Efficacy assessment and complications of surgical management for superior semicircular canal dehiscence: a meta-analysis of published interventional studies

Third Window Syndrome: An Up-to-Date Systematic Review of Causes, Diagnosis, and Treatment

Third window syndrome (TWS) is an inner ear condition caused by an additional compliant point in the otic capsule that disrupts auditory and vestibular functions. Superior semicircular canal dehiscence is the most common cause, presenting with hearing loss, vertigo, and autophony, significantly impairing quality of life. This study evaluated the pathophysiology, diagnostics, treatments, and recent advancements in TWS while identifying research gaps. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 70 studies from Embase, MEDLINE, Cochrane, and UpToDate databases were analyzed. TWS affects inner ear mechanics, enhancing bone conduction and reducing air conduction. Diagnosis involves clinical evaluations, high-resolution imaging, and functional tests such as vestibular evoked myogenic potentials, which are known for their high sensitivity and specificity. Management strategies range from vestibular rehabilitation and pharmacotherapy to surgical interventions, including transmastoid and middle cranial fossa approaches, which achieve over 75% success. Emerging minimally invasive techniques, such as underwater endoscopic ear surgery and round window reinforcement, show promise but carry risks like cerebrospinal fluid leakage and inconsistent symptom relief. Advancements in TWS management have improved outcomes, yet gaps remain, particularly in terms of false-positive imaging and long-term efficacy. Future studies should prioritize predictive models and minimally invasive techniques. A multidisciplinary approach is essential to improve patient care.

World-wide survey on the treatment of peripheral vestibular disorders

Objective

The aim of this world-wide survey was to evaluate the currently applied treatment options for the six most frequent peripheral vestibular disorders: benign paroxysmal positional vertigo (BPPV), acute unilateral vestibulopathy (AUVP)/vestibular neuritis, Menière's disease (MD), bilateral vestibulopathy (BVP), vestibular paroxysmia (VP) and superior canal dehiscence syndrome (SCDS).

Background

For the therapy of vestibular disorders, there are four treatment options: vestibular physical therapy (canalith repositioning maneuvers or balance training), pharmacotherapy, surgery, and psychotherapy. Since there are very few state-of-the-art RCTs, the treatment of vestibular disorders is so far not standardized and various methods are applied with heterogeneous efficacy.

Design/methods

A web-based standardized survey questionnaire on the treatment of the six most frequent peripheral vestibular disorders was used to collect data.

Results

234 replies from five continents, 47 countries, 162 cities and 188 centers were received: (% from all 234 replies; multiple answers possible): BPPV: posterior canal BPPV: 71% Epley, 40% Semont, and 12% others. Horizontal canal BPPV canalolithiasis: 58% Lempert (roll-over) maneuver, 33% Gufoni, 7% prolonged rest, and 9% others. Horizontal canal BPPV cupulolithiasis: 35% Gufoni, 27% Lempert (roll-over) maneuver, 9% Zuma, and 7% head shaking: AUVP: 79% pharmacotherapy, namely 47% glucocorticoids, 39% antiemetics, and 24% betahistine; 67% vestibular physical therapy. MD: 85% pharmacotherapy, namely 65% betahistine, 21% diuretics, 20% steroids, 16% antiemetics, 14% gentamicin; 37% surgery. VP: 65% pharmacotherapy, namely 57% anticonvulsants; 7% surgery. BVP: 77% vestibular physical therapy. SCDS: 50% surgery, namely 38.8% canal plugging, 23.3% capping and 15.5% resurfacing.

Conclusion

In this world-wide survey with 234 replies from 188 centers, widely heterogeneous applied treatment options were reported for the six most frequent peripheral vestibular disorders. This study shows in particular that certain drugs are often used despite low or very low evidence. Namely in AUVP, MD and VP well-designed controlled trials with clinically meaningful endpoints are needed.

The History of Superior Semicircular Canal Dehiscence: A Bibliometric Analysis

OBJECTIVE

The treatment and understanding of superior semicircular canal dehiscence (SSCD) has seen significant developments over the past 25 years. Bibliographic analysis can provide insight into the evolution of research as well as highlight emerging areas. Reviewing a large volume of publications provides valuable insights into the citation patterns and collaborations of research groups. This study seeks to offer a comprehensive historical overview of SSCD and leading authors.

DATABASE REVIEWED

Web of Science Core Collection.

METHODS

A bibliometric analysis of the current literature on SSCD was conducted. A performance analysis and science mapping of the top 100 most cited articles was completed using a citation analysis. Two independent reviewers evaluated articles for relevance and adjugated by a third reviewer. Author and institution networks were examined.

RESULTS

Seven hundred ninety-one articles on the topic of SSCD were identified. The top 100 articles spanned over 23 years from 1998 to 2019 and were published in 30 different journals. The top 100 articles were cited 8253 times in literature. The document contents revealed 233 keywords and 238 author keywords. The articles were authored by a total of 291 authors, with only 4 single-authored documents.

CONCLUSIONS

SSCD has been highly researched in aspects of symptomatology, diagnosis, and treatment, as indicated by many highly cited articles that relate. However, the production of highly cited articles on SSCD displays a significant decrease after 2013, with only 17 of the top cited articles published since then.

Predictors of non-primary auditory and vestibular symptom persistence following surgical repair of superior canal dehiscence syndrome

Objective

Patients with superior canal dehiscence syndrome (SCDS) can present with a plethora of auditory and/or vestibular symptoms associated with a bony defect of the superior semicircular canal. While surgical repair is a reasonable option for patients with significant localizing symptoms, the degree of clinical improvement will vary among patients and poses challenges in outcome prediction. This study aims to assess the relationship between preoperative and postoperative symptoms and identify predictors of symptom persistence following repair.

Study design

Retrospective chart review.

Setting

Tertiary neurotology single-institution care center.

Main outcome measures

The primary outcome was to determine the proportion of resolved and persistent primary (most bothersome) and non-primary audiologic and vestibular symptoms following SCD repair. Secondary outcomes included comparison of patient, operative and radiologic characteristics between patients with resolved vs. persistent symptoms. Standardized patient questionnaires including 11 auditory and 8 vestibular symptoms were administered to patients at their preoperative and follow-up visits. Patient pre- vs. postoperative survey results, demographic and clinical characteristics, operative characteristics, audiometric data and cervical vestibular evoked myogenic potential (cVEMP) thresholds were compared via univariate χ2 and multivariate binary logistic regression analyses between those patients reporting full postoperative resolution of symptoms and persistence of one or more symptoms. Radiologic computed tomography (CT) measurements of superior canal dehiscence (SCD) defect size, location, and laterality were also compared between these two groups.

