Comparing Approaches for Repair of Superior Semicircular Canal Dehiscence

OBJECTIVE

Compare outcomes for subjects who underwent middle cranial fossa (MCF) or transmastoid (TM) repair of superior semicircular canal dehiscence (SSCD).

STUDY DESIGN

Retrospective cohort study.

SETTING

Quaternary-care, academic neurotology practice.

METHODS

Subjects who underwent MCF or TM repair of SSCD between December 1999 and April 2023 were identified. Main outcome measures included demographic data, length of surgery and hospital stay, clinical presentation, and audiometric testing.

RESULTS

Ninety-three subjects (97 ears) who underwent surgery for SSCD met inclusion criteria: 58.8% (57) via MCF, 39.2% (38) via TM, and 2.0% (2) via TM + MCF. Median operative time was shorter for the TM (35) compared to the MCF (29) approach (118 vs 151 minutes, P < .001). Additionally, median hospital stays were shorter for TM (36) compared to the MCF (56) approach (15.3 vs 67.7 hours, P < .001). Overall, 92% (49/53) of MCF and 92% (33/36) of TM surgeries resulted in an improvement or resolution of one or more symptoms (P = .84). There was no significant preoperative to postoperative change in the median air conduction pure-tone average (PTA), air-bone gap, or word recognition score in both the MCF and TM groups (P > .05). Improvements of >10 dB in the pre- to postoperative absolute change in bone conduction PTA were noted in 3 subjects in the MCF group and 4 subjects in the TM group (P = .49).

CONCLUSION

The TM approach for SSCD demonstrates shorter operative times and length of hospital stay. The TM and MCF approaches have comparable audiometric and clinical outcomes.

Low-Lying Tegmen and Surgical Outcomes Following the Middle Cranial Fossa Repair of Superior Canal Dehiscence

OBJECTIVE

To compare treatment response from the middle cranial fossa repair of superior canal dehiscence (SCD) between cases with and cases without low-lying tegmen (LLT).

STUDY DESIGN

Cohort study.

SETTING

Single tertiary care institution.

METHODS

Two investigators independently reviewed preoperative high-resolution temporal bone computed tomography images and classified the ipsilateral tegmen as either "low-lying" or "control." Patients completed a symptom questionnaire and underwent audiometric testing pre- and post-operatively. Multivariable regression models assessed for symptomatic resolution and audiometric improvement following surgery with tegmen status as the primary predictor. Models controlled for patient age, sex, bilateral SCD disease, dehiscence location, prior ear surgery status, surgery duration, and follow-up duration.

RESULTS

Among a total of 410 cases included, we identified 121 (29.5%) LLT cases. Accounting for all control measures, patients with LLT were significantly less likely to experience overall symptom improvement (adjusted odds ratio: 0.32, 95% confidence interval [CI]: 0.18-0.57, p < .001) and reported a significantly lower proportion of preoperative symptoms that resolved following surgery (adjusted β: -25.6%, 95% CI: -37.0% to -14.3%, p < .001). However, audiometric outcomes following surgery did not differ significantly between patients with and patients without LLT.

CONCLUSION

This is the first investigation on the relationship between LLT and surgical outcomes following the middle fossa repair of SCD. Patients with LLT reported less favorable symptomatic response but exhibited a similar degree of audiometric improvement.

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.

Auditory and Vestibular Symptom Improvement With Surgery for Superior Canal Dehiscence Syndrome

OBJECTIVE

(1) To measure the change in auditory and vestibular symptoms following superior canal dehiscence (SCD) surgery, and (2) to determine differences in clinical features and surgical outcomes between superior canal dehiscence syndrome (SCDS) patients with primarily auditory or vestibular complaints.

STUDY DESIGN

Retrospective cohort study.

SETTING

Single surgeon series at the tertiary academic medical center from 2002 to 2021.

METHODS

Retrospective review of SCDS patients who underwent surgical repair. (1) Patients were administered a standardized symptom questionnaire at preoperative and follow-up visits, and results were compared with paired statistical testing. (2) Patients were divided into 2 cohorts based on either auditory or vestibular chief complaint and differences in demographic, clinical, and outcome variables were examined.

RESULTS

Our study included 113 patients with 118 operated ears. Twenty-seven patients (24%) had radiographic bilateral dehiscence. 10/11 auditory symptoms (91%) and 5/8 vestibular symptoms (63%) solicited on the questionnaire improved significantly with surgery, except for nonpulsatile tinnitus, sense of imbalance, positional dizziness, and oscillopsia. Analyses stratified by chief complaint (auditory vs vestibular) revealed overall similar characteristics and surgical outcomes. Patients with chief vestibular complaints underwent surgery at an earlier age (45.5 vs 53.9 years, p < 0.05).

