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It is difficult to predict the development of carotid stenosis by means of the known risk factors. Using a computational fluid dynamics analysis, we examined the hemodynamic risks for carotid stenosis, focusing on wall shear stress (WSS) disturbances.In 59 patients with unilateral carotid stenosis, the plaque was removed from the original three-dimensional computed tomography angiographic images, and the vessel shape before stenosis was artificially reproduced. A multivariate regression analysis was performed to determine the associations between the degree of area stenosis and hemodynamic and morphologic factors after adjustment for 6 known risk factors.Metrics for WSS disturbances were higher at and distal to a bifurcation in the carotid arteries after plaque removal compared with the normal carotid arteries, and metrics for WSS magnitudes were lower. In the plaque-removed arteries, the degree of stenosis was significantly negatively correlated with the ratio of stenotic to distal values of metrics for WSS disturbances and the diameter ratio of the external to common carotid artery, and positively correlated with the ratio of proximal to stenotic values of metrics for WSS magnitudes.Rapid increases in WSS from the common carotid artery toward the bifurcation, rapid decreases in WSS disturbance from the bifurcation toward the internal carotid artery, and lower diameter ratio of the external to common carotid artery are more likely than other risk factors to cause future severe stenosis. In patients with these hemodynamic risks, underlying diseases should be controlled more strictly, with imaging examinations at shorter intervals.

BACKGROUND A craniocervical junction arteriovenous fistula (CCJAVF) is a rare vascular malformation, and its etiology remains unclear. Here, to the best of the authors’ knowledge, they present the first case of CCJAVF associated with thrombus formation in the ipsilateral internal jugular vein. OBSERVATIONS An 80-year-old man presented with a sudden occipital headache. Computed tomography revealed a subarachnoid hemorrhage surrounding the brainstem and upper cervical cord. Digital subtraction angiography showed a CCJAVF fed by the left C2 radiculomeningeal artery with ascending intracranial drainage and epidural plexus. After endovascular treatment, the authors retrospectively found that his ipsilateral internal jugular vein and innominate vein were occluded with a huge thrombus at admission. LESSONS This case suggested a restricted antegrade venous flow due to thrombus-induced progressive retrograde intracranial drainage causing hemorrhage. Venous hypertension should be considered one of the causes of hemorrhage due to CCJAVF as well as intracranial arteriovenous fistulas.

BACKGROUND An aneurysm arising in an upper basilar artery (BA) fenestration is extremely rare. The authors reported a case involving successful endovascular treatment of an aneurysm arising from the minor limb of an upper BA fenestration. OBSERVATIONS A 65-year-old woman presented with an incidentally detected upper BA aneurysm arising from the minor limb of an upper BA fenestration. The irregularly shaped aneurysm was 6.0 × 2.7 mm in diameter, and the minor limb had several perforators. The aneurysm was nearly completely occluded with a catheter-assisted technique. The authors preserved both limbs of the BA fenestration. The postoperative course was uneventful, and the patient had an excellent clinical course with no neurological deficits or aneurysmal recanalization. LESSONS The case is the first report of an unruptured aneurysm arising at the minor limb of an upper BA fenestration. In this case, the authors preserved the minor limb with endovascular treatment. The authors believe catheter-assisted coil embolization to be a feasible endovascular technique in such cases.

Bow hunter's stroke is a rare cause of vertebrobasilar infarction. There is no consensus regarding the optimal treatment. We herein report a case of bow hunter's stroke successfully treated by endovascular treatment. A 70-year-old man presented with central vertigo. Magnetic resonance imaging (MRI) showed posterior circulation infarcts. Dynamic angiography revealed thrombus formation and hypoperfusion of the right vertebral artery upon head rotation to the left. Endovascular parent artery occlusion of the right vertebral artery was performed, and there was no recurrence at follow-up MRI. Endovascular parent artery occlusion might be a useful treatment for bow hunter's stroke.

