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Background: Long-term outcomes are unknown in patients with asymptomatic moyamoya disease. In this report, we aimed to clarify their 5-year risk of stroke and its predictors. Methods: We are conducting a multicenter, prospective cohort study (Asymptomatic Moyamoya Registry) in Japan. Participants were eligible if they were 20 to 70 years, had bilateral or unilateral moyamoya disease, experienced no episodes suggestive of TIA and stroke; and were functionally independent (modified Rankin Scale score 0–1). Demographic and radiological information was collected at enrollment. In this study, they are still followed up for 10 years. In this interim analysis, we defined the primary end point as a stroke occurring during a 5-year follow-up period. Independent predictors for stroke were also determined, using a stratification analysis method. Results: Between 2012 and 2015, we enrolled 109 patients, of whom 103 patients with 182 involved hemispheres completed the 5-year follow-up. According to the findings on DSA and MRA, 143 hemispheres were judged as moyamoya disease and 39 hemispheres as questionable manifestations (isolated middle cerebral artery stenosis). The patients with questionable hemispheres were significantly older, more often male, and more frequently had hypertension than those with moyamoya hemisphere. Moyamoya hemispheres developed 7 strokes, including 6 hemorrhagic and 1 ischemic stroke, during the first 5 years. The annual risk of stroke was 1.4% per person, 0.8% per hemisphere, and 1.0% per moyamoya hemisphere. Independent predictor for stroke was Grade-2 choroidal anastomosis (hazard ratio, 5.05 [95% CI, 1.24–20.6]; P =0.023). Furthermore, microbleeds (hazard ratio, 4.89 [95% CI, 1.13-21.3]; P =0.0342) and Grade-2 choroidal anastomosis (hazard ratio, 7.05 [95% CI, 1.62–30.7]; P =0.0093) significantly predicted hemorrhagic stroke. No questionable hemispheres developed any stroke. Conclusions: The hemispheres with asymptomatic moyamoya disease may carry a 1.0% annual risk of stroke during the first 5 years, the majority of which are hemorrhagic stroke. Grade-2 choroidal anastomosis may predict stroke, and the microbleeds and Grade-2 choroidal anastomosis may carry the risk for hemorrhagic stroke. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: UMIN000006640.

Background: Moyamoya disease (MMD) is a very specific disorder in terms of spontaneous development of extracranial-to-intracranial collateral circulation through the dura mater, but the underlying mechanisms are unclear. This study aimed to investigate the role of the arachnoid membrane in this unique angiogenesis in MMD. Methods: A piece of arachnoid membrane and 1- to 2-mL cerebrospinal fluid were simultaneously harvested during surgery from 26 patients with MMD. The specimens were also collected during surgery as the controls from 6 patients with atherosclerotic carotid artery diseases. The arachnoid membrane was subjected to immunohistochemistry and the cerebrospinal fluid was used to measure the concentration of cytokines using ELISA. Results: The number of cells positive for PDGFR (platelet-derived growth factor receptor) α was significantly higher in MMD than in the controls (5.4±3.1 versus 2.3±2.1 cells/field; P =0.02). The results were same in PDGFRβ-positive cells (10.1±4.6 versus 4.8±2.8; P=0.01) and α-SMA (alpha-smooth muscle actin)–positive cells (8.8±3.1 versus 2.0±2.5; PP P P =0.04). On ELISA, the cerebrospinal fluid concentrations of bFGF (basic fibroblast growth factor), HGF (hepatocyte growth factor), and TGF (transforming growth factor)-β1 were significantly higher in MMD than in the controls. Conclusions: Based on these findings, MMD may elevate the concentrations of angiogenic factors in the cerebrospinal fluid and then promote the proliferation of fibroblasts in the arachnoid membrane and their differentiation into myofibroblasts, which may, in turn, enhance the production of collagen essential for spontaneous collateral formation across the arachnoid membrane.

It has been commonly accepted for a long time that the cerebrospinal fluid (CSF) drains into arachnoid granulations from the subarachnoid space to the dural venous sinus unidirectionally. However, recently, periventricular capillaries and lymphatic concepts have been introduced. The CSF moves along the perivascular space and drains into the capillary vessels or meningeal lymphatic tissues. CSF is involved in removing brain waste out of the brain. In this study, we investigated the outflow mechanism of substances in the CSF from the brain. We investigated the movement of CSF by injection of gold colloid conjugates (2, 40, and 200 nm) into the lateral ventricles of mouse fetuses and evaluated the deposition by silver stain with tissue transparency and electron microcopy. Cadaverine was also injected into the lateral ventricle to determine its movement tract. The gold particle deposition was mainly observed in the frontal skull base. Electron microscopic study showed that the gold particle deposition was observed on the choroid plexus and ependyma in the lateral ventricle and also red blood cells in the heart and liver. Two-nanometer particles were exclusively observed in the liver. Cadaverine injection study demonstrated that cadaverine was observed at the extracranial frontal skull base, choroid plexus, ependymal surface, and perivascular area in the brain white matter. The particles in the CSF were shown to move from the brain to the frontal skull base and also into the blood stream through the choroid plexus in the fetus. The outflow of particles in the CSF may be regulated by molecular size. This new information will contribute to the prevention of brain degeneration due to brain waste deposition.

BACKGROUND Although most cases of internal carotid artery (ICA) agenesis are clinically silent due to a well-developed collateral pathway, some cases may develop ischemic symptoms when they are associated with other occlusive cerebrovascular disorders. The authors describe herein the first case with ICA agenesis that developed ischemic attack because of coincidence with moyamoya disease. OBSERVATIONS A 3-year-old girl was admitted to the authors’ hospital due to sudden onset of right arm weakness followed by clonic convulsion. Skull computed tomography could not identify the carotid canal on the left side. Simultaneously, magnetic resonance (MR) imaging and MR angiography demonstrated the luminal stenosis and outer diameter reduction of the carotid fork and posterior cerebral artery on the left side. She was diagnosed with unilateral moyamoya disease associated with ipsilateral ICA agenesis. She successfully underwent combined bypass surgery on the left side and has been free from any cerebrovascular events during a follow-up period of 6 months. LESSONS When patients with ICA agenesis develop ischemic symptoms, careful investigation of the cause and appropriate care, including surgical treatment, are required.

