Posterior Semicircular Canal Dehiscence Research Articles

Posterior Semicircular Canal Dehiscence with Vestibulo-Ocular Reflex Reduction for the Affected Canal at the Video-Head Impulse Test: Considerations to Pathomechanisms.

Posterior semicircular canal dehiscence (PSCD) has been demonstrated to result in a third mobile window mechanism (TMWM) in the inner ear similar to superior semicircular canal dehiscence (SSCD). Typical clinical and instrumental features of TMWM, including low-frequency conductive hearing loss (CHL), autophony, pulsatile tinnitus, sound/pressure-induced vertigo and enhanced vestibular-evoked myogenic potentials, have been widely described in cases with PSCD. Nevertheless, video-head impulse test (vHIT) results have been poorly investigated. Here, we present six patients with PSCD presenting with a clinical scenario consistent with a TMWM and an impaired vestibulo-ocular reflex (VOR) for the affected canal on vHIT. In two cases, an additional dehiscence between the facial nerve and the horizontal semicircular canal (HSC) was detected, leading to a concurrent VOR impairment for the HSC. While in SSCD, a VOR gain reduction could be ascribed to a spontaneous "auto-plugging" process due to a dural prolapse into the canal, the same pathomechanism is difficult to conceive in PSCD due to a different anatomical position, making a dural herniation less likely. Alternative putative pathomechanisms are discussed, including an endolymphatic flow dissipation during head impulses as already hypothesized in SSCD. The association of symptoms/signs consistent with TMWM and a reduced VOR gain for the posterior canal might address the diagnosis toward PSCD.

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.

Audiovestibular Quantification in Rare Third Window Disorders in Children.

Third window disorders are structural abnormalities in the bony otic capsule that establish a connection between the middle/inner ear or the inner ear/cranial cavity. Investigated extensively in adults, they have hardly been studied in children. This study is a retrospective study of children (aged 5–17 years) diagnosed with rare third window disorders (third window disorders reported rarely or not reported in children) in a tertiary pediatric vestibular unit in the United Kingdom. It aimed to investigate audiovestibular function in these children. Final diagnosis was achieved by high resolution CT scan of the temporal bones. Of 920 children attending for audiovestibular assessment over a 42 month period, rare third windows were observed in 8 (<1%). These included posterior semicircular canal dehiscence (n = 3, 0.3%), posterior semicircular canal thinning (n = 2, 0.2%), X linked gusher (n = 2, 0.2%), and a combination of dilated internal auditory meatus/irregular cochlear partition/deficient facial nerve canal (n = 1, 0.1%). The majority of them (87.5%) demonstrated a mixed/conductive hearing loss with an air-bone gap in the presence of normal tympanometry (100%). Transient otoacoustic emissions were absent with a simultaneous cochlear pathology in 50% of the cohort. Features of disequilibrium were observed in 75% and about a third showed deranged vestibular function tests. Video head impulse test abnormalities were detected in 50% localizing to the side of the lesion. Cervical vestibular evoked myogenic potential test abnormalities were observed in all children in the cohort undergoing the test where low thresholds and high amplitudes classically found in third window disorders localized to the side of the defects in 28.5%. In the series, 71.4% also demonstrated absent responses/amplitude asymmetry, some of which did not localize to the ipsilesional side. Two children presented with typical third window symptoms. This study observes 2 new rare pediatric third window phenotypes and the presence of a cochlear hearing loss in these disorders. It emphasizes that these disorders should be considered as an etiology of hearing loss/disequilibrium in children. It also suggests that pediatric third window disorders may not present with classical third window features and are variable in their presentations/audiovestibular functions.

Posterior Semicircular Canal Dehiscence: Case Series and Systematic Review.

To conduct a systematic review of posterior semicircular canal dehiscence (PSCD) and to present a series of patients with PSCD with and without classic third-window symptoms. PubMed, Scopus, and the Cochrane Library from inception until April 2019. Case series of five patients seen in a multidisciplinary, vestibular-focused, neurotology clinic. Inclusion criteria: PSCD studies of symptomatology, diagnostic testing, radiology, and histopathology. non-English articles, reviews, letters, animal studies. Quality evaluated according to Oxford Center for Evidence-Based Medicine criteria and funnel plot via the Stern and Egger method. Two hundred five studies were found, and 58 studies were included. In 47 total patients, sound-induced vertigo, mixed hearing loss, and tinnitus were the most common presenting symptom. A meta-analysis of proportions using eight radiological and histopathological studies revealed an incidence of 0.38% adult ears [95% CI 0.08, 0.89] and 2.16% of adult patients [0.64, 4.54]. The incidence in pediatric patients ranged from 1.3 to 43%. Jugular bulb abnormalities were common. In our case series, four of five patients presented without third-window symptoms, while one had sound- and pressure-induced vertigo. Hearing loss in these patients was not salvageable. PSCD is a rare phenomenon most commonly presenting with third-window type symptoms. However, PSCD might also present with dizziness and hearing loss inconsistent with third-window symptomatology. One should be conscious of potentially poorer prognosis for hearing recovery in these patients.

