Tadashi Yamaguchi, Takeshi Miyamoto, Keiko T. Kitazato, Eiji Shikata, Izumi Yamaguchi, Masaaki Korai, Kenji Shimada, Kenji Yagi, Yoshiteru Tada, Yoshihito Matsuzaki, Yasuhisa Kanematsu and Yasushi Takagi
The pathogenesis of intracranial aneurysm rupture remains unclear. Because it is difficult to study the time course of human aneurysms and most unruptured aneurysms are stable, animal models are used to investigate the characteristics of intracranial aneurysms. The authors have newly established a rat intracranial aneurysm rupture model that features site-specific ruptured and unruptured aneurysms. In the present study the authors examined the time course of changes in the vascular morphology to clarify the mechanisms leading to rupture.
Ten-week-old female Sprague-Dawley rats were subjected to hemodynamic changes, hypertension, and ovariectomy. Morphological changes in rupture-prone intracranial arteries were examined under a scanning electron microscope and the association with vascular degradation molecules was investigated.
At 2–6 weeks after aneurysm induction, morphological changes and rupture were mainly observed at the posterior cerebral artery; at 7–12 weeks they were seen at the anterior Willis circle including the anterior communicating artery. No aneurysms at the anterior cerebral artery–olfactory artery bifurcation ruptured, suggesting that the inception of morphological changes is site dependent. On week 6, the messenger RNA level of matrix metalloproteinase–9, interleukin-1β, and the ratio of matrix metalloproteinase–9 to the tissue inhibitor of metalloproteinase–2 was significantly higher at the posterior cerebral artery, but not at the anterior communicating artery, of rats with aneurysms than in sham-operated rats. These findings suggest that aneurysm rupture is attributable to significant morphological changes and an increase in degradation molecules.
Time-dependent and site-dependent morphological changes and the level of degradation molecules may be indicative of the vulnerability of aneurysms to rupture.
Kenji Shimada, Tadashi Yamaguchi, Takeshi Miyamoto, Shu Sogabe, Masaaki Korai, Toshiyuki Okazaki, Yasuhisa Kanematsu, Junichiro Satomi, Shinji Nagahiro and Yasushi Takagi
Although intravenous indocyanine green (ICG) videoangiography has been reported to be useful when applied to cerebral arteriovenous malformation (AVM) surgery, the ICG that remains after the procedure makes it difficult to understand the anatomy, to evaluate nidus blood flow changes, and to repeat ICG videoangiography within a short time. Intraarterial ICG videoangiography has emerged as a way to overcome these limitations. The current study presents the results of intraarterial ICG videoangiography undertaken in patients with cerebral AVMs.
Intraarterial ICG videoangiography was performed in 13 patients with cerebral AVMs. Routine intraoperative digital subtraction angiography at the authors’ institution is performed in a hybrid operating room during AVM surgery and includes the added step of injecting ICG to the contrast medium that is administered through a catheter.
Predissection studies were able to visualize the feeder in 12 of 13 cases. The nidus was visualized in 12 of 13 cases, while the drainer was visualized in all cases. After total dissection of the nidus, there was no ICG filling in the drainers found in any of the cases. Washout of the ICG took 4.4 ± 1.3 seconds in the feeders, 9.2 ± 3.5 seconds in the drainers, and 20.9 ± 3.4 seconds in all of the vessels. Nidus flow reduction was confirmed during dissection in 9 of 9 cases. Flow reduction was easy to recognize due to each span being very short. Color-encoded visualization and objective data obtained by Flow 800 analysis reinforced these findings.
The results showed that intraarterial ICG videoangiography was more useful than intravenous ICG videoangiography in cerebral AVM surgery. This was especially effective in the identification of the feeder, nidus, and drainer and in the assessment of the flow dynamics of the nidus. Use of Flow 800 made it simpler and easier to evaluate these findings.