Posterior Semicircular Canal Dehiscence Research Articles

Surgical treatment of posterior semicircular canal dehiscence syndrome caused by jugular diverticulum

We report a rare case of posterior semicircular canal dehiscence caused by a jugular diverticulum, and we describe its surgical treatment using a dehiscence resurfacing manoeuvre. The clinical findings, surgical procedure and outcomes are presented. A 66-year-old man presented with disequilibrium, sound-induced vertigo, a reduced ocular vestibular evoked myogenic potential threshold, and pressure-induced vertical and torsional nystagmus. Computed tomography revealed a right posterior semicircular canal dehiscence caused by a diverticulum of the jugular bulb. The defect in the posterior semicircular canal was localised and resurfaced with bone paté, temporalis muscle fascia and conchal cartilage, under direct visualisation. Post-operatively, the patient's symptoms disappeared and his ocular vestibular evoked myogenic potential threshold normalised. This case illustrates that posterior semicircular canal dehiscence can be surgically managed by resurfacing the defect site via a transmastoid approach.

Audiological signs in pediatric cases with dehiscence of the bony labyrinth caused by a high jugular bulb

Clinical findings were assessed in three pediatric cases of dehiscence of the bony labyrinth caused by a high jugular bulb (HJB). Two children had two dehiscent lesions, which included posterior semicircular canal dehiscence (PSCD) and vestibular aqueduct dehiscence (VAD). One child had VAD alone. Two subjects with PSCD, but not with VAD alone, had mixed hearing loss and showed wave motion of the baseline on tympanometry and acoustic reflex testing, and a reduced response on otoacoustic emission. These findings may reflect jugular venous pulsations transmitted through the PSC and represent characteristics of cases with PSCD caused by HJB.

Canal dehiscence

The aim is to review canal dehiscence involving the superior, lateral, and posterior semicircular canals. The main focus will be on superior semicircular canal dehiscence. Canal dehiscence involving the superior, lateral, and posterior semicircular canal can have different etiologies, including developmental abnormality, congenital defect, chronic otitis media with cholesteatoma, and high-riding jugular bulb. However, their clinical presentation can be very similar, with patients complaining of vertigo, oscillopsia, and sometimes hearing loss. Canal dehiscence causes an abnormal communication between the inner ear and the surrounding structures. This creates a third mobile window within the inner ear, disrupting its normal mechanics and causing symptoms. Superior semicircular canal dehiscence is now a well-established entity in the medical literature. Surgical repair is effective at relieving patients' vestibular symptoms. Lateral semicircular canal dehiscence is usually associated with chronic otitis media. Posterior semicircular canal dehiscence is a rare entity, with similar clinical presentations and treatment options as the other canal dehiscences.

New findings in the semicircular canal dehiscence syndrome

We describe a young patient with conductive hearing loss (CHL) associated with a posterior semicircular canal dehiscence (PCD) next to a large jugular bulb. Vestibular evoked myogenic potentials (VEMPs), audiogram, and computed tomography (CT) confirmed the diagnosis. The contralateral ear also showed lowered VEMP thresholds and PCD on CT, but no CHL. Increased vigilance is warranted in the evaluation of CHL in patients with uninfected, normal-appearing ears. PCD as a cause of CHL is just beginning to surface in the otologic literature. This case, along with two other recent case series, demonstrates the need for CT imaging in cases of atypical CHL.

The Association Between Semicircular Canal Dehiscence and Chiari Type I Malformation

To investigate the association between semicircular canal dehiscence (SCD) and Chiari type I malformation (CM-I). Retrospective case series. Military tertiary referral center. Adult patients with SCD. Review of records of patients diagnosed as having SCD for the radiologic diagnosis of CM-I and presenting symptoms. The prevalence of CM-I among patients with SCD and the presenting symptoms of patients with SCD with and without a coexistent CM-I. Of 32 patients diagnosed as having SCD, 30 underwent magnetic resonance imaging of the brain. Seven patients (23%; 95% confidence interval [CI], 12%-41%) were found to have a CM-I. Chiari type I malformation was associated with superior SCD in 3 of 26 patients (12%; 95% CI, 3%-30%). Of 10 patients with bilateral superior SCD, 2 (20%; 95% CI, 5%-52%) had a CM-I. Five of 6 patients (83%; 95% CI, 42%-99%) had a CM-I with unilateral or bilateral posterior SCD. Twenty-nine records were reviewed for presenting symptoms, and no significant difference was observed between patients with SCD alone and those with an associated CM-I (P = .09-.64). Among patients with SCD, the prevalence of CM-I is elevated. This association is especially marked in patients with posterior SCD. This finding suggests a relationship between CM-I and SCD, particularly with posterior SCD.

