Endoscopic-assisted surgical repair of superior canal dehiscence using a keyhole middle fossa craniotomy approach

Abstract

Superior canal dehiscence (SCD) is a bony defect of the superior semicircular canal that is called SCD syndrome (SCDS) when associated with vestibular and auditory dysfunction. Surgical management of SCD is reserved for patients with intractable auditory and/or vestibular symptoms. As direct visualization of an arcuate eminence defect is most easily achieved from above, the majority of cases use a microscope-assisted middle fossa craniotomy. However, approximately 30% of SCD cases have a medial arcuate eminence defect along a downsloping tegmen. These defects can be difficult to visualize without a large cranial window, drilling down a prominent lateral skull base ridge, and/or prolonged brain retraction. In line with recent development of endoscopic ear surgery, the endoscope has been employed at our institution via a middle fossa craniotomy approach to repair a SCD. We believe that skull base endoscopy is a safe and effective way to identify and repair a medial or blue-lined SCD when used with a middle fossa craniotomy approach. The angled endoscope enhances visualization and transillumination of the SCD and reduces temporal lobe retraction. The following chapter highlights an endoscopic-assisted middle fossa craniotomy repair of SCD.