We review recent progress and perspectives in etiology, pathophysiology, diagnosis, surgical treatment, and perioperative management of moyamoya disease. Endothelial progenitor cells may closely be involved in the development of the disease. The clinical impact of microbleeds seen on T2*-weighted imaging should be clarified. Long-term outcome and treatment strategy in asymptomatic moyamoya disease should also be assessed. A novel multi-center study, called the Asymptomatic Moyamoya Registry (AMORE) study, will be started very soon. Surgical revascularization is accepted as a useful option for moyamoya disease with ischemic onset. An ongoing randomized clinical trial, the Japan Adult Moyamoya (JAM) trial, is expected to elucidate the efficacy of direct or combined bypass surgery on moyamoya disease with hemorrhagic onset. Direct bypass procedures help lower the incidence of perioperative ischemic stroke, but careful management should be emphasized to reduce the incidence of major complications due to postoperative hyperperfusion. The pathophysiology and treatment strategy of headaches in pediatric patient should be further discussed. Infantile cases are at very high risk for repeated ischemic stroke and perioperative ischemic complications, and should be intensively managed before and after surgery.
Based on these considerations, we should further clarify the unsolved issues and improve the short- and long-term outcome by advancing our basic research, diagnostic modalities, surgical technique, and perioperative management.

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Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis prevents cerebral ischemic attack by improving cerebral blood flow in patients with moyamoya disease. Cerebral hyperperfusion (CHP) is a potential complication of STA-MCA anastomosis for moyamoya disease, but the optimal postoperative management has not been determined. To establish the optimal postoperative management protocol, we prospectively performed prophylactic blood pressure lowering during the acute stage after STA-MCA anastomosis for moyamoya disease.
N-isopropyl-p-[¹²³I]iodoamphetamine single-photon emission computed tomography was performed 1 and 7 days after STA-MCA anastomosis on 59 hemispheres from 43 consecutive patients (aged 9–69, mean 33.4 years) with moyamoya disease, who were prospectively subjected to intensive blood pressure lowering (below 130 mmHg of systolic blood pressure) immediately after surgery. Then the incidence and the clinical presentation of symptomatic CHP were evaluated.
Systolic blood pressure the day after surgery was as low as 120.9 mmHg (mean) in this series. Symptomatic CHP was seen only in four patients with four surgeries (6.7%, 4/59), which was much lower than the incidence of CHP in the previous reports. Three patients suffered temporary focal neurological deterioration, and one patient manifested as symptomatic subarachnoid hemorrhage due to CHP. Symptomatic CHP was relieved in all patients without developing permanent neurological deficit due to CHP, while one patient with symptomatic subarachnoid hemorrhage had a cerebral infarction in the ipsilateral occipital lobe during the blood pressure lowering.
Prophylactic blood pressure lowering prevents symptomatic CHP after STA-MCA anastomosis in patients with moyamoya disease. Accurate diagnoses of CHP and blood pressure lowering, while considering the severity of hemodynamic compromise in the contralateral and/or remote areas, are essential for postoperative management of moyamoya disease.

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We present the preservation of middle meningeal artery (MMA) in surgical revascu-
larization for moyamoya disease. We examined 10 patients with moyamoya disease and performed surgical revascularization. The mean age of the patients was 27.8 years. We presurgically evaluated the three-dimensional (3-D) relationships of MMA and cranial sutures in the pterion by volumetric imaging of 3-D contrast enhanced computed tomography (CT). The 3-D anatomies were visualized by adjusting the window width, window level, and opacity level of the specific CT value for each structure, and the relationship of the MMA and the suture. This visualization was crucial for drilling to perform craniotomies. The MMA from bone to dura is exposed for drilling around the pterion. The preservation of the MMA with this method was achieved in all patients with moyamoya disease.
Presurgical evaluation using volumetric imaging of 3-D CT is a convenient and valuable method for obtaining the anatomic information. The usefulness of the drilling distal to the pterion in patients with moyamoya disease to preserve MMA was confirmed.

