Pediatric superior semicircular canal dehiscence: illustrative case and systematic review

Superior semicircular canal dehiscence postoperative outcomes: a case series of 350 repairs

BACKGROUND

Superior Semicircular Canal Dehiscence (SSCD) is a dehiscence of the otic capsule which normally lies over the superior semicircular canal. This database constitutes the largest series of SSCD patients to date.

OBJECTIVE

To determine what preoperative factors, if any, contribute to postoperative outcomes and evaluate symptom resolution in a large SSCD patient cohort.

METHODS

A single-institution, retrospective chart review collected patient demographics, intraoperative findings, and pre-and postoperative symptoms. Fisher's exact t-test was performed for unpaired categorical variables, with a significance level of p < 0.05.

RESULTS

350 SSCD repairs were performed. The median age was 52 years (range: 17-86 years, ± 6.4 years), and the median follow-up duration was 4.6 months (range: 0.03-59.5 months, ± 6.8 months). Preoperative hearing loss was significantly associated with female sex (p = 0.0028). The most reported preoperative symptoms were tinnitus (77.4%), dizziness (74.0%), autophony (66.3%), amplification (63.7%), and disequilibrium (62.6%). Between patients who received unilateral versus bilateral SSCD repair, the greatest postoperative symptomatic resolution was seen in autophony (74.9%, p < 0.001), amplification (77.3%, p = 0.00027), hyperacusis (77.4%, p = 0.023), hearing (62.9%, p = 0.0063), and dizziness (54.6%, p < 0.001) for patients with unilateral SSCD repair.

CONCLUSION

Surgical repair via the middle cranial fossa approach can significantly resolve auditory, vestibular, and neurological symptoms of patients with SSCD. Although this is one of the largest single-institution SSCD studies to date, future multi-institutional, prospective studies would be beneficial to validate these results.

Matched Cohort Study of Radiographic Superior Semicircular Canal Dehiscence and Tegmen Dehiscence and Obstructive Sleep Apnea

OBJECTIVE

To report the frequency of radiographic superior semicircular canal dehiscence (SSCD) and tegmen dehiscence in patients with and without obstructive sleep apnea (OSA).

STUDY DESIGN

Retrospective matched cohort study.

SETTING

Tertiary care center.

PATIENTS

Adults with OSA and fine-cut computed tomographic scans including the temporal bone were matched to patients without OSA by age, sex, and type of computed tomography (protocol, scanner type, slice thickness). Ears with otologic surgery or temporal bone tumors were excluded.

MAIN OUTCOME MEASURES

Prevalence of SSCD and tegmen dehiscence assessed by two independent reviewers.

RESULTS

The average body mass index of the OSA patients was 29.2 kg/m 2 with an average apnea-hypopnea index of 36.8. The control group had an average body mass index of 26.2 kg/m 2 . Of the 352 temporal bones, 34 (9.7%) had SSCD in the OSA cohort versus 37 (10.5%) in the control group ( p > 0.05). Seven OSA patients (25.6% of those with SSCD) had bilateral SSCD versus 8 controls (27.6% of those with SSCD; p > 0.05). The majority (87.3%) of dehiscences involved the temporal lobe, with the remaining involving the superior petrosal sinus or both. Of the 352 OSA ears, 90 (25.6%) had a tegmen dehiscence versus 95 (27.0%) in the control group ( p > 0.05). Neither group had a laterality preference for SSCD or tegmen dehiscence.

CONCLUSION

The prevalence of radiographic SSCD and tegmen dehiscences in OSA patients does not significantly differ from age- and sex-matched controls. This is in contrast to a previous case-control study finding patients with symptomatic SSCD to have higher rates of OSA. This may suggest that the effect size of OSA on SSCD prevalence may be limited despite OSA being a risk factor for elevated intracranial pressure.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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 (r_pb= 0.29; P = 0.03), and preoperative disequilibrium (r_pb= -0.32; P = 0.02). Serum calcium values correlated with preoperative hearing loss (r_pb= 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).

CONCLUSIONS

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.

Relationship Between Superior Semicircular Canal Dehiscence Volume with Clinical Symptoms: Case Series

BACKGROUND

Superior semicircular canal dehiscence (SSCD) is an osseous defect of the arcuate eminence of the petrosal temporal bone. Patients typically present with auditory and vestibular symptoms, such as hearing loss and disequilibrium. Using advanced imaging segmentation techniques, we evaluated whether the volume of SSCD correlated with preoperative symptoms and postoperative outcomes.

