Minimally Invasive Endoscopic Retrosigmoid Approach to the Cerebellopontine Angle Using a Novel Surgical Instrument: A Cadaveric Study.

Objectives: In this study, we aimed to describe how endoscopes show the neural and vascular structures at the cerebellopontine angle (CPA) through a minimal craniotomy in a well-described anatomic point in the retrosigmoid region and at the same time, evaluate the endoscopic anatomic exposure and maneuverability. We planned to use the new surgical instrument (endoscope cannula), which we designed on fresh frozen cadavers to simulate a real surgical procedure.

Materials And Methods: The surgical procedure was planned to be performed on 20 sides of 10 fresh cadaver heads. The distance between the asterion and mastoid process was determined, and the midpoint was then marked. From this midpoint, a craniotomy 2 cm in size was posteriorly made. The endoscope cannula together with 0° or 30° endoscopes was inserted to capture the panoramic views of the neurovascular structures in CPA. Endoscopic anatomic exposure and maneuverability were evaluated using 0° and 30° endoscopes with/without the endoscope cannula.

Results: The surgeon could easily use both hands during the surgical simulation, and maneuverability was seen to increase in CPA with the use of the endoscope cannula.

Conclusion: The surgeon can work actively with both hands when the endoscopes and the endoscope cannula are used together. We believe that owing to this, the surgeon's maneuverability would increase and a more effective minimally invasive endoscopic retrosigmoid surgery would ensue.