Micro-CT study of the dehiscences of the tympanic segment of the facial canal

Endoscopic Findings on Facial Nerve Anatomy During Exclusive Endoscopic Stapedotomy: Clinical Considerations and Impact on Surgical Results

BACKGROUND

Variations along the facial nerve (FN) course present considerable challenges in the surgical treatment of otosclerosis, often complicating the procedure. Existing knowledge of its tympanic tract and its implications primarily comes from microscopical procedures. This study aims to assess endoscopic findings of FN anatomy in a healthy tympanic cavity and its impact on the stapedotomy procedure, focusing on the risk of complications and functional hearing outcomes.

METHODS

A retrospective study on exclusive endoscopic stapedotoplasties between October 2014 and October 2021 at our Otorhinolaryngology University Department was carried out. An evaluation of intraoperative endoscopic findings reviewed in surgical descriptive and/or video records was conducted to assess their potential negative impact on the surgery. Demographic data, preoperative and postoperative hearing thresholds, as well as intraoperative and postoperative complications were analyzed.

RESULTS

One hundred fifty-seven subjects were included. A FN partially overhanging the oval window was observed in 7.3% (n=12): 10 prolapsing with bony canal dehiscence and 2 without any detected dehiscence. Each procedure was successfully completed without any issues related to the anomalous anatomy, and in no case, switching to the microscope for the handling of the prosthesis near the dehiscent nerve was required. No facial paralysis occurred, with an early- or long-term postoperative House-Brackman grade of 1 (n=157, 100%). Only 3/157 patients (1.9%) showed a sensorineural threshold reduction of ≥20 dB HL, but a significant air-bone gap improvement was observed (mean closure of 18.36 dB HL, P -lt; .0001).

CONCLUSION

The endoscope promotes a concrete description of tympanic FN anatomy, and endoscopic stapes surgery appears to be a safe and viable option when dehiscent or prolapsed FNs reduce the footplate's exposure.

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.

Chronic otitis media and middle ear variants: Is there relation?

BACKGROUND

Chronic otitis media (COM) is an inflammatory disease that lasts for a long time. It is common in developing countries. Hearing loss can result from COM. The relationship between variations in middle ear anatomy and COM was investigated in our study.

AIM

To compare the prevalence of middle ear anatomic variations between the cases with COM and healthy individuals.

METHODS

This retrospective study included 500 patients with COM and 500 healthy controls. The presence of those variants was determined: Koerner’s septum, facial canal dehiscence, high jugular bulb, jugular bulb dehiscence, jugular bulb diverticulum, sigmoid sinus anterior location and deep tympanic recesses.

RESULTS

A total of 1000 temporal bones were examined. The incidences of these variants were respectively (15.4%-18.6%), (38.6%-41.2%), (18.2%-4.6%), (2.6%-1.2%), (1.2%-0%), (8.6%-0%), (0%-0%). It was observed that only high jugular bulb (P < 0.001) and anteriorly located sigmoid sinus frequencies (P = 0.002) in the case group were statistically significantly higher than the control groups.

CONCLUSION

COM is a multifactorial disease and variants of middle ear have always been important in terms of potential risk for complication during surgery but rarely associated with COM as an etiology or as a consequence of the disease. We didn't find a positive correlation between COM and Koerner’s septum and facial canal defect. We ended up with a significant conclusion with the variants of dural venous sinuses -high jugular bulb, dehiscence of jugular bulb, diverticulum of jugular bulb and anteriorly located sigmoid sinus- that have been studied less and frequently associated with inner ear illnesses.

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.

Effects of Age on Delayed Facial Palsy After Otologic Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

To report 4 cases of delayed facial palsy (DFP) after pediatric middle ear (ME) surgery and systematically review and analyze the associated literature to evaluate the effects of age on DFP etiology, management, and prognosis.

METHODS

Systematic review of PubMed, Cochrane Library, and Embase for articles related to DFP after cochlear implantation (CI) was performed. These articles were assessed for level of evidence, methodological limitations, and number of cases. Meta-analysis was performed to assess the effects of age on DFP incidence. Furthermore, a comprehensive list of all pediatric DFP cases after otologic surgery was assembled through a multi-institutional retrospective review and systematic review of the literature.

