Analysis of tympanic sinus shape for purposes of intraoperative hearing monitoring: a microCT study

Purpose Sinus tympani is the space in the retrotympanum, with variable morphology. Computed tomography is a common tool to investigate sinus tympani anatomy. During cochlear implantation or tympanoplasty, electrocochleography can be used for hearing monitoring. In such a surgical strategy the electrode is placed in the round window’s region throughout posterior tympanotomy. Common accessible needle-shaped electrodes using is difficult in achieving intraoperative stabilization. The aim of the study is to assess the dimensions and shape of sinus tympani, basing on the micro computed tomography scans for purposes of establishing the possible new electrocochleography electrode shape. Materials and methods Sixteen fresh frozen cadaveric temporal bones were dissected. MicroCT measurements included the depth and the width of sinus tympani, width of facial canal with stapedius muscle chamber. Obtained data were analyzed statistically with the use of RStudio 1.3.959 software. Results The highest average width of sinus tympani amounted for 2.68 mm, depth measured at the round window plane for 3.19 mm. Width of facial canal with stapedius muscle chamber highest average values at the round window plane- 3.32 mm. The lowest average minimum and maximum values were calculated at the 1 mm above the round window plane. The highest average posterior tympanotomy width was 2.91 mm. Conclusions The shape of the tympanic sinus is like a trough with the narrowest and deepest dimensions in the middle part. The ST shape and dimensions should be taken into account in constructing the ECochG electrode, designed for optimal placement through posterior tympanotomy approach.

“Cone Beam Imaging of Cochlear Implants “

Objectives to assess the role of Cone Beam CT (CBCT) in the postoperative cochlear implant (CI) imaging in determining details about the electrode position, insertion depth, angle and other fine anatomical details. Methods This retrospective study included 32 patients (34 ears) with post-CI CBCT imaging. All images were anonymized and reviewed by two experienced head and neck radiologists in consensus for the measurements of the implant insertion depth, facial canal (vertical part) diameter, wall thickness and distance between it and the electrode cable, then assessment of the quality of visualization of fine structures as the facial nerve canal, chorda tympani, separate electrode contacts and scalar position of electrodes were done using 4-point scale. Results The insertion angles for the electrodes were measured in all the ears with a mean ± SD = 430.24 ± 121.43, the facial canal diameters were measured in 97.1% (33 ears) with a mean ± SD = 1.54 ± 0.33, the facial wall thickness was measured in 79.4% (27 ears) with a mean ± SD = 0.62 ± 0.32, the facial canalelectrode cable distances were measured in 97.1% (33 ears) with a mean ± SD = 1.64 ± 0.50 and the chorda tympani was visualized in 88.2% (30 ears). Perfect visualization of the scalar position of electrodes were encountered in 76.5% (26 ears), separate electrode contacts in 20.6% (7 ears), facial canal in 35.3% (12 ears), facial canal wall in 26.5% (9 ears), and chorda tympani in 41.2% (14 ears). Conclusion CBCT is a valuable tool in the postoperative assessment of cochlear implants

Postoperative radiological assessment of the mastoid facial canal in cochlear implant patients in correlation with facial nerve stimulation