Posterior Semicircular Canal Dehiscence and Auditory Neuropathy in a 22-month-old Male Baby

Semicircular canal dehiscence (SCD) is usually seen in children, but it rarely occurs in adults. Posterior SCD in children is scarcely reported in the literature. This study reports the presence of posterior SCD and comorbid auditory neuropathy in a 22-month-old male baby. The video head impulse test was normal, but cervical vestibular-evoked myogenic potential test supported SCD on the left side. Also, temporal CT of the patient revealed posterior SCD. Cochlear microphonic was detected bilaterally by the Auditory Brainstem Response test. Posterior SCD may cause different audio-vestibular signs. Early vestibular assessment in children with congenital hearing loss, especially auditory neuropathy, is suggested because knowing the additional problems associated with the vestibular function will ease the prognosis of vestibular disorder and protect the children's balance functions.

A Case of Posterior Semicircular Canal Dehiscence Caused by High Jugular Bulb

Posterior semicircular canal dehiscence represents a third-window lesion manifesting as hearing loss with vestibular dysfunction. Computed tomography findings of a dehiscent posterior canal can be verified with increased vestibular evoked myogenic potential responses as in other third-window lesions. The jugular bulb is the bulbiform connection between the sigmoid sinus and the internal jugular vein at the skull base. High jugular bulb can erode into inner ear structures. According to the literature review, there has been no case report about posterior semicircular canal dehiscence caused by high jugular bulb in Asia. Therefore, the authors report a case with a review of literature. Key words: High jugular bulb ㆍ Posterior semicircular dehiscence

Posterior Semicircular Canal Dehiscence Presenting with Recurrent Positional Vertigo

Posterior Semicircular Canal Dehiscence Presenting with Recurrent Positional Vertigo

Magnetic resonance imaging and computed tomography for diagnosing semicircular canal dehiscence.

We investigated the semicircular canal (SC) dehiscence using temporal computed tomography (CT) and magnetic resonance (MR) imaging. We retrospectively reviewed 114 (228 ears) consecutive MR images and CT scans of the temporal bones for dehiscence of the SCs. In the 1.5 Tesla (T) MR imaging, T1 and T2-weighted images were obtained. Dehiscence of the SCs was defined by absence of high attenuation bone coverage on the CT scans, and absence of low-signal bone margins on the MR images. Superior SC dehiscence was detected in 4 (1.8%) ears using CT scans and 5 (2.2%) ears using MR imaging. Posterior SC dehiscence was detected in 4 (1.8%) ears using CT scans and 4 (1.8%) ears using MR imaging. In the non-dehiscent cases, there was hypointense bone coverage between the canal and the cerebrospinal fluid (CSF). However, in the cases of semicircular canal dehiscence, hypointense bone tissue did not appear between the canal and the CSF in the MR imaging. If there is clinical doubt about the presence of SC dehiscence, we recommend that MR imaging be conducted first. When dehiscence is not seen in the MR, a CT examination should be performed. MR imaging is preferred primarily, because it does not contain ionizing radiation.

Posterior Semicircular Canal Dehiscence: Third Window to the Inner Ear- A Rare Cause of Vertigo

Posterior Semicircular Canal Dehiscence: Third Window to the Inner Ear- A Rare Cause of Vertigo

Posterior semicircular canal dehiscence secondary to jugular enlargement

Semicircular canal dehiscence is an important entity often presenting with symptoms of noise or pressure induced vertigo, autophony, aural fullness and conductive hearing loss. Due to its varied presentation and mimic of other otologic conditions its consideration is of increased importance. Within we report a case of right sided posterior semicircular canal dehiscence secondary to an enlarged and high jugular bulb. The results of this observation indicate a need for patients with auditory symptoms and high riding jugular bulbs to be evaluated for possible posterior semicircular canal dehiscence.

Pediatric Semicircular Canal Dehiscence: Radiographic and Histologic Prevalence, With Clinical Correlation.