Background: Middle meningeal artery (MMA) pseudoaneurysm following revascularization surgery for moyamoya disease (MMD) is rare. Case Description: Here, a 29-year-old man presented with an MMA pseudoaneurysm after he underwent revascularization surgery (superficial temporal artery-to-middle cerebral artery bypass and encephalo-duro-myoarterio-pericranial synangiosis) for hemorrhagic MMD. At 3 months post-surgery, digital subtraction angiography showed a pseudoaneurysm in the right MMA. Transdural anastomosis to the parietal and occipital lobes was opacified at the distal MMA of the pseudoaneurysm. Intra-aneurysmal coil embolization was performed for preservation of transdural anastomosis. The postoperative course was uneventful. At 1 month post-embolization, angiography revealed an entirely occluded pseudoaneurysm. Conclusion: An increase in blood flow in the MMA due to bypass surgery may accelerate aneurysm development by increasing the hemodynamic stress. This case suggested that intra-aneurysmal embolization may be a potential treatment.

The purpose of the present study was to clarify the characteristics of endothelial cell (EC) proliferation in intraplaque microvessels in vulnerable plaques and impact on clinical results. The present study included 76 patients who underwent carotid endarterectomy. Patients were classified into three groups based on their symptoms: asymptomatic, symptomatic without recurrent ischemic event, and symptomatic with recurrent ischemic event. MR plaque imaging was performed and surgical specimens underwent immunohistochemical analysis. The number of CD31+ microvessels, and Ki67+ and CD105+ ECs in the carotid plaques was quantified, as measurements of maximum CD31+ microvessel diameter. MR plaque imaging yielded 41 subjects (54.0%) diagnosed with plaque with intraplaque hemorrhage (IPH), 14 subjects (18.4%) diagnosed with fibrous plaques, and 21 (27.6%) subjects diagnosed with lipid-rich plaques. The average largest diameter of microvessel in fibrous plaques, lipid-rich plaques, and plaque with IPH was 12.7 ± 4.1 μm, 31.3 ± 9.3 μm, and 56.4 ± 10.0 μm, respectively (p 40 μm) were observed in 9.6% of plaques with IPH but only in 2.8% of lipid-rich plaques and 0% of fibrous plaques (p < 0.01). Ki67+/CD31+ ECs were identified in 2.8 ± 1.2% of fibrous plaques, 9.6 ± 6.9% of lipid-rich plaques, and in 19.5 ± 5.9% of plaques with IPH (p < 0.01). The average largest diameter of microvessels in the asymptomatic group was 17.1 ± 8.7 μm, 32.3 ± 10.8 μm in the symptomatic without recurrence group, and 55.2 ± 13.2 μm in the symptomatic with recurrence group (p < 0.01). Dilated microvessels with proliferative ECs may play a key role in IPH pathogenesis. Furthermore, dilated microvessels are likely related to clinical onset and the recurrence of ischemic events. The purpose of the present study was to clarify the characteristics of EC proliferation in intraplaque microvessels in vulnerable plaques and their impact on clinical results, focusing on dilated intraplaque microvessels.

There are no reports describing the surgical procedure for moyamoya disease (MMD) patients with severe cerebral ischemia in the territory of the posterior cerebral artery (PCA) at initial presentation. In this study, therefore, we describe their clinical and radiological features and clinical results of one-stage revascularization surgery for both anterior and posterior circulation. This study included 6 MMD patients who had severe cerebral ischemia in the PCA territory and underwent one-stage revascularization surgery for both anterior and posterior circulation. Of these, one patient underwent it on both sides. Their clinical and radiological data were precisely analyzed. Compared with usual procedure, craniotomy was extended towards the temporo-parietal area more widely. The parietal branch of superficial temporal artery (STA) was anastomosed to the angular or posterior temporal artery, while the frontal branch was anastomosed to the frontal branch of MCA. Ultimate indirect bypass was added. Their clinical and radiological outcomes were evaluated. Their neurological symptoms included visual and speech disturbance as well as numbness of the extremities. Cerebral infarct was distributed in the posterior temporal, parietal, and/or occipital lobe. Cerebral hemodynamics and metabolism were also impaired in the same regions. These findings were completely different from those in MMD patients without PCA lesion. Postoperative course was uneventful, and none of them recurred stroke during a mean follow-up period of 10.5 years. Surgical collaterals widely provided blood flow to the entire hemispheres, including the occipital lobe. Cerebral hemodynamics and metabolism markedly improved after surgery. One-stage revascularization surgery for both anterior and posterior circulation is feasible and effective to prevent future stroke in MMD patients with severe cerebral ischemia in the PCA territory at initial presentation.

Some of the pediatric moyamoya patients spend their childhood without diagnosed as moyamoya disease (MMD) because of their mild ischemic attacks and emerge again with ischemic or hemorrhagic stroke in their adulthood. This study was aimed to clarify the clinical characteristics of adult moyamoya patients with childhood onset and elucidate the impact of long disease period on their clinical features. Present study included 116 untreated hemispheres of 69 adult patients with MMD. They were divided into two groups: childhood onset group (26 hemispheres of 14 patients) and adult onset group (90 hemispheres of 55 patients). Clinical features were compared between the two groups. The incidence of hemorrhagic stroke was significantly higher in childhood onset group (P = 0.0091). Lenticulostriate and choroidal channels were more developed in childhood onset group (P = 0.044 and P

Calcification pathogenesis and the relationship between calcification and plaque composition remain unclear. This study explored the calcification characteristics of vulnerable plaques, especially focusing on calcification thickness, using computed tomography angiography and magnetic resonance plaque imaging.Demographic, computed tomography angiography, and magnetic resonance plaque imaging data were acquired from 178 patients with 229 lesions diagnosed with carotid stenosis. The calcification types were categorized by calcification thickness. We evaluated their features, including the anatomical location and the plaque composition compared with MR plaque imaging, and clarify the clinical characteristics. Furthermore, an immunohistochemical subgroup analysis was performed on 84 lesions treated with carotid endarterectomy.The result of the ROC analysis suggested the threshold between symptomatic and asymptomatic calcification was 2.04 mm (AUC;0.841, 95%CI; 0.771-0.894). Calcification with ≥ 2 mm thickness was classified as thick calcification and 2 mm thickness as thin calcification. Multivariate analysis suggested the prevalence of symptomatic patients in the thin calcification group was significantly higher than others (P = 0.01; odds ratio, 4.1; 95% confidence interval 2.8-7.2). Plaques with thin calcification were associated with plaque with intraplaque hemorrhage (P 0.01). The interobserver reliability (κ) of calcification type was 0.962 (95% confidence interval, 0.941-0.988). Immunohistochemical analysis demonstrated that the numbers of CD68-positive cells and CD31-positive microvessels in shoulder lesions were significantly higher in the thin calcification group than in the non-thin group (both P 0.01).Thin calcification was associated with plaques with intraplaque hemorrhage and had different clinical implications than thick calcification.

