Superior Canal Dehiscence Research Articles

Assessment of Metabolic Markers and Osteoporosis in 250 Patients with Superior Semicircular Canal Dehiscence Treated With Middle Fossa Craniotomy

Superior semicircular canal dehiscence (SSCD) is caused by bony defects in the osseous shell of the arcuate eminence separating the labyrinth and the intracranial space. This pathologic third window causes hydroacoustic transmission resulting in debilitating symptoms. We examine the pathophysiologic association between metabolic markers, previous medical history, and SSCD symptoms before and after middle fossa craniotomy (MFC) treatment. This study was conducted between March 2011 and September 2020 with patients with SSCD who underwent MFC. We used a Fisher test to compare variables, including bilateral SSCD, second surgery, ear anomaly, osteoporosis, arthritis, vitamin D, and preoperative/postoperative symptoms, and others. Point-biserial correlation analysis was performed to test correlations between continuous variables and categorical variables. A total of 250 patients with SSCD underwent MFC repair. There was significant postoperative resolution in all symptoms (P < 0.0001). Laboratory 25-hydroxyvitamin D values correlated with preoperative aural fullness (rpb= 0.29; P= 0.03), and preoperative disequilibrium (rpb= -0.32; P= 0.02). Serum calcium values correlated with preoperative hearing loss (rpb= 0.16; P= 0.02). Osteoporosis history (n= 16; 6%) was more prevalent in female patients (P= 0.0001), associated with higher levels of preoperative hearing loss (odds ratio, 4.56; P= 0.02) and higher postoperative hearing loss resolution (odds ratio, 2.89; P= 0.0509). Certain metabolic markers may predict SSCD presentation before and after surgery. Previous history of osteoporosis, autoimmune conditions, or arthritis may play a role in SSCD pathophysiology and can help predict clinical outcomes. Future evaluation should take metabolic laboratory values and acquire an exact medical history.

Postoperative Pneumolabyrinth Following the Middle Cranial Fossa Approach for Superior Semicircular Canal Dehiscence Repair, 2014-2020.

The present study investigates risk factors and clinical outcomes of postoperative pneumolabyrinth following the middle cranial fossa approach for superior semicircular canal dehiscence repair, a complication that has not been documented previously. Retrospective cohort study. Tertiary/quaternary care referral center. We conducted a retrospective review of 332 middle cranial fossa procedures from 2014 to 2020 at a tertiary/quaternary care institution. Upon identifying pneumolabyrinth cases from postoperative computed tomography temporal bone scans, we conducted multivariable logistic regression analysis to explore demographic and clinical factors that were independently linked to this complication. We also compared the rates of postoperative symptoms among patients with different grades of pneumolabyrinth. We identified 41 (12.3%) pneumolabyrinth cases. Patients with older age, higher preoperative pure tone average, and frank dehiscence were at higher risk for pneumolabyrinth. Furthermore, patients with pneumolabyrinth reported significantly higher rates of postoperative dizziness and exhibited significantly greater pure tone average and air-bone gap postoperatively as compared with patients without pneumolabyrinth. Finally, higher-grade pneumolabyrinth was associated with increased rates of postoperative hearing loss, and grade III pneumolabyrinth was associated with higher rates of postoperative tinnitus vs grade I and II cases. Pneumolabyrinth following the middle cranial fossa approach was associated with poor clinical outcomes, including dizziness and auditory impairment. Old age, high preoperative pure tone average, and frank dehiscence were risk factors for this complication. The highlighted parameters may be important to note when considering this approach as a treatment option and while monitoring postoperative recovery.

Prevalence of otic capsule dehiscence in temporal bone computed tomography scan.