Objectives To correlate the radiological assessment of the mastoid facial canal in postoperative cochlear implant (CI) cone-beam CT (CBCT) and other possible contributing clinical or implant-related factors with postoperative facial nerve stimulation (FNS) occurrence. Methods Two experienced radiologists evaluated retrospectively 215 postoperative post-CI CBCT examinations. The mastoid facial canal diameter, wall thickness, distance between the electrode cable and mastoid facial canal, and facial-chorda tympani angle were assessed. Additionally, the intracochlear position and the insertion angle and depth of electrodes were evaluated. Clinical data were analyzed for postoperative FNS within 1.5-year follow-up, CI type, onset, and causes for hearing loss such as otosclerosis, meningitis, and history of previous ear surgeries. Postoperative FNS was correlated with the measurements and clinical data using logistic regression. Results Within the study population (mean age: 56 ± 18 years), ten patients presented with FNS. The correlations between FNS and facial canal diameter (p = 0.09), wall thickness (p = 0.27), distance to CI cable (p = 0.44), and angle with chorda tympani (p = 0.75) were statistically non-significant. There were statistical significances for previous history of meningitis/encephalitis (p = 0.001), extracochlear-electrode-contacts (p = 0.002), scala-vestibuli position (p = 0.02), younger patients’ age (p = 0.03), lateral-wall-electrode type (p = 0.04), and early/childhood onset hearing loss (p = 0.04). Histories of meningitis/encephalitis and extracochlear-electrode-contacts were included in the first two steps of the multivariate logistic regression. Conclusion The mastoid-facial canal radiological assessment and the positional relationship with the CI electrode provide no predictor of postoperative FNS. Histories of meningitis/encephalitis and extracochlear-electrode-contacts are important risk factors. Key Points • Post-operative radiological assessment of the mastoid facial canal and the positional relationship with the CI electrode provide no predictor of post-cochlear implant facial nerve stimulation. • Radiological detection of extracochlear electrode contacts and the previous clinical history of meningitis/encephalitis are two important risk factors for postoperative facial nerve stimulation in cochlear implant patients. • The presence of scala vestibuli electrode insertion as well as the lateral wall electrode type, the younger patient’s age, and early onset of SNHL can play important role in the prediction of post-cochlear implant facial nerve stimulation.

Clinicoradiological correlation between preoperative high-resolution computed tomography findings and intraoperative findings in chronic otitis media (squamous type)

<p class="abstract"><strong>Background:</strong> Chronic otitis media is a major health problem with significant morbidity. High-resolution computed tomography (HRCT) is extremely useful for middle ear pathology and extension of the disease. The objective was to study the correlation between preoperative HRCT and intraoperative findings in chronic suppurative otitis media (squamous type).</p><p class="abstract"><strong>Methods:</strong> This analytical study included 61 cases of chronic otitis media (squamous type). Preoperative HRCT findings were correlated with intraoperative findings. Sensitivity, specificity, PPV, NPV and kappa value were estimated.</p><p class="abstract"><strong>Results:</strong> Out of 61 cases 32 were males and 29 were females. Presence of cholesteatoma found on HRCT with 80% sensitivity with k value 0.83 suggesting very good agreement. About ossicular status k value of incus, malleus and stapes were 0.76, 0.65 and 0.54 respectively with sensitivity of 91%, 85% and 58% respectively. Other critical areas on HRCT like sigmoid sinus plate erosion, tegmen tympani dehiscence, scutum erosion, lateral semicircular canal erosion, facial canal erosion and jugular bulb were seen with k value was about 1, 0.8, 0.9, 0.82, 0.72 and 0.65 respectively. So, HRCT shows perfect radiosurgical agreement for sinus plate erosion, very good agreement for disease extension, incus erosion, tegmen tympani erosion, scutum erosion and LSCC erosion and fair agreement for malleus erosion, facial canal erosion and jugular bulb dehiscence and poor agreement for stapes erosion.</p><p class="abstract"><strong>Conclusions:</strong> HRCT is a reliable preoperative investigation in cases of chronic otitis media, squamosal type which would provide a bird’s eye view in the disease process in the ear.</p>

Diagnostic efficacy of high-resolution computed tomography findings in patients of chronic suppurative otitis media atticoantral type

<p><strong>Background: </strong>High resolution computed tomography (HRCT) provides information about anatomy and pathology of temporal bone and middle ear cleft, thus becoming important imaging modality in diagnosis and pre-operative planning in patients of chronic suppurative otitis media (attico-antral) CSOM (AA) type. The aim of study was to study disease extension and plan surgery accordingly in patients of CSOM (AA) and to study correlation between the HRCT findings and intra-operative findings of CSOM (AA) like soft tissue density mass, ossicular chain erosion, facial canal dehiscence, semi-circular canal erosion.</p><p><strong>Methods: </strong>Study of 70 patients clinically diagnosed of having CSOM (AA) in period between August 2018 to March 2020 was done at Sola civil hospital, Ahmedabad. All patients were advised HRCT temporal bone except those who had contraindications to CT scan, analysed and operated. Pre-operative CT-scan findings and intra-operative findings were compared for statistical analysis.</p><p><strong>Results: </strong>Soft tissue density was found in 100% of cases on HRCT temporal bone. Bony erosion seen in 25% of cases. 90% showed ossicular erosion. Lateral semi-circular canal fistula was observed in 10% of cases with facial canal dehiscence in 10% of cases. Intra-operative findings showed accuracy of HRCT in detecting soft tissue density to be 100%; bony erosion was observed in 25% cases. 10% patients had lateral semi-circular canal fistula. Facial canal dehiscence was seen in 15% cases.</p><strong>Conclusion: </strong>HRCT has proved quite useful and reliable to identify the disease extension before surgery and plan surgery accordingly.<p> </p>