To determine the prevalence of radiographic and histologic superior semicircular canal dehiscence (SSCD) and posterior semicircular canal dehiscence (PSCD) and associated changes in temporal bone thickness in children aged 0 to 7 years. Retrospective chart review and histopathologic review of cadaveric bone specimens. Two tertiary referral centers. Children younger than 7 years who underwent high-resolution computed tomography scan including the temporal bones between 1998 and 2013 and temporal bones harvested from children younger than 7 years. Two hundred twenty-eight computed tomography studies and 58 temporal bone specimens were reviewed. Available patient demographics were tabulated. Prevalence of SSCD and PSCD and bone thickness over semicircular canals, with comparison across age groups. Clinical data were extracted for patients with radiographic dehiscence. Prevalence by ear of SSCD was 11.9%, 4.9%, 2.8%, and 0% and of PSCD was 16.7%, 2.4%, 1.4%, and 0% in children aged less than 6 months, 6 to 11 months, 12 to 35 months, and 3 to 7 years, respectively. SSCD was statistically more common before 1 year of age and PSCD before 6 months of age. Bone thickness overlying both the SSC and the PSC increased with age. Radiographic PSC bone was significantly thicker than SSC bone in patients older than 12 months. No dehiscences were found in the histologic specimens. Radiographic dehiscence of the canals is common in the first 6 months of life, with thin bone seen histologically. Prevalence decreases with increasing age as the bone overlying the canals increases in thickness.

Otic capsule dehiscence syndrome: Superior semicircular canal dehiscence syndrome with no radiographically visible dehiscence.

We conducted a prospective longitudinal study of two cohorts of patients who had superior semicircular canal dehiscence syndrome (SSCDS); one group had radiographically confirmed superior canal dehiscence (SCD), and the other exhibited no identified otic capsule dehiscence on imaging (no-iOCD). We compiled data obtained from prospective structured symptomatology interviews; diagnostic studies; three-dimensional, high-resolution, temporal bone computed tomography; and a retrospective case review from our tertiary care referral center. Eleven adults and 1 child with SSCDS were identified, surgically managed, and followed. Six of these patients-1 man and 5 women, aged 29 to 54 years at first surgery (mean: 41.8)-had radiologically confirmed SCD. The other 6 patients-1 man, 4 women, and 1 girl, aged 1 to 51 years (mean: 32.2)-had no-iOCD. The 6 adults with SCD underwent surgery via a middle cranial fossa approach with plugging procedures. The 5 adults and 1 child with no-iOCD underwent round window reinforcement (RWR) surgery. One SCD patient developed no-iOCD 1.5 years after SCD surgery, and she subsequently underwent RWR surgery. Our main outcome measures were patient symptomatology (with video documentation) and the results of diagnostic studies. Other than the character of migraine headaches, there was no difference in preoperative symptomatology between the two groups. Postoperatively, resolution of SSCDS symptoms ultimately occurred in all patients. Both the SCD and the no-iOCD groups experienced a highly significant improvement in postural control following treatment (Wilcoxon signed rank test, p < 0.001). We conclude that the term otic capsule dehiscence syndrome more accurately reflects the clinical syndrome of SSCDS since it includes both superior semicircular canal dehiscence and no-iOCD, as well as posterior and lateral semicircular canal dehiscence, all of which can manifest as SSCDS. We have also included links to videos in which 4 of the SSCDS patients with no-iOCD in this study discussed their symptoms and the results of their surgery; these links are found in the "References" section in citations 12-15. Links to three other videos of interest are contained in citations 10, 11, and 24.

Quantification of hearing loss in patients with posterior semicircular canal dehiscence

Conclusion: Patients with posterior semicircular canal dehiscence (PSCD) have low frequency conductive hearing loss similar to patients with superior semicircular canal dehiscence (SSCD) secondary to a pathologic third window. Objectives: PSCD can result in conductive hearing loss, but the magnitude of this hearing loss remains to be quantified. Patients with SSCD have been shown to have low frequency conductive hearing loss. The underlying pathophysiology of hearing loss from PSCD and SSCD is similar and related to a pathologic third window. Method: A PubMed search was completed for a meta-analysis of patients with PSCD. Articles with quality audiograms were obtained. Air conduction thresholds for ears with posterior semicircular canal dehiscence were compared to the opposite ear as well as normal control data. Results: Eight articles with 21 patients with PSCD and quality audiograms were included. Two patients had bilateral PSCD and one of those was excluded because hearing thresholds were at the limit of the audiometer. Patients with posterior semicircular canal dehiscence have statistically significant lower air conduction thresholds in frequencies at and below 2000 Hz.

Clinical Characteristics of Posterior and Lateral Semicircular Canal Dehiscence.

