Endoscopic Intradural Subtemporal Keyhole Approach with Neuronavigational Assistance to the Suprasellar, Petroclival, and Ventrolateral Brainstem Regions: An Anatomic Study.

OBJECTIVE: The purposes of this study were to evaluate the feasibility of a purely endoscopic intradural approach to the suprasellar, petroclival, and ventrolateral brainstem regions through a subtemporal keyhole and to assess the value of neuronavigational assistance in the Kawase approach.

METHODS: Twenty endoscopic intradural subtemporal keyhole approaches were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through 4-mm 0° and 30° endoscopes; data were measured by a frameless navigational device. In addition, 2 types of the milled Kawase rhombus ranges and the thicknesses of the residual bones were compared.

RESULTS: This keyhole endoscopic technique clearly visualized the anatomic structures in the suprasellar, petroclival, and ventrolateral brainstem regions via an intradural subtemporal route. Most of the structures in the suprasellar region were observed by the oculomotor nerve-posterior communicating artery space. Using a frameless navigational device, the mean area of the milled Kawase rhombus increased by 32.04 mm(2) (P < 0.05), and the thicknesses of the residual bones including the superior wall of the internal acoustic meatus, the medial superior wall of the cochlea, and the superior wall of the petrous segment of the internal carotid artery reduced by 1.55, 2.03, and 2.19 mm on average, respectively (P < 0.05).

CONCLUSIONS: The endoscopic intradural subtemporal keyhole approach could facilitate excellent observation of the suprasellar, petroclival, and ventrolateral brainstem regions with less invasiveness. More anatomic exposure and surgical freedom could be achieved via neuronavigational assistance with fewer complications.