Operative Management of Posterior Semicircular Canal Dehiscence from a High Jugular Bulb

Operative Management of Posterior Semicircular Canal Dehiscence from a High Jugular Bulb

Posterior Semicircular Canal Dehiscence

Posterior semicircular canal dehiscence has been shown to cause ear symptoms. To evaluate the incidence of dehiscence of the posterior semicircular canal, thin bone overlying the posterior semicircular canal, and the normal development of the distance between the posterior semicircular canal and posterior cranial fossa. The shortest distance between the posterior semicircular canal and posterior cranial fossa was measured in 1,051 adult human temporal bones (557 cases), and temporal bones with a distance less than 0.1 mm were evaluated. The shortest distance also was measured in 4 fetal temporal bones (2 cases) and 110 temporal bones from children. Of the 1,051 temporal bones, 23 temporal bones (2.2%) had a distance less than 0.1 mm between the posterior semicircular canal and posterior cranial fossa. Two temporal bones (0.2%) had posterior semicircular canal dehiscence, and 2 temporal bones had microfractures in the thin bone; however, related clinical symptoms were not confirmed. In children, the distance between the posterior semicircular canal and the posterior cranial fossa increased with age (rho = 0.68, p < 0.01). The histopathologic incidence of posterior semicircular canal dehiscence was lower than the previous radiographic reports. The dehiscence of the posterior semicircular canal may be due to a developmental anomaly. In our study, none of the cases with a distance less than 0.1 mm had apparent symptoms related to canal dehiscence syndrome. Other factors, in addition to thinning of the bone, may be required to cause the clinical manifestations.

Posterior semicircular canal dehiscence in asymptomatic ears

Conclusions: This study revealed that, in the adult population, the final diagnosis of this entity can only be made by combining imaging with clinical tests. Objective: We developed the largest temporal bone multislice computed tomography (CT) scan study so far by including 410 cases to investigate the prevalence of posterior semicircular canal dehiscence in patients with symptoms unrelated to the inner ear. Methods: A prospective study was performed in 410 consecutive adult individuals who underwent temporal bone multislice CT scan examinations. Results: The prevalence of posterior semicircular canal dehiscence was determined to be 1.2%. No superior or lateral semicircular canal defect was detected in these five patients. All cases with posterior semicircular canal defect were male. In two cases the canal was located unilaterally, while in three cases the defects were present bilaterally. Otological examination and audiovestibular tests revealed no abnormal findings in any of the individuals.

Posterior Semicircular Canal Dehiscence

To identify clinical, audiological, and vestibular characteristics of posterior semicircular canal dehiscence. Retrospective case review. Tertiary referral center. Twelve patients aged 2 to 67 years identified with posterior semicircular canal dehiscence. Patients identified by suspicious clinical history and examination, confirmed by high-resolution computed tomography. Audiological evaluation included air and bone audiometry, tympanometry, acoustic reflexes, and vestibular evoked myogenic potential testing. Hearing loss was mixed in 9 patients, conductive in 2 patients, and sensorineural in 1 patient, with downward-sloping configuration being the most common. Imaging revealed that 7 of 12 patients had dehiscence into a high-riding jugular bulb and 1 patient had an enlarged vestibular aqueduct with a Mondini malformation. One patient had Apert syndrome and another patient had microtia/atresia. Vestibular symptoms were more common in the adult patients than in the pediatric patients, with chronic disequilibrium the most common complaint. Vestibular evoked myogenic potential testing confirmed dehiscence with the characteristic response of reduced threshold and higher amplitude compared with healthy patients. This is the first reported series of adult and pediatric patients with symptomatic posterior semicircular canal dehiscence. 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. Patients found to have a high-riding jugular bulb and hearing loss should have specific inspection of the posterior canal to ensure it is not dehiscent.

Anatomo-radiological study of the Superior Semicircular Canal Dehiscence: Radiological considerations of Superior and Posterior Semicircular Canals

Introduction The main purpose of this study is to determine the radiological incidence of Superior (SSCD) and Posterior Semicircular Canal Dehiscence (PSCD) and to compare radiologic SSCD to the incidence of this condition on cadaver specimen. We have also analysed the relation between the ossification state of the semicircular canals and the degree of mastoid pneumatization and integrity of Tegmen Tympani. Material and methods Temporal bones have been investigated by means of CT scan on patients and direct observation on cadaver specimen, respectively. Results 604 ears and 160 cadaver temporal bones have been investigated by means of CT scan and direct observation, respectively. 3.6% and 0.3% of the studied ears had SSCD and PSCD, respectively, on CT scan. Only 0.6% of the cadaver specimen ears did have anatomical SSCD. Degree of pneumatization of the mastoid bone is related to the mean thickness of bone overlying the Superior and Posterior Semicircular Canal. Radiological absence of Tegmen Tympani is more frequent in ears that also have radiologic SSCD. Conclusion CT scanning gives higher incidence figures of SSCD than anatomical studies, 3.6% vs. 0.6%. We also found a 0.6% incidence of radiological PSCD in the studied ears. There is a direct relation between the degree of ossification of Superior and Posterior Semicircular Canal and certain temporal bone anatomic features: temporal bone pneumatization and absence/presence of Tegmen Tympani or Antri.

