Facial Canal Dehiscence Research Articles

Role of High Resolution Computed Tomography of Temporal Bone in Patients with Cholesteatoma, in a Tertiary Care Health Center.

The aim of this study is to evaluate the necessity of high resolution computed tomography (HRCT) temporal bone in patients with active squamosal chronic otitis media, by comparing the preoperative HRCT temporal bone findings with intra operative findings in a tertiary care health center where patient load is tremendous.This study was conducted in the department of otorhinolaryngology, over a period of two years from November 2017 to November 2019 in which 100 patients with active squamosal chronic otitis media diagnosed clinically were taken. All patients underwent preoperative HRCT temporal bone and subsequent tympanomastoidectomy.The results of HRCT temporal bone of all the patients were evaluated and correlated with intraoperative findings which revealed that HRCT is highly sensitive for detecting,soft tissue extension, tympanic membrane perforation, ossicular erosion, tegmen erosion, sigmoid sinus erosion, facial canal dehiscence and lateral semicircular canal fistula, which helps in guiding the surgical approach and treatment plan preoperatively.

Role of HRCT Temporal Bone in Diagnosis of Chronic Suppurative Otitis Media in Correlation with Intraoperative Findings

This study aims to evaluate the role of preoperative HRCT temporal bone in the diagnosis of the disease, itsextension and complications and plan for surgery. The involved structures and also in knowing prognosisis compared with Intraoperative findings made by the surgeon to know its precision in diagnosis. It alsohelps in diagnosing intracranial complications of CSOM at an early stage and help to plan surgery. Patientspresenting/Suspected to have CSOM who were planned for mastoid exploration surgery in Departmentof ENT, within a period of 2 years–from February 2019 to September 2020, were taken up for study. Thepatient will undergo HRCT temporal bone with Aquilon 160 slice CT scanner producing sub millimetric thinaxial scans Following areas of interest were looked up in preoperative scans:-• Pneumatization of mastoid • Extent of disease• Tegmen tympani erosion • Sinus plate erosion• Facial canal dehiscence • Lateral semicircular canal dehiscence• Ossicular status • Disease outside middle ear cleftOut of total 30 patients of CSOM, 26 (52%) were males. Majority of the patients (70%) were in the agegroup of 11 to 30 years. Left ear was involved in 40% of the patients. Majority of the patients (80%)presented with chief complaints of otorrhoea. In the present study, External Auditory Canal (EAC) was seennormal in majority of patients (82%) both radio logically and per operatively. HRCT scan was found to behighly sensitive (100%) in diagnosing cholesteatoma. CT scans diagnosed erosion of malleus with 100%sensitivity and specificity and erosion of incus with 91% sensitivity and 100% specificity.HRCT has a veryhigh reliability for diagnosis of erosion of scutum, erosion of ossicles and its disruption, Pneumatization ofmastoid, anterior lying sigmoid, extent of cholesteatoma in the middle ear and MAC. The study concludesthat HRCT can be recommended not just for symptomatic cases but in all suspected cases in knowing theextent of the disease thereby reducing the morbidity.

Paediatric acquired cholesteatoma, our experience in a tertiary care: two year prospective study