This study was designed to observe the changes in the carotid canal over time by measuring the carotid canal diameter longitudinally in adult patients with moyamoya disease in whom disease stage progressed spontaneously.Of 70 adult patients with moyamoya disease, 10 adult patients on 15 sides with spontaneous progression of the disease stage during conservative follow-up were included in this study. Another 10 moyamoya cases on 15 sides were selected as the controls without disease progression. All patients were followed up for at least 60 months after the progression of disease stage was confirmed. In addition, 5 patients who underwent microvascular decompression were included as healthy controls. The carotid canal diameter was measured with bone window computed tomography (CT) and source images of time-of-flight magnetic resonance angiography at initial presentation, and then were serially monitored with the latter.There was a significant correlation between the values obtained from CT and magnetic resonance imaging (RThe carotid canal diameter can decrease in response to disease progression even in adult moyamoya disease. "Negative" bone remodeling may play a key role in this unique phenomenon.

We report a 22-year-old man who had abdominal shunt tube migration into colon. He was diagnosed with pilocytic astrocytoma at optic-chiasm to hypothalamus at age of 7, and treated by resection, chemotherapy, and irradiation. He developed hydrocephalus and had multiple ventriculo-peritoneal shunt surgery. At age of 19, he fell in coma due to the subarachnoid and intra-ventricular hemorrhage due to the aneurysm rupture. The ventricle tube was removed, leaving the shunt valve and abdominal tube. The new shunt system was reconstructed at the contralateral side. He was at bed rest after this episode. At age of 20, he had high fever unable to control with antibiotics. The abdominal computed tomogram showed the shunt tube migration in the descending colon. The tube was removed under laparoscopy, and the inflammation was cured. The abandoned peritoneal shunt tube should be removed in patients with high tube migration risks.

Background: Cerebral hyperperfusion syndrome (HPS) is a serious complication. Recently, staged angioplasty has been reported as an effective strategy to avoid HPS. Severe calcification has been reported as contraindication of carotid artery stenting (CAS). In these cases, carotid endarterectomy (CEA) might be an alternative second stage treatment. We present a case of severe circular calcified plaque with hemodynamic impairments, treated with CEA following percutaneous transluminal angioplasty (PTA) to prevent HPS. Case Description: A 77-year-old woman presented with severe stenosis at the proximal left internal carotid artery. A CT scan of the neck demonstrated circular calcification. 123I-iodoamphetamine single-photon emission computed tomography (123I-IMP SPECT) showed reductions in cerebral blood flow (CBF) and cerebral vascular reserve in the left hemisphere. Staged therapy was subsequently performed as this patient had a high risk of HPS after conventional CAS or CEA. In the first stage, PTA was performed under local anesthesia. Two days after the procedure, 123I-IMP SPECT revealed improvements in CBF. There were no neurological morbidities. CEA was then performed under general anesthesia 7 days later, for the second stage. We found a calcified plaque with a large thrombus at its proximal end. A hematoxylin-eosin stain of the thrombus showed mostly intact and partially lytic blood cells. Postoperative 123I-IMP SPECT revealed CBF was improved, with no hyperperfusion immediately and 2 days after CEA. The patient was discharged with no neurological deficits. Conclusion: CEA following PTA for severe circular calcified plaque can be an alternative treatment strategy to prevent HPS. A disadvantage is the formation of thrombi. Early CEA should be considered if thrombus formation is suspected.

OBJECTIVEThis study aimed to assess longitudinal changes in the collateral channels originating from the lenticulostriate artery (LSA), posterior communicating artery (PCoA), and anterior and posterior choroidal arteries (AChA and PChA, respectively) during disease progression and/or aging. The impact of collateral channels on onset type was also examined.METHODSThis study included 71 involved hemispheres in 41 patients with moyamoya disease. The disease was categorized into 6 stages according to Suzuki’s angiographic staging system. The degree of development of each moyamoya vessel was categorized into 3 grades.RESULTSThe LSA started to dilate in stage 2, showed the most prominent development in stage 3, and decreased in more advanced stages (p < 0.001). The AChA most notably developed in stage 3 and gradually shrank (p = 0.04). The PCoA started to dilate in stage 3 and showed the most prominent development in stage 4 (p = 0.03). The PChA started to dilate in stage 3 and showed the most prominent development in stages 4 to 5 (p < 0.001). Patient age was negatively related to LSA development (p = 0.01, R = 0.30) and was positively associated with the abnormal dilation and extension of the PCoA (p = 0.02, R = 0.28) and PChA (p < 0.001, R = 0.45). The PCoA, AChA, and PChA more distinctly developed in hemispheres with intracerebral or intraventricular hemorrhage than in hemispheres with ischemic stroke or transient ischemic attack (p < 0.001, p = 0.03, and p = 0.03, respectively).CONCLUSIONSThis study suggests that the collateral channels through moyamoya vessels longitudinally shift from the anterior to posterior component during disease progression and aging, which may be closely related to the onset of hemorrhagic stroke in adult moyamoya disease.

Background Carotid endarterectomy (CEA) is known to reduce stroke risk in patients with symptomatic, moderate to severe carotid stenosis but has no apparent impact in patients with symptomatic, mild (less than 50%) carotid stenosis. However, recent development of noninvasive imaging modalities has shown that a certain subgroup of patients are at high risk for further ischemic events despite antiplatelet therapy. This study, therefore, aimed to clarify the patients’ clinical features and explore the impact of CEA for them. Methods This prospective cohort study included 74 patients who underwent CEA for symptomatic carotid stenosis between April 2012 and December 2016. Of these, 16 (22%) had mild (less than 50%) carotid stenosis. Their demographic, radiologic, intraoperative, and pathologic findings were precisely analyzed, and their outcome after CEA was examined for 38.5 ± 13.3 months. Results Of these 16 patients, 12 had already been treated with antiplatelets against previous ischemic cerebrovascular or coronary artery diseases. Plaque magnetic resonance imaging revealed that all patients had vulnerable plaque, including lipid-rich plaque (n = 6) and intraplaque hemorrhage (n = 10). Intraoperative observations confirmed this. Histologic analysis revealed that inflammatory cells and fragile angiogenesis were widely found in the specimens. Only 1 patient experienced transient (less than 30 days) neurologic deficit after CEA, and none of them repeated cerebrovascular events during the follow-up period. Conclusions It is not rare the patients who are at high risk for subsequent ischemic events because of vulnerable plaque despite mild (less than 50%) carotid stenosis. Magnetic resonance imaging is quite useful to noninvasively detect such vulnerable plaque. CEA is a promising procedure to treat these patients.

