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Left sided cadaveric temporal bone showing the Incudostapedial joint angulation in bones with normal morphology of the LPI/SSS/ISJ complex. (LPI -long process of incus; SSS-stapes suprastructure; ISJ-incudostapedial joint; 1-Handle of malleus; 2-Head of malleus; 3-Short process of incus; 4-Long process of incus; 5-Lenticular process; 6-Stapedius tendon (cut); 7-Footplate of stapes; 8-Head of Stapes; 9-Crura of stapes; 10-Lateral Semicircular Canal).
Source publication
Introduction
Optimal sound transmission across the ossicular chain is dependent on the appropriate alignment of the middle ear ossicles. Incudostapedial joint (ISJ) is conventionally considered to be at right angle.
Objective
We intended to study the ISJ anatomy and the impact of temporal bone pneumatization on the same.
Methods
In a cadaveric st...
Context in source publication
Context 1
... F12 microscope with LED with inbuilt 3-mega pixel camera and HD video system (Wetzlar, Germany) and the pictures of ISJ angle were taken in a posterior to anterior direction, in exact alignment to the anterior-posterior direction of crura, following the direction of stapedial tendon, co-planar with the Stapes footplate, at a magnification of 25Â (Fig. ...
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Background
Otosclerosis is a pathology that interferes with the conduction of vibrations to the inner ear, triggering changes in the auditory ossicles and their associated joints due to mechanical overload. This study primarily aims to evaluate these overload-induced modifications in the stapes head resulting from the immobilization of the base of...
Citations
... These investigators concluded that variations in incudo-stapedial angle should be considered when selecting the length of stapes prostheses and to be considered for the crimping maneuver. In an anatomical study by Singh et al. on forty-seven human cadaveric temporal bones, the incudo-stapedial joint angle ranged differently according to the bone pneumatization, being from 54 to 122 degrees (mean of 90.5 ± 15) in well-pneumatized bones, and from 68 to 118 degrees (mean of 88.7 ± 14) in sclerotic bones, without a statistically significant difference between both groups [12]. Fang et al. measured the incudo-stapedial angle in thirty-nine patients' preoperative multiplanar CT scans, finding an angle of 93.3 ± 8.8 degrees, with a weak and negative correlation between this angle and the postoperative hearing gain [13]. ...
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%.
Hypothesis:
Automated image registration techniques can successfully determine anatomical variation in human temporal bones with statistical shape modeling.
Background:
There is a lack of knowledge about inter-patient anatomical variation in the temporal bone. Statistical shape models (SSMs) provide a powerful method for quantifying variation of anatomical structures in medical images but are time-intensive to manually develop. This study presents SSMs of temporal bone anatomy using automated image-registration techniques.
Methods:
Fifty-three cone-beam temporal bone CTs were included for SSM generation. The malleus, incus, stapes, bony labyrinth, and facial nerve were automatically segmented using 3D Slicer and a template-based segmentation propagation technique. Segmentations were then used to construct SSMs using MATLAB. The first three principal components of each SSM were analyzed to describe shape variation.
Results:
Principal component analysis of middle and inner ear structures revealed novel modes of anatomical variation. The first three principal components for the malleus represented variability in manubrium length (mean: 4.47 mm; ±2-SDs: 4.03-5.03 mm) and rotation about its long axis (±2-SDs: -1.6° to 1.8° posteriorly). The facial nerve exhibits variability in first and second genu angles. The bony labyrinth varies in the angle between the posterior and superior canals (mean: 88.9°; ±2-SDs: 83.7°-95.7°) and cochlear orientation (±2-SDs: -4.0° to 3.0° anterolaterally).
Conclusions:
SSMs of temporal bone anatomy can inform surgeons on clinically relevant inter-patient variability. Anatomical variation elucidated by these models can provide novel insight into function and pathophysiology. These models also allow further investigation of anatomical variation based on age, BMI, sex, and geographical location.
Objective
Proposed methods of minimally invasive and robot-assisted procedures within the temporal bone require measurements of surgically relevant distances and angles, which often require time-consuming manual segmentation of preoperative imaging. This study aims to describe an automatic segmentation and measurement extraction pipeline of temporal bone cone-beam computed tomography (CT) scans.
Study Design
Descriptive study of temporal bone measurements.
Setting
Academic institution.
Methods
A propagation template composed of 16 temporal bone CT scans was formed with relevant anatomical structures and landmarks manually segmented. Next, 52 temporal bone CT scans were autonomously segmented using deformable registration techniques from the Advanced Normalization Tools Python package. Anatomical measurements were extracted via in-house Python algorithms. Extracted measurements were compared to ground truth values from manual segmentations.
Results
Paired t test analyses showed no statistical difference between measurements using this pipeline and ground truth measurements from manually segmented images. Mean (SD) malleus manubrium length was 4.39 (0.34) mm. Mean (SD) incus short and long processes were 2.91 (0.18) mm and 3.53 (0.38) mm, respectively. The mean (SD) maximal diameter of the incus long process was 0.74 (0.17) mm. The first and second facial nerve genus had mean (SD) angles of 68.6 (6.7) degrees and 111.1 (5.3) degrees, respectively. The facial recess had a mean (SD) span of 3.21 (0.46) mm. Mean (SD) minimum distance between the external auditory canal and tegmen was 3.79 (1.05) mm.
Conclusions
This is the first study to automatically extract relevant temporal bone anatomical measurements from CT scans using segmentation propagation. Measurements from these models can streamline preoperative planning, improve future segmentation techniques, and help develop future image-guided or robot-assisted systems for temporal bone procedures.
PurposeThe aims of this article are: (1) is there an ideal incudostapedial joint (ISJ) angle after stapedotomy? (2) is there any difference between pre- and postoperative ISJ angle? and (3) what is the significance of the ISJ angle in postoperative hearing outcomes?Methods
Forty six ears from 39 different adult patients (28 women and 11 men; 21 left and 25 right ears) with a mean age of 39 years with clinical otosclerosis who underwent stapedotomy between May 2017 and May 2019 were retrospectively registered, including seven bilateral surgery cases. ISJ angle and intravestibular depth of the stapes prosthesis were measured from multiple planar reconstruction-computed tomography images and the length of the prosthesis was measured during surgery. Relationships between the ISJ angle parameters and postoperative hearing outcomes and parameters of the prosthesis were analyzed.ResultsThe mean ISJ angle was 93.3° ± 8.8° preoperatively and 101.9° ± 6.3° postoperatively, increasing by 8.6° during stapedotomy (p < 0.01). There were weak and negative correlations between ISJ angle changes and postoperative air conduction gains at frequencies ≤1 kHz and bone conduction gains at 0.5 kHz. When the postoperative ISJ angle changed more than 20°, the success rate of the procedure decreased to 0%.Conclusion
The stapedotomy operation increased the ISJ angle. The success of postoperative auditory outcomes had more to do with the ISJ angle change than the value of the angle itself, indicating there is no universal ideal ISJ angle that surgeons should aim for during stapedotomy.
