Prevalence of facial canal dehiscence and other bone defects by computed tomography

An evaluation of morphometry and dehiscence of facial canal: a systematic review and meta-analysis of observational studies

INTRODUCTION

The facial canal (FC) is an extensive bony canal that houses the facial nerve and occupies a central position in the petrous part of temporal bone. It is of utmost significance to otologists due to its dehiscence and relationship to the inner or middle ear components. The main objectives of current investigation are to detect variations in the reported values ​​of FC anatomy that may occur due to different methodology and to elucidate the influence of age and ethnic factors on the morphological features of FC.

METHODS

The methodology is adapted to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled weighted estimation was performed to calculate the mean length, angle, and prevalence of dehiscence.

RESULTS

The cross-sectional shape of FC varied from circular to ellipsoid index and is 1.45 [95% CI, 0.86-2.6]. The mean length of the FC is 34.42 mm [95% CI, 27.62-40.13 mm] and the mean width or diameter is 1.35 mm [95% CI, 1.013-1.63 mm]. The length of the FC in fetuses and children is 21.79 mm [95% CI, 18.44-25.15 mm], and 26.92 mm [95% CI, 23.3-28.3 mm], respectively. In meta-regression, age is observed as a predictor and accounts for 36% of the heterogeneity. The prevalence of FC dehiscence in healthy temporal bones is 29% [95% CI, 20-40%].

CONCLUSION

The different segments of the FC exhibit significant variability and an unusually high incidence of dehiscence, which could potentially have clinical implications for the etiopathogenesis of facial nerve dysfunction.

Developing a production workflow for 3D-printed temporal bone surgical simulators

INTRODUCTION

3D-printed temporal bone models enable the training and rehearsal of complex otological procedures. To date, there has been no consolidation of the literature regarding the developmental process of 3D-printed temporal bone models. A brief review of the current literature shows that many of the key surgical landmarks of the temporal bone are poorly represented in models. This study aims to propose a novel design and production workflow to produce high-fidelity 3D-printed temporal bone models for surgical simulation.

METHODS

Developmental phases for data extraction, 3D segmentation and Computer Aided Design (CAD), and fabrication are outlined. The design and fabrication considerations for key anatomical regions, such as the mastoid air cells and course of the facial nerve, are expounded on with the associated strategy and design methods employed. To validate the model, radiological measurements were compared and a senior otolaryngologist performed various surgical procedures on the model.

RESULTS

Measurements between the original scans and scans of the model demonstrate sub-millimetre accuracy of the model. Assessment by the senior otologist found that the model was satisfactory in simulating multiple surgical procedures.

CONCLUSION

This study offers a systematic method for creating accurate 3D-printed temporal bone models for surgical training. Results show high accuracy and effectiveness in simulating surgical procedures, promising improved training and patient outcomes.

Exploring Prevalence Trends of Jaw Bone Pathologies: A Three-Year Institutional Study

Background Head and neck bone pathologies cover various conditions with diverse causes. Infections like osteomyelitis and dental abscesses can spread to soft tissues and bones, causing tissue death, inflammation, and systemic effects. Benign and malignant tumors can develop from soft tissue, cartilage, or bone, posing challenges for diagnosis and treatment. Studies on their prevalence in local populations are rare, obscuring our understanding of regional health dynamics. Aim In this study, we aimed to assess the prevalence of bone pathologies documented over the last three years from 2021 to 2023. Materials and methods Histopathologically confirmed cases of bone pathologies at Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, India, were gathered from the institutional database (DIAS: Dental Information Archiving Software) from January 1, 2021, to December 31, 2023. They were categorized into groups of infectious and inflammatory lesions, fibro-osseous lesions, malignancies originating from bone, malignancies invading bone, and miscellaneous conditions. The data was then compiled into a Google spreadsheet (Google, Inc., Mountain View, USA) for further analysis. Graphs were created to visualize the prevalence of bone pathologies enabling a descriptive exploration of temporal trends. Results A total of 2626 biopsy records were reviewed. Among these, 242 (9.21%) cases of bone-related pathologies were included, and the remaining 2384 (90.79%) entities without any mention of bone were excluded. Overall, considering all three years, 43.8% (100) bone-related lesions were reported in 2021, 30.3% (77) in 2022 and 25.9% (65) in the year 2023. Under each category, infectious and inflammatory lesions for 40.5% (98), fibro-osseous lesions for 14.9% (36), benign lesions for 2.9% (7), malignancies originating from bone for 1.7% (4), malignancies invading bone for 38% (93), and miscellaneous conditions for 1.65% (4) were reported. The highest number of infectious and inflammatory pathologies (53%) were reported in 2021. A steep fall was observed in 2022 and 2023 under the infectious and inflammatory category. The malignancies invading the bone showed almost similar distribution in all three years. Conclusion The observed variations highlight the unpredictability of bone pathologies, involving the jaw bones. We emphasize continuous observation and analysis to comprehend changing patterns in bone health.