To investigate the radiologic prevalence of otic capsule dehiscence in temporal bone computed tomography (CT) scan. This was a cross-sectional study. The temporal bone CT scans of the patients presenting to a tertiary center were evaluated for possible dehiscence in any part of the otic capsule; then, all of the dehiscence were confirmed by a trained academic radiologist. For each type of otic capsule dehiscence, at least three planes were used with a specific type of reconstruction. When a dehiscence was present in at least two consecutive images in all planes, it was considered as a true dehiscence. Six hundred patients (mean age: 40 ± 18.1years) were enrolled. The prevalence of superior and posterior semicircular canal dehiscence was 6.0% and 2.7%, respectively. The prevalence of cochlear-facial dehiscence, cochlear-internal auditory canal dehiscence, and cochlear-carotid dehiscence was 6.3%, 0.7%, and 0.7%, respectively. The prevalence of vestibular aqueduct-jugular bulb dehiscence was 6.3% and the prevalence of posterior semicircular canal-jugular bulb dehiscence was 0.2%. Considering different types of otic capsule dehiscence described, care should be taken in patients with vestibular and auditory signs and symptoms to diagnose these dehiscences.

Incidence of Concomitant Semicircular Canal Dehiscence With Otosclerosis.

The concurrence of otosclerosis and superior semicircular canal dehiscence (SSCD) presents a diagnostic challenge and failure to differentiate between these 2 diagnoses results in mischaracterization and unsuccessful surgery. The objective of this study is to identify the incidence of SSCD in patients who have computed tomography (CT) evidence of otosclerosis. Retrospective chart review. Tertiary referral hospital. Adults with CT scan of the temporal bone diagnosed with radiological unilateral or bilateral fenestral otosclerosis from January 1995 to April 2018. Retrospective review of patient imaging from a multi-center tertiary-referral health system from January 1995 to April 2018. Imaging was reviewed to quantify the incidence of SSCD among patients with CT-diagnosed bilateral fenestral otosclerosis. Poor quality imaging was excluded from review. One-thousand two-hundred eight patients (1214 CT scans) were identified with otosclerosis, of which 373 were diagnosed with fenestral otosclerosis (663 ears) with imaging of sufficient quality for review. This population was predominantly female (57.2%) with bilateral fenestral otosclerosis (78%). Of these, 23 ears (3.5%) had definitive evidence of SSCD, with an additional 15 ears (2.3%) with possible radiographic evidence of SSCD. There was no significant difference in laterality between the SSCD and otosclerosis. Among 373 patients with fenestral otosclerosis per CT temporal bone imaging at a tertiary referral hospital, as many as 8.3% of patients had radiographic evidence of SSCD. Given this incidence, it continues to be important to consider SSCD when diagnosing and treating otosclerosis.

Six-canal video head impulse test in patients with labyrinthine and retrolabyrinthine pathology: detecting vestibulo-ocular reflex deficits.

Abnormal gains in six-canal video head impulse test are attributed to semi-circular canal deficits. However, as video head impulse test responses are linked to the vestibulo-ocular reflex, it was hypothesised that abnormal gains can be caused by vestibulo-ocular reflex pathway deficits. This study compared video head impulse test gains in 20 patients with superior semi-circular canal dehiscence (labyrinthine cause) and 20 side- and gender-matched patients with vestibular schwannomas (retrolabyrinthine cause), and investigated correlations between them (Mann-Kendall trend test). Vestibular schwannoma but not superior semi-circular canal dehiscence was significantly associated with abnormal lateral (odds ratio = 9.00 (95 per cent confidence interval = 1.638-49.44), p = 0.011) and posterior (odds ratio = 9.00 (95 per cent confidence interval = 2.151-37.659), p = 0.003) canal status. In vestibular schwannoma patients, there was a statistically significant degree of dependence between all ipsilesional canal video head impulse test gains; such dependence was not observed in superior semi-circular canal dehiscence. Vestibulo-ocular reflex gains differ in patients with labyrinthine and retrolabyrinthine disease; this suggests that abnormal gains can indicate deficits not only in the semi-circular canals but also elsewhere along the vestibulo-ocular reflex pathway.

Comparative study of cholesteatoma in paediatric and adult patients.

