Trans-mastoid plugging of superior semicircular canal dehiscence: long-term follow-up

OBJECTIVE

To evaluate the long-term outcomes of trans-mastoid plugging of superior semicircular canal dehiscence (SSCD), focusing on complicated cases.

METHODS

In this cohort study, we included all patients who underwent trans-mastoid plugging of SSCD between 2009 and 2019. We evaluated the symptoms (autophony, sound-/pressure-induced vertigo, disequilibrium, aural fullness and pulsatile tinnitus) before and 1 year after surgery in the medical records. We systematically assessed the current symptoms 6.2 ± 3 years postoperative (range 2.2-12.3 years) using questionnaires sent by post and validated by telephone interviews. We also documented any complications and the need for further procedures. We compared pure tone and speech audiometry before and 1 year after surgery. Finally, the degree of mastoid pneumatisation and mastoid tegmen anatomy were reviewed on preoperative CT scans.

RESULTS

We included 24 ears in 23 patients. No complications were recorded, and none required a second procedure for SSCD. Following surgery, oscillopsia and Tullio phenomena resolved in all patients. Hyperacusis, autophony, and aural fullness were also settled in all patients except one. Balance impairment persisted to some degree in 35% of patients. No deterioration over the years was reported regarding the above symptoms. On average, bone conduction pure tone average pre- and 1 year postoperative were 13.7 ± 17 and 20.5 ± 18 dB, respectively (P = 0.002). Air bone gaps were reduced from 12.7 ± 8 to 5.9 ± 6 (P = 0.001). Two patients had a significant sclerotic mastoid, three had a prominent low-lying mastoid tegmen, and two had both. Anatomy had no effect on outcome.

CONCLUSION

Trans-mastoid plugging of SSCD is a reliable and effective technique which achieves long-lasting symptom control, even in cases with sclerotic mastoid or low-lying mastoid tegmen.

Comparison of Superior Semicircular Canal Bone Thickness and Patterns in Unilateral and Bilateral Cleft Patients and Normal Controls: A CBCT Study

Superior Semicircular Canal Dehiscence (SSCD) is a recently-defined developmental defect may be associated with several craniofacial anomalies such as Cleft Lip/Palate (CLP). The present study aimed to compare subjects with unilateral and bilateral CLP and normal controls in terms of Superior Semicircular Canal (SSC) bone thickness and pattern.

A total of 238 Cone Beam Computed Tomography (CBCT) images were collected from 52 unilateral Cleft Lip and Palate (UCLP) subjects (104 temporal bones) and 38 Bilateral Cleft Lip and Palate (BCLP) (76 temporal bones) subjects and 148 healthy controls (296 temporal bones). The SSC bone thickness was measured twice and validated by a maxillofacial radiologist. The samples were then classified into five categories based on bone thickness: papyraceous or thin, normal, thick, pneumatized, and dehiscence. After all, the UCLP, BCLP, and normal control groups were compared concerning the SSC pattern and thickness.

The results revealed no significant difference among the three groups regarding the SSC pattern and thickness based on gender. The SSC patterns (P value = .001) and SSC thickness (0.01) were strongly correlated to the cleft type. The thinnest bone thickness and the highest incidence of SSCD were observed among the subjects with BCLP.

The results showed a significant association between the SSC patterns and SSC thickness and the study groups.

Investigation of serum calcium and vitamin D levels in superior semicircular canal dehiscence syndrome: A case control study

Objective

It remains unknown whether calcium metabolism has any effect on the clinical presentation of superior semicircular canal dehiscence (SSCD). Our aim was to analyse the adjusted calcium and vitamin D levels in SSCD patients compared to a control group.

Methods

This was a prospective case-control study performed in a tertiary referral center, university teaching hospital in the UK. It included all new patients with SSCD seen in a dedicated skull base clinic over a 5-year period (2015-2019) compared to a gender and age matched control group. The main outcome of the study was adjusted calcium and Vitamin D levels between the two groups.