Object Recent clinical studies have recently demonstrated a strong association between carotid artery stenosis and coronary artery disease (CAD). However, the clinical impact of carotid plaque composition on CAD remains unclear. This study was aimed to determine the relationship between carotid plaque composition and CAD in patients who underwent carotid endarterectomy (CEA) or carotid artery stenting (CAS). Methods This prospective cohort study included a total of 97 patients who were admitted to our institution between January 2012 and April 2016. Magnetic resonance (MR) imaging was performed to semi-quantitatively analyze the components of carotid plaques by calculating the ratio of plaque intensity to muscle intensity on T1-weighted image. Diagnosis of CAD was based on patient history and clinical examinations during preoperative, postoperative and follow-up periods. Multivariate logistic analysis was performed to determine the risk factors for CAD. The relationship between contralateral plaque composition and CAD was also investigated. Results Of 97 patients, 33 were diagnosed as having 44 episodes of CAD. Multivariate logistic analysis revealed that ASO (odds ratio [OR], 5.7; 95% confidence interval [CI], 1.8-18.9), contralateral carotid occlusive disease (OR, 6.5; 95%CI, 1.7-22.9), and plaque/muscle ratio (OR, 3.0; 95%CI, 1.4-10.1) were independent factors for predicting CAD. The patients diagnosed as having CAD during the follow-up period had significantly higher plaque/muscle ratio than those with CAD on preoperative evaluations (2.29 ± .21vs. 1.97 ± .33, P Conclusions This study clearly demonstrates that ASO, contralateral carotid artery stenosis, and high-intensity carotid plaque on T1-weighted MRI independently predict CAD. Contralateral carotid plaque composition was also associated with concomitant CAD. Moreover, high-intensity carotid plaque may predict the future development of CAD. Therefore, unstable carotid plaque should be considered as the clinical phenotype of systemic inflammation and a novel, robust marker for future CAD.

Background and purpose This study was aimed to assess the hypothesis that unstable plaque formation in the carotid artery is one of phenotypes of chronic and systemic inflammation. Methods This study included 8 symptomatic patients with internal carotid stenosis (ICS) and 7 healthy controls. All subjects underwent 18F-fluorodeoxyglucos positron emission tomography (18F-FDG PET) of whole body. Plaque vulnerability was evaluated on magnetic resonance imaging (MRI). On 18F-FDG PET, the maximum standardized uptake (SUVmax) value was measured in the carotid plaque, aorta, spleen, liver, and bone marrow. The SUVmax ratio of the spleen or bone marrow to the liver was also calculated. These values were compared between 2 groups. All 8 patients in ICS group underwent carotid endarterectomy, and surgical specimens were subjected to immunohistochemistry. Results All 8 patients in ICS group had unstable plaque on MRI. The mean SUVmax of carotid plaque was 2.5 ± .2 in ICS group. The SUVmax of spleen was significantly higher in ICS group than in the controls (3.20 ± .25 and 2.51 ± .40, respectively; P = .003). The SUVmax ratio (spleen/liver) was also significantly higher in ICS group than in the controls (1.12 ± .06 and .85 ± .12, respectively; P = .001). The SUVmax of aorta was also significantly higher in ICS group than in the controls (2.16 ± .27 and 1.48 ± .15, respectively; P = .001). However, there were no significant differences in the SUVmax in the bone marrow and SUVmax ratio (bone marrow/liver) between the 2 groups (P = .811 and P = .731, respectively). Histological examination showed that the plaque strongly expressed endothelial progenitor cells, microvessels, and M1 macrophages. Conclusions These data strongly suggest the inflammation coupling between the spleen and unstable carotid plaque, and may be useful to develop novel therapeutic strategies against systemic inflammation in patients with ICS.

Objective Intracerebral hematoma involves two mechanisms leading to brain injury: the mechanical disruption of adjacent brain tissue by the hematoma and delayed neurological injury. Delayed neurological injury involves perihematomal edema (PHE) formation. Infectious complications following intracerebral hemorrhage (ICH) are a significant contributor to post-ICH recovery. We sought to identify a correlation between PHE volumes and infectious complications following ICH. We also sought to explore the clinical impact of this association. Materials and Methods This retrospective study included 143 patients with spontaneous ICH. CT scans were performed on admission, and 3 h, 24 h, and 72 h following admission. Hematoma and PHE volumes were calculated using a semi-automatic method. The absolute PHE volume at each time point and changes in PHE volume (ΔPHE) were calculated. Neutrophil to lymphocyte ratio (NLR) and serum C-reactive protein (CRP) levels were measured from the obtained blood samples. Neurological deterioration (ND) was assessed in all patients. Results Infectious complications were associated with ΔPHE72-24 (P Conclusions This study revealed a correlation between ΔPHE72-24 and infectious complications after spontaneous ICH, which was associated with markers of systemic inflammation. This phenotype linkage is a negative cascade that drives ND.

There are no reports describing the surgical procedure for moyamoya disease (MMD) patients with severe cerebral ischemia in the territory of the posterior cerebral artery (PCA) at initial presentation. In this study, therefore, we describe their clinical and radiological features and clinical results of one-stage revascularization surgery for both anterior and posterior circulation.This study included 6 MMD patients who had severe cerebral ischemia in the PCA territory and underwent one-stage revascularization surgery for both anterior and posterior circulation. Of these, one patient underwent it on both sides. Their clinical and radiological data were precisely analyzed. Compared with usual procedure, craniotomy was extended towards the temporo-parietal area more widely. The parietal branch of superficial temporal artery (STA) was anastomosed to the angular or posterior temporal artery, while the frontal branch was anastomosed to the frontal branch of MCA. Ultimate indirect bypass was added. Their clinical and radiological outcomes were evaluated.Their neurological symptoms included visual and speech disturbance as well as numbness of the extremities. Cerebral infarct was distributed in the posterior temporal, parietal, and/or occipital lobe. Cerebral hemodynamics and metabolism were also impaired in the same regions. These findings were completely different from those in MMD patients without PCA lesion. Postoperative course was uneventful, and none of them recurred stroke during a mean follow-up period of 10.5 years. Surgical collaterals widely provided blood flow to the entire hemispheres, including the occipital lobe. Cerebral hemodynamics and metabolism markedly improved after surgery.One-stage revascularization surgery for both anterior and posterior circulation is feasible and effective to prevent future stroke in MMD patients with severe cerebral ischemia in the PCA territory at initial presentation.

