The natural history of unruptured intracranial aneurysms (uIAs) in Japan was revealed by the SUAVe study and UCAS Japan. The SUAVe study was a prospective study in which small uIAs (less than 5 mm in diameter) were observed without treatment. In the SUAVe study, the average annual rupture rate of small uIAs was 0.54% per year. UCAS Japan was a prospective cohort study of newly diagnosed uIAs in which 6,697 uIAs were enrolled. In UCAS Japan, the average annual rupture rate was 0.95% per year, and the risk factors for rupture were size, location and bleb formation. In comparison with the ISUIA cohort which consists of North Americans, the rupture rate of uIAs of equal size was higher in Japanese. Posterior communication artery aneurysms were prone to rupture in both cohorts, but anterior communicating artery aneurysms showed a higher risk of rupture only in the Japanese cohort. A wide variety of evidence supports the notion that IA formation is closely associated with inflammation. Hemodynamic stress provokes inflammatory reactions in endothelial cells including the activation of nuclear factor-kappa B (NF-κB), which causes the recruitment of macrophages into IA walls. Macrophages secrete matrix metalloproteinases (MMPs)-2 and -9 that promote IA wall degradations. Treatment with statins suppressed the progression of rat IAs by inhibiting inflammatory reactions. A multi-center prospective randomized trial examining the inhibitory effect of statins on the progression and rupture of human IAs, Small Unruptured Aneurysm Verification-Prevention Effect against Growth of cerebral Aneurysm Study Using Statin (SUAVe-PEGASUS) study is now ongoing.

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  Hemodynamics plays an important role in the initiation, growth, and rupture of cerebral aneurysms. Due to limitations in the spatial and temporal resolutions of medical image data, it is difficult to obtain detailed hemodynamic information such as the velocity field or the wall shear stress. If an aneurysm is located in a bifurcation segment, the hemodynamics are affected by flow distributions and the compliance of the arterial wall. Thus, the effects of the entire circulatory system become essential, as well as the vascular dynamics.
  This paper presents the fundamentals of hemodynamics and the recent developments in patient-specific modeling and simulation for cerebral aneurysms. Particularly, this paper focuses on the multi-scale simulation of the interaction between the blood flow and arterial wall in order to consider the effects of the entire circulatory system and the wall dynamics.

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  We analyzed the roles of intraoperative supporting tools in aneurysm surgery with special reference to electrophysiological monitoring.
  Clinical materials were 270 patients (103 ruptured, 167 unruptured) who underwent aneurysm surgery after the introduction of the Neuromaster (16 Ch). Monitoring methods such as, transcranial motor evoked potential (MEP), direct cortical stimulation MEP, lower extremity somatosensory evoked potential (SEP), or visual evoked potential (VEP) were selected mainly depending upon the site of the aneurysm. MEP was monitored to detect blood flow insufficiency (BFI) of the anterior choroidal artery, lenticulostriate artery and middle cerebral artery. Lower extremity SEP was used to detect the BFI of the anterior cerebral artery. VEP was used to detect the BFI of the posterior cerebral artery and superior hypophyseal artery, and mechanical damage of the optic nerve and chiasm.
  In all 270 patients, intraoperative monitoring was performed successfully. In 22 patients out of 177 who underwent MEP monitoring, both transcranial MEP and direct cortical MEP disappeared almost simultaneously. In 20 of these, both MEPs recovered almost simultaneously after release of temporary occlusion or replacement of the clip. In 2 patients out of the 22 patients, both MEPs did not recover and the patients developed persistent hemiparesis. Seventy-five patients who underwent lower extremity SEP did not developed paresis of the lower extremity. Thirty-three patients who underwent VEP monitoring did not develop any visual disturbance at all.
  In aneurysm surgery, various intraoperative monitoring methods were useful to detect the state of ischemia and to provide feed back during the surgery.