We present an adult case of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS). A 26-year-old man with a family history of MERS presented to our hospital owing to dysarthria and dysesthesia of the right side of his body. The duration of these symptoms was approximately 4 hours. T

The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, are administered as first-line therapy for hypercholesterolemia, both as primary and secondary prevention. Besides the lipid-lowering effect, statins have been suggested to inhibit the development of cardiovascular disease through anti-inflammatory, antioxidant, vascular endothelial function-improving, plaque-stabilizing, and platelet aggregation-inhibiting effects. The preventive effect of statins on atherothrombotic stroke has been well established, but statins can influence other cerebrovascular diseases. This suggests that statins have many neuroprotective effects in addition to lowering cholesterol. Furthermore, research suggests that statins cause pro-apoptotic, growth-inhibitory, and pro-differentiation effects in various malignancies. Preclinical and clinical evidence suggests that statins inhibit tumor growth and induce apoptosis in specific cancer cell types. The pleiotropic effects of statins on cardiovascular and cerebrovascular diseases have been well established; however, the effects of statins on cancer patients have not been fully elucidated and are still controversial. This review discusses the recent evidence on the effects of statins on cardiovascular and cerebrovascular diseases and cancer. Additionally, this study describes the pharmacological action of statins, focusing on the aspect of ‘beyond lipid-lowering.&rsquo

Our hospital, located on the mainland, serves as a hub center for nine hospitals on the remote islands of Nagasaki Prefecture, Japan. There are no stroke specialists on these islands. We can transfer emergency patients from these islands to our hospital at any time, using a teleradiology system and three types of helicopter transport. We examined the efficacy of the drip and ship (DS) method for treating patients with acute ischemic stroke (AIS) on these islands, in comparison with patients on the mainland. From 2010 to 2017, we reviewed 98 consecutive patients with AIS who received intravenous recombinant tissue plasminogen activator (IV rt-PA) in our hospital or were transported to our hospital after IV rt-PA. Patients were divided into the Islands group (received IV rt-PA on the islands, DS; 31 cases) and the Mainland group (67 cases). The median transport distance from the islands was 112 km. The rate of patients achieving favorable outcomes was 54.8% in the Islands group and 64.2% in the Mainland group, with no significant differences. Multivariate analysis revealed that patients living on isolated islands did not have increased risks of unfavorable outcomes. Endovascular therapy (EVT), as part of the drip, ship, and retrieve method, was performed in 22.6% of patients in the Islands group and EVT in 38.8% of those in the Mainland group. The DS method seems feasible and safe for patients living on isolated islands with the use of 24-h helicopter transportation and teleradiology., Neurologia medico-chirurgica, 59(12), pp.504-510; 2019

Background: Carotid endarterectomy (CEA) is a conventional surgical technique to prevent ischemic stroke and the effectiveness for advanced lesions is established in many large studies. The vagus nerve is one of the cranial nerves that we usually encounter during CEA manipulation, which is identified as located posterior to the vessels in a position posterolateral to the carotid artery and posteromedial to the internal jugular vein. Case Description: We experienced an extremely rare case of the vagus nerve passing anterior to the internal carotid artery during CEA. Conclusion: We should be careful not to accidentally cut off because the variation of the vagus nerve can be mistaken for an ansa cervicalis. A delicate and complete dissection to understand the variation of the vagus nerve is crucial to minimize the risk of cranial nerve injury during CEA.