RESULTS

Twenty-nine articles fit the criteria for inclusion in the meta-analysis. The incidence of DFP after CI was 0.23% and 1.01% for pediatric and adult cases, respectively. This difference was statistically significant (P < .001, odds ratio 4.36). Twenty-three cases, adding to the 4 presented herein, were suitable for a comprehensive list. The mean age was 6.9 years. Average postoperative day of paresis onset was 5.4, with an average maximum House-Brackmann grade of 3.5. All patients obtained full facial recovery after an average of 23.5 days.

CONCLUSIONS

The systematic review demonstrates that DFP after pediatric CI is rare and occurs at a significantly lower rate than in adults, further supporting the viral reactivation hypothesis of DFP. The prognosis for pediatric DFP after otologic surgery is excellent, with a high rate of full recovery in a short time frame. However, steroid administration can be considered.

LEVEL OF EVIDENCE

IIa.

A novel view of computed tomography images similar to the visual field of otologic surgeons

OBJECTIVES

In preparation for endoscopic sinus surgery (ESS), the most important computed tomography (CT) image for otolaryngologists is the coronal plane image because it has a viewpoint similar to that of the surgical visual field. Contrastingly, otologic surgeons refer to axial and coronal plane images before ear surgery and must imagine the anatomical structure of the temporal bone by reconstructing three-dimensional (3D) images in their minds. We propose a "surgical position view (SPV) image," a novel viewpoint of CT images that enables otologic surgeons to see a perspective similar to the surgical visual field.

METHOD

Sagittal plane CT images of the temporal bone were created from axial plane images with multi-planar reconstruction (MPR). Then, the SPV image was obtained by rotating it 90° to the supine position. The entire process can be performed anywhere in the hospital within 1 minute using the electronic medical record computer's image viewer.

RESULTS

SPV images show anatomical structures of the temporal bone, external ear canal, mastoid cavity, sigmoid vein, facial nerve, ossicles, and cochlea, in a similar view to the actual ear surgery. Soft tissue such as cholesteatoma is depicted in the same concentration as the normal CT image.

CONCLUSION

The SPV image enables an otologic surgeon to see the temporal bone CT image from the actual ear surgery viewpoint simply and quickly. It helps to visualize the 3D anatomical structure of the temporal bone and can be useful for ear surgery planning.

LEVEL OF EVIDENCE

5.

Facial canal dehiscence rate: a retrospective analysis of 372 chronic otitis media cases

PURPOSE

This study aimed to investigate the rate and location of facial canal dehiscence (FCD) observed during surgery for chronic otitis media (COM) with or without cholesteatoma.

MATERIAL AND METHOD

Operative details of 1296 patients who underwent chronic otitis media surgery from January 2000 to January 2017 by the same surgeon were included in this retrospective study focusing on intraoperative observations of FCD.

RESULTS

Because of the type of the surgery, the Fallopian canal could not be seen completely, so 924 of the cases which only involved performing a tympanoplasty were not included in the study. A total of 372 patients (196 males and 176 females) who had a canal wall down (CWD) or canal wall up (CWU) mastoidectomy were included in the study. A CWD mastoidectomy was performed on 250 patients, while 122 patients underwent a CWU mastoidectomy. The prevalence of FCD was 11.29% (42/372 patients). The dehiscence was more common in patients with cholesteatoma (n = 37; 88.1%) than those with non-cholesteatoma (n = 5; 11.9%). The tympanic segment (n = 32; 76.19%) was the most common location for FCD. When we compared the ossicular erosion results of the cases that had FCD, erosion in three ossicles together was more statistically significantly frequent than the other possibilities.

CONCLUSION

It is possible to see FCD because of COM, especially with cholesteatoma. FCD is most commonly seen around the oval window. If stapes or all three ossicles are eroded, the surgeons must be more careful regarding FCD to be more effective in preventing facial nerve damage.