We report intraoperative difficulties we have encountered during clipping surgery for unruptured cerebral aneurysms.
There is a low risk of intraoperative rupture, but when it occurs, it can be managed either by tentative clipping or proximal flow control. The risk of aneurysm rupture can be decreased by gentle manipulation of the aneurysm, as well as full mobilization of the aneurysm and its neighboring vessels. Adhesions of vascular structures, arteries, and/or veins can be separated from the aneurysm in almost all cases with careful and sharp dissection. Injuries to perforating vessels are the most common problems. The risk of permanent injury can be reduced by combining multiple monitoring methods, especially MEP (motor evoked potential) and micro-Doppler.
It is vitally important that we be aware of the difficulties that may occur during surgery and develop methods to avoid or manage them.

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Postoperative ischemic sequelae are the most frequent complication of aneurysm surgery. We have performed various types of intraoperative monitoring to prevent postoperative ischemic complications. In this manuscript, we report methods and results of motor evoked potential (MEP), visual evoked potential (VEP) and fluorescence angiography (FAG) with representative cases. MEP monitoring enables us to predict the blood flow insufficiency of arteries that supply the corticospinal tract. We can detect the blood flow insufficiency of not only the perforating artery, such as the anterior choroidal artery or lenticulostriate artery, but also the cortical artery of the middle cerebral artery. VEP monitoring enabled us to detect the ischemia and mechanical damage of the visual pathway from the optic nerve to the occipital lobe. FAG by intravenous administration of fluorescein sodium made it possible to detect the patency of the arteries, such as the hypothalamic artery or posterior thalamoperforating artery, which could not be detected by various electrophysiological monitoring methods. Ischemic complications after aneurysm surgery were markedly reduced after introduction of these monitoring methods. We discuss the usefulness and limitation of these methods.

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Urgent treatment of ruptured vertebral artery dissecting aneurysm (VADA) is imperative because of the high incidence of rebleeding and high mortality of recurrent bleeding. Especially, ruptured posterior inferior cerebellar artery (PICA)-involved VADA requires both prevention of rebleeding and revascularization of the PICA. Since 2001, we have treated 8 patients with ruptured PICA-involved type VADA during the acute stage, within 3 days after the hemorrhage. The treatment strategy included endovascular proximal occlusion followed by occipital artery-PICA bypass and PICA origin clipping (3 cases), proximal occlusion followed by internal trapping of the aneurysm after successful balloon test occlusion (1 case), only proximal occlusion (1 case), coil embolization of the aneurysmal dilatation followed by OA-PICA bypass and PICA origin clipping (1 case), internal trapping of the aneurysm (1 case), OA-PICA bypass, proximal clipping and proximal clipping (1 case). Aneurysmal shape change after acute treatment was observed in 5 cases. In 1 case to which the aneurysm decreased in size, PICA supplied only vermis branches. In 2 cases in which the size of the aneurysm did not change, PICA supplied vermis, tonsilar and hemispheric branches in 2. In 2 cases in which the size of the aneurysm increased, PICA supplied vermis, tonsilar and hemispheric branches in 1 and PICA supplied vermis, tonsilar, hemispheric and meningeal branches in 1. Because the possibility is high that the aneurysm will remain cases in which PICA supplied vermis, tonsilar and hemispheric branches, it is necessary to plan additional treatment with PICA revascularization.

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Pathophysiology after subarachnoid hemorrhage (SAH) has not been well examined. We observed platelet-leukocyte-endothelial cell interactions as indexes of inflammatory and prothrombogenic responses in the acute phase of SAH, using an in vivo cranial window method.
Subarachnoid hemorrhage was induced in C57Bl/6J mice by the endovascular perforation method. Regional cerebral blood flow (rCBF) was measured with laser-doppler flowmetry. The platelet-leukocyte-endothelial cell interactions were observed with an intravital microscopy 30 minutes, 2 hours, and 8 hours after SAH. The effect of P-selectin antibody and apocynin on these responses was examined, and compared with a different SAH model, in which autologous blood was injected into the foramen magnum.
SAH was accompanied by a 60% decrease in rCBF, whereas no changes in rCBF were observed on the contralateral side. SAH elicited time- and size-dependent increases in rolling and adherent platelets and leukocytes in cerebral venules, attenuated by a P-selectin antibody, or apocynin. There was no significant blood cell recruitment in the blood-injected SAH model.
SAH at the skull base induced P-selectin- and oxygen radical-mediated platelet-leukocyte-endothelial cell interactions in venules at the cerebral surface. These early inflammatory and prothrombogenic responses may cause a whole brain injury immediately after SAH.

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While a rigid-type endoscope has been used for the surgery of intracerebral hemorrhage, a flexible fiberscopie is more maneuverable. But flexible fiberscopic surgery for intracerebral hemorrhage is challenging in terms of visual resolution of the operative field. We compared the results of this new method with that of our conventional method using a rigid-type endoscope.
A flexible fiberscope with an outer diameter of 4.8-mm was inserted into hematoma cavity by free hands, or in some cases under CT-guided stereotaxy. An irrigation-suction system is used to facilitate aspiration of hematoma with hard clots. The problem of interference of the visual field with clots was solved by water irrigation of the endoscopic lens. The operation time was comparable to that of our past surgery using a rigid endoscope (58 min vs. 53 min), and the mean removal rate of hematoma was also similar to that of the rigid endoscopic surgery (77% vs. 86%). Although the results of the flexible fiberscopic surgery were comparable to that of the rigid endoscopic surgery, effective hemostat instruments are unavailable. For this reason, we select this surgery only for patients in subacute stage in which hemostat process is completed.
This method is only in the developmental stage, and advances in instruments are necessary to establish it.

