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.

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