Common features in patients with superior canal dehiscence declining surgical treatment.

BACKGROUND: Superior canal dehiscence (SCD) is a benign condition in which a surgical treatment may be considered depending on the patients' tolerance of their symptoms. In this study, we aim to identify driving factors behind the patients' choice of a surgical management over watchful waiting. METHODS: Sixty-two patients with cochlear and/or vestibular symptoms and a temporal bone high-resolution CT (HRCT) scan showing SCD were included in the study. All patients have been offered either surgical management or watchful waiting. RESULTS: Of these, 28 elected surgery and 34 declined it. The operated group showed more cochlear (6.6 vs. 2.4) symptoms than the non-operated group (P < 0.001) except for hypoacousis, but no significant difference (P = 0.059) was found for the number of vestibular symptoms between both groups (3.4 vs. 1.1). Footstep and eating hyperacousis were both present in 57.1% of operated vs. 3% of non-operated patients (P < 0.001). Oscillopsia with effort and with walking was found in 50% and 35.7% of operated patients, respectively, but none in the non-operated group (P < 0.001). Hearing tuning fork at malleolus and Valsalva and pneumatic speculum induced vertigo showed a statistically significant difference between the two groups (P = 0.003, P < 0.001, P = 0.010 respectively). Cervical vestibular-evoked myogenic potential (cVEMP) thresholds, air and bone conduction thresholds, and mean air-bone gap (ABG) were similar in the two populations (P > 0.05). The average dehiscence size was 4.7 mm (2.0 - 8.0 mm) and 3.8 mm (1.3 - 7.7 mm) in the operated and non-operated patients, respectively (P = 0.421). CONCLUSIONS: The natures of cochleovestibular signs and symptoms were shown to be key factors in patients' choice of a surgical management whereas paraclinical tests seem to be less significant in the patients' decision for a surgical treatment.

Superior canal dehiscence: can we predict the diagnosis?

OBJECTIVE: Identify independent clinical and audiometric factors to predict a positive high-resolution computed tomography (HRCT) scan for superior canal dehiscence (SCD). STUDY DESIGN: Retrospective chart review. SETTING: Tertiary referral center. PATIENTS: Patients presenting SCD. INTERVENTION(S): Audiogram, VEMP, temporal bone HRCT, and SCD symptoms and signs chart. MAIN OUTCOME MEASURE(S): ABG, VEMP threshold, and symptoms and signs. RESULTS: Approximately 106 patients with SCD symptoms were included: 62 had a positive and 44 had a negative CT scan. The positive scan group showed a higher average of cochlear symptoms than the negative CT scan group (4.3 versus 2.6) (p < 0.001), but no statistical difference for vestibular symptoms (2.2 versus 1.8) was identified. CVEMP thresholds of the positive and negative CT scan groups were of 66 and 81 dB, respectively (p < 0.001). The positive CT scan group showed higher ABGs at 250 Hz (24 versus 14 dB) and 500 Hz (17 versus 8 dB) (p = 0.008 and p = 0.008, resectively). No statistical significance was found when comparing both groups for air and bone conduction thresholds. Approximately 23% of the positive CT scan group showed a Valsalva-induced vertigo against 2.3% of the negative scan group (p = 0.003); 27% of the positive CT scan group showed speculum-induced vertigo but none of the negative scan patients (p < 0.001). Using logistic regression, we found that each 10-dB unit increase in the 250 Hz ABG is associated to an increase odd of having SCD of 51% (OR, 1.51; 95% CI, 1.10-2.08). CONCLUSION: Nature and number of cochlear symptoms, Valsalva and pneumatic speculum-induced vertigo, VEMP thresholds, and ABGs seem to correlate with a positive HRCT. The ABG at 250 Hz is the most accurate predictor of SCD.

Superior canal dehiscence syndrome: clinical manifestations and radiologic correlations.

The objective of this study is to describe the superior canal dehiscence syndrome (SCDS) and its vestibule-cochlear manifestations, while analyzing dehiscence size, audiogram and vestibular-evoked myogenic potential (VEMP) changes following dehiscence obliteration. We conducted a prospective study in a tertiary referral center. All Patients diagnosed and surgically treated for SCDS were operated through a middle fossa craniotomy (MFC). Clinical and radiological data were collected. The main outcome measures were Air-bone gaps, Pure-tone average (PTA), speech discrimination scores (SDS) and VEMP thresholds and were correlated to dehiscence size. 28 patients were included in this study with a mean dehiscence size of 4.68 mm. Phonophobia and imbalance were the most debilitating cochlear and vestibular symptoms, respectively. At 2 months postoperatively, low-frequency air-bone gaps showed a statistically significant improvement (p < 0.001). SDS and PTA did not show any statistically significant changes 2 months postoperatively (p = 0.282 and p = 0.295, respectively). VEMP threshold differences between operated and contralateral ears were statistically significant preoperatively (p < 0.001) and non-significant 2 months postoperatively (p = 0.173). Dehiscence size only showed a statistically significant correlation with preoperative total cochlear symptoms, while remaining insignificant with all other variables measured. Air-bone gaps, VEMP and computerized tomography remain essential tools in diagnosing and following SCDS. Dehiscence size is an independent factor in the analysis of SCDS, with cochlear symptomatology being associated to dehiscence sizes. Finally, it is shown that overall symptomatology, audiometric results and VEMP thresholds return to normal values post-obliteration, confirming the continuing success of the MFC approach for SCDS obliteration.