<p><strong>Background:</strong> Aim of the study was to estimate the benefits of having high-resolution computed tomography (HRCT) of temporal bone on clinically evaluated paediatric patients of acquired cholesteatoma.</p><p><strong>Methods:</strong> A total of 60 patients of paediatric age group (2-18 years) who were diagnosed with active squamosal type of chronic otitis media were selected for the study. HRCT of temporal bone was done in all the patients and findings were recorded.</p><p><strong>Results:</strong> Most patients were in the age group of 11-15 years (46.6%). Findings of pars tensa were subtotal perforation in 2 patients (3.3%), small central perforation in 8 patients (13.3%) and postero-superior marginal perforation in 12 patients (20%). Pars flaccida retraction pocket with cholesteatoma was seen in 31 patients (51.6%) and perforation with cholesteatoma in 13 patients (21.6%). Scutum erosion was seen in 31 patients (51.6%), ossicular erosion in 12 patients (20%) and facial nerve paralysis in 2 patients (3.3%). On HRCT temporal bone we found soft tissue density in middle ear in 60 patients (100%), soft tissue density in mastoid in 53patients (88.3%), osscicular erosion in 54 patients (90%), scutum erosion in 46 patients (76.6%), facial nerve canal dehiscence in 5 patients (8.3%), semicircular canal dehiscence in 2 patients (3.3%) and dural plate dehiscence in 11 patients (18.3%).</p><p><strong>Conclusions:</strong> HRCT of temporal bone is helpful in depicting a clearer picture of middle ear cavity structures involved by cholesteatoma and thus helpful in formulating a strategy for further management.</p>

Facial Nerve Dehiscence and Cholesteatoma: A Comparison between Decades.

To evaluate the incidence of facial canal dehiscence (FCD) and other intraoperative findings over the last 20 years as well as correlation with the Japanese Otological Society/European Academy of Otology and Neurotology classification in patients with cholesteatoma. A total of 469 patients operated from 1998 to 2018 were selected and divided into 2 groups of 10 years each. Dehiscence was significantly higher in patients with a history of pathology longer than 5 years (22.7%). Higher values were observed in revision surgery, 44.4% in the first period and 41.7% in the second. The tympanic segment was the one most frequently involved, affecting 92% of patients in the first period and 97% of patients in the second. Dehiscence occurred significantly more often in patients with a semicircular canal fistula, 14.8% in the first decade and 8.8% in the second. The incidence of FCD was significantly higher in patients with primary cholesteatoma (especially in those with combined pars tensa-flaccida) than in those with a secondary acquired one, 31.5% vs 7.4% in the first period, 21.1% vs 7.4% in the second, and in those with a stage III disease, 42% in the first period, 33.3% in the second. Patients with a shorter history of cholesteatoma as well as those not previously operated had a lower incidence of FCD. The tympanic tract of the facial nerve remains the most frequent site of dehiscence, while the association between dehiscence and fistula of the semicircular canal remains strong. Patients with combined pars tensa-pars flaccida and stage III cholesteatoma have a higher incidence of FCD.

Recurrent transient facial nerve palsy on commercial air flights

IntroductionFacial baroparesis is a rare event, usually associated with a favourable outcome. It is related to atmospheric pressure changes that are responsible for neuropraxia. Most cases of facial baroparesis have been reported in the context of underwater diving, but very few cases have been reported during commercial flights. Case reportWe report the case of a patient who experienced several episodes of spontaneously resolving left facial palsy during long-haul flights. The work-up revealed bilateral facial nerve canal dehiscence visible on CT scan and clinical features of bilateral otitis media with effusion associated with hearing loss. DiscussionThe pathogenesis of this disease involves the combination of these two elements inducing ischaemia of the exposed facial nerve submitted to pressure variations. In most cases, ischaemia is rapidly reversible with complete recovery after landing or in response to Valsalva manoeuvres. It is therefore important not to miss this entity to avoid delayed or inappropriate management.

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.

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. Methods: It 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. Results: Among 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. Conclusion: Among 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.