Results

A total of 31 SSCD patients were recruited with a matched number of control patients. The mean Vitamin D level on the SSCD group was 44.8 nmoL/l (SD: 20.8) compared to 47.5 nmoL/l (SD: 27.4) on the control group (p = 0.702). Mean Adjusted calcium level was 2.34 mmoL/l (SD: 0.7) for SSCD compared to 2.41 mmoL/l (SD: 0.11) for controls (p = 0.01), being within normal limits for both the SSCD and the control group.

Conclusion

Our study did not identify a link between Vitamin D levels and presence of SSCD. Normal adjusted calcium values were found in both groups. Despite that a statistically significant lower calcium level was found in the SSCD group which could indicate that suboptimal levels of calcium may affect the micro-environment of the otic capsule at the SSC region.

Three-dimensional imaging for the localization of related anatomical structures during surgery on the internal auditory canal

Background

The Fisch infra-temporal fossa approach (Fisch’s method), first proposed in 1970, is commonly used during internal auditory canal (IAC) surgery with an approach that advances through the middle cranial fossa. This study was designed to address the technical difficulties encountered in recognizing and localizing the arcuate eminence with respect to the superior semicircular canal (SSC).

Methods

Forty men and 40 women (18–57 years of age) without space-occupying lesions in the petrous part of the temporal bone were selected for the study. In total, 160 samples were obtained from both sides of the temporal bone. The temporal bone in these 160 samples was scanned using computed tomography, and a three-dimensional coordinate system was established to measure the three-dimensional coordinate values of structures adjacent to the arcuate eminence, the SSC, and the IAC.

Results

The results showed that the shape of the arcuate eminence is highly variable. Approximately 23.12% of samples had no obvious arcuate eminence, which prevented the use of Fisch’s method to localize the SSC. The arcuate eminence was difficult to identify in 37 samples.

Conclusions

Analysis samples showed that the SSC was located in a fan ring centered at the midpoint of the upper edge of the petrous portion of the temporal bone. The arcuate eminence did not correspond directly with the SSC, as the former was located posterolateral to the latter in 85.83% of samples. The angle between the SSC and the IAC ranged from 0° to 60° degrees, as reported previously by Fisch. However, the angle typically ranged from 10–30° in our study.

Anatomical study between the correlation of the arcuate eminence and the superior semicircular canal

OBJECTIVE

To study the anatomical correlation between the arcuate eminence and the superior semicircular canal.

MATERIAL AND METHODS

A study of the height of the arcuate eminence was carried out in 295 temporal bones. In addition, 30 temporals with different heights of the arcuate eminence (10 flat, 10 prominent and 10 very prominent) were randomly selected and radiological tests were performed by computed tomography (Pöschl projection) and subsequent dissection by milling until the apex of the superior semicircular canal was found, establishing, with both methods, the anatomical relationship with the arcuate eminence.

RESULTS

The arcuate eminence was classified as: smooth, when there was no relief (1.7%); flat, measured less than 1 mm (20.3%), prominent, measured between 1 and 2 mm, in (62%), and very prominent, measured above 2 mm (12.6%). The tomographic study (CT) and its subsequent dissection by bone milling showed a direct relationship between the arcuate eminence and the semicircular canal only when it was flat, while the rest of the types corresponded to the presence of pneumatized peri-labyrinthine cells and/or cancellous bone without a direct anatomical relationship with the apex of the superior semicircular canal.

CONCLUSION

The correlation between the arcuate eminence and the superior semicircular canal is direct only when it is flat (1 mm), being related to peri-labyrinthine cells and/or cancellous bone when the arcuate eminence is prominent or very prominent.

The evaluation of superior semicircular canal bone thickness and radiological patterns in relation to age and gender

PURPOSE

The present study aims to evaluate the superior semicircular canal (SSC) bone thickness and radiological patterns in relation to age and gender in a Turkish population using cone beam computed tomography (CBCT).

METHODS

A total of 450 temporal bones were evaluated in the study by two examiners. The radiological patterns of SSC were categorized as follows: dehiscent, papyraceous, normal, thick and pneumatised patterns. The bone thickness of SSCs were measured.