Results

Of 126 patients (132 ears) included in our study, 119 patients (90.2%) reported postoperative resolution (n = 82, 62.1%) or improvement (n = 37, 28.0%) of primary (most bothersome) symptoms, while 13 patients (9.8%) reported persistence of primary symptoms. The median (interquartile range) and range between surgery and questionnaire completion were 9 (4-28), 1-124 months, respectively. Analyzing all symptoms (primary and non-primary) 69 (52.3%) and 68 (51.1%) patients reported complete postoperative auditory and vestibular symptom resolution, respectively. The most likely persistent symptoms included imbalance (33/65/67, 50.8%), positional dizziness (7/20, 35.0%) and oscillopsia (44/15, 26.7%). Factors associated with persistent auditory symptoms included history of seizures (0% vs. 7.6%, p = 0.023), auditory chief complaint (50.0% vs. 70.5%), higher PTA (mean 19.6 vs. 25.1 dB, p = 0.043) and higher cervical vestibular evoked myogenic potential (cVEMP) thresholds at 1000 Hz (mean 66.5 vs. 71.4, p = 0.033). A migraine diagnosis (14.0% vs. 41.9% p < 0.010), bilateral radiologic SCD (17.5% vs. 38.1%, p = 0.034) and revision cases (0.0% vs. 14.0%, p = 0.002) were associated with persistent vestibular symptoms. Neither SCD defect size nor location were significantly associated with symptom persistence (P > 0.05).

Conclusions

Surgical repair for SCDS offers meaningful reduction in the majority of auditory and vestibular symptoms. However, the persistence of certain, mostly non-primary, symptoms and the identification of potential associated factors including migraines, PTA thresholds, cVEMP threshold, bilateral SCD, and revision cases emphasize the importance of individualized patient counseling and management strategies.

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.

Impaired Vestibulo-Ocular Reflex on Video Head Impulse Test in Superior Canal Dehiscence: "Spontaneous Plugging" or Endolymphatic Flow Dissipation?

Surgical plugging of the superior semicircular canal (SSC) represents an effective procedure to treat disabling symptoms in superior canal dehiscence (SCD), despite resulting in an impaired vestibulo-ocular reflex (VOR) gain for the SSC. On the other hand, SSC hypofunction on video head impulse test (vHIT) represents a common finding in patients with SCD exhibiting sound/pressure-induced vertigo, a low-frequency air-bone gap (ABG), and enhanced vestibular-evoked myogenic potentials (VEMPs). "Spontaneous canal plugging" has been assumed as the underlying process. Nevertheless, missing/mitigated symptoms and/or near-normal instrumental findings would be expected. An endolymphatic flow dissipation has been recently proposed as an alternative pathomechanism for SSC VOR gain reduction in SCD. We aimed to shed light on this debate by comparing instrumental findings from 46 ears of 44 patients with SCD exhibiting SSC hypofunction with post-operative data from 10 ears of 10 patients with SCD who underwent surgical plugging. While no difference in SSC VOR gain values was found between the two groups (p = 0.199), operated ears developed a posterior canal hypofunction (p = 0.002). Moreover, both ABG values (p = 0.012) and cervical/ocular VEMP amplitudes (p < 0.001) were significantly higher and VEMP thresholds were significantly lower (p < 0.001) in ears with SCD compared to operated ears. According to our data, canal VOR gain reduction in SCD should be considered as an additional sign of a third window mechanism, likely due to an endolymphatic flow dissipation.

Hearing Results after Transmastoid Superior Semicircular Canal Plugging for Superior Semicircular Canal Dehiscence: A Meta-Analysis

OBJECTIVE

The transmastoid plugging of a superior semicircular canal is considered a safe and effective technique for the management of superior semicircular canal dehiscence (SSCD). The aim of this meta-analysis is to assess the postoperative hearing outcomes after the transmastoid plugging of the superior semicircular canal. Search method and data sources: A systematic database search was performed on the following databases until 30 January 2023: MEDLINE, Embase, Cochrane Library, Web of Science, CINAHL, ICTRP, and clinicaltrials.gov. A systematic literature review and meta-analysis of the pooled data were conducted. We also included a consecutive case series with SCDS for those who underwent transmastoid plugging treatment at our clinic.

RESULTS

We identified 643 citations and examined 358 full abstracts and 88 full manuscripts. A total of 16 studies were eligible for the systematic review and 11 studies for the meta-analysis. Furthermore, 159 ears (152 patients) were included. The postoperative mean air conduction threshold remained unchanged (mean difference, 2.89 dB; 95% CI: -0.05, 5.84 dB, p = 0.58), while the mean bone conduction threshold was significantly worse (mean difference, -3.53 dB; 95% CI, -6.1, -0.95 dB, p = 0.9).

CONCLUSION

The transmastoid plugging technique for superior semicircular canal dehiscence syndrome, although minimally worsening the inner ear threshold, is a safe procedure in terms of hearing preservation and satisfactory symptom relief.

Video Head Impulse Test Demonstrates a Residual Function after Plugging of Dehiscent Superior Semicircular Canal

OBJECTIVE

Plugging a symptomatic dehiscent superior semicircular canal (SSCC) often leads to a nonfunctional postoperative canal. However, in some instances, a residual function has been described. This study attempts to describe what factors may lead to such residual function.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

Thirty-five patients with confirmed SSCC dehiscence.

INTERVENTION

Video head impulse test was conducted pre- and postoperatively to assess any difference in the function of the SSCC.

MAIN OUTCOME MEASURES

Mean gain and pathological saccades were recorded according to well-established thresholds along with dehiscence length and location to evaluate any associations to residual canal function.

RESULTS

When comparing preoperative to postoperative SSCC abnormal gains, a significant increase was observed after plugging ( p = 0.023). This also held true when abnormal gain and pathologic saccades were taken together ( p < 0.001). Interestingly, 55.3% of patients were observed to remain with a residual SSCC function 4 months postoperatively even with a clinical improvement. Of these, 47.6% had normal gain with pathologic saccades, 38.1% had an abnormal gain without pathologic saccades, and 14.3% had normal gain without pathologic saccades (normal function). Preoperatively, SSCC abnormal gain was associated with a larger dehiscence length mean ( p = 0.002). Anterosuperior located dehiscences were also associated with a larger dehiscence length mean ( p = 0.037). A residual SSCC function after plugging was associated with a shorter dehiscence length regardless of location ( p = 0.058).

CONCLUSION

Dehiscence length and location may be useful in predicting disease symptomatology preoperatively and canals function recovery after plugging. These factors could be used as indicators for preoperative counseling and long-term management.

A report on quality-of-life outcomes following transmastoid plugging of superior semicircular canal dehiscence in a newly established service in a UK hospital

OBJECTIVE

This study aimed to evaluate the quality-of-life outcomes following transmastoid plugging of semicircular canal dehiscence in a newly established service in a UK hospital.

METHOD

Quality-of-life outcomes were measured using the Glasgow benefit Inventory score in three patients who underwent transmastoid plugging for superior semicircular canal dehiscence between September 2019 and March 2020. Patients also completed pre- and post-operative symptomatic questionnaires and vestibular-evoked myogenic potential testing.

RESULTS

All three patients reported an improvement in overall quality-of-life outcomes with a mean overall Glasgow Benefit Inventory score of +37 (range, +22.2-66.6). There were no immediate post-operative complications and hearing was preserved in all patients.

CONCLUSION

This study reported an initial successful experience with transmastoid plugging of superior semicircular canal dehiscence. In all patients, improvement in quality-of-life measures and symptoms was reported.

