study., Intervention: Diagnostic., Main Outcome Measure: Percentage of visible normal and calcified malleal ligaments., Results: Scans with submillimeter slice thickness were more likely to demonstrate all three malleal ligaments than those with 1 ml and larger slices (83.7% versus 50.0% for nonradiologist, p < 0.0001; 59.6 versus 34.8% for radiologist, p < 0.0001). Calcification was seen in 11.8% of ears reviewed. The ability to detect malleal ligaments with cone beam CT was 86.2%, while the rate with conventional CT was 71.1%, a difference that persisted when controlling for slice thickness. Interobserver agreement for the detection of malleal ligaments was 65% with a Cohen's kappa coefficient of κ = 0.27., Conclusion: Visualization of the malleal ligaments using CT scans is feasible in a majority of aerated ears. Detection of malleal ligaments improves with thinner slice thickness and cone-beam technique. Low interobserver agreement suggests the importance of experience and a need for standardized review.

Human middle ears show large morphological variations. This could affect our perception of hearing and explain large variation in experimentally obtained transfer functions. Most morphological studies focus on capturing variation by using landmarks on cadaveric temporal bones. We present statistical shape analysis based on clinical cone beam CT (CBCT) scans of 100 patients. This allowed us to include surface information on the incudomallear (IM) complex (joint, ligaments and tendon not included) of 123 healthy ears with a scanning resolution of 150 μm and without a priori assumptions. Statistical shape modeling yields an average geometry for the IM complex and the variations present in the population with a high precision. Mean values, variation and correlations among anatomical features (length of manubrium, combined length of malleus head and neck, lengths of incus long and short process, enclosing angles, ossicular lever ratio, incudomallear angle, and principal moments of inertia) are reported and compared to results from the literature. Most variation is found in overall size and the angle between incus and malleus. The compact representation provided by statistical shape modeling is demonstrated and its benefits for surface modeling are discussed., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Petrotympanic fissure (PTF) is a fissure in the temporal bone that runs from the temporomandibular joint (TMJ) to the tympanic cavity (TC). In PTF, the discomallear ligament (DML) connects the malleus in the tympanic cavity and the articular disc and capsule of the temporomandibular joint. PTF with the DML is a possible cause of aural symptoms related to temporomandibular joint dysfunction (TMD)., Purpose: To investigate the prevalence of different types of PTF in TMD using dental volumetric tomography (DVT) and determine whether PTF type correlates with age., Material and Methods: DVT scans in the sagittal planes of PTFs of 134 patients with TMD were examined for the types of PTF present. Three main PTF types were described: wide, tunnel-shaped structure (type 1); tunnel-shaped structure that is wide open in the PTF entrance to the mandibular fossa and gradually thins out in the tympanic cavity (type 2), tunnel-shaped structure that is wide open in the entrance of the mandibular fossa, with a middle region with a flat-shaped tunnel structure and a narrow exit in the tympanic cavity (type 3)., Results: In DVT scans, PTF types 1, 2 and 3 were seen in 67.2%, 1.5%, and 31.3% of cases, respectively. We found no significant relationship between age or gender and PTF type., Conclusion: The low percentage of type 2 PTF and high percentage of type 1 PTF must be taken into consideration during pre-surgical planning related to TMD. However, future well-designed clinical studies involving larger numbers of subjects will be necessary to confirm the findings of this study.

The middle ear is too complex a system for its function to be fully understood with simple descriptive models. Realistic mathematical models must be used in which structural elements are represented by geometrically correct three-dimensional (3D) models with correct physical parameters and boundary conditions. In the past, the choice of boundary conditions could not be based on experimental evidence as no clear-cut data were available. We have, therefore, studied the deformation of the tympanic membrane (TM) at its boundaries using X-ray microscopic computed tomography in human and gerbil while static pressure was applied to the ear canal. The 3D models of the TM and its bony attachments were carefully made and used to measure the deformation of the TM with focus on the periphery and the manubrium attachment. For the pars flaccida of the gerbil, the boundary condition can, for the most part, be described as simply supported. For the human pars flaccida, the situation is more complicated: superiorly, the membrane contacts the underlying bone more and more when pushed further inward, and it gradually detaches from the wall when sucked outward. In gerbil, the attachment of the TM to the manubrium can be described as simply supported. In human, the manubrium is attached underneath the TM via the plica mallearis and the contact of the TM with the bone is indirect. For both human and gerbil, a simple boundary condition for the peripheral edge of the pars tensa is not appropriate due to the intricate structure at the edge: the TM thickens rapidly before continuing into the annulus fibrosis which finally makes contact with the bone.

The mean resonance frequency of the human middle ear under air conduction (AC) excitation is known to be around 0.8-1.2 kHz. However, studies suggest that the mean resonance frequency under bone conduction (BC) excitation is at a higher frequency around 1.5-2 kHz. To identify the cause for this difference, middle-ear responses to both AC and BC excitations were measured at the umbo and lateral process of the malleus using five human cadaver temporal bones. The resonance modes identified from these measurements, along with finite element analysis results, indicate the presence of two ossicular modes below 2 kHz. The dominant mode under AC excitation is the first mode, which typically occurs around 1.2 kHz and is characterized by a "hinging" ossicular motion, whereas the dominant mode under BC excitation is the second mode, which typically occurs around 1.7 kHz and is characterized by a "pivoting" ossicular motion. The results indicate that this second mode is responsible for the translational component in the malleus handle motion. The finding is also consistent with the hypothesis that a middle-ear structural resonance is responsible for the prominent peak seen at 1.5-2 kHz in BC limit data.

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.