METHODS

Our laboratory previously described a novel method of quantifying the size of an SSCD via manual segmentation. High-resolution computed tomography images of the temporal bones were imported into a specialized segmentation software. The volume of the dehiscence was outlined on consecutive slices of the coronal and axial planes via a single-pixel-thick paintbrush tool and was then calculated according to the number of nonzero image voxels.

RESULTS

This study included 111 patients (70 women and 41 men; mean age, 55.1 years; age range, 24-87 years) with a total of 164 SSCDs. Mean postoperative follow-up time was 5.2 months (range, 0.03-59.5 months). The most common preoperative and postoperative symptoms were tinnitus (n = 85) and dizziness (n = 45), respectively. Surgery resulted in improvement of symptoms in most patients. The average volume of 164 SSCDs was 1.3 mm³. SSCD volume was not significantly associated with either preoperative symptoms or postoperative outcomes.

CONCLUSIONS

Advances in imaging techniques have allowed increased visualization of SSCD. Further research will be necessary to evaluate the potential correlation of volume of the dehiscence with clinical variables.

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.

Sealing of superior semicircular canal dehiscence is associated with improved balance outcomes postoperatively versus plugging of the canal in middle fossa craniotomy repairs: a case series

OBJECTIVE

The authors compared postoperative symptoms between patients with sealed and those with plugged semicircular canal dehiscence repairs.

METHODS

In total, 136 ears from 118 patients who underwent surgical repair for semicircular canal dehiscence were identified via chart review. Data from postoperative MRI scans showing preservation or loss of semicircular canal fluid signal and postoperative reports of autophony, amplification, aural fullness, tinnitus, hyperacusis, hearing loss, vertigo, dizziness, disequilibrium, oscillopsia, and headache were amalgamated and analyzed.

RESULTS

Patients with preservation of fluid signal were far less likely to have dizziness postoperatively (p = 0.007, OR 0.158, 95% CI 0.041-0.611). In addition, these patients were more likely to have tinnitus postoperatively (p = 0.028, OR 3.515, 95% CI 1.145-10.787).

CONCLUSIONS

The authors found that superior semicircular canal dehiscence patients who undergo sealing without plugging have improved balance outcomes but show more tinnitus postoperatively than patients who undergo plugging.

Functional and Objective Audiovestibular Evaluation of Children With Apparent Semicircular Canal Dehiscence-A Case Series in a Pediatric Vestibular Center

Semicircular canal dehiscence is a bony abnormality in the otic capsule especially involving the superior semicircular canal. Since its identification in 1998, there is significant research regarding the pathology in the adult population. This condition generates a third window effect that is well–described in the literature. However, the entity is rare in the pediatric population with limited research. Difficulties encountered in children are obtaining a direct history that is essential for the diagnosis followed by neurovestibular tests that may be difficult to perform. This study presents observations regarding different clinical and diagnostic aspects of semicircular canal dehiscences in children as a retrospective audit in a tertiary pediatric vestibular center. Of 580 children assessed in a 30 months period undergoing comprehensive functional and objective audiovestibular assessment, 13 children (2.2%) were detected to possess radiological semicircular canal dehiscences (high resolution computed tomography scans at 0.625 mm slices reformatted in the axial, coronal and sagittal planes). The right superior semicircular canal was most commonly affected (66.6%). There were 4 bilateral semicircular canal dehiscences. Clinical suspicion of the condition was raised with reliable surrogate history from carers or from older children (100%), a mixed or conductive hearing loss (80% of hearing losses) in the presence of normal impedance audiometry (92.3%), normal transient otoacoustic emissions (84.6%) on the side of the dehiscence and the presence of replicable pathological saccades in the video head impulse test (76.9%). Disequilibrium symptoms and typical third window symptoms were absent or difficult to elicit in children (46.15 and 30.76% respectively). Only 3 (0.5%) fulfilled the adult criteria of a superior semicircular canal dehiscence syndrome. The abnormal video head impulse test characterized by pathological saccades may affect other non-dehisced ipsilateral canals. Semicircular canal dehiscences are rare in children but may be considered as an etiology for hearing losses and imbalance. Children with semicircular canal dehiscence may present differently from the classical superior semicircular canal dehiscence syndrome found in adults.