Superior semi-circular canal dehiscence syndrome: quantifying the effectiveness of treatment from the patient's perspective

Background

Superior semi-circular canal dehiscence syndrome is a disorder characterised by auditory and vestibular symptoms that can significantly impact quality of life, and yet it has no disease-specific quality of life instrument.

Method

Thirty-six patients who underwent transmastoid superior semicircular canal resurfacing and plugging were included from an initial cohort of 60 surgically managed patients. A sub-cohort of 19 consecutive patients completed validated symptom and quality of life questionnaires before and after surgery. Of the 36 patients, 31 participated in a telephone semi-structured interview post-operatively.

Results

Following surgery, there was a statistically significant improvement in autophony index score (p = 0.02), symptom severity score (p < 0.001) and sound hypersensitivity (p = 0.01). Thematic analysis of telephone interviews suggested three main symptom themes: auditory hypersensitivity, dysequilibrium, headache and concentration difficulties. Dysequilibrium was found to persist post-operatively.

Conclusion

Surgery improves overall symptoms and quality of life. However, important symptom themes may be overlooked using the outcome measures that are currently available. A unified disease-specific outcome measure is urgently required to better understand the impact of symptoms and measure treatment effects.

Development of semicircular canal occlusion

Surgical treatment of vertigo is performed with in-depth study of inner ear diseases. Achieving an effective control of vertigo symptoms while reducing damage to hearing and reducing surgical complications is the principle followed by scholars studying surgical modalities. Semicircular canal occlusion is aimed at treatment of partial peripheral vertigo disease and has attracted the attention of scholars because of the above advantages. This article provides a review of the origins of semicircular canal occlusion, related basic research, clinical applications, and the effects of surgery on vestibular and hearing function.

Transmastoid Occlusion Surgery for Superior Semicircular Canal Dehiscence Syndrome Improves Patient-Reported Quality-of-Life Measures and corrects cVEMP Thresholds and Amplitudes

OBJECTIVE

To determine the pre- and postoperative clinical, audiological, vestibular, and patient-reported measures in patients undergoing transmastoid occlusion surgery for superior canal dehiscence syndrome (SCDS).

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral centre, UK.

PATIENTS

All primary transmastoid occlusion surgeries for SCDS were included (tertiary centre, single-surgeon), January 2008 to July 2019.

INTERVENTIONS

Transmastoid superior canal occlusion surgery for SCDS.

MAIN OUTCOME MEASURES

We collated audiological (pure tone audiogram), vestibular (cervical vestibular evoked myogenic potentials [cVEMPs]), and patient-reported outcome measures (Dizziness Handicap Inventory and subjective symptom grading).

RESULTS

Fifty-two patients (55 ears) met the inclusion criteria. Thirty-one (56%) were female. Mean age was 47 years (range 29-63) and mean follow-up of 11.2 months. Six patients had bilateral disease, four of whom underwent sequential, bilateral surgery.Autophony was the most frequent presenting symptom, improving in 92%.Significant improvements were self-reported in patients' autophony (p < 0.0001), pressure- and noise-induced dizziness (p < 0.0001 and p < 0.0001), aural fullness (p = 0.0159), pulsatile tinnitus (p < 0.0001), perceived hearing loss (p = 0.0058), and imbalance (p = 0.0303).Overall Dizziness Handicap Inventory scores reduced from 45.9 to 27.4 (p < 0.0001), and across all subgroups of functional (p = 0.0003), emotional (p < 0.0001), and physical handicap (p = 0.0005).A 6.4-dB HL improvement in the air-bone gap (500-1000 Hz) occurred (95% confidence intervals 3.3-9.4 dB HL, p < 0.0001). There were no dead ears. cVEMP thresholds, when recordable, normalized in all except two ears.

CONCLUSIONS

Transmastoid occlusion is effective at improving patient-reported outcomes and normalizing cVEMP thresholds, though some symptoms, notably disequilibrium, persist to a variable degree.

Surgical treatments of superior semicircular canal dehiscence: A single-centre experience in 63 cases

OBJECTIVE

Different procedures have been described to treat superior canal dehiscence. The present study aims to describe the results obtained with middle fossa approach, transmastoid approach, and round window reinforcement in a large series of patients.

METHODS AND DESIGN

In this single-center retrospective study, we report the results of the procedures performed between 2006 and 2019 using the three main surgical approaches, middle fossa approach (MFA), transmastoid approach (TMA), and round window reinforcement (RWR). The outcome on cardinal cochlear and vestibular symptoms, audiometric results, and changes in cervical vestibular evoked myogenic potentials (cVEMPs) were analyzed. The patients were also interviewed 12 months to 13 years post-treatment to establish their overall satisfaction following surgery.

RESULTS

Sixty-three patients were divided into three groups: 42 MFA; 12 RWR; 9 TMA. Postsurgical control rates exceeded 80% for the majority of symptoms in the MFA and TMA groups, and ranged from 11.1% to 83.3% for the RWR group. Over 90% of MFA or TMA patients and 60% of the RWR cohort were satisfied overall with their treatment. Hearing thresholds were intact following surgery in the MFA and TMA groups. There was one case of profound postoperative deafness in the RWR group.

CONCLUSION

MFA and TMA are both safe and effective techniques in the treatment of disabling SSCD. Since MFA is the more invasive technique, we suggest that TMA should be proposed as first-line treatment, temporal bone anatomy permitting. RWR outcomes are more variable in term of symptomatic control, and this option could be offered to patients at risk under general anesthesia.

LEVEL OF EVIDENCE

Level 4 evidence.

Hearing Outcomes After Surgical Manipulation of the Membranous Labyrinth During Superior Semicircular Canal Dehiscence Plugging or Posterior Semicircular Canal Occlusion

OBJECTIVE

To analyze audiometric data after surgical manipulation of the membranous labyrinth during plugging of superior semicircular canal dehiscence (SSCD) or posterior semicircular canal occlusion (PSCO) for benign paroxysmal positional vertigo.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Patients undergoing plugging of SSCD or PSCO between 2009 and 2019.

MAIN OUTCOME MEASURES

Pre- and postoperative audiometric data were collected per AAO-HNS guidelines. Hearing outcomes at initial and last follow-up were compared. Subanalyses were performed for surgical approach and age.

RESULTS

Eighty-seven total procedures in 76 patients including 43 middle cranial fossa for SSCD, 29 transmastoid SSCD, and 15 PSCO. Mean preoperative air-conduction-pure-tone averages was 21.1±14.9 dB compared with 26.1 ± 19.6 dB at initial follow-up and 24.4 ± 18.6 dB at last follow-up (p = 0.006). Mean preoperative bone-conduction-pure-tone average was 14.3 ± 11.9 dB compared with 18.3 ± 15.6 dB at initial follow-up and 18.5 ± 16.9 dB at last follow-up (p < 0.001). There were five cases of hearing loss >20 dB including one case of profound sensorineural hearing loss >55 dB. PSCO resulted in the most hearing loss at initial follow-up but largely resolves with time. Transmastoid approaches for SSCD resulted in more hearing loss compared with middle cranial fossa. Hearing outcomes were generally stable for SSCD approaches but showed improvement over time for PSCO. Age >50 was associated with greater hearing loss of 5.2 ± 11.1 dB compared with 1.3 ± 10.5 dB but did not reach statistical significance (p = 0.110).