CONCLUSION

SCD surgery alleviates a wide range of auditory and vestibular symptoms. Overall, we did not find significant differences between patients with chief auditory versus vestibular complaints, and both groups benefited from surgery. Symptoms are not directly linked to third-window physiology and certain vestibular symptoms may be more likely to persist. Bilateral dehiscence may play an important role in persistent symptoms as well.

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.

Postoperative Pneumolabyrinth Following the Middle Cranial Fossa Approach for Superior Semicircular Canal Dehiscence Repair, 2014-2020

OBJECTIVE

The present study investigates risk factors and clinical outcomes of postoperative pneumolabyrinth following the middle cranial fossa approach for superior semicircular canal dehiscence repair, a complication that has not been documented previously.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary/quaternary care referral center.

METHODS

We conducted a retrospective review of 332 middle cranial fossa procedures from 2014 to 2020 at a tertiary/quaternary care institution. Upon identifying pneumolabyrinth cases from postoperative computed tomography temporal bone scans, we conducted multivariable logistic regression analysis to explore demographic and clinical factors that were independently linked to this complication. We also compared the rates of postoperative symptoms among patients with different grades of pneumolabyrinth.

RESULTS

We identified 41 (12.3%) pneumolabyrinth cases. Patients with older age, higher preoperative pure tone average, and frank dehiscence were at higher risk for pneumolabyrinth. Furthermore, patients with pneumolabyrinth reported significantly higher rates of postoperative dizziness and exhibited significantly greater pure tone average and air-bone gap postoperatively as compared with patients without pneumolabyrinth. Finally, higher-grade pneumolabyrinth was associated with increased rates of postoperative hearing loss, and grade III pneumolabyrinth was associated with higher rates of postoperative tinnitus vs grade I and II cases.

CONCLUSION

Pneumolabyrinth following the middle cranial fossa approach was associated with poor clinical outcomes, including dizziness and auditory impairment. Old age, high preoperative pure tone average, and frank dehiscence were risk factors for this complication. The highlighted parameters may be important to note when considering this approach as a treatment option and while monitoring postoperative recovery.

Auditory Outcomes Following Transmastoid and Middle Cranial Fossa Approaches for Superior Semicircular Canal Dehiscence Repair

OBJECTIVE

To describe postoperative hearing outcomes following transmastoid (TM) and middle cranial fossa (MCF) approaches for semicircular canal dehiscence (SSCD) repair.

STUDY DESIGN

Retrospective review.

SETTING

Academic, tertiary referral center.

PATIENTS

Adults with SSCD who underwent repair between 2005 and 2019.

INTERVENTIONS

Pure tone audiometry pre- and postoperatively after SSCD repair.

MAIN OUTCOME MEASURES

Change in air-bone gap (ABG) at 250 and 500 Hz, pure tone average (PTA), bone conduction (BC), and air conduction (AC) thresholds at 500, 1000, 2000, and 4000 Hz for patients undergoing TM and MCF approaches for SSCD repair.

RESULTS

The average change in BC PTA for patients undergoing TM (n = 26) and MCF (n = 24) SSCD repair was not significantly different between the two groups. The first and final postoperative PTAs were recorded an average of 1.7 (range 0.30-3.0) and 29.1 (range 3.5-154) months postoperatively. For patients who underwent MCF repair, the average BC PTAs increased (+) by 2.2 dB HL (p 0.43) and 0.57 dB HL (p 0.88) at the first and final audiograms respectively compared to +1.27 dB HL (p 0.53) and a decrease (-) of 0.57 dB HL (p 0.63) for the TM group. The average changes in low frequency ABG for patients undergoing MCF repair were -4.7 dB (p 0.08) and -6.9 dB (p 0.15) at first and final audiograms respectively compared to -4.9 dB (p 0.06) and -4.1 dB (p 0.36) for patients who underwent TM repair. There was a high frequency hearing loss noted at 8000 Hz for the MCF (30.0 dB ± 18.7 preop; 41.7 dB ± 21.7 postop; p 0.01) and TM (32.1 dB ± 23.2 preop; 44.3 dB ± 29.6 postop; p 0.001) groups which persisted on long term follow up.

CONCLUSIONS

Both TM and MCF approaches to SSCD repair can be performed with long-term preservation of hearing. ABGs were reduced in each treatment group but did not reach significance. A high frequency hearing loss (8000 Hz) may be expected with either approach.

