BackgroundThe causes of dural arteriovenous fistula have not been clearly defined. The aim of this study was to investigate the mechanism of dural arteriovenous fistula formation induced by high intracranial venous pressure using a rabbit model.ResultsBy using rabbit model, dural arteriovenous fistula formation induced by high intracranial venous pressure could be produced by end-to-end and end-to-side anastomosis of the right side common carotid artery with the posterior facial vein plus ligation of the contralateral external jugular vein. As compared the post arteriovenous fistula formation among 1 week, 2 weeks, 3 weeks, and 90 days, the expression level of vascular endothelial growth factor in the 1- and 2-weeks groups was significantly higher compared with the control group, 3 weeks and 90 days groups (p ≤0.002). There was significantly higher hypoxia inducible factor-1α expression in the one week group compared with the control, 2 weeks, 3 weeks, and 90 days groups (p ≤0.002). The results of Western blotting showed that vascular endothelial growth factor expression level was highest in the 1 week group. The expression level of vascular endothelial growth factor was significantly different between all groups.ConclusionsThe results of the experiments in our rabbit model indicate that high intracranial venous pressure is a key for dural arteriovenous fistula formation. Cerebral ischemia caused by lack of cerebral perfusion pressure plays a key role in the process that leads from high intracranial venous pressure to increased hypoxia inducible factor-1α expression and then increased vascular endothelial growth factor expression.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2202-15-101) contains supplementary material, which is available to authorized users.
All surgical approaches to the anterior skull base involve the olfactory cistern and have the risk of damaging the olfactory nerve. The purpose of this study was to describe the microanatomical features of the olfactory cistern and discuss its surgical relevance. In this study, the olfactory cisterns of 15 formalin-fixed adult cadaveric heads were dissected using a surgical microscope. The results showed that the olfactory cistern was situated in the superficial part of the olfactory sulcus, which separated the gyrus retus from the orbital gyrus. In coronal section, the cistern was triangular in shape; its anterior part enveloped the olfactory bulbs and was high and broad; its posterior part was medial-superior to internal carotid artery and was also much broader. There were one or several openings in the inferior wall of the posterior part in 53.4% of the cisterns. The olfactory cistern communicated with the surrounding subarachnoind cisterns through these openings. The middle part of the olfactory cistern gradually narrowed down posteriorly. Most cisterns were spacious with a few fibrous trabeculas and bands between the olfactory nerves and cistern walls. However 23% of the cisterns were narrow with the cistern walls tightly encasing the olfactory nerve. There were two or three of arterial loops in each olfactory sulcus, from which long, fine olfactory arteries originated. The olfactory arteries coursed along the olfactory nerve and gave off many terminal branches to provide the main blood supply to the olfactory nerve in most cisterns, but the blood supply was in segmental style in a few cisterns. Moreover, the veins of the cistern appeared to be more segmental than the olfactory arteries in most cisterns. These results suggested that most olfactory cisterns are spacious with relatively independent blood supply, and it is reasonable to separate the olfactory tract with its independent blood supply from the frontal lobe by 1-2 cm in the subfrontal approach, the pterional approach, or anterior interhemispheric approach. However, in the minority of cases, separation of the olfactory tract is not safe because of the anterior origin of the olfactory arteries or segmental blood supply. It is difficult to separate the olfactory nerve without any damage to the olfactory nerve, even with very skilled hands.
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