Measurement of luminal stenosis and determination of plaque instability using MR plaque imaging are effective strategies for evaluating high-risk carotid stenosis. Nevertheless, new methods are required to identify patients with carotid stenosis at risk of future stroke. We aimed to clarify the mechanisms and clinical implications of the hyperintense vessel sign (HVS) as a marker of high-risk carotid stenosis. We included 148 patients who underwent carotid stent (CAS) or carotid endarterectomy (CEA). MRI FLAIR was performed to detect HVS prior to and within 7 days after CAS/CEA. MR plaque imaging and 123I-iodoamphetamine SPECT was performed prior to CEA/CAS. Detailed characteristics of HVS were categorized in terms of symptomatic status, hemodynamic state, plaque composition, and HVS on time series. Forty-six of 80 symptomatic hemispheres (57.5%) and 5 of 68 asymptomatic hemispheres (7.4%) presented HVS (P < 0.01). Of the 46 symptomatic hemispheres with HVS, 19 (41.3%) presented with hemodynamic impairment and 27 (58.7%) presented without hemodynamic impairment. Of 19 hemispheres with hemodynamic impairment, 12 subjects (63.2%) showed high intensity and 7 (36.8%) showed iso-intensity plaques on T1WI. All 27 hemispheres without hemodynamic impairment showed high-intensity plaques. Of the five asymptomatic and HVS-positive hemispheres, one showed hemodynamic impairment; MR plaque imaging revealed T1 iso-intensity. The other four hemispheres that did not show hemodynamic impairment showed T1WI high-intensity plaques. There are two possible mechanisms of HVS, hemodynamic impairment due to severe carotid stenosis and micro-embolism from unstable plaques. HVS could be a radiological marker for high-risk carotid stenosis.

Background and Purpose: Surgical revascularization is now known to improve the outcome in patients with moyamoya disease. However, majority of previous studies reported their short-term ( Methods: Cumulative incidence of late morbidity/mortality and disease progression were evaluated among 93 patients who underwent STA-MCA anastomosis and EDMAPS. All of them were prospectively followed up for longer than 5 years post-surgery (mean, 10.5±4.4 years). There were 35 pediatric and 58 adult patients. Clinical diagnosis included TIA or ischemic stroke in 80 patients, hemorrhagic stroke in 10, and asymptomatic in 3. STA-MCA anastomosis and EDMAPS were performed onto their 141 hemispheres. MRI and MRA were performed every 6 or 12 years during follow-up periods. Results: During follow-up periods, 92/93 patients were free from any stroke or death, but one recurred hemorrhagic stroke (0.10% per patient-year). Disease progression occurred in the territory of the contralateral carotid or posterior cerebral artery (PCA) in 19 hemispheres of 15 patients (1.5% per patient-year). The interval between initial surgery and disease progression varied from 0.5 to 15 years. Repeat bypass surgery for anterior and posterior circulations resolved ischemic attacks in all 10 patients. Conclusion: STA-MCA anastomosis and EDMAPS would be the best choice to prevent further cerebrovascular events for longer than 10 years by widely providing surgical collaterals to both the MCA and ACA territories. However, regular follow-up would be essential for longer than 10 years post-surgery to identify the disease progression in the territory of contralateral carotid artery and PCA and prevent late cerebrovascular events.

Object: The calibers of donor arteries can change dynamically after bypass surgery in moyamoya disease (MMD). The present study aimed to evaluate the cut-offs of caliber changes in donor arteries associated with good surgical revascularization and to assess the impact of clinical factors potentially related to bypass development. Methods: We studied 71 hemispheres of 30 adults and 16 children with MMD, who underwent combined revascularization. We quantitatively measured the calibers of the superficial temporal artery (STA), deep temporal artery (DTA), and middle meningeal artery (MMA) with magnetic resonance angiography (MRA) source images and calculated the postoperative caliber change ratios (CCRs), to assess direct and indirect bypass development. They were compared with the findings of digital subtraction angiography, in which revascularization areas were categorized into 3 groups (poor, good, and excellent). Results: In both adult and pediatric hemispheres, median STA and DTA CCRs were higher in better revascularization groups (p < 0.05), while MMA CCRs were not significantly different among the groups. Receiver operation characteristic analysis revealed that the cut-off of >1.1 and >1.3 STA CCRs were associated with good direct revascularization in adult and pediatric hemispheres, respectively. The cut-off of >1.6 and >1.2 DTA CCRs were associated with good indirect revascularization in adult and pediatric hemispheres, respectively. Considering these cut-off values, STA and DTA CCRs showed high median values, irrespective of age, severity of cerebrovascular reserve, disease stage, and disease onset type. Conclusions: Caliber changes in STA and DTA can be easily measured by MRA, which could be indicators of direct and indirect bypass development. The combined bypass procedure could maximize revascularization in both adults and children with MMD.

Objective Although several studies have reported that some meteorological factors such as ambient temperature and atmospheric pressure, affect the incidence of spontaneous intracerebral hemorrhage (ICH), the correlation remains unclear. This retrospective time-series analysis was aimed to clarify the effects of meteorological parameters on the incidence of ICH. Materials and Methods Data of patients with ICH were obtained from a population-based survey of acute stroke patients between April 2016 and March 2019. All days during the study period were categorized into “no ICH day” when no ICHs occurred, “single ICH day” when only one ICH occurred, and “cluster day” when two or more ICHs occurred. Meteorological data were compared for among the three categories. Results 1,691 ICH patients from 19 hospitals were registered. In a total of 1,095 days, 250 were categorized as no ICH days, 361 as single ICH days, and 484 as cluster days. Daily ambient temperature declined in parallel with the daily number of ICHs, and it was a significant predictor for single ICH days and cluster days. Furthermore, the incidence of ICH in patients aged 65 years or above, men, those who emerged at home, those with modified Rankin Scale 3-5; and those with hypertension; and ICHs in the basal ganglia, brain stem, and cerebellum were more likely to be affected by low ambient temperature. Conclusion Daily ambient temperature was significantly associated with ICH incidence. Patients’ activity, history of hypertension, and location of hemorrhage were also related to the impact of low ambient temperature on the incidence of ICH.

