脚間・迂回槽内および周囲の血管性病変に対するtrans-choroidal fissure approachの手術適応

Abstract

The microsurgical anatomy of trans-choroidal fissure (CF) approach for vascular lesions in and around the interpeduncular and ambient cisterns was studied using 3 cadavers treated by arterial and venous injection of the mixture of silicon with dye and barium sulfate. The angiographical “plexal point,” which shows the entrance of the anterior choroidal artery (AChA) coming into the inferior horn (IF) of the lateral ventricle, is thought to be the key anatomical landmark in the surgery for the vascular lesions in the ambient and interpeduncular cisterns. The transcortical route into IF through the inferior temporal gyrus is better for avoiding the injury of the optic radiation around IF.After opening CF posterior to the plexal point between the hippocampal formation (fimbria) and the choroid plexus, the posterior cerebral artery (PCA) in the ambient cistern can be seen with minimal retraction of the hippocampal formation (fimbria). When retracting the brain, great care must be taken not to injure the hippocampus, the tail of caudate nucleus, and the lateral geniculate body. Additional partial resection of the uncus permits opening the interpeduncular cistern and can give neurosurgeons a working space large enough for access to the high basilar tip aneurysm and the retrochiasmatic lesions such as parasellar tumors.Patients with PCA aneurysm or arteriovenous malformation (AVM) in and around the ambient cisterns, as well as those with AChA AVM in the medial temporal lobe, are likely to be good surgical candidates for trans-CF approach when their PCA is running nearly as high as the “plexal point” of AChA or higher.For patients, however, whose PCA is running far lower than this point on the lateral angiography, the subtemporal approach is likely to be better than the trans-CF approach. Clinically for a patient with the ruptured PCA aneurysm and one with the AVM in the medial temporal lobe, good surgical results were achieved with this trans-CF approach.