The aggressiveness of paediatric cholesteatoma has long been a matter of debate. While much of the evidence is substantiated by data from the Western world, it is further limited by the retrospective nature of most studies. Therefore, this paper presents a comparative analysis of various characteristics of cholesteatoma between paediatric and adult populations seen at our centre. A total of 50 patients (25 adults and 25 paediatric) with clinical diagnosis of chronic suppurative otitis media with cholesteatoma underwent canal wall down mastoidectomy over a period of two years. The intra-operative findings were noted and patients were followed up for six months. There was more extensive spread and ossicular erosion in paediatric cases. However, complications such as facial canal dehiscence and lateral semicircular canal dehiscence were more common in adults. Paediatric cholesteatoma is more aggressive and invasive than adult cholesteatoma, and the clinical behaviour is consistent with findings from other parts of the world.

New bone formation over dehiscent semicircular canal with cartilage cap.

Cartilage cap resurfacing is a method to seal a superior semicircular canal dehiscence. The purpose of this study was to evaluate the detection of new bone formation after surgical placement of a cartilage cap over a dehiscent semicircular canal. In this retrospective review, two neuroradiologists blinded to each other's interpretation reviewed the temporal bones of 20 patients, five of which had a pre-operative computed tomography (CT) exam which was interpreted as unilateral superior semicircular canal dehiscence and with new bone formation following repair on follow-up CT. There were also 15 control subjects. Each neuroradiologist was blinded to history, including post-operative changes, and asked to determine if there was a dehiscence or no dehiscence. Out of the 15 controls, there was 100% inter-observer agreement. On the five post-operative patients, there was agreement in 4/5 that there was no dehiscence post-operatively and 1/5 agreement of dehiscence post-operatively, but ectopic bone adjacent to the dehiscence. Our results indicate that new bone formation can be seen at the site of cartilage cap placement over the dehiscence and be interpreted as bony closure of the dehiscence.

Diagnostic Accuracy of High-resolution Computed Tomography (HRCT) Temporal Bone in the Evaluation of Chronic Suppurative Otitis Media

Chronic suppurative otitis media is a disease presented with recurrent purulent discharge through perforated tympanic membrane. Other clinical presentation varies form variable hearing loss, tinnitus, vertigo according to extent and complication of disease. Cholesteatoma is most common association of CSOM, and is characterized by presence of keratin and other desquamated tissue covered by squamous epithelium. Diagnosis of CSOM is readily made by otorhinolaryngologist with otoscopy or oto-endoscopy, though extent of disease can be evaluated through HRCT temporal bone or MRI of middle and inner ear. HRCT temporal bone is now widely acceptable as investigation of choice for evaluation of CSOM as it has high efficacy to detect bony erosion. The present study is conducted over 73 patients in the department of radiodiagnosis, Dr. S.N. medical college, Jodhpur, Rajasthan over a period between 2020 to 2021 with the aim to evaluate the diagnostic efficacy of HRCT temporal bone to identify presence and extension of disease, alteration of mastoid aeration, bony and ossicular erosion with the comparison of intraoperative findings in the form of sensitivity, specificity, positive and negative predictive value. In this study 44 patients(60%) were male, mean age of presentation is 30.52 ± 9.70 years. Common clinical presentation was ear discharge (91.8%) and hard of hearing(64%). presence of soft tissue density is most consistent finding present in 71(97.3%) patients, alteration of aeration of mastoid is observed in 67 (91.8%) patients, erosion of incus in frequent followed by maleus and stapes. Facial canal and lateral semicircular canal erosion is less common observation. The study concluded that HRCT temporal bone is reliable and evidentiary diagnostic tool in identifying the presence of disease, ossicular erosion, and detecting complication following CSOM.&#x0D; Keywords: Cholesteatoma, Ossicular erosion, Facial canal dehiscence, Lateral semicircular canal dehiscence

Skull Vibration-Induced Nystagmus and High Frequency Ocular Vestibular-Evoked Myogenic Potentials in Superior Canal Dehiscence.