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The use of intraluminal shunting during carotid endarterectomy (CEA) remains controversial. From January 2001 to September 2010, 400 CEAs without shunting were performed under general anesthesia by 14 neurosurgeons (2 consultants, 12 trainees). We used electroencephalography (EEG) and somatosensory evoked potential (SEP) to monitor under selective burst suppression using barbiturate or propofol administration during cross-clamping. In 66 of the 400 CEAs (16.5%), intraoperative monitoring demonstrated abnormalities after cross-clamping. In 26 (6.5%) of the 400 CEAs, new areas of diffusion hyperintensity were identified postoperatively. Within 30 days, the combined mortality and morbidity (symptomatic ischemia) rate was 2.8%. Thirteen (3.3%) patients presented with TIA.
CEA without shunting can be safely performed with EEG and SEP monitoring under induced hypertention and selective burst suppression.

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Carotid endarterectomy (CEA) is a standard treatment for internal carotid artery (ICA) stenosis. The level of carotid bifurcation of Japanese is reportedly higher than that of Europeans. Therefore, it is somewhat difficult to develop an operative field on the distal side of ICA stenosis. We conducted of this study to clarify the usefulness and feasibility of 3D-CTA and 2D-CT imaging using 16-raw CT for CEA with a high-positon ICA stenosis.
Between 2006 and 2010, 51 CEAs for 50 consecutive patients with ICA stenosis were performed in our institutes. Thirteen of these were high-position ICA stenosis. For CEA with high-position ICA stenosis, we tried to visualize the anatomical structures of the retromandibular space using 3D-CTA with 2D-CT, which is perpendicular to the operative approach, at the three depths of the sternocleidomastoid muscle, jugular vein, and carotid bifurcation. In all 13 patients, the parotid gland, jugular vein, and plaque position could be visualized. However, in one of the 13 patients, the distal side of the ICA stenosis could not be visualized, and we unexpectedly needed to cut the occipital artery, and in six of the 13 patients, the common facial vein could not be observed. In the last 10 patients, the MRI diffusion image revealed no additional ischemic lesion. In our series, no persistent morbidity or mortality was observed.
Preoperative simulation using 3D-CTA+2D-CT might be useful for CEA with high-position ICA stenosis, despite the limitation of the visualization of the common facial vein.

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There are two surgical approaches to anterior communicating artery aneurysms: the pterional approach and the interhemispheric approach. We have performed the interhemispheric approach for all cases of anterior communicating artery aneurysms because it is possible to obtain a wide operative field and to confirm the anatomical structure of the anterior communicating artery complex. It is relatively easier in interhemispheric approach to confirm and preserve the hypothalamic arteries arising from Acom complex, even in a superior or posterior projecting aneurysm. We reviewed the interhemispheric approach for the unruptured anterior communicating artery aneurysms between 1996 and 2007 in our institution and analyzed complications in 47 cases. Complete obliteration of the aneurysm was confirmed in all 47 cases during at least three years after operation. Diffusion-weighted MRI imaging disclosed ischemic lesions in one patient. Symptomatic epilepsy resulted in one patient from a right frontal lobe contusion. The other complications were anosmia in two cases and liquorrhea in one case.
Based on our experience, we improved the interhemispheric approach. We have not experienced cases of the complication since 2008. We describe the problems and technical points of the interhemispheric approach for anterior communicating artery aneurysms.

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We report three cases with endocarditis-related mycotic intracranial aneurysms. Two presented with hemorrhage and one with cerebral infarction followed by aneurysm formation in the same territory. All three suffered bacteremia and infectious endocarditis. Two had multiple aneurysms. Ruptured and/or enlarging aneurysms were treated with endovascular coil embolization. For unruptured, asymptomatic aneurysms that were stable in size, systemic antibiotic therapy and a serial follow-up with angiography was done. Embolization was successful in all cases. Two had cardiac surgery uneventfully. Two had untreated unruptured aneurysms that disappeared on the follow-up angiography after long-term systemic antibiotic therapy. There was no reassurance of treated aneurysms.