Facial nerve dehiscence and cholesteatoma: Pediatrics vs adults

Objectivesthe aim of this paper is to study the incidence of facial canal dehiscence (FCD) in pediatric and non-pediatric patients, analyzing eventual differences in frequency, localization, primary or revision surgery and duration of the disease. Methods527 patients suffering from chronic otitis media with acquired cholesteatoma, divided into two groups, those aged 18 years or over (470 patients), and those aged below 18 years (57 patients). ResultsTotal incidence of FCD in adult population was 25,7% (121/470) and 7% (4/57) in pediatric one. Globally higher values were found in revision surgery, 43,5% (40/92) in adults and 16,7% (1/7) in children. Diseases longer than 5 years have been correlated to higher incidence of FCD in adults, 29,9% (109/364), than in pediatrics, 7,3% (3/41). No statistical significant difference has been found in those with a disease shorter than 5 years: 11,3% in adults (12/106) and 6,2% in children (1/16). The majority of patients, both adults and pediatrics, had a dehiscence in the tympanic tract of facial nerve. No statistical correlation regarding concomitant semicircular canal fistula and FCD has been found due to the absence of data in children. ConclusionsIncidence of FCD is higher in adult population than in pediatric. Adults have a higher incidence in primary surgery than children. No statistical significant difference has been found in adults and pediatrics with a less than 5 years disease, while diseases longer than 5 years expose adults to higher risk of FCD. Middle tract of tympanic segment is the most involved site of dehiscence in both populations.

Correlation of Preoperative High-resolution Computed Tomography Temporal Bone Findings with Intra-operative Findings in Various Ear Pathologies.

High resolution computed tomography (HRCT) is a tool which provide fine details of temporal bone and its associated pathologies which are of extreme use in making diagnosis, to evaluate extension of disease and most important to plan surgical approach. Aim of the present study was to correlate HRCT findings with operative findings in different ear pathologies. This observational, prospective study enrolled 70 patients of different ear pathologies required surgical intervention. They were subjected to HRCT temporal bone and its findings were correlated with surgical findings. Mean age of the study population was 20.3 ± 12.04years with M: F = 1.12: 1. HRCT showed specificity and sensitivity of 100% and 92.31% respectively in detecting ossicular erosion. It was 100% sensitive and 98.51% specific in detecting LSCC erosion, 85.71% sensitive and 96.83% specific in detecting facial canal dehiscence, 100% sensitive and 98.11% specific in detecting scutum erosion, 75% sensitive and 96.97% specific to detect tegmen erosion, 100% sensitive and 97.01% specific in detecting sinus plate erosion, 100% sensitive and 95.38% specific in detecting high jugular bulb, sensitivity and specificity both are 100% in detecting labyrinthitis ossificans and 100% sensitive in detecting otosclerotic foci. HRCT findings showed a good association with operative findings in terms of sensitivity and specificity. Thus, HRCT is a acceptable tool to make diagnosis and to plan surgical approach.

Sensitivity and Specificity of High-Resolution Computed Tomography (HRCT) of Temporal Bone in Diagnosing Cholesteatoma and Its Correlation with Intraoperative Findings.

High resolution computed tomography (HRCT) of temporal bone helps in understanding the complex anatomy of temporal bone and in identifying disease in temporal bone. However, its role in diagnosing cholesteatoma and analyzing its extent and complications is not established unequivocally. Present study was undertaken to check sensitivity and specificity of HRCT in diagnosing cholesteatoma and assessing its extent and in identifying ossicular destruction and other complications. In this prospective study in 50 patients with clinical diagnosis of cholesteatoma, preoperative high-resolution temporal bone CT scans axial and coronal view were carried out and compared with intra-operative findings. Kappa statistics was used for radio-surgical correlation. Comparison of CT scan findings with intraoperative findings revealed perfect correlation for sigmoid plate erosion, mastoid cortex dehiscence and scutum erosion, strong correlation for erosion of malleus, posterior superior wall and peri labyrinthine cells, good for erosion of incus and stapes, labyrinthine fistula, tegmen erosion and extent of disease and moderate correlation for facial canal dehiscence. HRCT scan of the temporal bone is useful preoperative investigation for cholesteatoma surgery for identification and documentation of ossicular status, location and extent of disease, erosion of tegmen or sinus or labyrinthine dehiscence, with the exception of facial canal dehiscence. Although it serves as road map for surgery, it still has some false positives and false negatives and the importance of a skilful, aware and alert surgeon cannot be overemphasized.