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Fluorescence angiography was first used by ophthalmologists to measure retinal blood flow by using the fluorescent dye fluorescein. With the use of indocyanine green (ICG) as a novel fluorescent dye, and its integration into a compact system that takes advantage of modern video technology, fluorescence angiography has recently re-emerged as a viable option. We present representative cases of which ICG videoangiography is useful in the treatment to show the efficacy of ICG videoangiography in cerebrovascular surgery. ICG videoangiography is a safe and simple method with which to assess the microcirculation of the brain.

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Recent multi-center studies in Western countries have clarified various aspects of aneurysmal subarachnoid hemorrhage (SAH) as part of evidence-based medicine (EBM). In Japan, however, much less evidence on aneurysmal SAH has been established. In this study, therefore, we prospectively enrolled 836 patients with aneurysmal SAH admitted to Hokkaido University Hospital and its affiliate hospitals in Sapporo area between 2003 and 2007, and analyzed their epidemiology, therapy and functional outcome. Of totally 836 patients, 130 (15.6%) and 214 (25.6%) were categorized into WFNS Grade 4 and 5, respectively. Totally, 689 patients (82.4%) underwent some interventions for ruptured aneurysms, including surgical clipping in 548 patients and endovascular coiling in 121. Of these, favorable functional outcome at 1 month after the onset was obtained in 461 patients (66.9%). Multivariate logistic regression analysis revealed that age, neurological severity, intracerebral hematoma, symptomatic vasospasm, and normal pressure hydrocephalus were independent predictors for poor functional outcome.
The present results suggest the importance of prospective multi-center, cohort or randomized study on aneurysmal SAH in Japan.

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In April 2008, carotid artery stenting (CAS) was approved for high-risk candidates for carotid endarterectomy (CEA) in Japan, a difficult procedure for young neurosurgeons. From January 2001 to March 2008, in our hospital, CEA was performed on 68 vessels by 2 expert surgeons and 234 vessels by 10 beginner surgeons with a defined protocol. This protocol includes propofol anesthesia with electroencephalography (EEG) and somatosensory evoked potential (SEP) monitoring, the avoidance of an intraluminal shunting, brain protection, and strict control of postoperative hypertention. At 30 days, combined permanent mortality and morbidity rate was 2.9% in the experts’ group and 0.9% in the beginners’ group. We report a series of 302 consecutive CEAs performed by 2 expert and 10 beginner surgeons within a defined protocol and the results.

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Clipping surgeries for unusual middle cerebral artery (MCA) aneurysm are not always easy because of ischemic complications of the lenticulostriate arteries (LSAs) and MCA branches. Superior-wall type of M1 aneurysms have highest risks of perforator infarction caused by LSA occlusion or kinking by applied clips. At clipping surgeries for deeply located MCA aneurysms of the early MCA bifurcation and M1 aneurysms (superior-wall type, inferior-wall type, and early branch portion), excessive brain retraction and frequent use of temporary clips should be avoided as much as possible and a wide working field should be obtained against ischemic complications. Surgeons should be aware that LSAs are branching not only at the MCA trunk but also at the MCA bifurcation and M2 when applying clips to MCA aneurysms.
Vascular reconstruction of bypass surgery is a good surgical option for complicated MCA aneurysms not amenable to microsurgical clipping.

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A 64-year-old woman presented with dissecting aneurysm of the anterior cerebral artery (ACA) manifesting as subarachnoid hemorrhage (SAH). On a computerized tomographic scan (CTA) a saccular aneurysm was absent, but there was a finding of dilatation of the left proximal segment of ACA (A1). The patient underwent a left craniotomy. Intraoperative observation revealed that the vessel wall of the left A1 was dark purple, a typical finding of dissecting aneurysm.
With increasing frequency, dissecting aneurysms of the intracranial arteries are recognized as a possible cause of SAH. In a majority of cases of intracranial dissecting aneurysms, the aneurysm afflicted the vertebral and basilar arteries.
It is relatively rare for this type of aneurysm to be confined to the anterior cerebral artery. In the literature, 19 cases of dissecting aneurysm in A1 segment were reported including our case. Majority cases of dissecting aneurysm in A1 segment eventually ruptured, resulting in SAH.
In the case of SAH of unknown origin, dissecting aneurysm should always be kept in mind even if the angiogram does not show any abnormal findings.

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Superior hypophyseal arteries originate from the paraclinoid segment of the internal carotid artery. They distribute to the optic pathway and pituitary gland. It has not been reported whether occlusion of these arteries produces visual loss. We experienced 2 patients whose vision deteriorated after clipping surgery for bilateral paraclinoid aneurysms. Those aneurysms were found to arise at the junction with superior hypophyseal arteries. Those arteries were obliterated bilaterally together with the aneurysms. The patients suffered visual disturbance in both eyes temporarily in 1 patient and permanently in another.
Bilateral superior hypophyseal arteries should not be obliterated simultaneously and visual evoked potential should be monitored even when a single superior hypophyseal artery needs to be sacrificed if its caliber is large.

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