Cadaveric Study of an Endoscopic Keyhole Middle Fossa Craniotomy Approach to the Superior Semicircular Canal.

Objective: Demonstrate that an endoscopic keyhole approach to the middle cranial fossa is technically feasible for repair of semicircular canal dehiscence.

Study Design: Cadaveric technical feasibility/methods development study.

Setting: Tertiary care military medical center.

Patients: Three fresh cadaveric heads (six sides).

Intervention(s): Endoscopic minimally invasive approach to the middle cranial fossa using the Medtronic Fusion Guidance system.

Main Outcome Measure(s): Ability to identify the surgical landmarks of the middle cranial fossa and successfully identify and instrument the superior semicircular canal.

Results: In every attempt, the arcuate eminence was successfully identified under endoscopic visualization and with the assistance of surgical navigation. The superior semicircular canal was unroofed, and its location confirmed visually and with the navigation system. The opened canal was then plugged with bone wax, bone pate, and covered with fascia. The 15-mm burr hole craniotomy provided ample room for one working instrument and a 4-mm 0-degree endoscope.

Conclusion: The endoscopic keyhole approach to superior semicircular canal dehiscence is technically feasible in a human cadaveric model. Further studies will determine 1) if this approach is possible and safe in vivo, 2) is associated with improved surgical outcomes, and 3) if surgical navigation aids in this approach.