Background Although the natural course of extracranial carotid artery aneurysms (ECAAs) is still unknown, they may cause stroke or cranial nerve dysfunction unless they are treated. In this report, we reviewed the clinical results of 6 patients who underwent endovascular and surgical treatments for ECAAs. Methods A total of 6 patients underwent endovascular and surgical treatments for ECAAs for 9 years. The primary causes of ECAAs included Marfan syndrome (1 patient), infection (1 patient), trauma (2 patients), and unknown (2 patients). All 6 ECAAs were symptomatic. Results One patient underwent surgical resection of the ECAA followed by end-to-end anastomosis of the internal carotid artery (ICA). Another patient underwent proximal ICA ligation combined with high-flow external carotid artery-to-middle cerebral artery bypass using a radial artery graft, because the patient also had a giant thrombosed aneurysm in the cavernous portion of the ipsilateral ICA. Endovascular treatment was selected in the other 4 patients using a covered stent or a bare metal stent combined with coil embolization. Of these patients, one required proximal ICA ligation followed by superficial temporal artery-to-middle cerebral artery anastomosis due to an anatomical problem for stent placement. There was no neurological deterioration at the discharge in all but 1 patient who suffered ischemic stroke during surgery. Conclusion Surgical or endovascular treatment yielded a relatively satisfactory outcome in patients with ECAAs.

The middle meningeal artery (MMA) is well known to function as an important collateral channel to the territory of the anterior cerebral artery in moyamoya disease. This study was aimed to evaluate whether indocyanine green (ICG) videoangiography could visualize the anterior branch of the MMA before craniotomy during surgical revascularization for moyamoya disease.This study included 19 patients who developed TIA, ischemic stroke or hemorrhagic stroke due to moyamoya disease. Plain CT scan and three-dimensional time-of-flight MR angiography were performed in all patients before surgery. All of them underwent superficial temporal artery to middle temporal artery anastomosis and indirect bypass on 27 sides in total.ICG videoangiography could clearly visualize the anterior branch of the MMA in 10 (37%) of 27 sides. The patients with a "visible" MMA are significantly younger than those without. Radiological analysis revealed that ICG videoangiography could visualize it through the cranium when the diameter of the MMA is1.3 mm and the sphenoid bone thickness over the MMA is3.0 mm. The MMA could be preserved during craniotomy in all "visible" MMAs, but not in 4 (23.5%) of 17 "invisible" MMAs. The results strongly suggest that ICG videoangiography can visualize the anterior branch of the MMA before craniotomy in about one-third of patients with a large-diameter MMA (1.3 mm) and thin sphenoid bone (3.0 mm).ICG videoangiography is a safe and valuable technique to preserve the anterior branch of the MMA during craniotomy for moyamoya disease.

OBJECTIVESurgical revascularization is known to reduce the incidence of further ischemic and hemorrhagic events in patients with moyamoya disease, but the majority of previous studies report only short-term (< 5 years) outcomes. Therefore, in this study the authors aimed to evaluate late (5–20 years) outcomes of moyamoya patients after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass (encephalo-duro-myo-arterio-pericranial synangiosis [EDMAPS]).METHODSCumulative incidences of late morbidity/mortality and disease progression were evaluated among 93 patients who underwent STA-MCA anastomosis and EDMAPS. All of the patients were prospectively followed up for longer than 5 years postsurgery (10.5 ± 4.4 years). There were 35 pediatric and 58 adult patients. Initial presentation included transient ischemic attack/ischemic stroke in 80 patients and hemorrhagic stroke in 10 patients, and 3 patients were asymptomatic. Surgery was performed in a total of 141 hemispheres. Follow-up MRI/MRA was performed within a 6- or 12-month interval during the follow-up periods.RESULTSDuring the follow-up periods, 92/93 patients were free from any stroke or death, but 1 patient had a recurrence of hemorrhagic stroke (0.10% per patient-year). Disease progression occurred in the territory of the contralateral carotid or posterior cerebral artery (PCA) in 19 hemispheres of 15 patients (1.5% per patient-year). The interval between initial surgery and disease progression varied widely, from 0.5 to 15 years. Repeat bypass surgery for the anterior and posterior circulation resolved ischemic attacks in all 10 patients.CONCLUSIONSThe study results indicate that STA-MCA anastomosis and EDMAPS would be the best choice to prevent further ischemic and hemorrhagic stroke for longer than 10 years on the basis of the demonstrated widespread improvement in cerebral hemodynamics in both the MCA and ACA territories in the study patients. However, after 10 years postsurgery regular follow-up is essential to detect disease progression in the territory of the contralateral carotid artery and PCA and prevent late cerebrovascular events.

OBJECTIVEThe calibers of donor arteries can change dynamically after bypass surgery in patients with moyamoya disease (MMD). The present study aimed to evaluate the cutoffs of caliber changes in donor arteries associated with good surgical revascularization and to assess the impact of clinical factors potentially related to bypass development.METHODSThe authors studied 71 hemispheres of 30 adults and 16 children with MMD who underwent combined direct and indirect revascularization. They quantitatively measured the calibers of the superficial temporal artery (STA), deep temporal artery (DTA), and middle meningeal artery (MMA) with MR angiography (MRA) source images and calculated the postoperative caliber change ratios (CCRs) to assess direct and indirect bypass development. These values were compared with the findings of digital subtraction angiography, in which revascularization areas were categorized into 3 groups (poor, good, and excellent).RESULTSIn both adult and pediatric hemispheres, the median STA and DTA CCRs were higher in better-revascularization groups (p < 0.05), while MMA CCRs were not significantly different among the groups. Receiver operating characteristic analysis revealed that the cutoff STA CCRs of > 1.1 and > 1.3 were associated with good direct revascularization in adult and pediatric hemispheres, respectively. Cutoff DTA CCRs of > 1.6 and > 1.2 were associated with good indirect revascularization in adult and pediatric hemispheres, respectively. Considering these cutoff values, STA and DTA CCRs showed high median values, irrespective of age, severity of cerebrovascular reserve, disease stage, and disease-onset type.CONCLUSIONSCaliber changes in STAs and DTAs can be easily measured using MRA, and they could be indicators of direct and indirect bypass development. The dual development of a direct and indirect bypass was most frequently observed in the context of a combined bypass procedure in both adults and children with MMD.

