Minimally invasive middle fossa craniotomy approach with endoscopic repair of superior canal dehiscence

Abstract

Superior canal dehiscence (SCD) is a bony defect of the superior semicircular canal. SCD syndrome occurs when vestibular or auditory dysfunction accompanies SCD. Although not all patients with SCD are symptomatic, surgical repair is an option in patients with incapacitating symptoms and are unresponsive to conservative treatment. Traditionally, repair of SCD when involving the arcuate eminence can be achieved using a middle fossa craniotomy approach. However, approximately 30% of SCD cases have a medial arcuate eminence defect along a downsloping tegmen, making the defect difficult to visualize with the binocular microscope without a large craniotomy, extensive temporal lobe retraction, and drilling of the skull base. As complete visualization of an arcuate eminence defect is essential for successful repair, we describe an operative approach to visualize the SCD that combines a small middle fossa craniotomy and rigid endoscopy. The wide-field view and superior transillumination with skull base endoscopy can be achieved with a minimal access skin incision, small bony window, less dural dissection, and reduced brain retraction, resulting in unequivocal identification of the entire arcuate eminence defect.