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

The facial nerve is the most vulnerable structure during otological surgeries. Facial canal dehiscence (FCD) is the main risk factor for iatrogenic injuries. Its prevalence in clinical studies ranges between 6 and 33.3%, while anatomical studies report 25-57%. The objective was to determine the prevalence of FCD stratified by age and gender in a healthy population. Temporal bones from high-resolution computed tomography (CT) were analyzed. Patients with a history of trauma or tumors of the temporal bone, cholesteatomas, chronic middle ear disease, and any pathology that could modify the bone's anatomy, were excluded. A total of 184 temporal bones were included. FCD was observed in 94 (51.2%) of the analyzed bones. The tympanic portion was the most frequently affected site with 91 (49.5%), followed by the mastoid segment with 3 (1.6%). No dehiscence was found in the labyrinth portion. We observed 30 (31.9%) of the FCD involved the oval window. Other bone defects identified with the FCD included: 11 (11.7%) with a lateral semicircular canal fistula and 7 (7.4%) with tegmen tympani erosions. FCD has a high prevalence among healthy patients. A pre-surgical otological evaluation using high-resolution CT should be indicated to properly assess the patient and reduce the risk of injury.

Does Mastoid Pneumatization Affect Facial Canal Dimensions and Distances of Facial Tympanic Segment-Scutum and Lateral Semicircular Canal-Scutum?

In the present study, we investigated whether mastoid pneumatization affects facial canal dimensions and distances of facial tympanic segment and scutum, and lateral semicircular (LSS) canal and scutum. One hundred sixty-one temporal multidetector computed tomography scans were reviewed. Patients with unilateral sclerotic mastoid pneumatization (no aeration) (group 1, n = 81) and unilateral total mastoid pneumatization (100.0% aeration) (group 2, n = 80) were included. Facial canal dimensions at the labrythine, tympanic, and mastoid segments; facial canal dehiscence and length; and facial tympanic segment-scutum and LSS canal-scutum distances were evaluated. In the present study, facial canal dimensions of labyrinthine, tympanic, and mastoid segments in total pneumatized mastoid group were significantly lower than sclerotic mastoids on axial and coronal images (P < 0.05). Facial tympanic segment and scutum distance of the sclerotic mastoid group was significantly lower than those of the total pneumatized mastoid group (P < 0.05). However, LSS canal-scutum distance was not different between both groups (P > 0.05). The LSS canal-scutum distance of the females was lower than those of the males (P < 0.05). Facial canal dehiscence ratio was 11.3% and 11.1% in sclerotic and total pneumatized mastoids, respectively. The mean ± SD length of the dehiscence was 2.46 ± 1.29 mm in pneumatized mastoids and 1.92 ± 0.68 mm in sclerotic mastoids. In cholesteatoma cases, scutum erosion may occur. Because facial tympanic segment and scutum distance decreased in sclerotic mastoids compared with completely pneumatized ones, maximum care must be taken in the operations for avoiding to damage facial canal and nerve. Revision cases may be more difficult because of distorted anatomy. However, in pneumatized mastoids, the mean length of the facial canal was more than 2 mm, which must be kept in mind during operations.

Correlation of intraoperative and HRCT of temporal bone findings in CSOM

Introduction: The aim of the study was to assess diagnostic role of High Resolution Multi-detector Computed Tomography (HRMDCT) of temporal bone in the evaluation of Chronic Suppurative Otitis Media (CSOM) and to correlate intraoperative and HRCT findings in CSOM in selective cases. Material and Methods: 57 patients presented with CSOM in ENT department, referred to Radio diagnosis department were included in this study. The suspected patients were subjected to HRCT of Temporal bone using GE Bright speed Elite16 multi slice CT machine with 0.6mm plain axial and coronal slices with multi planar reformations. Results: The reported findings were correlated with clinical and surgical findings in subset of cases. Sensitivity, Specificity of HRMDCT with respect to clinical and surgical correlation in selective cases was evaluated. Among 30 surgical cases, most of them were atticoantral (53.4%) followed by tubotympanic CSOM (46.6%). On surgical correlation, HRCT has a high sensitivity (84.36%), specificity (80%), PPV of 90.4% and accuracy of 90% in the diagnosis of type of CSOM. A significant association with p value Conclusion: a good sensitivity, specificity of HRCT of temporal bone has a major role in the diagnosis of type of CSOM with respect to surgical correlation. HRCT of Temporal bone affords essential information regarding the disease extent, associated complications, aiding clinicians in deciding the appropriate surgical planning and management, thereby making HRMDCT an essential pre workup diagnostic tool. Keywords: Temporal bone, Cholesteatoma, HRCT, Facial canal dehiscence.

