Superior Canal Dehiscence and the Risk of Additional Dehiscences: A Retrospective CT Cohort Study.

OBJECTIVE: Determine if superior canal dehiscence (SCD) found on flat-panel CT increases the risk for other defects in the otic capsule. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary care center. PATIENTS: One hundred ears (50 with SCD and 50 matched controls without SCD). INTERVENTIONS: Flat-panel CT imaging. MAIN OUTCOME MEASURES: (1) Prevalence of other dehiscences in SCD ears, (2) dehiscences in controls, and (3) otic capsule thickness in other reported dehiscence locations (cochlea-carotid, lateral semicircular canal [SCC] and mastoid, facial nerve-lateral SCC, vestibular aqueduct, posterior SCC-jugular bulb, posterior SCC-posterior fossa). Between-group comparisons were considered significant at p < 0.007 after applying the Bonferroni correction for multiple comparisons. RESULTS: Not including the SCD, there was a mean of 0.04 additional dehiscences in the SCD group (n = 2/50, 4%) and 0.04 non-SCD dehiscences in the controls (n = 2/50, 4%, p > 0.007). In the SCD group, there was one dehiscence between the cochlea and carotid artery and one between the posterior SCC and posterior fossa. The control group had one enlarged vestibular aqueduct and one dehiscence between the facial nerve and lateral SCC. As a group, SCD ears had wider vestibular aqueducts (0.68 ± 0.20 vs 0.51 ± 0.30 mm, p < 0.007) and thinner bone between the posterior SCC and posterior fossa (3.12 ± 1.43 vs 4.34 ± 1.67 mm, p < 0.007). The bone between the facial nerve and lateral SCC was thicker in SCD ears (0.77 ± 0.23 vs 0.55 ± 0.27 mm, p < 0.007) and no different for cochlea-carotid, and lateral SCC and mastoid (p > 0.007). CONCLUSIONS: SCD does not increase the likelihood of a second dehiscence in the same otic capsule. SCD patients may have congenitally thinner otic capsule bones compared to controls, particularly near the posterior SCC, where the vestibular aqueduct may be enlarged.

Measurement of stapes footplate thickness using ultra-high-resolution computed tomography: stapes axial plane correlates better with otosclerosis than lateral semicircular canal plane.

BACKGROUND, AIMS: Stapes footplate thickness measurement using ultra-high-resolution CT has been described only in the lateral semicircular canal plane. The purpose of this study was to compare stapes footplate thickness between the lateral semicircular canal and stapes axial planes in patients with otosclerosis compared to controls. MATERIAL AND METHODS: We performed a retrospective single-center study of patients undergoing high-resolution temporal bone CT. Two radiologists measured stapes footplate thickness in both the lateral semicircular canal and stapes axial planes. RESULTS: Between February 2020 and October 2022, we collected 81 ears from 49 patients (75% of women; mean age 51.22 ± 16.6 years, 17 otosclerosis, and 64 controls). In the stapes axial plane, there was a significant anterior thickening in otosclerosis patients (Reader 1: 0.52 ± 0.12 [0.3-0.7] vs. 0.41 ± 0.08 [0.3-0.6], p = 0.001; Reader 2: 0.54 ± 0.06 [0.5-0.7] vs. 0.39 ± 0.08 [0.2-0.6], P < 0.001) compared to controls. These differences were not significant using the lateral semicircular canal plane. CONCLUSION: The stapes footplate was thickened at its AC in otosclerosis patients using only the stapes axial plane. SIGNIFICANCE: We propose to use the stapes axial plane instead of the lateral semicircular canal plane when analyzing the stapes.

The importance of bone density and anatomical structure in superior semicircular canal dehiscence.

OBJECTIVE: This study investigates the importance of bone density, surface area, and diameter of anatomical structures of the superior semicircular canal (SSC), lateral semicircular canal (LSC), posterior semicircular canal (PSC), utricle, and saccule in patients diagnosed with superior semicircular canal dehiscence (SSCD). MATERIALS AND METHODS: The bone density, surface area, and diameter of SSC, LSC, PSC, utricle, and saccule were measured and compared between the SSCD group and control group. Fifteen ears in the SSCD group and 60 ears in the control group were evaluated. Additionally, within the SSCD group, the dehiscent and healthy sides were evaluated independently. RESULTS: SSC's bone density was significantly lower in the SSCD group compared to the control group (p = 0.008). No significant differences were found in surface area and diameter between the groups (p > 0.05). While most of the anatomical structures showed no significant difference in bone density between dehiscent and healthy ears (p > 0.05), SSC bone density was significantly lower in affected ears (p = 0.000) in SSCD group. CONCLUSION: Based on the data obtained in this study, bone density and anatomical structure may be useful in patients diagnosed with SSCD.