The involved carotid forks in moyamoya disease (MMD) will show decreases in both luminal caliber and outer diameter. The present study aimed to clarify the changes in the outer diameter associated with luminal stenosis/occlusion of the posterior cerebral artery (PCA) in patients with MMD.The present study included 24 pediatric and 48 adult patients with MMD and 17 healthy adult controls. Using magnetic resonance angiography, the degree of PCA involvement was classified into 3 grades: grade 0, normal; grade 1, stenotic; and grade 2, occluded. Using 3-dimensional constructive interference in steady state, the outer diameters were quantified in the P2 segment. All the patients were followed up to identify the disease progression in the PCA.The outer diameter of the P2 segment significantly decreased in a stepwise fashion in parallel with the severity of the luminal stenosis. In pediatric patients, the outer diameters of the P2 segments were 2.0 ± 0.26 mm, 1.5 ± 0.42 mm, and 0.87 ± 0.15 mm in those with grade 0, 1, and 2, respectively (P0.001). In adult patients, the outer diameters of the P2 segments were 2.0 ± 0.34 mm, 1.5 ± 0.34 mm, and 1.1 ± 0.17 mm in those with grade 0, 1, and 2, respectively (P0.001). We found no significant difference between grade 0 PCA of the adult patients and the PCA of the healthy controls (P = 0.92). Disease progression led to further arterial shrinkage of the P2 segment (n = 4).The results of our study have shown that the involved PCA demonstrates, not only luminal stenosis, but also arterial shrinkage in MMD. This finding strongly suggests that the underlying mechanism in the development of MMD is common in both the carotid fork and PCA.

Abnormal collateral channels, so-called moyamoya vessels, play a critical role to compensate cerebral ischemia, but carry the risk for hemorrhagic stroke in moyamoya disease (MMD). The present study was aimed to clarify if superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and encephalo-myo-duro-arterio-pericranial synangiosis (EDMAPS) can efficiently regress the abnormal collateral channels in MMD patients.This study included 92 hemispheres of 61 MMD patients who underwent STA-MCA anastomosis combined with EDMAPS between 2013 and 2019. There were 17 children and 44 adults. We retrospectively analyzed the findings on cerebral angiography before and 3 to 6 months after surgery, including Suzuki's angiographical stage, the development of surgical collaterals, and the extent of abnormal collateral channels such as lenticulostriate, thalamic, and choroidal channels.Following surgery, no pediatric and adult patients experienced any stroke during follow-up periods (40.2±25.5 and 54.9±19.7 months, respectively). Suzuki's stage significantly advanced in both adult and pediatric patients after surgery (P=0.042 and P0.001). In adult patients, all of the lenticulostriate, thalamic, and choroidal channels significantly regressed after surgery (P0.001, P=0.012, and P=0.004, respectively). In pediatric patients, however, lenticulostriate and choroidal channels significantly regressed (P=0.005 and P=0.034, respectively). Correlation analysis revealed that the development of surgical collaterals determined the postoperative regression of choroidal channels (P0.001).STA-MCA anastomosis and EDMAPS may be one of the most effective procedures to widely provide surgical collaterals to the operated hemispheres and prevent not only ischemic but also hemorrhagic stroke by regressing the hemorrhage-prone abnormal collateral channels in MMD.

The authors present a rare case of moyamoya disease emerged with corpus callosum hemorrhage. A 31-year-old woman suddenly complained of severe headache followed by consciousness disturbance. Radiological examinations revealed the bleeding in the splenium of corpus callosum, which was associated with intraventricular hemorrhage. On cerebral angiography, the carotid fork was severely stenotic on both sides, and a marked dilatation was observed in the anterior/posterior choroidal arteries and posterior pericallosal artery as well as the lenticulostriate arteries. Therefore, she was diagnosed as moyamoya disease. She successfully underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass on both sides. Postoperative course was uneventful. Follow-up cerebral angiography performed 4 months after surgery showed well-developed surgical collaterals via the external carotid system and a marked decrease of the dilated moyamoya vessels. She has been free from any cerebrovascular events for 36 months after surgery. Radiological findings strongly suggest that splenial bleeding occurred due to the rupture of the dilated abnormal collateral vessels that originate from the medial posterior choroidal artery and penetrate the corpus callosum in this case. Three-dimensional computer graphic analysis was useful to determine the complex collateral circulation in moyamoya disease.

Purpose: Chronic systemic inflammation is prevalent in patients with chronic kidney disease (CKD) and is linked to the development of cerebrovascular disease. In this study, we explored the association between the unstable plaques and preoperative CKD in patients who underwent carotid endarterectomy (CEA)/carotid artery stenting (CAS). Furthermore, this study also aimed to explore whether there is a difference in the aggravation of renal function with the presence of stable or unstable plaques. Patients and Methods: The study included 90 patients who underwent CEA/CAS for carotid artery stenosis. Multivariate analysis was performed to determine the risk factors for CKD. Kaplan-Meier estimation was employed to evaluate the aggravation of renal function following CEA/CAS. Results: Multivariate analysis revealed that contralateral carotid occlusive disease (odds ratio [OR], 4.45; 95% confidence interval [CI], 1.36-14.6), and T1 high-intensity carotid plaque (OR, 3.26; 95% CI, 1.2-8.86) were independent factors of CKD. Kaplan-Meier estimation demonstrated a higher aggravation of renal function in the T1 high-intensity group compared to those in the iso-intensity (P =.03). Following CEA/CAS, the time until aggravation of renal insufficiency was 12.0 ± 9.4 months in the T1 high-intensity group and 24.5 ± 9.6 months in the iso-intensity group (P =.03). Conclusions: This study demonstrated that contralateral carotid artery stenosis and T1 high-intensity plaques are more frequently observed in patients with CKD. T1 high-intensity carotid plaque is well linked to CKD development in future.

Objective: Present study was aimed to precisely evaluate the angio-architectures in patients with asymptomatic moyamoya disease (MMD) by comparing with those with hemorrhagic stroke. Methods: This study used the data set of cerebral angiography in Asymptomatic Moyamoya Registry (AMORE) Study and Japan Adult Moyamoya (JAM) Trial at enrollment. The development of 3 subtypes of collateral vessels, including lenticulostriate, thalamic, and choroidal anastomosis, was evaluated on cerebral angiography. Suzuki's angiographical stage and posterior cerebral artery (PCA) involvement were also assessed. These findings were compared between asymptomatic (AMORE) and hemorrhagic (JAM) groups. Results: This study included 55 hemispheres of 35 patients in asymptomatic group and 75 hemispheres of 75 patients in hemorrhagic group. In asymptomatic group, thalamic anastomosis was less developed than in hemorrhagic group (P = .011), but there were no significant differences in the development of lenticulostriate and choroidal anastomosis between the 2 groups (P = .077 and P = .26, respectively). Suzuki's stage was more progressed and the prevalence of PCA involvement was significantly higher in hemorrhagic group than in asymptomatic group (P = .0033 and P = .016, respectively). Conclusions: This study reveals no significant differences in the development of choroidal anastomoses between asymptomatic and hemorrhagic-onset MMD. On the other hand, disease stage and PCA involvement were less advanced in asymptomatic MMD than in hemorrhagic-onset MMD. These findings strongly suggest a certain subgroup of asymptomatic patients with MMD is at potential risk for hemorrhagic stroke.