CONCLUSIONS

Surgical manipulation of the membranous labyrinth results in statistically significant hearing loss in a pooled analysis. Transient hearing loss is observed in PSCO and TM SSCD plugging was associated with postoperative hearing loss. There was a trend toward increased hearing loss in patients >50 years old.

Hearing Preservation in Patients Who Undergo Labyrinthectomy and Translabyrinthine Procedures: A Case Report and Systematic Review

Importance

Preservation of endolymphatic fluids, maintenance of a fluid-filled vestibule, and preservation of the cochlear nerve and its vasculature are believed to be necessary to retaining hearing after an inner-ear operation. However, some studies have reported no hearing loss despite the violation of the vestibule, questioning the importance of maintaining a fluid-filled vestibule in preserving hearing.

Objective

To report on the preservation of hearing after a complete labyrinthectomy for Meniere disease and after disruption of the vestibule.

Evidence Review

This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. A search of PubMed, Scopus, Ovid, and Cochrane Library databases was conducted to identify English-language articles on hearing preservation after labyrinthectomy, published from 1947 through December 11, 2019. The search strategy used a combination of boolean operators and included the following Medical Subject Heading terms and keywords: hearing preservation, labyrinth surgery, labyrinthectomy, vestibule violation, vestibule disruption, translabyrinthine approach, schwannoma removal, and semicircular canal ablation. Studies that included disruption of the vestibule and hearing preservation were included.

Findings

This systematic review identified 10 studies with 10 patients who underwent surgical removal of cholesteatoma or vestibular schwannoma and displayed postoperative hearing preservation. This study also reported on 1 patient with Meniere disease who retained hearing after undergoing a complete labyrinthectomy. Among these 11 patients, the mean (range) age was 45.1 (27-55) years, and 8 patients (73%) were women. Multiple theories exist that explain the mechanism behind hearing preservation, such as sealing of the ductus reuniens or closure of the remaining vestibule.

Conclusions and Relevance

This systematic review describes a set of patients who did not experience hearing loss after a labyrinthectomy or surgical violation of the vestibule, which seems to contradict prevailing principles for retaining hearing after inner-ear surgical procedures. This finding suggests that hearing preservation is possible after labyrinthine destruction despite the absence of a fluid-filled vestibule and that other mechanisms, such as occlusion of the ductus reuniens with granulation tissue or bone dust, may be sufficient to achieve that outcome.

Transmastoid Superior Semicircular Canal Plugging: A Prospective Analysis of Surgical Outcomes

OBJECTIVES

To assess the outcomes of the transmastoid superior semicircular canal plugging in patients with superior semicircular canal dehiscence (SSCD).

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary, university center.

PATIENTS

Patients with SSCD undergoing transmastoid superior semicircular canal plugging within a 30-month period.

INTERVENTIONS

Transmastoid superior semicircular canal occlusion.

MAIN OUTCOME MEASURES

We documented the surgical technique, pre- and postoperative (3-month review) dizziness handicap inventory scores, average hearing thresholds, low-frequency air-bone gap, six-canal video head-impulse-test responses, improvement of the auditory symptoms and complications.

RESULTS

Out of 30 patients with SSCD, 11 patients (12 ears) were enrolled with an average age 41.17 years (range 32-65 years). Oscillopsia resolved in all patients; DHI score improved from 56.7 (range 22-84) preoperatively to 25.83 (10-46) postoperatively (p = 0.001), while out of the nine patients with troublesome auditory symptoms, five patients noticed an improvement. The average pre- and postoperative hearing thresholds were 15.2 dB (range 3-32.5 dB) and 14.17 dB (range 5-30 dB) (p = 0.73), respectively. The average pre- and postoperative low-frequency air bone gap was 12.3 dB (range 5-20 dB) and 9.4 dB (range 0-20 dB), respectively (p = 0.24) (Table 1). There were no major complications; two patients developed postoperative benign paroxysmal positional vertigo.

CONCLUSION

Transmastoid plugging of the superior semicircular canal can safely and significantly improve the vestibular symptoms of the patients with SCDS, as well as the auditory symptoms in a substantial number of patients in a hearing-preservation way.

Current Trends, Controversies, and Future Directions in the Evaluation and Management of Superior Canal Dehiscence Syndrome

Patients with superior canal dehiscence syndrome (SCDS) can present with a range of auditory and/or vestibular signs and symptoms that are associated with a bony defect of the superior semicircular canal (SSC). Over the past two decades, advances in diagnostic techniques have raised the awareness of SCDS and treatment approaches have been refined to improve patient outcomes. However, a number of challenges remain. First, there is currently no standardized clinical testing algorithm for quantifying the effects of superior canal dehiscence (SCD). SCDS mimics a number of common otologic disorders and established metrics such as supranormal bone conduction thresholds and vestibular evoked myogenic potential (VEMP) measurements; although useful in certain cases, have diagnostic limitations. Second, while high-resolution computed tomography (CT) is the gold standard for the detection of SCD, a bony defect does not always result in signs and symptoms. Third, even when SCD repair is indicated, there is a lack of consensus about nomenclature to describe the SCD, ideal surgical approach, specific repair techniques, and type of materials used. Finally, there is no established algorithm in evaluation of SCDS patients who fail primary repair and may be candidates for revision surgery. Herein, we will discuss both contemporary and emerging diagnostic approaches for patients with SCDS and highlight challenges and controversies in the management of this unique patient cohort.

Case Report: Local Anesthesia Round Window Plugging and Simultaneous Vibrant Soundbridge Implant for Superior Semicircular Canal Dehiscence

The aim of the present study is to report the outcomes of round window reinforcement surgery performed with the application of a Vibrant Soundbridge middle ear implant (VSB; MED-EL) in a patient with superior semicircular canal dehiscence (SSCD) who presented with recurrent vertigo, Tullio phenomenon, Hennebert's sign, bone conduction hypersensitivity, and bilateral moderate to severe mixed hearing loss. Vestibular evoked myogenic potentials (VEMPs) and high-resolution computed tomography (HRCT) confirmed bilateral superior semicircular canal dehiscence while this was not seen in magnetic resonance imaging. The surgical procedure was performed in the right ear as it had worse vestibular and auditory symptoms, a poorer hearing threshold, and greatly altered HRCT and VEMPs findings. With local-assisted anesthesia, round window reinforcement surgery (plugging) with perichondrium was performed with simultaneous positioning of a VSB on the round window niche. At the one and 3 months follow-up after surgery, VSB-aided hearing threshold in the right ear improved to mild, and loud sounds did not elicit either dizziness or pain in the patient.