The objective of this study was to evaluate the characteristic symptoms of and treatments for lateral semicircular canal dehiscence (LSCD) and posterior semicircular canal dehiscence (PSCD) and its proposed mechanism. A dehiscence acquired in any of the semicircular canals may evoke various auditory symptoms (autophony and inner ear conductive hearing loss) or vestibular symptoms (vertigo, the Tullio phenomenon, and Hennebert sign) by creating a "third mobile window" in the bone that enables aberrant communication between the inner ear and nearby structures. A PubMed search was performed using the keywords lateral, posterior, and semicircular canal dehiscence to identify all relevant cases. Our data suggest that PSCD, although clinically rare, is most likely associated with a high-riding jugular bulb and fibrous dysplasia. Patients may experience auditory manifestations that range from mild conductive to extensive sensorineural hearing loss. LSCD is usually associated with chronic otitis media with cholesteatoma.

The relationship between jugular bulb position and jugular bulb related inner ear dehiscence: a retrospective analysis

ObjectiveHigh jugular bulb (HJB) can erode inner ear structures creating a jugular bulb related inner ear dehiscence (JBID). The aim of this study was to analyze the relationship between the position of jugular bulb (JB) and JBID using high-resolution computed tomography (HRCT). Material and methodsIn this retrospective study HRCT images of 552 ears of 276 patients with hearing loss, otogenic vertigo, tinnitus or idiopathic peripheral facial nerve paralysis were analyzed. HJB type-1 was defined when JB dome reached above the inferior part of the round window, but was below the inferior edge of the internal acoustic meatus (IAM). HJB type-2 was defined when the dome of JB was higher than the inferior edge of IAM. The frequencies and types of HJB were evaluated. JBID for each HJB type was determined. Frequencies of JBID eroding the vestibular aqueduct (VA), the cochlear aqueduct and the posterior semicircular canal were examined. ResultsHJB type-1 and HJB type-2 were found in 19% (105/552) and in 15.8% (87/552) of studied ears. JBID showed to be in 3.8% (21/552) of all ears. 90.5% (19/21) of JBID revealed eroding of VA. Jugular bulb related cochlear aqueduct dehiscence and jugular bulb related posterior semicircular canal dehiscence were found in one ear each. The frequency of jugular bulb related vestibular aqueduct dehiscence (JBVAD) in patients with HJB reaching above IAM was higher than in patients with HJB lower than IAM. ConclusionsHJB is common, but JBID is rare. JBID prevalently erodes VA. HJB rising above IAM is most at risk to show JBVAD.

Jugular bulb abnormalities in patients with Meniere’s disease using high-resolution computed tomography

Temporal bone abnormalities such as hypoplasia of the vestibular aqueduct or hypopneumatization of the mastoid have been described in Meniere's disease (MD). Jugular bulb abnormalities (JBA) are one of the most common temporal bone abnormalities. The aim of this study was to evaluate the frequency of JBA in MD. Radiological data obtained by temporal bone high-resolution computed tomography of 200 ears of 167 MD patients (MD group) and 218 ears of 109 patients with normal inner ear function (control group) were analyzed retrospectively. The frequencies of high jugular bulb (HJB), jugular bulb diverticulum (JBD), inner ear adjacent jugular bulb (IAJB) and jugular bulb related inner ear dehiscence (JBID) were evaluated and compared between MD group and control group. IAJB was differentiated into vestibular aqueduct adjacent jugular bulb (VAAJB), cochlear aqueduct adjacent jugular bulb and posterior semicircular canal adjacent jugular bulb. JBID was further analyzed by differentiating into jugular bulb related vestibular aqueduct dehiscence (JBVAD), jugular bulb related cochlear aqueduct dehiscence and jugular bulb related posterior semicircular canal dehiscence. The frequencies of HJB, JBD and IAJB were higher in MD group compared to control group (21, 13.3 %, p = 0.036; 8.5, 3.7 %, p = 0.037; 13.5, 4.6 %, p = 0.001). No differences between both groups were seen in JBID (4.0, 2.3 %, p = 0.315). Most IAJB and JBID were seen in VAAJB and JBVAD. There is a higher frequency of JBA in patients with MD than in patients without inner ear symptoms. Temporal bones of MD patients might be constituted anatomically different, carrying predisposing factors for the development of clinically apparent MD.