Clinical Assessment of Patients with Bilateral Superior Semicircular Canal Dehiscence

OBJECTIVE

Superior semicircular canal dehiscence (SSCD) is caused by a deformity in the arcuate eminence, leading to various vestibular and auditory symptoms that can manifest unilaterally or bilaterally. The aim of the present study was to distinguish the differences in symptoms, treatment options, and outcomes between patients with unilateral and bilateral SSCD.

METHODS

A retrospective medical record analysis was conducted to identify patients with SSCD treated at a tertiary care center from March 2011 to May 2017. The patient demographic data, preoperative symptom presentation, and postoperative outcomes were extracted. Statistical analyses were performed using IBM SPSS Statistics. Fisher's exact tests were computed to investigate the relationships between binary variables, with a significance level of P < 0.05.

RESULTS

A total of 99 patients with SSCD had been treated at our institution from March 2011 to May 2017. Of these 99 patients, 41 (41.4%) had a diagnosis of bilateral SSCD. Of the 41 patients with bilateral SSCD, 27 (65.9%) were women, and the mean age was 53.6 ± 10.9 years (range, 31.7-73.9). The most common presenting symptom was tinnitus (n = 33; 80.4%) and dizziness (n = 33; 80.4%). Previous trauma to the head correlated with a bilateral SSCD presentation (P = 0.04). Trends were reported between female sex and bilateral SSCD [r(35) = 0.32379; P = 0.0506]. Postoperatively, trends were also found, with greater rates of dizziness in patients with bilateral SSCD compared with those with unilateral SSCD (odds ratio, 3.81; P = 0.0659), and less improvement in dizziness (odds ratio, 0.186; P = 0.0627). No other significant differences were found between the symptoms or clinical outcomes and improvements between the bilateral and unilateral cohorts.

CONCLUSION

Bilateral SSCD might result in different clinical symptoms that are more prevalent compared with unilateral SSCD. The findings from the present series of patients with bilateral SSCD suggest that patient symptoms and history are important in the diagnosis of bilateral SSCD and deciding whether 1 or both dehiscences requires surgical intervention.

The Gopen-Yang Superior Semicircular Canal Dehiscence Questionnaire: development and validation of a clinical questionnaire to assess subjective symptoms in patients undergoing surgical repair of superior semicircular canal dehiscence

OBJECTIVE

To characterise subjective symptoms in patients undergoing surgical repair of superior semicircular canal dehiscence.

METHODS

Questionnaires assessing symptom severity and impact on function and quality of life were administered to patients before superior semicircular canal dehiscence surgery, between June 2011 and March 2016. Questionnaire sections included general quality of life, internal amplified sounds, dizziness and tinnitus, with scores of 0-100 points.

RESULTS

Twenty-three patients completed the questionnaire before surgery. Section scores (mean±standard deviation) were: 38.2 ± 25.2 for general quality of life, 52.5 ± 23.9 for internal amplified sounds, 35.1 ± 28.8 for dizziness, 33.3 ± 30.7 for tinnitus, and 39.8 ± 22.2 for the composite score. Cronbach's α statistic averaged 0.93 (range, 0.84-0.97) across section scores, and 0.83 for the composite score.

CONCLUSION

The Gopen-Yang Superior Semicircular Canal Dehiscence Questionnaire provides a holistic, patient-centred characterisation of superior semicircular canal dehiscence symptoms. Internal consistency analysis validated the questionnaire and provided a quantitative framework for further optimisation in the clinical setting.

Pediatric vestibular testing: Tolerability of test components in children

INTRODUCTION

Objective of the study is to define rates of successful completion of components of pediatric vestibular testing (VT).

METHODS

Retrospective review of VT performed on patients less than 18 years of age from 2004 to 2015.

RESULTS

188 pediatric patients (mean age: 13.9 ± 3.56 years old, range 2-17 years) underwent testing. Thirty-five (18.6%) had abnormal test results. Pediatric patients unable to complete all aspects of VT could still complete an average of 7.9 ± 4.0 of 12 test components. The optokinetic tracking test was the most commonly omitted component of the vestibular tests. In a multivariate analysis, failure to perform Nylen-Barany positional testing (χ² 27.5, p < 0.0001) or Dix-Hallpike (5.66, p = 0.0174) testing was associated with inability to obtain final diagnosis on VT.

CONCLUSIONS

Interpretable VT may be obtained in most children, even in those that do not tolerate the full testing protocol. Spontaneous and gaze-evoked nystagmus testing maybe considered as part of initial testing protocol before attempting less well-tolerated components such as bithermal calorics or components that require VNG goggles.