Cautionary High-resolution Computed Tomography Findings for the Presence of Facial Canal Dehiscence in Patients with Cholesteatoma.

ObjectiveThis study aimed to investigate the abnormal high-resolution computed tomography (HRCT) findings in cholesteatomatous chronic otitis media (CCOM) patients preoperatively and the coexistence of abnormal HRCT findings with facial canal dehiscence (FCD) observed intraoperatively to identify the predictive factors associated with FCD.MethodsThe medical records of 151 CCOM patients who had undergone tympanomastoidectomy at our center were retrospectively examined in terms of the patients’ age and gender, preoperative HRCT findings [scutum defect, posterior wall of external auditory canal (PWEAC) defect, lateral semicircular canal (LSSC) defect, tegmen defect, and sigmoid plate erosion]. Operation records containing information about FCD were also analyzed.ResultsThe prevalence of FCD was found to be 33.8% (51/151). There was a significant correlation between the presence of scutum, PWEAC, LSSC, and tegmen defects and the presence of FCD. However, no statistically significant correlation was found between the presence of sigmoid plate erosion and the presence of FCD. The results of regression analysis of the coexisting pathologic findings for FCD showed that the risk of FCD was highest in patients with LSSC + scutum defects (34.3-fold increase), followed by LSSC + PWEAC defects (31.6-fold increase).ConclusionOur study revealed that the presence of scutum, PWEAC, LSSC, and tegmen defects on HRCT indicates a higher risk of FCD preoperatively. This risk is even greater when multiple abnormal findings coexist.

Cautionary Findings for the Presence of Facial Canal Dehiscence During Cholesteatoma Surgery

Our aim was to investigate the relationship between facial canal dehiscence (FCD) and surgical findings and procedures in patients with cholesteatoma. A total of 186 patients (118 males, 39.2 ± 15 years) who underwent surgery for advanced cholesteatoma between 2013 and 2018 were included in the study. The relationship between FCD and surgical findings was investigated via the surgical registries. The prevalence of FCD was 36.6% (68/186). The prevalence of FCD was 44%, and 13.2% for the patients who underwent canal wall down mastoidectomy (62/141) and canal wall up mastoidectomy (6/45), respectively (P < .001). Facial canal dehiscence was detected in 73.9% of the 23 patients who had a lateral semicircular canal (LSCC) defect (P < .001), in 61.9% of 21 patients who had a tegmen tympani defect, and in 58.1% of the 31 patients who had erosion on the posterior wall of the external auditory canal (EAC; P < .05). The prevalence of FCD was 3.1% in patients with isolated incus erosion, 59.1% in patients with erosion of malleus and incus, 60.7% in patients with erosion of stapes suprastructure and incus, and 43.2% in patients with whole ossicular chain deformation (P < .001). The defects on LSCC, EAC, tegmen tympani, and malleus and incus might be cautionary findings for the presence of FCD during cholesteatoma surgery.

Is there a relationship between mastoid pneumatisation and facial canal dimensions?