RESULTS

The mean bone thickness of the SSC for females was 1.079 ± 0.8 mm. For males, the mean bone thickness was 0.952 ± 0.6 mm. There was no significant difference between males and females for the mean bone thickness of the SSC. (p > 0.05) The normal pattern was found in 258 temporal bones (57.3%). Seventy-two cases (16%) were defined as "papyraceous pattern"; 23 cases (5.1%) were defined as "thick pattern" and 42 cases (9.3%) were defined as "pneumatised pattern". SSC dehiscence was determined in 55 cases (12.2%). There was no significant difference between radiological patterns for age groups and gender (p > 0.05).

CONCLUSION

There was no significant relationship between SSC bone thickness with age and gender. The radiological patterns of SSC were not associated with age and gender. Radiologists evaluating the head and neck region for various reasons should be aware of these structures and report not only the SSC dehiscence but also the papyraceous pattern.

The variation of superior semicircular canal bone thickness in relation to age and gender

BACKGROUND

Superior semicircular canal dehiscence syndrome (SSCD) is a current diagnosis that is due to a loss of bone covering the superior semicircular canal (SSC). This results in pressure-/sound- induced vertigo and oscillopsia.

OBJECTIVE

To find the variation of the thickness of the bone that covers the Superior Semicircular Canal with relation to age and gender among the Chinese descents.

MATERIALS AND METHODS

Three hundred and eleven temporal bone Cone Beam Computed Tomography (CBCT) images of patients who attended Otology clinic at Second Hospital of Shandong University from January, 2017 to April, 2018 were retrospectively studied. The images were reconstructed in the line of Poschl and the thinnest area of the bone covering the SSC was taken.

RESULTS

We included 172 (55.31%) females and 139 (44.69%) males. Mean age was 41 years. Overall mean difference in thickness was found to be -0.0210. There was no significant difference between the female and male bone thickness (p = .7113). With age the mean difference was 0.0801 (p = .1557) which was not statistically significant.

CONCLUSION AND SIGNIFICANCE

There was no significant change in bone thickness with advancing age. CBCT is the best method of assessing SSCD.

Development of ossification in the vertical semicircular canals: tomographic study

PURPOSE

To describe the ontogeny of vertical semicircular canals using computed tomography.

MATERIALS AND METHODS

We have studied 39 human fetuses aged between 17 and 38 weeks of development through multi-helicoidal CT.

RESULTS

The first signs of ossification in the semicircular canals, superior and posterior, are from 19 weeks of development, through two primary ossification centers in each canal, which will take part in the formation of the outer cover oriented towards the middle and posterior brain fossae, respectively. In this process it must be added the intervention of the common branch. Internal bone covers are formed by ossification of the fossa subarcuata in the superior semicircular canal, and from the compact center of the labyrinthine capsule into the posterior canal. The tomographic study has allowed us to demonstrate how ossification follows a variable rate, establishing a period between 21 and 26 weeks where there are completely closed canals with others still open to the brain fossae.

CONCLUSIONS

The tomographic study of the semicircular canals has enabled us to establish a critical period in its ossification that could explain the etiology of the congenital-type dehiscence.

Analysis of non-posterior canal benign paroxysmal positional vertigo in patients treated using the particle repositioning chair: A large, single-institution series

PURPOSE

Benign paroxysmal positional vertigo (BPPV) involving the horizontal and superior semicircular canals is difficult to study due to variability in diagnosis. We aim to compare disease, treatment, and outcome characteristics between patients with BPPV of non-posterior semicircular canals (NP-BPPV) and BPPV involving the posterior canal only (P-BPPV) using the particle repositioning chair as a diagnostic and therapeutic tool.

METHODS

Retrospective review of patients diagnosed with and treated for BPPV at a high volume otology institution using the particle repositioning chair.

RESULTS

A total of 610 patients with BPPV were identified, 19.0% of whom had NP-BPPV. Patients with NP-BPPV were more likely to have bilateral BPPV (52.6% vs. 27.6%, p < 0.0005) and Meniere's disease (12.1% vs. 5.9%, p = 0.02) and were more likely to have caloric weakness (40.3% vs. 24.3%, p = 0.01). Patients with NP-BPPV required more treatments for BPPV (average 3.4 vs. 2.4, p = 0.01) but did not have a significantly different rate of resolution, rate of recurrence, or time to resolution or recurrence than patients with posterior canal BPPV.

