Endoscopic examination of the cerebellar pontine angle.

This anatomic study describes how to optimize the use of the endoscope in the cerebellar pontine angle (CPA) through a retrosigmoid approach. Unlike the microscope, that only permits visualization of structures directly ahead, the endoscope can see 'around the corner', also showing the structures down narrow. Nevertheless, to use the endoscope it is necessary to insert it into the CPA that is full of neurovascular structures which limit its movements. Thus, to avoid damages it is important to inspect this region accurately, by means of preferential trajectories to insert the endoscope. A retrosigmoid approach was performed in cadaver heads, and the CPA region was inspected employing 0degrees, 45degrees rigid endoscopes (4 mm in diameter). The neurovascular structures of the CPA have been visualized using three trajectories. The limits of view offered by each trajectory as well as the neurovascular structures together with the obstacles encountered on each route have been described. The systematic adoption of three different endoscope trajectories at the CPA level permits to view from different angulation the same structure as well as its relationships with the surrounding nerves and vessels. Considerable experience on cadavers should have already been obtained with the endoscope prior to any application in the operating room.