Superior canal dehiscence syndrome: A review.

Superior canal dehiscence syndrome (SCDS) is a vestibular disorder in which the presence of a pathological third window in the labyrinth causes several vestibular and cochlear symptoms. Herein, we review the diagnostic criteria and treatment of SCDS. The cause of SCDS is considered to be congenital or acquired; however, its etiology is not well known. Symptoms: Vertigo and/or oscillopsia induced by loud sounds (Tullio phenomenon) or stimuli that change the middle ear or intracranial pressure (fistula symptoms) with vestibular symptoms and hyperacusis and aural fullness with cochlear symptoms are characteristic clinical complaints of this syndrome. Neurological tests: Vertical-torsional eye movements can be observed when the Tullio phenomenon or fistula symptoms are induced. Conductive hearing loss with both a decrease in the bone conduction threshold at lower frequencies and an increase in the air conduction threshold at lower frequencies may be present on audiometry. Cervical and/or ocular vestibular evoked myogenic potentials are effective in strongly suspecting the presence of a pathologic third window in the labyrinth. Computed tomography (CT) imaging: High-resolution CT findings with multiplanar reconstruction in the plane of the superior semicircular canal consistent with dehiscence indicate SCDS. The Pöschl view along the plane of the superior semicircular canal and the Stenvers view perpendicular to it are recommended as CT imaging conditions. Findings from all three major diagnostic categories (symptoms, neurological tests, and/or CT imaging) are needed to diagnose SCDS. The surgical approaches for SCDS are as follows: the 1) middle cranial fossa approach, 2) transmastoid approach, and 3) round window and oval window reinforcement. Each technique has advantages and disadvantages.

Third window lesions of the inner ear: A pictorial review.

PURPOSE: Radiographic review of pathologies that associate with third window syndrome. METHODS: Case series and literature review. RESULTS: Eight unique third window conditions are described and illustrated, including superior, lateral, and posterior semicircular canal dehiscence; carotid-cochlear, facial-cochlear, and internal auditory canal-cochlear dehiscence, labyrinthine erosion from endolymphatic sac tumor, and enlarged vestibular aqueduct. CONCLUSION: The present study highlights the characteristic imaging features and symptoms to differentiate third window pathologies for expedient diagnosis and management planning.

Canalith jam del horizontal: Revisión y reporte de dos casos / Horizontal canalith jam: Review and two cases report

El vértigo posicional paroxístico benigno (VPPB) es un síndrome vestibular episódico (SVE) que es reconocido por ser el trastorno más frecuente observado en la clínica, siendo de buena y pronta resolución en la gran mayoría de los casos. Sin embargo, pueden presentarse variantes muy poco habituales o atípicas, donde el canalith jam es una de las formas más resistentes al tratamiento mediante maniobras de reposición, y por lo mismo, el reconocimiento adecuado de este cuadro es esencial para su correcto abordaje. Se presentan dos casos de VPPB con canalith jam en el CSC horizontal y se proponen cinco criterios diagnósticos para su identificación.

Benign paroxysmal positional vertigo (BPPV) is an episodic vestibular syndrome (EVS) that is recognized for being the most frequent disorder observed in the clinic, with good and prompt resolution in the vast majority of cases. However, very unusual or atypical variants can occur, where the canalith jam is one of the forms most resistant to treatment by means of repositioning maneuvers, and for the same reason, the adequate recognition of this condition is essential for its correct approach. Two cases of BPPV with canalith jam in the horizontal semicircular canal and five diagnostic criteria for its identification are presented.

Prevalence of Cochlear-Facial and Other Non-Superior Semicircular Canal Third Window Dehiscence on High-Resolution Temporal Bone CT.

