Near-dehiscence: Clinical findings in patients with thin bone over the superior semicircular canal

Bryan K. Ward, Angela Wenzel, Eva K. Ritzl, Sergio Gutierrez-Hernandez, Charles C. Della Santina, Lloyd B. Minor, John P. Carey

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Objective: To determine whether patients with thin bone over the superior semicircular canal can develop signs or symptoms of superior canal dehiscence syndrome (SCDS). Study Design: Retrospective case series. Setting: Tertiary referral center. Patients: All patients from our institution found to have thin but not frankly dehiscent bone over the superior canal despite symptoms and signs of SCDS. Main Outcome Measures: Preoperative CT imaging, symptoms, audiometry, vestibular evoked myogenic potentials (VEMP), and intraoperative electrocochleography (ECochG) results were reviewed. Symptoms were assessed at least 1 month postoperatively in all patients, and postoperative physiologic data are presented when available. Results: Ten patients (11 ears) had thin bone over the superior semicircular canal at surgery. All presented with autophony or sound- and/or pressure-induced vertigo, in addition to at least 1 physiologic measure consistent with SCDS. CT imaging was read as showing either dehiscence (36%) or marked thinning of bone overlying the affected canal (64%). Preoperative median low-frequency air-bone gap (ABG) was elevated (10.9 dB; interquartile range [IQR], 8.8-12.5), with 4 patients demonstrating negative bone conduction thresholds. Patients had elevated oVEMP amplitude (median, 20.7; IQR, 6.7-22.1) μV and ECochG SP/AP ratios (median, 0.59; IQR, 0.54-0.67). Postoperative ABG and SP/AP ratio decreased significantly compared with preoperative values (p < 0.05), and all patients reported symptomatic improvement. Conclusion: Symptoms typical of SCDS can occur in cases with thin but not dehiscent bone. Surgical plugging or resurfacing can reduce symptoms in such cases.

Original languageEnglish (US)
Pages (from-to)1421-1428
Number of pages8
JournalOtology and Neurotology
Volume34
Issue number8
DOIs
StatePublished - Oct 2013

Keywords

  • Middle cranial fossa
  • Superior canal dehiscence syndrome
  • Third mobile window

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Sensory Systems
  • Clinical Neurology

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