Changes in Vestibulo-Ocular Reflex Gain After Surgical Plugging of Superior Semicircular Canal Dehiscence

Superior semicircular canal dehiscence (SCD), which is characterized by a “third mobile window” in the inner ear, causes various vestibular and auditory symptoms and signs. Surgical plugging of the superior semicircular canal (SC) can eliminate the symptoms associated with increased perilymph mobility due to the presence of the third window. However, the natural course of vestibular function after surgical plugging remains unknown. Therefore, we explored longitudinal vestibular function after surgery in 11 subjects with SCD who underwent SC plugging using the middle cranial fossa approach. Changes in vestibulo-ocular reflex (VOR) gain in all planes were measured over 1 year with the video head impulse test. We also evaluated surgical outcomes, including changes in symptoms, audiometric results, and electrophysiological tests, to assess whether plugging eliminated third mobile window effects. The mean VOR gain for the plugged SC decreased from 0.81 ± 0.05 before surgery to 0.65 ± 0.08 on examinations performed within 1 week after surgery but normalized thereafter. Four of seven subjects who were able to perform both VOR tests before surgery and immediately after surgery had pathologic values (SC VOR gain < 0.70). Conversely, the mean VOR gain in the other canals remained unchanged over 1 year. The majority of symptoms and signs were absent or markedly decreased at the last follow-up evaluation, and no complications associated with the surgery were reported. Surgical plugging significantly attenuated the air-bone gap, in particular at low frequencies, because of increased bone conduction thresholds and deceased air conduction thresholds. Moreover, surgical plugging significantly increased vestibular-evoked myogenic potential thresholds and decreased the ratio of summating potential to action potential in plugged ears. Postoperative heavily T2-weighted images were available for two subjects and showed complete obliteration of the T2-bright signal intensity in the patent SC lumen in preoperative imaging based on filling defect at the site of plugging. Our results suggest that successful plugging of dehiscent SCs is closely associated with a transient, rather than persistent, disturbance of labyrinthine activity exclusively involved in plugged SCs, which may have clinical implications for timely and individualized vestibular rehabilitation.

Gauging the effectiveness of canal occlusion surgery: how I do it

BACKGROUND

Transmastoid occlusion of the posterior or superior semicircular canal is an effective and safe management option in patients with refractory benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence. A method of quantifying successful canal occlusion surgery is described.

METHODS

This paper presents representative patients with intractable benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence, who underwent transmastoid occlusion of the posterior or superior semicircular canal respectively. Vestibular function was assessed pre- and post-operatively. The video head impulse test was included as a measure of semicircular canal and vestibulo-ocular reflex functions.

RESULTS

Post-operative video head impulse testing showed reduced vestibulo-ocular reflex gain in occluded canals. Gain remained normal in the non-operated canals. Post-operative audiometry demonstrated no change in hearing in the benign paroxysmal positional vertigo patient and slight hearing improvement in the superior semicircular canal dehiscence syndrome patient.

CONCLUSION

Transmastoid occlusion of the posterior or superior semicircular canal is effective and safe for treating troublesome benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence. Post-operative video head impulse testing demonstrating a reduction in vestibulo-ocular reflex gain can reliably confirm successful occlusion of the canal and is a useful adjunct in post-operative evaluation.

Comparison of Transmastoid and Middle Fossa Approaches for Superior Canal Dehiscence Repair: A Multi-institutional Study

OBJECTIVE

To compare outcomes for patients undergoing a transmastoid approach versus a middle fossa craniotomy approach with plugging and/or resurfacing for repair of superior semicircular canal dehiscence. Outcome measures include symptom resolution, hearing, operative time, hospital stay, complications, and revision rates.

STUDY DESIGN

Multicenter retrospective comparative cohort study.

SETTINGS

Three tertiary neurotology centers.

SUBJECTS AND METHODS

All adult patients undergoing repair for superior canal dehiscence between 2006 and 2017 at 3 neurotology centers were included. Demographics and otologic history collected by chart review. Imaging, audiometric data, and vestibular evoked myogenic potential measurements were also collected for analysis.

RESULTS

A total of 68 patients (74 ears) were included in the study. Twenty-one patients underwent middle fossa craniotomy repair (mean age, 47.9 years), and 47 underwent transmastoid repair (mean age, 48.0 years). There were no significant differences in age or sex distribution between the groups. The transmastoid group experienced a significantly shorter duration of hospitalization and lower recurrence rate as compared with the middle fossa craniotomy group (3.8% vs 33%). Both groups experienced improvement in noise-induced vertigo, autophony, pulsatile tinnitus, and nonspecific vertigo. There was no significant difference among symptom resolution between groups. Additionally, there was no significant difference in audiometric outcomes between the groups.

CONCLUSION

Both the transmastoid approach and the middle fossa craniotomy approach for repair of superior canal dehiscence offer symptom resolution with minimal risk. The transmastoid approach was associated with shorter hospital stays and lower recurrence rate as compared with the middle fossa craniotomy approach.

[Superior canal dehiscence syndrome : Diagnosis with vestibular evoked myogenic potentials and fremitus nystagmus. German version]

BACKGROUND

Superior canal dehiscence syndrome (SCDS) is a relatively rare neurotological disorder that is characterized by a heterogeneous clinical picture. Recently, vestibular evoked myogenic potential (VEMP) measurementwas established for the diagnosis of SCDS. In the present study, a case series of patients with SCDS were analyzed, with a focus on VEMP.

METHODS

Four patients with SCDS were prospectively examined with ocular VEMP (oVEMP) and cervical VEMP (cVEMP). The clinical features and the standard audiovestibular test battery results are summarized and analyzed. The diagnostic accuracy of VEMP testing is evaluated.

RESULTS

The increased oVEMP amplitudes had a specificity of 100% in this patient population. All patients had normal caloric function and head impulse testing. The Tullio sign was observed in two patients. Three patients had autophony. The airbone gap was not greater than 10 dB in any of the patients. Two patients had marked fremitus nystagmus. All patients had a bony dehiscence of the superior semicircular canal on computed tomography imaging.

CONCLUSION

The subjective and clinical features in this case series of SCDS patients were heterogeneous. However, objective oVEMP testing had the highest diagnostic value. Furthermore, we describe a new diagnostic clinical sign: fremitus nystagmus.

Anterior Canal benign paroxysmal positional Vertigo following surgical Management of superior canal dehiscence

OBJECTIVE

Benign paroxysmal positional vertigo (BPPV) is a common post-surgical finding in patients managed for superior semicircular canal dehiscence (SSCD). The posterior semicircular canal has been reported as the involved canal in the majority of cases of post-surgical BPPV, with only two cases reported of lateral canal involvement. The objective of this report is to present a case in which an anterior semicircular canal BPPV response was identified in a patient following surgical management for SSCD.

METHOD

This case report presents an adult with residual dizziness following surgical management of SSCD and vestibular rehabilitation therapy (VRT). During subsequent evaluation of vestibular function, a transient and torsional, down-beating nystagmus was provoked along with vertigo during Dix-Hallpike positioning to the right. This was consistent with BPPV affecting the left superior (anterior) semicircular canal.

RESULTS

The patient was treated with a repositioning maneuver to manage anterior semicircular canal BPPV and no nystagmus response was recorded with post-repositioning Dix-Hallpike test. Review of radiographic images, obtained prior to vestibular function testing, showed a hyperintensity in the area of the left anterior semicircular canal ampulla. It was felt this was likely a bone chip from the SSCD repair that was pushing against the ampulla with further mobile debris within the canal.