Background: Although diagnostic criteria have been established for superior canal dehiscence syndrome, cases in which the diagnosis is not easy are frequent. On those occasions, some tests such as vibration-induced nystagmus or vestibular-evoked myogenic potentials can offer invaluable help due to their high sensitivity and specificity. Methods: We studied 30 patients showing superior canal dehiscence or “near-dehiscence” in a CT scan. Skull vibration-induced nystagmus and high frequency ocular vestibular-evoked myogenic potentials are performed in each patient. The aim of the study is to determine how useful both tests are for detection of superior canal dehiscence or near-dehiscence. Results: Of the 60 temporal bones studied, no dehiscence was the result in 22, near-dehiscence in 17 and a definite finding in 21. In 10/30 patients, there was no SVIN (Skull vibration induced nystagmus) during otoneurological testing, while in 6/30, induced nystagmus was mainly horizontal, and in 14/30 there was vertical up-beating. All patients had a positive oVEMP (Ocular vestibular evoked myiogenic potentials) at 0.5 kHz in both ears and the HFoVEMP (High frequency ocular vestibular evoked myiogenic potentials) response was positive in 25/60 (41.6%) of the ears studied and in 19/30 of the patients evaluated (in 6 it was positive in both ears). Up-beat SVIN will point to a SCD (Superior Canal Dehiscence) mainly when HFoVEMP are present, and when this is negative there is a high probability that it is not a SCD. Conclusions: When SVIN and HFoVEMP results are added (or combined), they not only improve the possibilities of detecting SCD, but also the affected side.

Persistent Positional Vertigo in a Patient with Partial “Auto-Plugged” Superior Semicircular Canal Dehiscence: A Case Study

A 73-year-old female was referred to our department for persistent left anterior benign paroxysmal positional vertigo refractory to multiple repositioning procedures and training physiotherapist exercises. The audiovestibular assessment and high resonance computed tomography of the petrosal bone confirmed the presence of a 5.4 mm large paucisymptomatic left anterior semicircular canal dehiscence. The connection between the 2 apparently distinct neurotological entities in the same patient was further sustained by additional imagery. T2-weighted and 3-dimensional labyrinthine sequences confirmed the presence of a partially “auto-plugged” superior semicircular canal dehiscence which progressively entrapped greater otolith particles proximal to the cupula of the superior semicircular canal.

Wideband acoustic immittance in superior semicircular canal dehiscence

ObjectiveThe apparent effect of superior semicircular canal dehiscence (SSCD) on middle ear- and cochlear impedance has led researchers to investigate the use of wideband acoustic immittance as a screening tool when SSCD is suspected. The purpose of the study was to describe the absorbance characteristics and tympanometric values of ears with confirmed SSCD measured at tympanometric peak pressure (TPP) and at ambient pressure. MethodsWideband Acoustic Immittance was performed at ambient pressure and at TPP on ten participants (12 ears) with confirmed SSCD, as well as on an age- and gender matched control group (12 ears). Inferential statistics were used to determine whether statistical differences existed for the absorbance values at each of the averaged frequencies, the resonance frequency (RF) and tympanometric data between the SSCD and control groups. ResultsThe mean absorbance of the SSCD group reached a maximum at 890.9 Hz and a minimum at 6349.6 Hz. When testing absorbance at TPP, a statistically significant increase/peak in the absorbance values of the SSCD group (compared to those of the control group) was found from 630 to 890.9 Hz and a decrease from 4489.8 to 6349.6 Hz. Similar patterns were observed for absorbance at ambient pressure. A lower mean RF for ears with SSCD as well as an increased mean admittance magnitude (AM) value at RF was found compared to those of the control group. ConclusionThe use of SSCD as a screening tool when SSCD is suspected was strengthened by results similar to those of previous studies. As a result of the significant difference in RF of SSCD ears compared to the RF of the control group, the potential value of measuring the RF of the middle ear to differentiate between mass-and stiffness dominated pathologies, was also illustrated.

Evaluation of the transmastoid plugging approach for superior semicircular canal dehiscences: a retrospective series of 30 ears.