CONCLUSIONS

Comparison of NP-BPPV and P-BPPV is presented with reliable diagnosis by the particle repositioning chair. NP-BPPV affects 19% of patients with BPPV, and these patients are more likely to have bilateral BPPV and to require more treatment visits but have similar outcomes to those with P-BPPV. NP-BPPV is common and should be part of the differential diagnosis for patients presenting with positional vertigo.

Computed Tomography Evaluation of the Correspondence Between the Arcuate Eminence and the Superior Semicircular Canal

BACKGROUND

The arcuate eminence (AE) has been traditionally used in middle cranial fossa (MCF) surgery as a guide to accurate location of the superior semicircular canal (SSC) deep within the temporal bone. However, the anatomic relationship between the AE and SSC is controversial. We evaluated the anatomic coincidence between the AE and the SSC in the MCF surface. Distances between the most relevant anatomic structures in the MCF and prevalence of SSC dehiscence were measured.

METHODS

We analyzed 75 (150 sides) 0.75-mm slice thickness temporal bone computed tomography scans and classified the AE and SSC relationship as coincident and noncoincident. Radiologic findings were reported independently in a blind fashion by 2 authors. Data were presented as mean ± SD or frequency and percentage. Student t test or an unequal variance t test was used. Interobserver agreement among readings was assessed using κ statistic for categorical variables and intraclass Kendall tau-a correlations for continuous measures. P < 0.05 was considered to indicate statistical significance.

RESULTS

The AE matched the SSC in only 31.3% of cases. The AE could be localized as lateral as 11.6 mm from the SSC. It was impossible to identify the AE in 33 scans (22.0%). SSC dehiscence was found in 5 cases (3.3%). A few millimeters separated most analyzed landmarks, and a wide variability in secondary measurements was observed.

CONCLUSIONS

The AE does not systematically overlie the SSC and should not be routinely used as a reference to reach this structure in MCF surgery.

A radiologic and anatomic study of the superior semicircular canal

OBJECTIVES

The present study sought to determine whether there is a correlation between the prevalence of superior semicircular canal (SSC) dehiscence (SSCD) on temporal CT and population age. The secondary objective was to identify anatomic factors for SSCD by studying SSC diameter and its protrusion into the middle cranial fossa. The aim was to determine the acquired or congenital origin of SSCD (Minor's syndrome).

MATERIAL AND METHOD

A single-center retrospective radiological and anatomic study included 180 CT scans of 354 petrous parts of the temporal bone taken between January and December 2011 in a university hospital center. Bone thickness above the SSC was measured and classified in 4 grades: grade 1, >2.5mm; grade 2, <2.5mm: grade 3, predehiscent; grade 4, dehiscent. SSC diameter was also measured, as was the height of SSC protrusion into the middle cranial fossa.

RESULTS

SSCD was found in 0.8% of cases and predehiscence in 12%. Patients with dehiscence were older; patients with grade 3 or 4 were significantly older than those free of dehiscence (P<0.05). There was no significant difference in SSC diameter according to grade. In grade 1, protrusion was greater than in other subjects, with a significant correlation between age and reduced protrusion (P<0.05).

CONCLUSION

The study demonstrated a correlation between aging and SSCD prevalence. Reduced SSC roof height with age suggests that SSCD may be an acquired phenomenon, related in some way to aging of the base of the skull.

Electrode array misplacement into the superior semicircular canal: as a rare complication of cochlear implantation

OBJECTIVE

To report electrode array misplacement into the superior semicircular canal occurring as an rare complication of cochlear implantation through round window insertion, and to explore the causative association between electrode array misplacement and cochlear implantation surgical techniques.

METHODS

A chart review of the electrode array misplacement into the superior semicircular canal and their management in 695 patients undergoing cochlear implantation was undertaken from January 2003 and January 2014 in Anhui Provincial Hospital.

RESULTS

There were two children of electrode array misplacement into the superior semicircular canal complication, and the rate was 0.28%.

CONCLUSIONS

Electrode array misplacement into the superior semicircular canal associated with cochlear implantation is rare. Surgeons should be aware of that the smaller round window maybe the reason of electrode array misplacement through round window insertion. Intra-operative neural response telemetry and X-ray can alert the surgeon the problem with the array's misplacement, which can be identified by postoperative CT.