Decompression of the geniculate ganglion and labyrinthine segments of the facial nerve through a middle cranial fossa approach using an ultrasonic surgical system: an anatomic study

Purpose: The aim of this study is to evaluate the feasibility and the safety of a novel, alternative method for bone tissue management in facial nerve decompression by a middle cranial fossa approach. Several applications of Piezosurgery technology have been described, and the technique has recently been extended to otologic surgery. The piezoelectric device is a bone dissector which, using micro-vibration, preserves the anatomic integrity of soft tissue thanks to a selective action on mineralized tissue. Methods: An anatomic dissection study was conducted on fresh-frozen adult cadaveric heads. Facial nerve decompression was performed by a middle cranial fossa approach in all specimens using the piezoelectric device under a surgical 3D exoscope visualization. After the procedures, the temporal bones were examined for evidence of any injury to the facial nerve or the cochleovestibular organs. Results: In all cases, it was possible to perform a safe dissection of the greater petrosal superficial nerve, the geniculate ganglion, and the labyrinthine tract of the facial nerve. No cases of semicircular canal, cochlea, or nerve damage were observed. All of the dissections were carried out with the ultrasonic device without the necessity to replace it with an otological drill. Conclusion: From this preliminary study, surgical decompression of the facial nerve via the middle cranial fossa approach using Piezosurgery seems to be a safe and feasible procedure. Further cadaveric training is recommended before intraoperative use, and a wider case series is required to make a comparison with conventional devices.