BACKGROUND AND PURPOSE: The radiologic prevalence of superior semicircular canal dehiscence in the asymptomatic population has been widely studied, but less is known about the rates of other forms of third window dehiscence. Per the existing literature, the radiologic prevalence of cochlear-facial nerve dehiscence, for example, exceeds that seen in histologic studies, suggesting that conventional CT is unreliable for cochlear-facial dehiscence. These studies relied on nonisometric CT acquisitions, however, and underused multiplanar reformatting techniques, leading to false-positive findings. Our purpose was to determine the rate of cochlear-facial dehiscence and other non-superior semicircular canal third window dehiscences on optimized CT in asymptomatic patients. MATERIALS AND METHODS: Sixty-four-channel temporal bone CT scans from 602 patients in emergency departments were assessed for cochlear-facial and other non-superior semicircular canal third window dehiscences by using high-resolution, multiplanar oblique reformats. Confidence intervals for dehiscence prevalence were calculated using the Newcombe 95% interval confidence method. RESULTS: Of 602 patients, 500 were asymptomatic, while 102 had an imaging indication consistent with possible third window syndrome (symptomatic). Eight asymptomatic patients (1.6%) had cochlear-facial dehiscence, while 43 (8.4%) had jugular bulb-vestibular aqueduct dehiscence. There was no statistically significant difference between the prevalence of cochlear-facial dehiscence or jugular bulb-vestibular aqueduct dehiscence in asymptomatic patients compared with symptomatic patients. Cochlear-carotid canal, cochlear-internal auditory canal, and cochlear-petrosal sinus dehiscences were not observed. CONCLUSIONS: Sixty-four-channel CT with multioblique reformatting is sensitive and specific for identifying cochlear-facial dehiscence, with rates similar to those in postmortem series. Jugular bulb-vestibular aqueduct dehiscence is a common incidental finding and is unlikely to produce third window physiology. Other non-superior semicircular canal third window dehiscences are rare in asymptomatic patients.

[Diagnosis and rehabilitation of anterior canal benign paroxysmal positional vertigo]. / Osobennosti diagnostiki i reabilitatsii dobrokachestvennogo paroksizmal'nogo pozitsionnogo golovokruzheniya pri otolitiaze perednego polukruzhnogo kanala.

OBJECTIVE: To assess clinical symptoms and rehabilitation of anterior canal benign paroxysmal positional vertigo (aBPPV) in comparison to horizontal canal BPPV (hBPPV) and posterior canal BPPV (pBPPV). PATIENTS AND METHODS: The study included 22 patients with aBPPV, 450 patients with pBPPV and 88 patients with hBPPV from total 640 patients with definite BPPV. Rehabilitation of BPPV included different manual repositioning maneuvers. In case of unsuccessful reposition during the visit the patients practiced various home-based repositioning maneuvers and underwent reposition in multipositional mechanical chair. Clinical symptoms and repositioning process in patients with aBPPV were compared to patients with hBPPV and pBPPV, nystagmus was analyzed in aBPPV during the rehabilitation. RESULTS: ABPPV is a rare type of otolithiasis (3.4% of all BPPVcases). aBPPV typically has no association with middle and inner ear pathology and head trauma. Clinical symptoms in aBPPV are equal to pBPPV and less severe than in hBPPV. In aBPPV cases dominates cupulolithiasis type of canal involvement, which leads to treatment resistance and complex rehabilitation process, which includes repeat visits, multiple repeat maneuvers by specialist, home-based treatment and use of multipositional mechanical chair. Residual dizziness with duration more than a week after successful reposition occurs more often in patients with aBPPV compared to hBPPV and pBPPV cases. In aBPPV cases atypical change of nystagmus could be observed which could be due to canal switch from anterior to posterior canals, primary location of otoliths in common crus of vertical canals or masking chronic otolithiasis of anterior short arm of posterior canal.

Benign Paroxysmal Positional Vertigo: Is It Really an Otolith Disease?

The current theory in physiopathology of benign paroxysmal positional vertigo is the mechanical theory, namely the cupulolithiasis-canalolithiasis theory. Repositioning maneuvers based on this theory has now taken place in therapy. However, mechanical theory is insufficient to explain some clinical situations and cannot fully enlighten the physiopathology. Mechanical theory is based on very few histological studies. Currently, these few articles are still used for reference. Anatomically, there are uncertainties that need to be explained in this theory. In this literature review, the histological and anatomical evidence is reviewed and the value of mechanical theory in benign paroxysmal positional vertigo physiopathology has been questioned. Studies suggest that the debris in the semicircular canals is caused by degeneration due to aging and may not be responsible for the symptoms in benign paroxysmal positional vertigo. Some patients with debris in semicircular canals do not have benign paroxysmal positional vertigo symptomatology, while some patients without debris may have benign paroxysmal positional vertigo symptomatology. Experimental and histological findings suggest that vestibulopathy due to inflammation caused by neurotropic viruses may lead to benign paroxysmal positional vertigo picture. For all these reasons, in benign paroxysmal positional vertigo physiopathology, there must be other factors besides particle debris in semicircular canals.