Posterior Semicircular Canal Dehiscence

To estimate the prevalence of and symptoms associated with posterior semicircular canal dehiscence (PSCD) compared to superior semicircular canal dehiscence (SSCD) and nondehiscent semicircular canals (NDSC). Retrospective review. Academic tertiary referral center. Review of 412 temporal bone CT scans and associated patient records, excluding patients with prior mastoid or skull base surgery. CT images (0.625 mm thick) were reviewed in the planes of the semicircular canals. Patient demographics and symptoms were tabulated and analyzed. Prevalence of PSCD and SSCD; degree of hearing loss; presence or absence of aural fullness, autophony, tinnitus, pulsatile tinnitus, disequilibrium, vertigo, and Tullio phenomenon. Review of the 412 CT scans revealed 5 cases of PSCD (1.2%) and 20 cases of SSCD (4.9%). All patients with PSCD were male, aged 16 to 73 years. One patient with PSCD reported tinnitus, autophony, disequilibrium, vertigo, and Tullio phenomenon; 2 patients reported only tinnitus and aural fullness, and 1 patient had no symptoms. PSCD was commonly associated with SSCD. There were no significant differences in symptoms between PSCD patients and the other groups. There were, however, statistically significant differences between SSCD patients and NDSC patients in the rates of autophony, tinnitus, and disequilibrium. The prevalence of PSCD in patients undergoing temporal bone CT scans is considerably less than SSCD (1.2% versus 4.9%), and the 2 conditions commonly coexist. Given the small numbers in our study, we were not able to demonstrate any distinguishable clinical features for the PSCD patients.

Congenital Dehiscence in the Posterior Semicircular Canal

Posterior semicircular canal dehiscence (PSCD) may be of congenital origin. PSCD is characterized by the lack of bone coverage, which results in its lumen being exposed to the meninges of the posterior cranial fossa or to the gulf of the jugular vein. It has an incidence of 0.2%. Its presence has been associated with several well-defined entities, although a congenital origin has not been proven. We have analyzed, from a macroscopic, microscopic, and radiologic (computed tomography) viewpoint, the right temporal bone of a 32-week-old human fetus that presented a defect in the bone coverage located in the rear. The macroscopic study showed a solution of continuity in the posterior semicircular canal, with elliptic morphology and smooth edges. This defect was 3.4 mm long with a width that varied between 0.67 mm in its apical portion and 1.42 in the basal portion. The radiologic study (computed tomography) showed the absence of bone coverage of the posterior semicircular canal, which was open to the intracranial space in the posterior fossa. Its histologic study showed good bone coverage of this canal at the expense of compact bone tissue. However, at the medial end, there is a lack of bone coverage, resulting in the lumen of the canal being open to the intracranial space. The bone edges of the defect did not present any osteoclast activity. The lack of bone coverage (dehiscence) of the posterior semicircular canal in a 32-week-old fetus suggests a congenital component of bony dehiscences of this canal. Even so, this single finding does not conclusively prove the congenital component, and the dehiscence is a finding that can be part of and not by itself a syndrome.

Repair of Posterior Semicircular Canal Dehiscence from a High Jugular Bulb

We describe the clinical evaluation and operative management of posterior semicircular canal dehiscence caused by a high jugular bulb. We performed a retrospective case report. The patient had clinical and audiometric findings consistent with semicircular canal dehiscence and imaging findings that demonstrated erosion of the posterior semicircular canal by a high jugular bulb. Resurfacing of the eroded canal provided resolution of the vestibular symptoms without damage to the inner ear. Dehiscence of the posterior semicircular canal can cause clinical and audiometric findings similar to those of superior semicircular canal dehiscence syndrome. Resurfacing of the area of dehiscence can successfully relieve the vestibular symptoms. In the case of dehiscence of the posterior canal from a high jugular bulb, resurfacing may offer advantages over canal plugging for definitive management.

Bilateral Posterior Semicircular Canal Dehiscence in the Setting of Hallermann-Streiff Syndrome

Hallermann-Streiff syndrome, also known as oculomandibulofacial syndrome, is a rare congenital disorder affecting growth and cranial, dental, ocular, pilocutaneous, and mental development. In addition to routine audiologic testing in patients with this syndrome, high-resolution computed tomography of the temporal bones should be performed in those with documented or suspected sensorineural hearing loss. Cochlear implantation may be considered, as in other children with syndromic hearing loss and certain inner ear abnormalities, if the appropriate audiologic, psychosocial, and medical criteria are met. The current case report radiographically and clinically characterizes inner ear dysplasia in an 8-year-old patient with Hallermann-Streiff syndrome. High-resolution computed tomography of the temporal bones revealed a hypoplastic bony island between the vestibule and horizontal semicircular canals, as well as incomplete bony coverage of the posterior semicircular canal crura bilaterally. To our knowledge, this is the first report of a pediatric patient demonstrating bilateral posterior semicircular canal dehiscence.