CONCLUSION

It is reported that BPPV is a common complication in patients surgically managed for SSCD. Posterior semicircular canal BPPV is reported most often, with a couple of cases of lateral semicircular canal BPPV also reported. As far as we are aware, the current case represents the first report of anterior semicircular canal BPPV in this type of patient.

Postoperative MR imaging features after superior semicircular canal plugging in Minor syndrome

PURPOSE

To report the postoperative magnetic resonance imaging (MRI) features after superior semicircular canal plugging in patients with Minor syndrome.

MATERIALS AND METHODS

The MRI examinations with 3D T2-weighted SPACE sequence of 12 patients with superior semicircular canal dehiscence syndrome (SCDS) were retrospectively assessed. Two radiologists independently evaluated the presence of a filling defect of the superior semicircular canal above the superior ampulla and the common crus using an oblique plane parallel to the superior semicircular canal (Pöschl's plane).

RESULTS

Postoperative MRI showed a filling defect above the ampulla of the superior semicircular canal and the common crus in 8/12 patients (67%). Three patients (3/12; 25%) had a filling defect involving also the superior ampulla that caused postoperative labyrinthitis with labyrinthine enhancement on MRI in 2 patients. One patient (1/12; 8%) had incomplete plugging of superior semicircular canal with abnormal functional tests and remaining symptoms.

CONCLUSION

Postoperative MRI shows a normal plugging aspect of the superior semicircular canal in 67% of patients. MRI can reveal complications that may have therapeutic implications.

Long-Term Patient-Reported Outcomes After Surgery for Superior Canal Dehiscence Syndrome

OBJECTIVE

Evaluate the long-term patient-reported outcomes of surgery for superior canal dehiscence syndrome (SCDS).

STUDY DESIGN

Cross-sectional survey.

SETTING

Tertiary referral center.

PATIENTS

Adults who have undergone surgery for SCDS with at least 1 year since surgery.

MAIN OUTCOME MEASURE(S)

Primary outcome: change in symptoms that led to surgery.

SECONDARY OUTCOMES

change in 11 SCDS-associated symptoms, change in psychosocial metrics, and willingness to recommend surgery to friends with SCDS.

RESULTS

Ninety-three (43%) respondents completed the survey with mean (SD) time since surgery of 5.3 (3.6) years. Ninety-five percent of respondents reported the symptoms that led them to have surgery were "somewhat better," "much better," or "completely cured." Those with unilateral symptoms were more likely to report improvement than those with bilateral symptoms. There was no difference between those with short (1-5 yr) versus long (5-20 yr) follow-up. Each of the SCDS-associated symptoms showed significant improvement. The largest improvements were for autophony, pulsatile tinnitus, audible bodily sounds, and sensitivity to loud sound. Headaches, imbalance, dizziness, and brain fog showed the least improvements. Most patients reported improvements in quality of life, mood, and ability to function at work and socially. Ninety-five percent of patients would recommend SCDS surgery.

CONCLUSIONS

Respondents demonstrated durable improvements in the symptoms that led them to have surgery. Auditory symptoms had the greatest improvements. Headaches, imbalance, dizziness, and brain fog showed the least improvements. Nearly, all patients would recommend SCDS surgery to others. These results can be used to counsel patients regarding the lasting benefits of surgery for SCDS.

Effectiveness of Transmastoid Plugging for Semicircular Canal Dehiscence Syndrome

Objectives (1) Evaluate changes in subjective symptoms in patients following transmastoid canal plugging for superior semicircular canal dehiscence (SSCD) syndrome. (2) Quantify changes in hearing in patients who have undergone transmastoid canal plugging for SSCD syndrome. Study Design Case series with chart review. Setting Single tertiary care institution. Subjects and Methods We retrospectively reviewed patients with SSCD who underwent repair with canal plugging via a transmastoid approach between January 2012 and January 2017. Symptom severity was assessed prospectively (autophony, sound/pressure-induced vertigo, disequilibrium, aural fullness, and pulsatile tinnitus) and after surgery. Pure-tone and speech audiometry were measured before and after surgery. Two-sided Wilcoxon rank-sum tests were used to evaluate changes in subjective symptoms and audiometric outcomes. Results Seventeen patients (19 ears) met inclusion criteria. The superior canal was successfully plugged via the transmastoid approach in all cases. Patients reported a statistically significant improvement in autophony, vertigo, aural fullness, and pulsatile tinnitus ( P < .01), without significant improvement in disequilibrium rating ( P = .06). There were no changes noted in pure-tone average or word recognition score; however, there was a statistically significant improvement in air-bone gap at 250 Hz of 10.9 dB ( P = .04) with 12.9-dB improvement in air conduction thresholds ( P = .02) and no difference (0.9 dB, P = .9) in bone conduction thresholds. Conclusion In our study, patients with SSCD demonstrated excellent hearing outcomes and resolution of most otologic symptoms after surgical repair. Transmastoid canal plugging, which has been described to date only in smaller case series, is a safe and effective alternative to the traditional middle cranial fossa approach.

Recent surgical options for vestibular vertigo

Vertigo is not a well-defined disease but a symptom that can occur in heterogeneous entities diagnosed and treated mainly by otolaryngologists, neurologists, internal medicine, and primary care physicians. Most vertigo syndromes have a good prognosis and management is predominantly conservative, whereas the need for surgical therapy is rare, but for a subset of patients often the only remaining option. In this paper, we describe and discuss different surgical therapy options for hydropic inner ear diseases, Menière's disease, dehiscence syndromes, perilymph fistulas, and benign paroxysmal positional vertigo. At the end, we shortly introduce the most recent developments in regard to vestibular implants. Surgical therapy is still indicated for vestibular disease in selected patients nowadays when conservative options did not reduce symptoms and patients are still suffering. Success depends on the correct diagnosis and choosing among different procedures the ones going along with an adequate patient selection. With regard to the invasiveness and the possible risks due to surgery, in depth individual counseling is absolutely necessary. Ablative and destructive surgical procedures usually achieve a successful vertigo control, but are associated with a high risk for hearing loss. Therefore, residual hearing has to be included in the decision making process for surgical therapy.

Revision Surgery for Superior Canal Dehiscence Syndrome

OBJECTIVE

To identify factors associated with surgical failure for superior canal dehiscence syndrome (SCDS) and define rates of complications and cure after revision SCDS repair.

STUDY DESIGN

Retrospective patient series.

SETTING

Tertiary care referral center.

PATIENTS

Adults who underwent revision surgery for SCDS.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Initial surgical approach, intraoperative findings at the time of revision, persistence of symptoms, and complications for revision surgery.