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  In patients with blood blister-like or dissecting aneurysms (Group A) or large-giant aneurysms (Group B) of the internal carotid artery (IC), a surgical strategy may include selective clipping or parent artery occlusion (PAO) such as trapping, blind-alley formation, or flow alteration.
  Between 2003 and 2012, 25 cases in Group A and 30 cases in Group B were operated on in our institution and their results were retrospectively analyzed. Patients in Group A underwent STA-MCA or high flow bypass followed by trapping of the IC in the acute stage of subarachnoid hemorrhage (SAH), if possible. The bypass was selected in consideration of the collateral flow and the risk of delayed vasospasm. Patients in Group B received clipping or PAO depending on the condition of the perforators and the optic nerve, or wall thickness of the aneurysm, etc. The associating bypass was selected mainly according to the results of a carotid artery test occlusion.
  In Group A, 60% of the patients were in good recovery at discharge. The most influencing factors on the prognosis included rerupture before surgery (6 cases), primary brain injury (2 cases) and perforator injury (2 cases). Although two thirds of the surgeries were performed in the acute stage, no infarctions due to delayed vasospasm were experienced.
  In Group B, 93% of the patients were discharged in good recovery. Nineteen cases the ended with clipping showed relatively good results but surgical perforator injury occurred in one patient. In eleven cases that required PAO and bypass, two cases of bypass occlusion that required reconstruction and one case of transient ischemia in the perforator territory were experienced.
  In Group A patients, prevention of rerupture seems most important. Therefore, a bypass prior to PAO should be selected to supply enough blood flow to overcome the possible delayed spasm and trapping of the IC should be performed with a clip avoiding perforators and other branches as much as possible.
  In Group B patients in whom the surgical strategy may include selective clipping or PAO, intraoperative decision making of the selection seems important. When PAO and bypass surgery was selected, certainty of the bypass and a method of PAO to avoid perforator injury play a key role. Appropriate application of antithrombotic agents was thought to be important as well.

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  Recent progress in the neuroendovascular treatment of cerebral aneurysms is remarkable. In particular, the introduction of vascular stents for neck-bridge has enabled treatment for complex aneurysms such as wide neck, large/giant and fusiform aneurysms. On the other hand, surgical neck clipping is technically well established, gold-standard treatment. In our paper, we cover accessibility, neck management and parent artery preservation, perforator problems, curability for large/giant aneurysms particularly for intraluminal thrombosis, and the neurological symptoms caused by mass effect according to each aneurysm's, anatomic profile. Finally, we discuss the problems faced and the future outlook in applying direct surgery and endovascular treatment for formidable cerebral aneurysms.

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  Temporal lobe epilepsy (TLE) often presents bilateral epileptiform discharges on an electroencephalogram (EEG). Epileptic seizures originating in the hippocampus can be propagated to the contralateral hippocampus earlier than to the ipsilateral temporal neocortex, so that careful investigation is necessary to determine the side of epileptic focus in TLE.
  A 35-year-old right-handed male was referred for surgical treatment of epilepsy. He started to have complex partial seizures at age 20, which were resistant to multiple antiepileptic medications. Brain MRI and interictal FDG-PET were both normal. Long-term video-EEG monitoring revealed bilateral temporal spikes interictally with ictal EEG changes starting in the right temporal region. Depth and subdural electrodes were implanted to the bilateral hippocampi and temporal neocortices to determine the laterality of the seizures. The invasive EEG revealed epileptic seizures originating in the left medial temporal structures with secondary propagation to the contralateral hippocampus. Left anterior temporal lobectomy and amygdalohippocampectomy rendered him seizure free for 12 months. Histopathological diagnosis was type I cortical dysplasia associated with mild hippocampal sclerosis.
  Scalp EEG occasionally presents the first ictal changes in the contralateral side to the epileptic focus in TLE. There fore careful presurgical evaluation with bilateral depth and subdural electrodes is important to determine the laterality of the epileptic focus in TLE, especially when the neuroimaging study shows no obvious abnormalities.

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  Dural tuberculoma mimicking meningioma is very rare.
  The 90-year-old woman was referred to our hospital due to her head trauma. A CT scan revealed a mass of low-density foci surrounded by edema in the right frontal lobe that had destroyed the inner table of the calvarium. Contrast-enhanced MRI demonstrated an irregular enhanced lesion with a dural tail sign, which suggested malignant meningioma or a dural metastatic tumor. Surgery was performed for further diagnosis and the enhanced dural lesion and the erosive bone flap were completely resected. The histological examination revealed the epitheloid granuloma with caseous necrosis. No tubercle bacilli could be identified either by Ziehl-Neelsen stain or its culture. The QuantiFERON-TB Test was positive and the diagnosis of tuberculoma was established. The patient was discharged uneventfully, and regrowth of the tuberculoma has not been observed to date following administration of antituberculous drugs.

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