The classical surgical approach for superior semicircular canal dehiscences (SSCD) is via the extradural middle cranial fossa. This pathway is used to resurface or to plug the SSC. In this paper, we present long-term data on an alternative route: the transmastoid pathway. The predictive factors for a successful surgery are equally presented in this paper. Thirty reports of patients operated between September 2007 to January 2020 were analysed. SSCD was confirmed by the association of concordant complaints, audiometric data, cervical vestibular evoked myogenic potentials (cVEMP) responses and computerized tomography findings. Before and after surgery, the following factors were analysed: auditory and vestibular subjective symptoms, Tullio phenomenon, pure-tone audiometry thresholds for air and bone conduction, air-bone gap, cVEMP threshold, and computerized tomography data, for instance the size of the dehiscence. The follow-up is 21months on average. The transmastoid approach significantly improves all symptoms (although there were less probing results for the vestibular symptoms). Objectively, we can observe, a closure of the audiometric air-bone gap on the low frequencies and an improvement in the cVEMP. The only correlation that was identified was between the preoperative cVEMP results and the postoperative air conduction. The originality of this study is the long postoperative follow-up. It allowed us to evaluate the symptoms in the long term and to determine a predictive factor of postoperative complication, which has not yet been described until today.The transmastoid plugging technique is safe and effective. Additional long-term data with a larger cohort are needed to confirm our results and correlation studies.

Predictive Factors for Concurrent Tegmen Dehiscence in Superior Canal Dehiscence Syndrome.

To describe factors predictive of tegmen dehiscence in subjects with superior semicircular canal dehiscence syndrome (SCDS). Retrospective case series. Tertiary referral center. Subjects with SCDS who underwent middle fossa craniotomy (MFC) for plugging/resurfacing. Operative and radiographic findings of tegmen dehiscences, preoperative low frequency air-bone gaps (LF-ABGs), ocular vestibular evoked myogenic potential (oVEMP) amplitudes, size of superior semicircular canal dehiscence (SCD), and history of obesity or obstructive sleep apnea (OSA). One hundred thirty six patients (avg. age, 50.6 yr, 55.1% female) underwent MFC for repair of SCDS. Tegmen dehiscences were commonly found intraoperatively (tegmen tympani dehiscence [TTD] in 19.9% [11% with dural contact of ossicles], tegmen mastoideum dehiscence [TMD] in 28.7%). There were no differences in preoperative LF-ABGs and preoperative oVEMP amplitudes with respect to tegmen status. The sensitivity and specificity of computed tomography (CT) for predicting an intraoperatively confirmed TTD was 85 and 74%, respectively, and 44 and 79% for TMD. History of obesity and OSA did not differ between those with and without tegmen dehiscences. The presence of contralateral SCD and increasing cross-sectional area of SCD were both significantly associated with concurrent tegmen defects. Obesity, OSA, preoperative oVEMP, and LF-ABG do not differ between those with SCD alone and those with SCD and concurrent tegmen dehiscences. Likewise, CT scans have relatively low sensitivity for identifying tegmen dehiscences. The presence of concurrent tegmen defects is more common in subjects with larger SCD cross-sectional areas and contralateral SCD.

Supervised machine learning models for classifying common causes of dizziness

PurposeThe objective of this study was to use a supervised machine learning (ML) platform and a national dataset to identify factors important in classifying common types of dizziness. MethodsUsing established clinical criteria and responses to the balance and dizziness supplement from the 2016 National health Interview Survey (n = 33,028), case definitions for vestibular migraine (VM), benign paroxysmal positional vertigo (BPPV) Ménière's disease (MD), persistent postural-perceptual dizziness (PPPD), superior canal dehiscence (SCD), and bilateral vestibular hypofunction (BVH) were generated. One hundred thirty-six variables consisting of sociodemographic characteristics and medical comorbidities were used to develop decision tree models to predict these common types of dizziness. ResultsThe one-year prevalence of dizziness in the U.S. was 16.8% (5562 respondents). VM was highly prevalent, representing 4.0% of the overall respondents (n = 1327). ML decision tree models were able to correctly classify all 6 dizziness subtypes with high accuracy (sensitivity range, 70–92%; specificity range, 89–99%) using responses to questions about functional limitations due to dizziness, such as falls due to dizziness and modification of social activities due to dizziness. ConclusionsIn a large population-based dataset, supervised ML models accurately predicted dizziness subtypes according to responses to questions that do not pertain to dizziness symptoms alone.

