Comparative Analysis of the Lateral and Superior Cerebellar Keyhole Approach and Subtemporal Keyhole Approach to the Ventrolateral Brainstem Regions: A Different Perspective.

Objective: To compare the exposure and working distances of lateral and superior cerebellar keyhole approach (LSCKA) with subtemporal keyhole approach (STKA) and Kawase approach (KA) in the ventrolateral brainstem regions.

Methods: The LSCKA was performed in 6 cadaveric heads (12 sides). The STKA was performed in another 6 cadaveric heads (12 sides), and then the KA was performed. The related anatomic structures for the 3 approaches were observed by a 0-degree endoscope and microscope. The distances of exposure and operation were measured and analyzed using a dedicated ruler and software ImageJ.

Results: The exposure margin provided by the microscope is equated to the surgical margin. The LSCKA gained greater superior and inferior exposure margin of the ventrolateral brainstem region created by the microscope than the STKA and KA (all P <0.001). When the anatomic structures of the ventrolateral brainstem region were observed and measured using the 0 endoscope, the LSCKA increased the superior and inferior exposure and working distances of the ventrolateral brainstem region, and also increased dorsal working distances, but decreased ventral exposure distance compared with the STKA and KA. In addition, the LSCKA provided fewer working distances in the ventral brainstem region than the KA.

Conclusions: The LSCKA offers greater advantages in the inferior and superior brainstem regions than the STKA and KA, but limitations in the ventral brainstem region than the KA. The LSCKA is a powerful window into lesions predominantly located in the posterior fossa with extension into the middle fossa.