Low accuracy of 1.5 Tesla magnetic resonance imaging in identification of the bony defect in patients with superior semi-circular canal dehiscence syndrome: case-control study.

OBJECTIVE: To determine the accuracy of 1.5 Tesla magnetic resonance imaging in identifying the bony defect in superior semi-circular canal dehiscence syndrome. METHODS: A retrospective case-control study was conducted in tertiary university settings. The study included 12 patients with a definite diagnosis of superior semi-circular canal dehiscence syndrome and a control group comprising 12 non-superior semi-circular canal dehiscence syndrome patients, all with available magnetic resonance imaging data. The imaging scans were anonymised, and reviewed blindly and independently by three experienced radiologists. RESULTS: There was low sensitivity and specificity, with average values of 47 per cent (range, 16.7-66.7 per cent) and 69 per cent (range, 66.7-75 per cent) respectively. Cohen's kappa was 0.75, indicating substantial inter-rater reliability. CONCLUSION: Given the low accuracy of 1.5T magnetic resonance imaging in identifying the bony defect in superior semi-circular canal dehiscence syndrome, despite its value in inner-ear imaging, computed tomography or equivalent should be used when superior semi-circular canal dehiscence syndrome is suspected.

Concomitant Dehiscences of the Temporal Bone: A Case-Based Study.

Otic capsule dehiscences create a pathological third window in the inner ear that results in a dissipation of the acoustic energy consequent to the lowered impedance. Superior semicircular canal dehiscence (SSCD) was identified by Minor et al in 1998 as a syndrome leading to vertigo and inner ear conductive hearing loss. The authors also reported the relation between the dehiscence and pressure- or sound-induced vertigo (Tullio's phenomenon). Prevalence rates of SSCD in anatomical studies range from 0.4% to 0.7% with a majority of patients being asymptomatic. The observed association with other temporal bone dehiscences, as well as the propensity toward a bilateral or contralateral "near dehiscence," raises the question of whether a specific local bone demineralization or systemic mechanisms could be considered. The present report regard a case of a patient with a previous episode of meningitis, with a concomitant bilateral SSCD and tegmen tympani dehiscence from the side of meningitis. The patient was affected by dizziness, left moderate conductive hearing loss, and pressure/sound-induced vertigo. Because of disabling vestibular symptoms, the patient underwent surgical treatment. A middle cranial fossa approach allowed to reach both dehiscences on the symptomatic side, where bone wax and fascia were used for repair. At 6 months from the procedure, hearing was preserved, and the vestibular symptoms disappeared.

Magnetic resonance imaging of endolymphatic hydrops in patients with unilateral Meniere's disease: a comparison between with and without herniation into the posterior and lateral semi-circular canals.

BACKGROUND: The presence of endolymphatic hydrops (ELH) in patients with Meniere's disease (MD) is considered a pathological hallmark. AIMS/OBJECTIVES: We aimed to conduct a quantitative volumetric measurement of inner ear ELH in patients with unilateral MD (uMD). The values of uMD with and without herniation into the posterior semi-circular canal (h-PSC) and the lateral semi-circular canal (h-LSC) were compared using 3 D magnetic resonance imaging. MATERIAL AND METHODS: This study included 130 individuals (47 controls and 83 patients with uMD). We measured the total fluid space (TFS) and endolymphatic space (ELS) volumes. We also evaluated the ELS/TFS volume ratios (%). RESULTS: The ELS/TFS volume ratios in the inner ear, cochlea, and vestibule were significantly different between the affected and contralateral sides in patients with h-PSC. Moreover, the ELS/TFS volume ratios of the inner ear, vestibule, and semi-circular canals in the affected ear were significantly higher in patients with h-PSC than in those without h-PSC. The vestibular ELS/TFS volume ratio in the affected ear was significantly higher in patients with h-LSC than in those without h-LSC. CONCLUSIONS AND SIGNIFICANCE: H-LSC is present in extended vestibular ELH. However, this is a result of ELH progression in the inner ear.

Intratympanic Steroid Injection Complicated by Iatrogenic Perilymphatic Fistula: A Cautionary Tale.