New classification of superior semicircular canal dehiscence in HRCT.

The complex anatomy of the temporal bone is difficult to understand and constitutes a challenge in the daily diagnostic routine even for experienced neuroradiologists. In the context of otoneurological (oVEMP) and preoperative diagnostics, the diagnosis of superior semicircular canal dehiscence (SSCD) is of great importance for Ear, Nose, and Throat (ENT) specialists. The gold standard for this diagnosis is a high-resolution CT (HRCT) of the temporal bone. In order to correctly diagnose SSCD, special oblique reconstructions are necessary in addition to standard (axial, coronal, sagittal) reconstructions. We evaluated the frequency of diagnosis and its location in HRCT in correlation with otoneurological examination. From this analysis, we present a new SSCD classification. This classification yields the potential of a differentiated analysis of the patient's clinical symptoms with correlation to the cross-sectional anatomy and may lead to a differentiated therapy approach. We evaluated 1370 temporal bone scans of patients with residual hearing and verified 343 superior semicircular canal dehiscence (SSCD). We conducted a subgroup analysis of these 343 HRCT scans displaying a SSCD and used them as a basis to create a classification. Three location types of SSCD were identified. These were anterior type 1, superior type 2 and posterior type 3. Type 2 were significantly more frequent in both sexes. SSCD at this location can be overlooked if diagnosis is performed only in the standard axial plane, since it can only be visualized by means of double oblique reconstruction. We present a standardized reconstruction algorithm. In total, three types of SSCD with differing incidences can be extrapolated from the locations. Superior type 2 is the most frequent one. Both sexes are affected with roughly equal incidence. The use of standardized double oblique reconstruction algorithm ensures that all three types are diagnosed in the HRCT.

Kronik Otitis Media Cerrahisinde Anatomik Varyasyonlar; Tomografi ve Perioperatif Bulguların Karşılaştırılması

Aim: For a correct and adequate chronic otitis media surgery, it is necessary to correctly define the anatomical structures and to know their possible variations, otherwise, an increase in the complication rate is inevitable. This study aims to present the anatomical variations detected both in preoperative computerized tomography scanning and during operation, and complication rates encountered in 308 patients who underwent tympanomastoidectomy due to chronic otitis media in the light of current literature knowledge. Materials and Methods: In this retrospective study, the files of 308 patients who underwent tympanomastoidectomy due to chronic otitis media in a tertiary clinic between September 2011 and July 2019 were scanned for encountered anatomical variations detected both in preoperative computerized tomography scanning and during operation and complications. Results: There was Körner septum in 12 (3.8%) cases, dehiscence in the facial nerve tympanic segment in 12 (3.8%) cases, and lateral semicircular canal dehiscence (LSCD) in 4 (1.3%) cases. In 4 (1.3%) cases, it was observed that the dura was located downward and in 6 (1.9%) cases, the sigmoid vein was located anterosuperiorly. Conclusion: Always being careful in terms of anatomical variations and possible complications during the operation will increase the success of the surgery. Knowing the anatomical variations and complications related to the temporal region is of great importance for clinicians dealing with ear surgery.

Superior semicircular canal dehiscence repair with small middle fossa craniotomy using an oto-microscopic and co-endoscopic assisted approach.

