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

Diagnostic Yield of Patients Undergoing Evaluation of Possible Superior Canal Dehiscence

OBJECTIVE

To characterize the diagnostic yield of patients undergoing evaluation for superior canal dehiscence syndrome (SCDS), and identify alternative conditions diagnosed in patients suspected of, but not ultimately diagnosed with, SCDS.

METHODS

Diagnostically undifferentiated adult patients suspected of having SCDS were identified between 2016 and 2021 at a tertiary academic medical system. Patients were categorized by diagnostic testing, radiographic superior semicircular canal (SSC) abnormality, symptoms, evaluating clinician specialty, operative intervention, and diagnosis. Differences among groups were assessed for statistical significance.

RESULTS

Of 1242 candidate patients, 477 met inclusion criteria-evaluation by a clinician with SCDS on their differential diagnosis prior to diagnostic imaging. The mean (SD) age was 53.0 (15.0) years and 70.6% were female. A total of 364 patients underwent subsequent diagnostic imaging, and among these, 164 (45.1%) had a radiographic SSC abnormality with 99 (27.2%) receiving a diagnosis of SCDS (two cases of "near dehiscence syndrome"). One third (33.3%) of patients with SCDS underwent operative repair. Most clinicians with the initial suspicion for SCDS were otolaryngologists (90.6%), who had greater diagnostic yield than clinicians from other specialties (22.2% vs. 6.7%, p = 0.012). Patients not diagnosed with SCDS alternatively received 21 unique diagnoses and 52.1% (138/265) were not definitively diagnosed with any condition.

CONCLUSIONS

This study characterizes the diagnostic incidence, or yield, of newly identified radiographic SSC abnormalities (45.1%) and SCDS (27.2%) among people suspected of having SCDS. Considerable overlap in presentation between SCDS and other conditions exists, and there is need for improvement in efficiently diagnosing patients with SCDS and audio-vestibular complaints in general.

LEVEL OF EVIDENCE

III Laryngoscope, 134:4095-4100, 2024.

Symptomatology in Unilateral Versus Bilateral Superior Canal Dehiscence Patients Undergoing Unilateral Surgery

OBJECTIVE

To compare symptomatology in patients with unilateral versus bilateral superior semicircular canal dehiscence who underwent unilateral surgical repair.

STUDY DESIGN

Retrospective cohort study.

SETTING

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

METHODS

Patients were administered a standardized questionnaire regarding the presence or absence of 16 symptoms (11 auditory and 8 vestibular) pre- and postoperatively. Symptom rates were compared between patients with unilateral and bilateral dehiscence, and paired statistical testing was used to analyze symptom improvement with surgery.

RESULTS

Our final cohort included 125 patients, 93 (74%) with unilateral superior canal dehiscence syndrome (SCDS) and 32 (26%) with bilateral SCDS. Bilateral patients had an increased burden of auditory and vestibular symptoms compared to unilateral patients before surgery (7.6 vs 6.2, P = .03) and after surgery (3.1 vs 1.9, P = .02). Both groups experienced a significant reduction of symptoms following repair (P < .01 for both).

CONCLUSION

Our study has 2 key findings: First, patients with bilateral dehiscence seem to be more symptomatic, reporting more auditory and vestibular symptoms both before and after surgery. Second, bilateral patients still seem to benefit from unilateral repair, demonstrating a significant reduction in the number of symptoms with surgery. Our findings may help inform the management of the sizable proportion of SCDS patients with bilateral defects.

Narrowing of Low-Frequency Air-Bone Gap and Its Association with Symptom Resolution Following Superior Canal Dehiscence Repair

OBJECTIVE

Low-frequency air-bone gap (LABG) on pure tone audiometry is an expected clinical finding of superior canal dehiscence (SCD) syndrome. We investigate how narrowing of LABG following SCD repairs translates to symptom resolution.

STUDY DESIGN

Cohort study.

SETTING

Tertiary Care Center.

METHODS

We analyzed consecutive SCD repairs at an institution between 2012 and 2022. Pure tone audiometry and symptom questionnaires were administered pre- and post-operatively. The independent variable assessed whether the LABG narrowed (≥5 dB) following surgery. Outcome measures were rates of Overall Symptom Improvement (OSI, net resolution of ≥1 symptom) and Symptom Resolution Score (SRS, % symptoms resolved). We conducted multivariable regression analyses with LABG narrowing as the primary predictor. All models controlled for demographics, bilateral disease, prior ear surgery, and follow-up.

RESULTS

Among total of 217 repairs analyzed, 161 (74%) reached OSI, and mean SRS was 39 (out of 100). LABG narrowing at 250 Hz (65%), 500 Hz (52%), and 1000 Hz (47%) was associated with a 41-point (β 95% confidence interval [CI] 5-77) increase in auditory, 15-point (β 95% CI 1-30) increase in auditory, and 23-point (β 95% CI 2-45) increase in vestibular SRS, respectively. However, LABG narrowing was not significantly associated with the rates of auditory and vestibular OSI at all frequencies assessed.

CONCLUSION

Lack of LABG narrowing following repair was associated with the persistence of a greater proportion of preoperative symptoms but similar likelihood of OSI. This relationship was more prominent for auditory symptoms at 250 to 500 Hz and for vestibular symptoms at 1000 Hz. Additional research is warranted to elucidate the mechanism through which symptoms resolve despite LABG persistence.

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.