Middle cranial fossa approach for the repair of superior semicircular canal dehiscence is associated with greater symptom resolution compared to transmastoid approach

BACKGROUND

Superior semicircular canal dehiscence (SSCD) is a disorder of the skull base that is gaining increasing recognition among neurosurgeons. Traditionally, the middle cranial fossa (MCF) approach has been used for the surgical repair of SSCD. However, the transmastoid (TM) approach is an alternative strategy that has demonstrated promising results.

METHODS

We performed independent searches of a popular database to identify studies that described outcomes following the surgical repair of SSCD through MCF and TM approaches. The primary outcome was symptom resolution.

RESULTS

Our analysis included 24 studies that described 230 patients that underwent either an MCF (n = 148, 64%) approach or a TM (n = 82, 36%) approach for primary surgical repair of SSCD. A greater percentage of patients in the MCF group experienced resolution of auditory symptoms (72% vs 59%, p = 0.012), aural fullness (83% vs 55%, p = 0.049), hearing loss (57% vs 31%, p = 0.026), and disequilibrium (75% vs 44%, p = 0.001) when compared to the TM group. The MCF approach was also associated with higher odds of symptom resolution for auditory symptoms (odds ratio [OR] 1.79, 95% confidence interval [CI] 1.14-2.82), aural fullness (OR 4.02, 95% CI 1.04-15.53), hearing loss (OR 2.91, 95% CI 1.14-7.42), and disequilibrium (OR 3.94, 95% CI 1.78-8.73). The mean follow-up was 9 months.

CONCLUSIONS

The literature suggests that the MCF approach for the repair of SSCD is associated with greater symptom resolution when compared to the TM approach. This information could help facilitate patient discussions.

The influence of the subarcuate artery in the superior semicircular canal dehiscence and its frequency on stillbirths: illustrative cases and systematic review

Literature describes that on the 25th gestational week the labyrinth is fully formed and with adult size. However, recent studies have shown that the cranial and labyrinth development continues until 3 years of age.

OBJECTIVES

To demonstrate through tomographic study the frequency of semicircular canal dehiscence on nine specimens of stillbirths between 32 and 40 weeks and, through literature review, present another possible etiology for its cause.

METHODS

Tomographic study of the temporal bone of 9 specimens of stillbirths between 32 and 40 weeks.

RESULTS

A frequency of 88.89% of alterations were found in our study, with 44% presenting bilateral alterations and 44% unilateral alteration; 11.11% had no dehiscence.

CONCLUSION

The tomographic study showed superior semicircular canal dehiscence (SSCD) in 88% of the specimens studied, protrusion of the superior semicircular canal (SSC) in all fetuses, and an enlarged SSC that may be caused by the expansion process provoked by the subarcuate artery entering the subarcuate canaliculus, leading to SSCD.

Bone Metabolic Markers in the Clinical Assessment of Patients with Superior Semicircular Canal Dehiscence

BACKGROUND

Superior semicircular canal dehiscence (SSCD) is a bony defect in the osseous shell of the petrous temporal bone. The pathophysiological association between osteoporosis and SSCD remains poorly understood. We investigated the relationship between bone metabolic markers and symptoms in patients with SSCD.

METHODS

We collected patient demographics and clinical parameters for adult patients diagnosed with SSCD on high-resolution computed tomography scans. We used point-biserial correlation analysis to investigate the relationship between bone metabolic markers and symptoms in patients with SSCD. We compared clinical symptoms before and after surgical repair of SSCD through a middle fossa craniotomy using McNemar's test for paired comparisons of binary measures.

RESULTS

We included a total of 99 patients (64 females and 35 males; average age 52 years; 118 surgeries). The level of serum calcium correlated with the need for a second surgery (r_pb = -0.35, P = 0.001). Postoperative calcium supplementation negatively correlated with improvement in dizziness (r_pb = -0.36, P = 0.01). The level of 25-hydroxyvitamin D correlated with preoperative hyperacusis (r_pb = -0.98, P = 0.02) and postoperative autophony (r_pb = 0.96, P = 0.04). Postoperative vitamin D supplementation positively correlated with hearing decline (r_pb = 0.04, P = 0.04) The level of thyroid stimulating hormone correlated with preoperative autophony, amplification, and tinnitus (r_pb = -0.71, r_pb = -0.75, r_pb = -0.70, all P < 0.001).

CONCLUSIONS

Bone metabolic markers could be important in the clinical assessment of SSCD patients and could be potential targets for symptom management.