Relationship Between Ossicular Chain Erosion and Facial Canal Dehiscence in Chronic Otitis Media Squamous

Introduction Chronic otitis media squamous is a gradually expanding destructive lesion and leads to complications by eroding the adjacent structures. Facial canal and ossicles are in close proximity in the middle ear space and they share the same pathogenesis of the bony erosion. Ossicular chain erosion found intraoperatively due to cholesteatoma, may suggest the likelihood of facial canal dehiscence. This study was conducted to assess the relationship between ossicular chain erosion and facial canal dehiscence in chronic otitis media squamous. MethodsIt is a retrospective chart review of patients who had mastoidectomy done for chronic otitis media squamous in Tribhuvan University Teaching Hospital from January 2014 to December 2018. The operative findings of facial canal dehiscence were correlated with ossicular chain status. ResultsAmong 158 cases, facial canal dehiscence was seen in 20 (12.7%), of which, 19/20 (95%) had ossicular erosion. Majority (90%) of dehiscence was in the horizontal segment. Incus was the most common ossicle to be eroded. Among the ossicles, stapes erosion was related to the facial canal dehiscence with odds ratio of 3.216 (1.235-8.374) and p-value 0.03. ConclusionAmong the ossicles, there is a relationship between the stapes erosion and the facial canal dehiscence in chronic otitis squamous. Erosion of ossicular chain especially stapes should alert surgeons towards the possibility of facial canal dehiscence.

Localization of Facial Nerve Canal and Therapeutic Effect of Acupuncture and Moxibustion at Hegu Point in Patients with Nerve Palsy Under Magnetic Resonance Computerized Tomography Scan

In order to study the condition of facial nerve bone canal in patients with nerve palsy and the therapeutic effect of acupuncture Hegu point therapy on patients with facial palsy, in this study, 70 patients with bell facial paralysis who were admitted to Beijing Friendship Hospital on July 30, 2018 solstice and July 30, 2019 were selected. The patients were randomly divided into a control group (CG) (n = 35) and an experimental group (EG) (n = 35). The EG received acupuncture and acupoint Hegu treatment, while the CG received conventional drug treatment. Magnetic Resonance Computerized Tomography (MRCT) image combined with multiplanar reconstruction (MPR) facial nerve tube measurement technique was used to detect genu ganglion segment, nerve labyrinth segment and tympanic compartment of bell facial paralysis patients in the EG. Patients in both groups were evaluated by House-Brackmann scale, Sunnybrook Facial Grading System (SFGS) scale, and Degree of facial Nerve Paralysis (DFNP). Finally, Logistic Regression Model (LRM) was used to analyze the factors influencing the treatment effect of bell facial paralysis patients. The results showed that the inner diameter of genu ganglion segment, labyrinth segment and tympanum segment of the EG was greatly smaller than that of the normal side, and the difference between the data was statistically significant (SS) (P < 0.05). After treatment, the House-Brackmann, SFGS and DFNP scores of patients in the two groups were greatly higher than before treatment, and the differences were SS (P < 0.05). After treatment, the scores of House-Brackmann, SFGS, and DFNP in the EG were greatly higher than those in the CG, and the differences were SS (P < 0.05). The analysis results of LRM indicated that DFNP score was negatively related to age and disease course (P < 0.05), and positively related to the neural labyrinth segment of the patient’s side (P < 0.05). MPR facial canal measurement technique based on MRCT can directly reflect the facial canal paralysis in patients with facial paralysis. Acupuncture at Hegu point can effectively improve facial nerve palsy and other symptoms in patients with facial paralysis of bell in clinic and the recovery effect may also be affected by the age of the patient and the course of the disease.