RESULTS

Two hundred twenty-two surgical SCDS patients were identified, including 21 subjects who underwent 23 revision surgeries. Fourteen (61%) underwent previous middle fossa and nine (39%) underwent previous transmastoid approaches. Intraoperative findings showed that in 17 (74%) the previous material used to plug or resurface the canal was present but not entirely covering the dehiscence. In one (4%) the material was not present. In one (4%) the material was in proper position, whereas in four (17%) the material was in proper position with very thin bone adjacent. After revision surgery, symptoms were completely resolved in eight (35%), partially resolved in seven (30%), and not resolved in seven (30%). Findings of thin bone adjacent to the previous plug was associated with failure of symptom resolution (p = 0.03). Hearing outcomes were compared to a previously studied cohort of primary surgery patients, and outcomes were similar. Three subjects (13%) had a significant decrease in their word recognition score after revision surgery (p=0.52), and seven (30%) had a significant increase in their pure-tone average (p=0.78).

CONCLUSION

Revision surgery for SCDS can be curative in carefully selected patients, but there may be a higher failure rate than primary surgery, with similar hearing outcomes.

Comorbidities confounding the outcomes of surgery for third window syndrome: Outlier analysis

Objective

Patients with third window syndrome and superior semicircular canal dehiscence (SSCD) symptoms whose surgical outcomes placed them as outliers were systematically studied to determine comorbidities that were responsible for their poor outcomes due to these confounding factors.

Study Design

Observational analytic case-control study in a tertiary referral center.

Methods

Twelve adult patients with clinical SSCD syndrome underwent surgical management and had outcomes that did not resolve all of their subjective symptoms. In addition to one of the neurotologists, 2 neurologists (one specializing in migraine and the other a neuro-ophthalmologist), and a psychologist clinician-investigator completed comprehensive evaluations. Neuropsychology test batteries included: the Millon Behavioral Medicine Diagnostic; Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder Screener (GAD-7); Adverse Childhood Experiences Scale; the Wide Range Assessment of Memory and Learning, including the 3 domains of verbal memory, visual memory, and attention/concentration; Wechsler Adult Intelligence Scale; and the Delis-Kaplan Executive Function System. The control cohort was comprised of 17 participants who previously underwent surgery for third window syndrome that resulted in the expected outcomes of resolution of their third window syndrome symptoms and cognitive dysfunction.

Results

There was a high rate of psychological comorbidity (n = 6) in the outlier cohort; multiple traumatic brain injuries were also a confounding element (n = 10). One patient had elevated cerebrospinal fluid (CSF) pressure requiring ventriculoperitoneal shunting to control the recurrence of dehiscence and one patient with a drug-induced Parkinson-like syndrome and idiopathic progressive neurological degenerative process.

Conclusions

Components of the Millon Behavioral Medicine Diagnostic, PHQ-9 and GAD-7 results suggest that these instruments would be useful as screening tools preoperatively to identify psychological comorbidities that could confound outcomes. The identification of these comorbid psychological as well as other neurological degenerative disease processes led to alternate clinical management pathways for these patients.

Level of Evidence

2b.

A Comparison of Surgical Treatments for Superior Semicircular Canal Dehiscence: A Systematic Review

OBJECTIVE

We investigate the postoperative subjective and objective outcomes of different surgical treatments for superior semicircular canal dehiscence (SSCD): vestibular signs, auditory signs, vestibular evoked myogenic potential test, pure tone audiogram, speech audiogram, or video-nystagmography.

DATA SOURCES

An electronic search performed in the PubMed, Cochrane Library, and EMBASE databases on 15th of September 2015. A systematic search was conducted. Articles were included if written in English, Dutch, German, or French language.

STUDY SELECTION

Original studies reporting on the pre and postoperative subjective and/or objective outcomes of surgical treatments for superior semicircular canal dehiscence were included.

DATA EXTRACTION

The methodological quality of the studies was independently assessed by two reviewers using a constructed critical appraisal, to assess the directness of evidence and the risk of bias. The results of the pre and postoperative subjective and/or objective outcomes were extracted.

DATA SYNTHESIS

Comparative study was conducted.

CONCLUSION

Surgical treatment for SSCD is particularly effective for vestibular symptoms and there is no evidence for improvement of hearing loss after surgical treatment. Since plugging using transmastoid approach had a lower complication rate, lower revision rate, and a shorter hospital stay, this treatment is recommended in high disabled SSCD patients.

Outcomes of Transmastoid Surgery for Superior Semicircular Canal Dehiscence Syndrome

OBJECTIVE

To present the management strategy and outcomes for our series of superior semicircular canal dehiscence syndrome (SSCDS) patients.

STUDY DESIGN

Retrospective cross-sectional study.

SETTING

Tertiary referral center.

PATIENTS

Thirty-seven consecutive patients referred from June 2011 to January 2015. Diagnosis of SSCDS based on presence of classical symptoms, computerized tomography, and concordant reduction in cervical vestibular evoked myogenic potentials.

INTERVENTIONS

Transmastoid resurfacing or plugging.

MAIN OUTCOME MEASURES

Pre- and postoperative pure tone audiometry. Nine item questionnaire grading pre- and postoperative symptom severity. Results of a short semi-structured telephone survey.

RESULTS

Twenty surgical patients: 13 women and 7 men. Mean age 52 years 6 months. Eighteen patients underwent transmastoid resurfacing and two underwent transmastoid plugging. Three of those who initially had resurfacing but had ongoing SSCD symptoms, subsequently had transmastoid plugging with complete resolution of third window symptoms. From the questionnaire there was improvement in mean scores for 8 of 9 of the SSCD symptoms, with statistically significant improvement in 6 of 9.

CONCLUSIONS

Management strategies and surgical techniques continue to evolve for SSCDS. We currently offer transmastoid resurfacing having informed patients of a 25% possibility of incomplete symptom resolution, and explain that plugging can be performed as a "second stage," if necessary. However, as we accrue more experience and there is more evidence from the literature we are considering whether to offer transmastoid plugging as our primary surgical procedure. In our experience, patients with multiple vestibular pathologies or atypical vestibular symptoms are the ones for whom SSCD surgery has not been curative, although they do report improvement in their SSCD symptoms.

Surgical Complications from Superior Canal Dehiscence Syndrome Repair: Two Decades of Experience

Objective

To determine the incidence of surgical complications associated with superior canal dehiscence syndrome (SCDS) repair and identify the demographic, medical, and intraoperative risk factors that are associated with SCDS complications.

Study Design

Cases series with chart review, including patients who underwent SCDS repair between 1996 and 2015.

Setting

A tertiary care academic medical center.

Subjects and Methods

Data were collected from 220 patients, including demographic information, medical comorbidities, prior otologic surgical history, surgical approach, intraoperative findings, and postoperative complications. Relative risk analysis and multivariable logistic regression evaluated the associations between perioperative risk factors and SCDS complications.

Results

A total of 242 consecutive cases were performed: 95.5% middle fossa and 4.5% transmastoid approach (mean age: 47.8 ± 10.6 years; 54.5% female). Surgical complications were reported in 27 (11.2%) cases; 20 (8.3%) had Clavien-Dindo grade I complications, most commonly benign paroxysmal positional vertigo (n = 11, 4.5%) and profound sensorineural hearing loss (n = 6, 2.5%). Two cases (0.8%) had grade II; 4 cases (1.7%), grade III; and 1 case (0.4%), grade IV complications. In the analysis of comorbidities, only preoperative coagulopathy was significantly associated with increased risk of complications (relative risk = 6.4, P < .01). Following multivariate logistic regression adjusting for demographic covariates, coagulopathy was still associated with increased odds of complications (odds ratio = 15.7, P = .03). There were no significant associations between other risk factors and complications.