An exploratory study of imaging diagnostic clues for overhanging facial nerve in ultra-high-resolution CT

PURPOSE

Overhanging facial nerve (FN) may be challenging in imaging diagnosis. The purpose of the study is to investigate the imaging clues for overhanging FN near the oval window on ultra-high-resolution computed tomography (U-HRCT) images.

METHODS

Between October 2020 and August 2021, images of 325 ears (276 patients) were included in the analysis obtained by an experimental U-HRCT scanner. On standard reformatted images, the morphology of FN was evaluated and its position was quantitatively measured using the following indices: protrusion ratio (PR), protruding angle (A), position of FN (P-FN), distance between FN and stapes (D-S), and distance between FN and anterior and posterior crura of stapes (D-AC and D-PC). According to the FN morphology in imaging, images were divided into overhanging FN group and non-overhanging FN group. Binary univariate logistic regression analysis was used to identify the imaging indices independently associated with overhanging FN.

RESULTS

Overhanging FN was found in 66 ears (20.3%), which manifested as downwards protrusion of either local segment (61 ears, 61/66) or the entire course near the oval window (5 ears, 5/66). D-AC [odds ratio: 0.063, 95% CI 0.012-0.334, P = 0.001) and D-PC (odds ratio: 0.008, 95% CI 0.001-0.050, P = 0.000) were identified as independent predictors of FN overhang (area under the curve: 0.828 and 0.865, respectively).

CONCLUSION

Abnormal morphology of the lower margin of FN, D-AC and D-PC on U-HRCT images provide valuable diagnostic clues for FN overhang.

A novel imaging scoring method for identifying facial canal dehiscence: an ultra-high-resolution CT study

OBJECTIVES

Facial canal dehiscence (FCD), typically found in the tympanic segment, is a risk factor for facial nerve injury. An imaging scoring method was proposed to identify FCD based on ultra-high-resolution CT.

METHODS

Forty patients (21 females and 19 males, mean age 44.3 ± 17.4 years), whose tympanic facial canal (FC) was examined during otological surgery, were divided into the FCD group (n = 29) and the control group (n = 11) based on surgical findings. Imaging appearance of tympanic FC was scored 0-3: 0 = no evident bony covering, 1 = discontinuous bony covering with linear deficiency, 2 = discontinuous bony covering with dotted deficiency, and 3 = continuous bony covering. Both lateral and inferior walls were assigned a score as L_FCD and I_FCD, respectively. An FCD score was calculated as L_FCD + I_FCD. The diagnostic value of the FCD score was tested using the ROC curve.

RESULTS

The inter-observer agreement was moderate for the lateral wall (Cohen's κ coefficient 0.416, 95% CI 0.193-0.639), and good for the inferior wall (Cohen's κ coefficient 0.702, 95% CI 0.516-0.888). In the FCD group, the most common appearance for both walls was discontinuous bony covering with linear deficiency (L_FCD = 1, 22/29, 75.9%; I_FCD = 1, 15/29, 51.7%). An FCD score of less than 4 was associated with high sensitivity (0.82) and specificity (0.93) for identifying FCD, with an AUC of 0.928.

CONCLUSIONS

Using the proposed scoring method, FCD score < 4 could identify FCD of the tympanic segment with high concordance with surgical findings.

KEY POINTS

• Imaging appearance of the tympanic facial canal (FC) is divided into four types based on ultra-high-resolution CT images. • The most common appearance of FC with facial canal dehiscence (FCD) is discontinuous bony covering with linear deficiency. • An FCD score, consisting of scores of the lateral and inferior walls, less than 4 is highly indicative of FCD.

DHI Increases the Proliferation and Migration of Schwann Cells Through the PI3K/AKT Pathway and the Expression of CXCL12 and GDNF to Promote Facial Nerve Function Repair

The facial nerve is one of the vulnerable nerves in otolaryngology. Repair and recovery of facial nerve injury have a high priority in clinical practice. The proliferation and migration of Schwann cells are considered of great significance in the process of nerve injury repair. Danhong injection (DHI), as a common drug for cardiovascular and cerebrovascular diseases, has been fully certified in neuroprotection research, but its role in facial nerve injury is still not clear. Our study found that DHI can promote the proliferation and migration of RSC96 cells, a Schwann cell line, and this effect is related to the activation of the PI3K/AKT pathway. LY294002, an inhibitor of PI3K, inhibits the proliferation and migration of RSC96 cells. Further studies have found that DHI can also promote the expression of CXCL12 and GDNF at gene and protein levels, and CXCL12 is, while GDNF is not, PI3K/AKT pathway-dependent. Animal experiments also confirmed that DHI could promote CXCL12 and GDNF expression and promote facial nerve function recovery and myelin regeneration. In conclusion, our in vitro and in vivo experiments demonstrated that DHI could promote the proliferation and migration of Schwann cells through the PI3K/AKT pathway and increase the expression of CXCL12 and GDNF to promote facial nerve function repair.