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Stenosis of the proximal common carotid artery (pCCA) is rare. It is difficult to treat by surgical or endovascular revascularization, and there are few published cases. In rare cases, the pCCA stenosis is concomitant with stenosis of the internal carotid artery (ICA) and it can be difficult to determine which is the truly symptomatic lesion in such cases. Current treatment of pCCA stenosis includes alternative vascular access routes like the combined use of carotid endarterectomy and retrograde angioplasty with or without stenting.
We report the method of percutaneous transfemoral approach for pCCA revascularization with stent supported by two guidewires. The guiding catheter is placed proximal to the ostium of the narrow pCCA with a co-axial method. First, the balloon type embolic protection device is introduced in the ICA to prevent embolic stroke and after, a 0.014 inch supporting stiff guidewire is carefully passed through the pCCA stenosis and placed in the external carotid artery (ECA). Finally, a balloon-expanding stent is advanced to the pCCA stenosis guided by both the protection device wire positioned in the ICA, and the supporting microguidewire positioned in the ECA. The two-guidewire technique provides a safer and more stable condition for the procedure, increasing its success rate.
We discuss the etiology and endovascular treatment of the proximal carotid artery stenosis, and review the literature.

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We evaluated the usefulness of intraoperative fluorescence angiography (FAG) to assess blood flow in the superior hypophyseal artery (SHA) involved in the clipping of the paraclinoidal aneurysm. The SHA of two internal carotid artery (ICA)-SHA aneurysms and one ICA-ophthalmic artery aneurysm were evaluated by fluorescein- or indocyanine green (ICG)-FAG. One SHA was evaluated by the fluorescein-FAG alone, one by fluorescein-FAG and neuroendoscope, and the other by ICG-FAG and visual evoked potential (VEP). Both FAGs provided excellent image quality and high spatial resolution to assess the blood flow in the SHA. The advantage of fluorescein-FAG to ICG-FAG was that the surgeons could observe the fluorescence through the microscope and that the angle of a beam could be optimized to observe the SHA, which was located deeply in the opticocarotid space. The simultaneous usage of FAG and neuroendoscope was useful for the observation of the origin of the SHA that was blind in the ICA-ophthalmic artery aneurysm.
The combination of FAG and VEP was helpful for preserving postoperative visual functions.

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We report two cases of true posterior communicating artery (Pcom.) aneurysms. The first case was a 73-year-old female who presented with a sudden onset of headache and was diagnosed to have a subarachnoid hemorrhage. Angiography and three-dimensional computed tomography angiography (3D-CTA) demonstrated a Pcom aneurysm. The intraoperative findings showed the presence of a true Pcom aneurysm. The second case was a 61-year-old female who presented with a headache and was diagnosed with an unruptured aneurysm. Angiography demonstrated an IC-Pcom aneurysm and a true Pcom aneurysm. The intraoperative findings showed that the true Pcom aneurysm was located at the branching site. Both cases were successfully clipped.
A careful preoperative diagnosis and intraoperative investigation are important for ensuring the correct treatment of such cases. We also discuss the pathogenesis of true Pcom aneurysms, and the advantages and pitfalls of the surgical treatment of true Pcom aneurysms.

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We report a very rare case of a ruptured intracranial anterior spinal artery (ASA) aneurysm. A 66-year-old man presented with gradually deteriorating occipitalgia and mild conscious disturbance. He had a history of hypercholesteremia and diabetes mellitus. There was no evidence of collagen disease or inflammation reaction in his physical examination and laboratory data. The first computed tomography (CT) scan revealed thick subarachnoid hemorrhage (SAH) in front of the brain stem with a little intraventricular clot. However, the cerebral angiography (CAG) showed no apparent aneurysm other than right vertebral artery (VA) occlusion with collateral circulation. Repeat cerebral angiography gradually disclosed the presence of an ASA aneurysm. Therefore, the ASA aneurysm was clipped through the right lateral suboccipital approach under trans-cranial motor evoked potential (MEP) monitoring on Day 61. The amplitude of MEP did not decrease during the operation. The patient did not neurologically deteriorate after surgery. It is previously reported that spinal artery aneurysm should be treated by direct or endovascular surgery because of the risk of rupture. However, recent reports showed that spinal artery aneurysm sometimes regressed spontaneously if it is not flow related. In this case, because of the right vertebral artery occlusion, the fenestrated ASA received hemodynamic stress by collateral circulation.
Ruptured aneurysm of the spinal artery requires precise diagnosis and meticulous handling depending on the individual pathogenesis.

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