To evaluate mastoid pneumatisation and facial canal dimensions. In this retrospective study, 169 multidetector computed tomography scans of temporal bone were reviewed. Facial canal dimensions were evaluated at the labyrinthine, tympanic and mastoid segments using axial and coronal multidetector computed tomography scans of temporal bone. Mastoid pneumatisation and facial canal dehiscence were evaluated. Facial canal dehiscence was measured if it was found to be present. This study showed that facial canal dimensions decreased in pneumatised mastoids. Facial canal dimensions in females were smaller than in males. Facial canal dehiscence was detected in 5.9 per cent and 6.5 per cent of the patients on the right and left sides, respectively. No correlations were found between facial canal dehiscence and mastoid pneumatisation. The length of dehiscence was 1.92 ± 0.44 mm (range, 0.86-2.51 mm) on the left side. In older subjects, left facial canal dehiscence was detected more, and the length of the dehiscence increased. This study concluded that during surgery, facial canal dehiscence should be kept in mind in order to avoid complications.

Facial canal dehiscence in patients with cholesteatoma: concordance between intraoperative inspection, computed tomography and neurophysiological findings.

To assess the diagnostic capacity of intraoperative neurophysiological monitoring with respect to "gold standard" microscopic findings of facial canal dehiscence in middle ear cholesteatoma surgery. We carried out a retrospective cohort study of 57 surgical interventions for cholesteatoma between 2008 and 2013 at Hospital Universitario de Canarias, Spain. Each patient underwent preoperative computed tomography (CT), intraoperative neurophysiological monitoring and intraoperative inspection of the facial nerve during microsurgery. Diagnostic concordance on the presence/absence of facial canal dehiscence was assessed in 54 surgical interventions. Presence of facial canal dehiscence. Of 57 interventions, 39 were primary surgeries; 11 (28.2%) showed facial canal dehiscence. and 18 were revision surgeries; 6 (33.3%) showed facial canal dehiscence. The facial nerve was not damaged in any patient. Facial canal dehiscence was observed in 17 (29.82%) interventions. We used intraoperative microscopic findings as the gold standard. Neurophysiological study showed a sensitivity of 94.1, specificity 97.3, positive predictive value (PPV) 57.8 and negative predictive value of 97.2. CT showed a sensitivity of 64.7, specificity 78.4, PPV 57.8 and negative predictive value of 82. Our neurophysiological study showed greater sensitivity and higher PPV than CT for the detection of facial canal dehiscence. We found no relationship between disease progression time and the presence of facial canal dehiscence.

Percutaneous Threshold of Facial Nerve Stimulation Predicts Facial Canal Dehiscence

ABSTRACTIatrogenic facial nerve (FN) injury is one of the most feared complications of otologic surgery. Dehiscence of the bony covering of the FN within the temporal bone increases FN vulnerability to accidental injury. High-resolution computed tomography (HRCT) of the temporal bone is used preoperatively to assess middle ear and mastoid anatomy; however, it is unreliable for detecting facial canal dehiscence. In this study, our aim was to determine if preoperative percutaneous FN stimulation could predict middle ear facial canal dehiscence. Between January 2015 and February 2017, we performed preoperative HRCT and percutaneous FN stimulation on adult patients who underwent otologic surgery at our institution. Stimulation was performed with a monopolar probe placed on the skin over the stylomastoid foramen. Electrical stimuli ranged from 0 to 40 milliamperes (mA). Recordings were made from ipsilateral facial muscles. Dependent variables included threshold to compound muscle action potential (CMAP), threshold to maximum amplitude of CMAP, and maximum amplitude of CMAP for each muscle. A retrospective chart review was performed. Seventy patients met inclusion criteria. Of the 24 with an intraoperatively confirmed dehiscence, 10 were identified preoperatively by the attending surgeon on HRCT. Averages of the lowest recorded threshold to CMAP (5.1mA v. 9.1mA), and an average of the threshold to CMAP (8.9 mA. 11.8 mA) of dehiscent versus non-dehiscent nerves were significantly different (p < .05). In conclusion, percutaneous FN stimulation is a simple and cost-effective tool that can give the surgeon important preoperative information about FN anatomy.

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

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. 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. 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. 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.