Microanatoniical Study Of The Endoscopy-assisted Extreme Lateral Supracerebellar Infratentorial Keyhole Approach To The Dorsolateral Mesencephalon Region

ObjectiveTo study the exposure range of the dorsolateral mesencephalon regions via the extremelateral supracerebellar infratentorial keyhole approach and provide anatomicalreferences for clinical surgical of the diseases in the dorsolateral mesencephalonregions.Meanwhile, discuss the advantages and disadvantages of using neuroendoscopyin this approach. According to the experimental results, summarize the microanatomytechniques and clinical significance of this keyhole approach.MethodsThe extreme lateral supracerebellar infratentorial keyhole approach was imitated in tenvascular perfusion adult cadaveric heads fixed in formalin from December2012toMarch2013. The cadaveric heads were fixed on the shelf in a lateral park benchposition.The skin incision was the C-shaped skin incision behind the ear, and thecraniotomy begined slightly front of the asterion, milling a3cm diameter round bonewindow.The dura opening was made in an inverted-T fashion,than exposured theimportant anatomical structures by pulling down cerebellum.The dorsolateralmesencephalon region was exposed,observed and recorded by microscopy andneuroendoscopy.Results1.The extreme lateral supracerebellar infratentorial keyhole approach can be fullyexposed the ambient cisterns,the posteromedial tentorial incisura,the dorsolateralmesencephalon region, the trochlear nerve, the root of the trigeminal nerve, the superiorcerebellar artery, the posterior cerebral artery and other important anatomical structures.The temporal lobe and parahippocampal gyrus can be exposed when the tentorial was incised.The inside of the trigeminal nerve and the brainstem ventral side were relativelyblind spots.2. The extreme lateral supracerebellar infratentorial keyhole approach can be fullyexposed the anatomic relationship among the root of the trigeminal nerve and thepetrosal vein, the superior cerebellar artery(SCA), the anteroinferior cerebellarartery(AICA). The trigeminal nerve was mostly pressed by the superior cerebellarartery(SCA)3. The application of neuroendoscopy can clearly reveal the region from the trigeminalnerve root to Meckel’s cave and the surrounding structures.Conclusion1. The extreme lateral supracerebellar infratentorial keyhole approach is feasible.2. The extreme lateral supracerebellar infratentorial keyhole approach can be fullyexposed the anatomical structure of dorsolateral mesencephalon regions,which can beused in the surgery at the dorsolateral mesencephalon region.3. The extreme lateral supracerebellar infratentorial keyhole approach can fully revealthe upper neurovascular complex and its relationship with surrounding vessels,which issuitable for the microvascular decompression and the surgery at the uppercerebellopontine angle area.4.The application of neuroendoscopy can make up for the observation on trigeminalnerve when using microscopy, expand the operative field partly,while the brainstem’sventral side was still a relatively blind spot.