Superior Semicircular Canal Dehiscence Revision Surgery Outcomes: A Single Institution's Experience

BACKGROUND

Superior semicircular canal dehiscence (SSCD) is an abnormality of the otic capsule, which normally overlies the superior semicircular canal. Surgical management is indicated in patients with persistent and debilitating symptoms. Given the complexity of the disease, there are patients who experience less favorable surgical outcomes and require revision surgery. The purpose of this study was to report to the rate of postoperative symptomatic improvement in patients who required revision surgery.

METHODS

A retrospective analysis of patients undergoing SSCD surgical repair at a single institution was performed. Information on patient demographics, primary and secondary surgical approaches, surgical outcomes, and follow-up length was collected.

RESULTS

Seventeen patients underwent 20 revision surgeries. There were eleven (65%) females and six (35%) males. Mean age of the cohorts was 50 years (range 30-68 years), and mean follow-up length was 6.8 months (range 0.1-31.1 months). Cerebrospinal fluid leak was noted in 67% of cases. The greatest postoperative symptomatic resolution was reported in oscillopsia (100%), headache (100%), and internal sound amplification (71%), while the least postoperative symptomatic resolution was reported in tinnitus (42%), aural fullness (40%), and dizziness (29%).

CONCLUSIONS

Revision surgery can provide symptomatic improvement in select SSCD patients; however, patients should be cautioned about the possibility of less favorable outcomes than in index surgery. Revision surgeries are associated with a considerably higher rate of perioperative cerebrospinal fluid leak.

Endoscope-Assisted Superior Semicircular Canal Dehiscence Repair: Single Institution Outcomes

OBJECTIVE

To compare outcomes of endoscope-assisted middle cranial fossa MCF) repair of superior semicircular canal dehiscence (SSCD) compared to microscopic MCF repair.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary medical center neurotology practice.

METHODS

Retrospective chart review and cohort study of patients who underwent surgical repair of SSCD via MCF approach from 2010 to 2019 at our institution. Patients were categorized according to use of endoscope intraoperatively. Pre- and post-operative symptom number was calculated from 8 patient-reported symptoms. Pre- and post-operative changes in symptom number were assessed using paired t-tests. Single-predictor binary logistic regression was used to compare final reported symptoms between cohorts. Linear regression was performed to assess air-bone gap (ABG) changes postoperatively between cohorts.

RESULTS

Forty-six patients received surgical management for SSCD. Of these, 27 (59%) were male and 19 (41%) were female. Bilateral SSCD was present in 14 cases (29%), of which 3 underwent surgical management bilaterally, for a total of 49 surgical ears. Surgery was performed on the right ear in 19 cases (39%) and on the left in 30 cases (61%). Forty ears (82%) underwent microscopic repair while 9 (18%) underwent endoscope-assisted repair. Microscopic and endoscope-assisted MCF repair both demonstrated significantly improved symptom number postoperatively (P < .001 for each). There was no significant difference in change in ABG between the 2 cohorts. On average, patient-reported symptoms and audiometrically-tested hearing improved postoperatively in both groups.

CONCLUSION

While endoscopic-assisted MCF repair has the potential to provide better visualization of medial and downslope defects, repair via this technique yields similar results and is equivalent to MCF repair utilizing the microscope alone.

Underwater Endoscopic Repair of Superior Canal Dehiscence

: Superior canal dehiscence (SCD) is a bony defect of the superior semicircular canal (SCC). Patients with SCD Syndrome (SCDS) may experience symptoms such as aural fullness, pulsatile tinnitus, hyperacusis, autophony, or pressure or noise-induced vertigo . The defect can be repaired in various ways, but there is potential for loss of perilymphatic fluid during transmastoid approaches that could result in postoperative sensorineural hearing loss . We hypothesize that if the procedure were performed "underwater" in balanced salt solution (BSS), loss of perilymphatic fluid would be minimized. CASE REPORT:: A 55-year-old male presented with right-sided autophony, pulsatile tinnitus, and hyperacusis. Audiometric testing demonstrated a low-frequency airbone gap and a supranormal bone-conduction threshold at 4 kHz. Ocular VEMP responses were increased amplitude. Temporal bone imaging revealed a SCC dehiscence.The patient was taken to the operating room for an underwater, endoscopic repair of the SCC using a transmastoid approach. A cortical mastoidectomy was performed using Landmarx image navigation. BSS filled the mastoid and a 0-degree endoscope with endoscrub was used to see the SCC underwater. The SCC was entered near the ampullated end with a bur. A stepwise plugging process included applying strips of wet and dried fascia and bone dust. The non-ampullated end was similarly plugged. BSS was suctioned, and under microscopic visualization, labyrinthotomies were capped with bone chips. The patient tolerated the procedure well and was discharged the next day. There was no sensorineural hearing loss postoperatively. CONCLUSION:: SCDS may be addressed surgically using multiple approaches. An underwater endoscopic repair of the SCC may be safe and effective surgical treatment.SDC video link: http://links.lww.com/MAO/A808.