Conclusion

SCDS repair has low rates of adverse events. We observed an incidence of 11.2% complications, most commonly postoperative benign paroxysmal positional vertigo. The risk of nonotologic intracranial complications (1.7%) is low.

Outcomes of middle fossa craniotomy for the repair of superior semicircular canal dehiscence

Superior semicircular canal dehiscence (SSCD) is a rare defect of the arcuate eminence that causes an abnormal connection between the superior semicircular canal and middle cranial fossa. Patients often present with a variety of auditory and vestibular symptoms. Trigger avoidance is the initial strategy, but surgery may be necessary in debilitating cases. We retrospectively reviewed SSCD patients undergoing repair via a middle fossa craniotomy between March 2011 and September 2015. Forty-nine patients undergoing 58 surgeries were identified. Autophony was the most common symptom at presentation (n=44; 90%). Mean follow-up was 10.9months, with 100% of patients reporting resolution of at least one symptom. Aural fullness was the most commonly resolved symptom following surgical repair (n=19/22; 86%). Hearing loss (n=11/25; 44%) and tinnitus (n=11/38; 29%) were the most common symptoms to persist following surgery. The most common symptom to develop after surgery was disequilibrium (n=4/18; 22%). Upon comparing the overall pre-operative and post-operative groups, the number of patients with autophony (p<0.0001), aural fullness (p=0.0006), hearing loss (p=0.0119), disequilibrium (p=0.0002), sound- and pressure-induced vertigo (p<0.0001), and tinnitus (p<0.0001) were significantly different. Improved clinical outcomes were demonstrated in patients undergoing SSCD repair through a middle cranial fossa approach. The most common presenting symptom (autophony) was also most likely to resolve after surgery. Hearing loss is less amenable to surgical correction. Disequilibrium developed in a small number of patients after repair.

Superior Semicircular Canal Dehiscence Syndrome - Diagnosis and Surgical Management

Introduction Superior semicircular canal dehiscence syndrome was described by Minor et al in 1998. It is a troublesome syndrome that results in vertigo and oscillopsia induced by loud sounds or changes in the pressure of the external auditory canal or middle ear. Patients may present with autophony, hyperacusis, pulsatile tinnitus and hearing loss. When symptoms are mild, they are usually managed conservatively, but surgical intervention may be needed for patients with debilitating symptoms.

Objective The aim of this manuscript is to review the different surgical techniques used to repair the superior semicircular canal dehiscence.

Data Sources PubMed and Ovid-SP databases.

Data Synthesis The different approaches are described and discussed, as well as their limitations. We also review the advantages and disadvantages of the plugging, capping and resurfacing techniques to repair the dehiscence.

Conclusions Each of the surgical approaches has advantages and disadvantages. The middle fossa approach gives a better view of the dehiscence, but comes with a higher morbidity than the transmastoid approach. Endoscopic assistance may be advantageous during the middle cranial fossa approach for better visualization. The plugging and capping techniques are associated with higher success rates than resurfacing, with no added risk of hearing loss.

Endoscopic-Assisted Repair of Superior Canal Dehiscence

Superior canal dehiscence (SCD) is a bony defect of the superior canal that can cause vestibular and/or auditory symptoms. Surgical repair of SCD provides effective relief from symptoms, and the middle fossa craniotomy approach with binocular microscopy offers direct visualization and surgical access to the arcuate eminence. However, for SCDs located along the downsloping tegmen medial to the peak of the arcuate eminence, a direct light of sight may be obscured, rendering visualization with traditional microscopy difficult. The endoscope is the ideal adjunct in middle fossa craniotomy approach SCD surgery and offers a safe, effective means to identify and repair arcuate eminence defects hidden from microscopic view.

Superior semicircular canal dehiscence syndrome

Superior semicircular canal dehiscence (SSCD) syndrome is an increasingly recognized cause of vestibular and/or auditory symptoms in both adults and children. These symptoms are believed to result from the presence of a pathological mobile "third window" into the labyrinth due to deficiency in the osseous shell, leading to inadvertent hydroacoustic transmissions through the cochlea and labyrinth. The most common bony defect of the superior canal is found over the arcuate eminence, with rare cases involving the posteromedial limb of the superior canal associated with the superior petrosal sinus. Operative intervention is indicated for intractable or debilitating symptoms that persist despite conservative management and vestibular sedation. Surgical repair can be accomplished by reconstruction or plugging of the bony defect or reinforcement of the round window through a variety of operative approaches. The authors review the etiology, pathophysiology, presentation, diagnosis, surgical options, and outcomes in the treatment of this entity, with a focus on potential pitfalls that may be encountered during clinical management.

Longitudinal Cognitive and Neurobehavioral Functional Outcomes Before and After Repairing Otic Capsule Dehiscence

Patients with peripheral vestibular dysfunction because of gravitational receptor asymmetries display signs of cognitive dysfunction and are assumed to have neurobehavioral sequelae. This was tested with pre- and postoperatively quantitative measurements in three cohort groups with superior semicircular canal dehiscence syndrome (SSCDS) symptoms with: 1) superior canal dehiscence (SCD) repaired via a middle cranial fossa craniotomy and canal plugging only; 2) otic capsule defects not visualized with imaging (no-iOCD) repaired with round window reinforcement (RWR) only; or 3) both SCD plugging and subsequent development of no-iOCD followed by RWR.

Characteristics of Wax Occlusion in the Surgical Repair of Superior Canal Dehiscence in Human Temporal Bone Specimens

HYPOTHESIS

Superior canal dehiscence (SCD) repair using surgical bone wax may result in variable outcomes if large wax volumes are applied.

BACKGROUND

SCD is a disorder characterized by a pathologic defect in the bony labyrinth of the superior semicircular canal (SSC), resulting in vestibular and/or auditory symptoms. Repair of SCD using bone wax can provide symptomatic relief, but surgical outcomes are variable. These observations may be associated with the inconsistency in the position and extension of intralabyrinthine bone wax during surgical repair.

METHODS

A pathological model of SCD was created using cadaveric human temporal bones and a microdrill. Defects in the arcuate eminence 0.5 to 3.5  mm in length were repaired by surgical occlusion with bone wax. The volume of wax used in the repair was quantified. The position of bone wax was evaluated by direct visualization and imaging (computed tomography [CT]). To visualize wax on CT, specimens were repaired using radiopaque wax.

RESULTS

Exceedingly small volumes of bone wax (3.0-5.0  mm2) reliably occluded the canal lumen. Multiple wax applications resulted in extension into the common crus and ampulla. The length of this extension was related to the number of applications.

CONCLUSIONS

Repair of SCD with bone wax occludes the bony defect completely in most patients. Wax can extend along the lumen of the superior canal beyond the limits of the dehiscence to reach the sensory neuroepithelium of the vestibular end organs. Limiting the number of wax applications is essential to avoid inadvertent injury to the delicate neurosensory systems.