Clinical and Diagnostic Characterization of Canal Dehiscence Syndrome

OBJECTIVE:: To identify otologic and audiologic characteristics of superior (and posterior) semicircular canal dehiscence (SCD). STUDY DESIGN:: Retrospective case review. SETTING:: Tertiary referral center. PATIENTS:: Sixty-five adult patients were evaluated for SCD; 26 of 65 (35 ears) had dehiscence. INTERVENTION(S):: Otologic examination, high-resolution computerized tomography (CT), air and bone audiometry, tympanometry, acoustic reflex, and vestibular evoked myogenic potential (VEMP). MAIN OUTCOME MEASURE(S):: Imaging demonstrating canal dehiscence, preferentially including Poschel and Stenvers reconstructions. Audiologic findings of pseudoconductive loss, intact ipsilateral stapedial reflex, and abnormally low VEMP thresholds. RESULTS:: The most common presenting complaints were autophony of voice and a "blocked ear" (94%), mimicking patulous eustachian tube, including relief with Valsalva or supine position (50%), but without autophony of nasal breathing. Pseudoconductive loss was found in 86% of dehiscence ears, and 60% (21 of 35) of these ears had better than 0-dB-hearing-loss bone conduction thresholds at 250 and/or 500 Hz. Acoustic reflex was present in 89%. Assuming CT as the criterion standard, VEMP resulted in 91.4% sensitivity and 95.8% specificity. One false-positive CT, with abnormal VEMP, resulted in surgical explorations negative for superior SCD but positive for posterior SCD. CONCLUSION:: Semicircular canal dehiscence may present with various symptoms such as autophony, ear blockage, and dizziness/vertigo. A combination of high-resolution CT and audiologic testing is recommended for diagnosis. Low-frequency conductive loss with better than 0 dB hearing level (HL) bone conduction threshold and normal tympanometry, with intact acoustic reflexes, are audiologic signs of SCD. Vestibular evoked myogenic potential is highly sensitive and specific for SCD, possibly better than CT.

Posterior Canal Dehiscence Syndrome Caused by an Apex Cholesteatoma

To compare audio-vestibular findings caused by a dehiscence of the posterior semicircular canal with those found in the superior canal dehiscence syndrome. Case report. University hospital, tertiary referral center. The 44-year-old woman suffered from a gradual hearing loss with pulse-synchronous tinnitus as well as sound and pressure-induced vertigo. Audio-vestibular testing and high-resolution computed tomography. The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound- and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle-ear function. We present a patient with very similar symptoms and findings who, instead, had a posterior semicircular canal dehiscence caused by an apex cholesteatoma. Patients with semicircular canal dehiscence have common auditory-vestibular features regardless of which of the two vertical semicircular canals is affected. The only obvious difference between the two is the vertical component of the sound and pressure-induced eye movements (which beats in opposite directions).

Operative Management of a Posterior Semicircular Canal Dehiscence

The objective of this study was to describe the operative management of posterior canal dehiscence. A transmastoid approach to and plugging of the posterior canal was performed for posterior semicircular canal dehiscence (PSCD). Postoperatively, the patient exhibited improvement in conductive hearing loss and vestibular symptoms. PSCD can cause symptoms identical to that of superior semicircular canal dehiscence. Successful PSCD plugging can be performed without visualization of the actual area of dehiscence.

Posterior semicircular canal dehiscence: a morphologic cause of vertigo similar to superior semicircular canal dehiscence.

The aim of this study was to assess imaging findings of posterior semicircular dehiscence on computed tomography and to evaluate incidence of posterior and superior semicircular canal dehiscence in patients presenting with vertigo, sensorineuronal hearing loss or in a control group without symptoms related to the inner ear. Computed tomography was performed in 507 patients presenting either with vertigo ( n=128; 23 of these patients suffered also from sensorineuronal hearing loss), other symptoms related to the inner ear, such as hearing loss or tinnitus ( n=183) or symptoms unrelated to the labyrinth ( n=196). All images were reviewed for presence of dehiscence of the bone, overlying the semicircular canals. Twenty-nine patients had superior semicircular canal dehiscence. Of these patients, 83% presented with vertigo, 10% with hearing loss or tinnitus and the remaining 7% with symptoms unrelated to the inner ear. In 23 patients dehiscence of the posterior semicircular canal was encountered. Of these patients, 86% presented with vertigo, 9% with hearing loss or tinnitus and 5% with symptoms unrelated to the inner ear. Defects of the bony overly are found at the posterior semicircular canal, in addition to the recently introduced superior canal dehiscence syndrome. Significant prevalence of vertigo in these patients suggests that posterior semicircular canal dehiscence can cause vertigo, similar to superior semicircular canal dehiscence.