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.

Advances and challenges in adeno-associated viral inner-ear gene therapy for sensorineural hearing loss

There is growing attention and effort focused on treating the root cause of sensorineural hearing loss rather than managing associated secondary characteristic features. With recent substantial advances in understanding sensorineural hearing-loss mechanisms, gene delivery has emerged as a promising strategy for the biological treatment of hearing loss associated with genetic dysfunction. There are several successful and promising proof-of-principle examples of transgene deliveries in animal models; however, there remains substantial further progress to be made in these avenues before realizing their clinical application in humans. Herein, we review different aspects of development, ongoing preclinical studies, and challenges to the clinical transition of transgene delivery of the inner ear toward the restoration of lost auditory and vestibular function.

Fluctuating Posterior Canal Function in Benign Paroxysmal Positional Vertigo Depending on How and Where Otoconia Are Disposed

OBJECTIVE

Though fluctuations in vestibular function represent a common finding in Menière's disease, we describe how benign paroxysmal positional vertigo (BPPV) may result in fluctuations of vestibulo-ocular reflex for the involved canal depending on the disposition of otoliths.

PATIENT

A 54-year-old woman suffering from refractory posterior canal (PC)-BPPV resulting in fluctuating PC function.

INTERVENTIONS

Diagnostic evaluation and rehabilitative treatment for BPPV involving the affected PC.

MAIN OUTCOME MEASURES

Video-Frenzel and video-head impulse test (vHIT) findings before and after canalith repositioning procedures for PC-BPPV.

RESULTS

BPPV involving the nonampullary arm of right PC was diagnosed based on presenting positional downbeat nystagmus and selective right PC hypofunction at the vHIT. During physical treatment, nystagmus first became positional paroxysmal upbeat likely due to a shift of debris into the ampullary arm of the canal, then turned to spontaneous downbeat nystagmus consistently with a plug effect exerted by particles entrapped within the nonampullary arm of PC and finally receded proving an otoliths fall within the utriculus. Simultaneously, vHIT documented fluctuations for right PC vestibulo-ocular reflex gain as it first increased to normal values, then severely declined and finally normalized, respectively. High-resolution computed tomography scan detected ipsilateral superior canal dehiscence.

CONCLUSIONS

In accordance with recently reported vHIT findings in different types of BPPV, fluctuation of PC function could be likely explained by the effect of particles on cupular dynamic responses depending on the portion of the canal gradually involved. Superior canal dehiscence may have played a role facilitating otoliths mobilization by reducing labyrinthine impedance.

Outcomes after mini-craniotomy middle fossa approach combined with mastoidectomy for lateral skull base defects

PURPOSE

Controversy exists regarding the ideal approach for repair of lateral skull base defects. Our goal is to report the outcomes following middle cranial fossa (MCF) mini-craniotomy combined with mastoidectomy for patients with superior semicircular canal dehiscence (SSCD), spontaneous cerebrospinal fluid (CSF) leak, and cholesteatoma.

MATERIALS AND METHODS

A retrospective database from chart review was formed consisting of 97 patients who met surgical criteria: SSCD, spontaneous CSF leak, and cholesteatoma. Mini-craniotomy MCF approach (<4 × 2 cm in size) combined with mastoidectomy was performed. All patients were admitted directly to the ICU postoperatively. Multiple factors were assessed, including need for revision surgery, duration of surgery, length of post-operative stay, and hospital readmission.

RESULTS

Average surgery time was 110 min with no intraoperative complications. The average length of hospitalization was 2 days with an average ICU stay of 1 day. There were no neurologic complications; however, there were 3 inpatient complications (3%) which included 1 patient (1%) that had wound breakdown and 2 patients (2%) that had severe post-operative vertigo. A total of 8 patients (8%) required revision surgery and these were primarily for SSCD. The 30-day readmission rate was 3%.

CONCLUSION

In the current series, all patients that underwent mini-craniotomy MCF surgery combined with mastoidectomy had minimal complications, short surgical time, limited hospital stay, low revision surgery rate and few hospital readmissions. This combined approach offers superior visualization of lateral skull base defects without the morbidity and risk typically associated with traditional, extensive MCF surgery.