Recent three-dimensional constructive interference in steady state (3D-CISS) studies have shown that the involved arteries decrease not only their own luminal caliber but also outer diameter in moyamoya disease (MMD). This study was aimed to clarify how the outer diameter of the involved arteries serially change during disease progression in MMD using qunatitaive 3D-CISS imaging.This study included 8 hemispheres of 7 patients with MMD whose Suzuki angiographic stage spontaneously progressed during follow-up. Using 3D-CISS, the outer diameter was quantified serially in supraclinoid portion of internal carotid artery (C1), the horizontal portion of middle and anterior cerebral arteries (M1 and A1, respectively) before and after the spontaneous disease progression, and also 3-12 months later.In 7 hemispheres with early disease stage (stage 1-3) at initial presentation, the involved arteries decreased in their outer dimater in parallel with luminal stenosis during spontaneous disease progression in the C1 (P = 0.005), M1 (P0.0001), and A1 portions (P = 0.0048). In the remaining 1 hemisphere with stage 4 at initial presentation, 3D-CISS imaging showed no significant change in the outer diameter of C1, M1, and A1 segments during disease progression.Using quantitative 3D-CISS imaging, this study clearly shows that the involved arteries serially decrease in their own outer diameter in parallel with luminal stenosis during spontaneous disease progression in early stages of MMD (stage 1-3). This phenomenon has not been reported previously and may result from the pathognomic mechanisms underlying the development of MMD.

BACKGROUND Fragile, dilated moyamoya vessels are the main source of hemorrhagic stroke in moyamoya disease (MMD). However, the prevalence of hemorrhagic stroke largely differs between Asian and western countries, although the underlying pathophysiology has not been clarified. OBJECTIVE To systematically analyze the difference of collateral angioarchitectures between Japanese and European Caucasians with MMD. METHODS This study included 71 patients with MMD, including Japanese (n = 41) and European Caucasians (n = 30). Using preoperative cerebral angiography, the developments of lenticulostriate artery (LSA), anterior choroidal artery (AChoA), posterior communicating artery (PcomA), and posterior choroidal artery (PChoA) were precisely evaluated, and ethic difference was analyzed in terms of patients' age and the onset type. RESULTS Cerebral angiography demonstrated that the marked dilatation of AChoA and PChoA were significantly more remarkable in Japanese than in European Caucasians (P = .004 and P = .002, respectively). Ageing advanced the dilatation and extension of PChoA and PcomA, and diminished the development of LSA in Japanese patients (P

We present a very rare case of suprasellar germinoma that spontaneously regressed before endoscopic biopsy. An 8-year-old boy was admitted to our hospital due to headache, polydipsia, and polyuria. Neurological examination performed on admission revealed bitemporal hemianopia. Enhanced MRI demonstrated a homogeneously enhanced tumor mass in the suprasellar region obstructing the foramen of Monro. Tests for all serum tumor markers were negative. Plain X-ray and CT scan were performed once and twice, respectively, for seven days between admission and endoscopic biopsy. The total dose of diagnostic radiation exposure before surgery was 110 mGy. Endoscopic observation during surgery revealed that the tumor had markedly decreased in size and the foramen of Monro had reopened. A very small piece of the tumor was harvested during surgery. Plain CT scan just after surgery showed a marked decrease in the tumor size, compared with the preoperative CT scan. The pathological diagnosis of the tumor was pure germinoma. The patient then underwent chemotherapy(four courses of CARE regimen)followed by radiation therapy with a dose of 24 Gy/15 fr. The tumor completely disappeared after treatment, and no recurrence was observed in the past four years.

Background Quasi-moyamoya disease (MMD) or moyamoya syndrome is based on various underlying diseases and radiologically simulates MMD, but its disease entity is still unclear. Recent studies have proven specific shrinkage of the involved arteries in MMD. Using 3-dimensional constructive interference in steady state (3D-CISS), therefore, this study aimed to analyze the outer diameter of the involved arteries in quasi-MMD. Methods This study included 9 patients with quasi-MMD (unilateral type, n = 2; bilateral type, n = 7). Using 3D-CISS, the outer diameter was quantified in the internal carotid artery distal to the posterior communicating artery (C1), the horizontal portion of the middle and anterior cerebral arteries (M1 and A1, respectively), and the basilar artery. Control values were obtained from 17 healthy subjects. Results In 7 of 9 patients, the outer diameters of C1, M1, and A1 were significantly smaller than those of the controls. On the other hand, the values were normal in other 2 patients. There was no significant difference in the underlying disorders between the 2 groups. All 3 pediatric patients are categorized into the arterial shrinkage group, but 2 of 6 adult patients were not. Conclusions These findings strongly suggest that quasi-MMD is not a uniform disease entity and includes at least 2 pathophysiologically different groups: the arterial shrinkage group and the nonarterial shrinkage group. A certain subgroup of MMD patients may be misdiagnosed as quasi-MMD because of the patients' comorbid disorders and mixed up with the patients who present angiographic findings similar to MMD in spite of the lack of arterial shrinkage.

Background: Recent development of magnetic resonance (MR) imaging has shown that silent microbleeds can be observed in a certain subgroup of adult patients with moyamoya disease. The patients with microbleeds are at higher risk for hemorrhagic stroke. However, the beneficial effects of surgical revascularization have not been established in asymptomatic patients with moyamoya disease. The authors present a case that underwent surgical revascularization for asymptomatic moyamoya disease because the number of silent microbleeds increases on serial MR examinations. Case Description: A 61-year-old female was referred to our hospital because of nonspecific headache. T2-weighted MR imaging revealed silent microbleeds in the corpus callosum. She was diagnosed as moyamoya disease on cerebral angiography. She was conservatively followed up, however, de novo microbleeds developed in the right temporal and frontal lobes on follow-up MR imaging 6 months later. Superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass were performed on the right side to prevent hemorrhagic stroke. Postoperative course was uneventful. Follow-up cerebral angiography performed 10 months after surgery showed a marked development of surgical collateral through both direct and indirect bypass and the diminishment of moyamoya vessels. For the last 7 years after surgery, she is free from any cerebrovascular events, and serial MR examinations revealed no further development of de novo microbleeds. Conclusions: Surgical revascularization may be useful to reduce the moyamoya vessels and prevent cerebrovascular events in a certain subgroup of patients with asymptomatic moyamoya disease, although its universal benefits on asymptomatic moyamoya disease have not been established yet.