Intratympanic (IT) steroid therapy is a mainstay treatment for sudden sensorineural hearing loss (SSNHL) for both initial therapy and salvage therapy. We report a rare case of iatrogenic perilymphatic fistula that resulted from trauma during an IT steroid injection for SSNHL. We discuss the diagnosis and treatment in the current case and compare it with previous reports from the literature. Laryngoscope, 131:2088-2090, 2021.

Optimized preoperative determination of nerve of origin in patients with vestibular schwannoma.

In vestibular schwannoma (VS) patients hearing outcome and surgery related risks can vary and depend on the nerve of origin. Preoperative origin differentiation between inferior or superior vestibular nerve may influence the decision on treatment, and the selection of optimal treatment and counselling modalities. A novel scoring system based on functional tests was designed to predict the nerve of origin for VS and was applied to a large number of consecutive patients. A prospective, double blind, cohort study including 93 patients with suspected unilateral VS was conducted at a tertiary referral centre. Preoperatively before tumor resection a functional test battery [video head-impulse test (vHIT) of all semicircular canals (SCC)], air-conducted cervical/ocular vestibular evoked myogenic potential tests (cVEMP, oVEMP), pure-tone audiometry, and speech discrimination was applied. Sensitivity and specificity of prediction of intraoperative finding by a preoperative score based on vHIT gain, cVEMP and oVEMP amplitudes and asymmetry ratios was calculated. For the prediction of inferior vestibular nerve origin, sensitivity was 73% and specificity was 80%. For the prediction of superior vestibular nerve origin, sensitivity was 60% and specificity was 90%. Based on the trade-off between sensitivity and specificity, optimized cut-off values of - 0.32 for cVEMP and - 0.11 for oVEMP asymmetry ratios and vHIT gain thresholds of 0.77 (anterior SCC), 0.84 (lateral SCC) and 0.80 (posterior SCC) were identified by receiver operator characteristic curves. The scoring system based on preoperative functional tests improves prediction of nerve of origin and can be applied in clinical routine.

Reversible Canalith Jam of the Horizontal Semicircular Canal Mimicking Cupulolithiasis.

OBJECTIVE: To describe a case of benign paroxysmal positional vertigo (BPPV) resulting in reversible horizontal semicircular canalith jam successfully treated with horizontal canal occlusion. A brief literature review of similar cases was performed. METHODS: Case report and literature review. RESULTS: A 68-year-old female presented with apogeotropic positional nystagmus, attributed to reversible horizontal canalith jam mimicking cupulolithiasis that was refractory to tailored repositioning maneuvers across months. She was unable to work due to the severity of her symptoms. She underwent surgical occlusion of the affected canal with immediate resolution of her symptoms. A literature review revealed similar cases of canalith jam mimicking cupulolithiasis. CONCLUSIONS: Reversible canalith jam, in which particles moving with horizontal head position alternate between obstructing the semicircular canal and resting on the cupula, can mimic signs of cupulolithiasis. This variant of BPPV can be effectively managed with surgical canal occlusion should symptoms fail to resolve after tailored repositioning maneuvers.

Visualization of horizontal canal benign paroxysmal positional vertigo using 3DCT imaging and its assessment.

BACKGROUND: There have been no useful imaging methods to diagnose benign paroxysmal positional vertigo (BPPV), a common cause of vertigo, depending on the characteristic symptom. OBJECTIVE: To visualize horizontal canal (HC) BPPV using 3DCT and assess its clinical usefulness. SUBJECTS AND METHODS: Ten BPPV patients were diagnosed with distinct BPPV, canalolithiasis, and cupulolithiasis of the HC (hc-BPPV, hc-BPPV-cu), which were definitely diagnosed on the basis of criteria of BPPV by the Barany Society and 10 healthy subjects without a history of dizziness were investigated using 3DCT with several different CT window values (CTWVs). RESULTS: The HCs of BPPV patients were clearly visualized and the luminal aspects showed differences among ears with cupulolithiasis, canalolithiasis and no symptoms healthy subjects. CONCLUSIONS AND SIGNIFICANCE: 3DCT images visualized the characteristic changes of the HC of patients with BPPV compared to healthy subjects. The HC images were coincident with the clinical condition of cupulolithiasis and canalolithiasis. This imaging technique is clinically useful for diagnosing, treating and assessing the prognosis of HC BPPV.