Practical aspects of inner ear gene delivery for research and clinical applications

The application of gene therapy is widely expanding in research and continuously improving in preparation for clinical applications. The inner ear is an attractive target for gene therapy for treating environmental and genetic diseases in both the auditory and vestibular systems. With the lack of spontaneous cochlear hair cell replacement, hair cell regeneration in adult mammals is among the most important goals of gene therapy. In addition, correcting gene defects can open up a new era for treating inner ear diseases. The relative isolation and small size of the inner ear dictate local administration routes and carefully calculated small volumes of reagents. In the current review, we will cover effective timing, injection routes and types of vectors for successful gene delivery to specific target cells within the inner ear. Differences between research purposes and clinical applications are also discussed.

Utility of Postoperative Magnetic Resonance Imaging in Patients Who Fail Superior Canal Dehiscence Surgery

OBJECTIVE

The etiology of symptoms following primary repair of superior canal dehiscence (SCD) may be due to a persistent third window. However, the extent of surgery cannot be seen on postoperative computed tomography (CT) since most repair materials are not radiopaque. We hypothesize that the extent of superior semicircular canal (SSC) occlusion following primary repair can be quantified based on postoperative magnetic resonance imaging (MRI) data.

STUDY DESIGN

Retrospective series.

SETTING

Tertiary care center.

PATIENTS

Adult patients with a history of SCD syndrome who 1) report persistent symptoms following primary SCD repair and 2) underwent heavily T2-weighted MRI postoperatively.

INTERVENTIONS

Analysis of SSC using 3D-reconstruction of CT co-registered with MRI data.

MAIN OUTCOME MEASURES

Arc length of fluid void on MRI and quantification of persistent SCD based on CT/MRI co-registration.

RESULTS

We identified 9 revision cases from a cohort of 145 SCD repairs at our institution (2002-2017) with CT/MRI data. A fluid void on postoperative MRI (indicating occlusion of the SSC) was observed in all cases (anterior limb: 50.1 degrees [±21.8 SD] and posterior limb 48.1 degrees [±28.5 SD]). Co-registration of CT/MRI revealed a residual defect that was most commonly found along the posterior limb in most patients with persistent symptoms.

CONCLUSIONS

The extent of SCD repair can be determined using reformatted or direct T2-weighted MRI sequences in the plane of Pöschl. Co-registration of CT/MRI may be useful to determine the location of a residual superior canal defect and when present was found most commonly along the posterior limb.

Reflections on the Last 25 Years of the American Otological Society and Thoughts on its Future

PURPOSE

To review contributions of the American Otological Society (AOS) over the most recent quarter century (1993-2018) and to comment on possible future evolution of the field during the quarter century to come.

METHODS

Retrospective review of selected topics from the AOS transactions, distinguished lectureships over the past 25 years, and selective reflection by the authors. Speculation on potential advances of the next quarter century derived from emerging topics in the current literature and foreseeable trends in science and technology are also proffered for consideration (and possible future ridicule).

RESULTS

Integration of multiple disciplines including bioengineering, medical imaging, genetics, molecular biology, physics, and evidence based medicine have substantially benefitted the practice of otology over the past quarter century. The impact of the contributions of members of the AOS in these developments cannot be over estimated.

CONCLUSIONS

Further scientific advancement will certainly accelerate change in the practice of otologic surgery and medicine over the coming decade in ways that will be marvelous to behold.

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.

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.

Stenting the Superior Petrosal Sinus in a Patient With Symptomatic Superior Semicircular Canal Dehiscence

Patients presenting superior semicircular canal dehiscence (SSCD) can experience symptoms such as conductive hearing loss, pulsatile tinnitus, autophony, and pressure-induced vertigo. Decreased cervical vestibular-evoked myogenic potentials (cVEMPs) thresholds and high-resolution computed tomography (HRCT) of the petrous bone are essential for diagnosis of SSCD syndrome. We report the case of a 43-year-old man suffering from constant right pulsatile tinnitus, intermittent autophony, and unsteadiness induced by physical exercise. An SSCD by the superior petrosal sinus (SPS) was confirmed on the right side by axial HRCT of the temporal bone reformatted in the plane of Pöschl and ipsilateral abnormally low elicited cVEMPs. Treatment options were discussed with the patient since the pulsatile tinnitus progressively became debilitating. Two options were considered: surgery or a new endovascular treatment; the patient chose the latter option. After stenting the right SPS, the intensity of the pulsatile tinnitus dramatically decreased. As there was no complication the patient was discharged at Day 1. The other symptoms improved progressively. By the 60-day follow-up visit the patient only reported a slight tinnitus worsened by physical exercise. Angiographic follow-up at 5 months confirmed the patency of the SPS. Stenting the SPS in patients with SSCD by the SPS appears to be an alternative to the existing surgical treatments.

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.