Superior semicircular canal dehiscence is an uncommon neurotological disorder in which the petrous temporal bone overlying the superior semicircular canal lacks bone. Its most common symptoms include amplification of internal sounds, autophony, tinnitus, sound- and pressure-induced vertigo, hyperacusis, oscillopsia, and hearing loss. This video presentation aimed to demonstrate endoscopic-assisted repair of superior semicircular canal dehiscence with middle fossa craniotomy. Eleven patients with superior semicircular canal dehiscence, verified with temporal computed tomography, were enrolled in the study. An endoscopy-assisted middle fossa approach was applied to all patients. Superior semicircular canal dehiscence was successfully repaired with an endoscope in 11 patients. Endoscopic-assisted repair of superior semicircular canal dehiscence may be a superior approach compared with binocular operative microscopy.

A Report on Quality of Life Outcomes Following Transmastoid Plugging of Superior Semicircular Canal Dehiscence in a Newly Established Service in a UK Hospital.

This study aimed to evaluate the quality-of-life outcomes following transmastoid plugging of semicircular canal dehiscence in a newly established service in a UK hospital. Quality-of-life outcomes were measured using the Glasgow benefit Inventory score in three patients who underwent transmastoid plugging for superior semicircular canal dehiscence between September 2019 and March 2020. Patients also completed pre- and post-operative symptomatic questionnaires and vestibular-evoked myogenic potential testing. All three patients reported an improvement in overall quality-of-life outcomes with a mean overall Glasgow Benefit Inventory score of +37 (range, +22.2-66.6). There were no immediate post-operative complications and hearing was preserved in all patients. This study reported an initial successful experience with transmastoid plugging of superior semicircular canal dehiscence. In all patients, improvement in quality-of-life measures and symptoms was reported.

Hearing Outcomes of Transmastoid Plugging for Superior Canal Dehiscence Syndrome by Underwater Endoscopic Surgery: With Special Reference to Transient Bone Conduction Increase in Early Postoperative Period.

To investigate the influence on hearing of transmastoid plugging of the superior semicircular canal accompanied with membranous superior canal transection by underwater endoscopic ear surgery (UWEES) for the superior semicircular canal dehiscence syndrome. Retrospective case review. Tertiary referral center. Seven patients underwent plugging with membranous superior canal transection with UWEES from 2017 to 2019. Bone conduction (BC) thresholds (250, 500, 1000, 2000, 4000 Hz) were repetitively examined in early postoperative period. Subjective symptoms and pure-tone audiometry. Transient BC threshold increase was detected in all cases in early postoperative period and hearing levels were ameliorated in 1 to 2 months. The mean maximum BC threshold elevations (dB) during the early postoperative period (within 1 mo) and the postoperative stable hearing period (after 2 mo) were 18.6 and 2.9 at 250 Hz, 24.3 and 8.6 at 500 Hz, 26.4 and 8.6 at 1000 Hz, 28.6 and 7.1 at 2000 Hz, and 30.0 and 0.8 (except for scale-out cases) at 4000 Hz. respectively. The mean maximum BC thresholds in the early period were significantly elevated compared with those in the stable period at each frequency (p < 0.01). Hearing outcomes of transmastoid plugging with transection of the membranous superior canal by using UWEES were found favorable in a long-term follow-up. However, it caused transient reversible hearing loss in all cases. The BC increase in early postoperative period may not cause permanent hearing loss but improvement for the surgical technique may still be necessary.

Bilateral Superior Semicircular Canal Dehiscence without Signs of Vestibular Involvement about a Case

Superior semicircular canal dehiscence (SSCD) is a rare entity recently described whose typical clinical symptomatology is represented by dizziness triggered by a variation of pressure. We reported a case of SSCD which was diagnosed thanks to computed tomography (CT) scan of the petrous bone conducted systematically in front of mixed deafness with normal eardrum. The SSCD was bilateral and was revealed by mixed deafness on the left side and perception deafness on the right with a normal eardrum without the notion of vertigo. The cervical vestibular evoked myogenic potential (cVEMP) and an ultra-high resolution CT scan of the petrous bones in coronal and sagittal sections allowed the diagnosis. The SSCD should be considered in the presence of any conductive or mixed hearing loss with a normal eardrum. The CT scan in coronal and sagittal submillimetric sections allows the diagnosis.