We report a rare case of asymptomatic aplastic or twig-like middle cerebral artery (Ap/T-MCA) with small unruptured aneurysms at the origin (A1) of the anomalous collateral artery containing plexiform (twig-like) networks and in the anterior communicating artery. In Ap/T-MCA, other cerebrovascular systems are usually considered to exhibit normal findings not associated with atherosclerosis. At first admission, atherosclerotic M1 occlusion was suspected because of the patient's risk factors and multiple stenoses in major intracranial arteries. Cerebral blood flow (CBF) studies revealed reduction of resting CBF and vascular reserve in the ipsilateral MCA territory. After 5 years, a diagnosis of Ap/T-MCA was reached based on detailed image examination and intraoperative findings during aneurysm clipping in combination with extracranial-intracranial (EC-IC) bypass. It should be noted that atherosclerosis can coexist with Ap/T-MCA, which is considered a congenital anomaly in which bleeding often occurs due to a ruptured aneurysm within the fragile collateral vessels. In previous reports, A1 aneurysms at the origins of the collateral arteries ruptured even when they were small. Aggressive radical surgery using EC-IC bypass can be considered for the treatment of unruptured aneurysms associated with Ap/T-MCA, but further research is needed. (Received September 14, 2020; Accepted November 4, 2020; Published 1 April, 2021).

Background: Mechanical thrombectomy (MT) is standard treatment for acute ischemic stroke (AIS) with large-vessel occlusion within 6 h of symptom onset to treatment initiation (OTP). Recent trials have extended the therapeutic time window for MT to within 24 h. However, MT treatment remains low in remote areas. Nagasaki Prefecture, Japan has many inhabited islands with no neurointerventionalists. Our hospital on the mainland is a regional hub for eight island hospitals. We evaluated clinical outcomes of MT for patients with AIS on these islands versus on the mainland. Methods: During 2014–2019, we reviewed consecutive patients with AIS who received MT at our hospital. Patients comprised the Islands group and Mainland group. Patient characteristics and clinical outcomes were compared between groups. Results: We included 91 patients (Islands group: 15 patients, Mainland group: 76 patients). Seven patients (46.7%) in the Islands group versus 43 (56.6%) in the Mainland group achieved favorable outcomes. Successful recanalization was obtained in 11 patients (73.3%) on the islands and 67 (88.2%) on the mainland. The median OTP time in the Islands was 365 min. In both the Islands and Mainland groups, the OTP time and successful recanalization were associated with functional outcome. The modified Rankin Scale (mRS) score at 90 days ≤2 was obtained in two patients and mRS = 3 in four patients among eight patients with OTP time >6 h. Conclusions: Few patients with AIS on remote islands have received MT. Although patients who underwent MT on the islands had longer OTP, the clinical outcomes were acceptable. OTP time on remote islands must be shortened, as this is related to functional outcome. In some cases with successful recanalization, a favorable outcome can still be obtained even after 6 h. Even if OTP exceeds 6 h, it is desirable to appropriately select patients and actively perform MT., PLOS ONE, 16(1), e0245082; 2021

Herein, we report a rare case of a dissecting aneurysm of the M2 segment of the middle cerebral artery(MCA), presenting with a deep white matter infarction triggered by minor head injury. A 31-year-old woman was admitted to our hospital with headache and vomiting 3 hours after a mild head impact. A magnetic resonance angiogram obtained 10 months earlier, when the patient had complained of sudden headache, showed mild fusiform dilatation of the left M2 segment. On admission, computed tomography angiography(CTA)revealed irregular fusiform dilatation of the superior trunk of the left M2. Magnetic resonance imaging showed an intramural hematoma on the wall of the left M2 and acute infarction in the left deep white matter. Eight days after admission, CTA revealed further dilation of the aneurysm, and it was diagnosed as a dissecting aneurysm. The patient was successfully treated with proximal clipping and superficial temporal artery(STA)-MCA(M4)bypass on day 15. Bypass to a cortical M4 recipient was performed after the efferent M4 was identified using indocyanine green videoangiography. Four weeks postoperatively, the patient was discharged without any neurological deficits. The M2 dissecting aneurysm gradually regressed, and the bypass remained patent for 10 months postoperatively. To our knowledge, this is the first case of a dissecting M2 aneurysm treated by proximal clipping and STA-MCA bypass. This procedure seems a feasible option when the distal portion of the dissected MCA is difficult to expose.

A 58-year-old woman underwent left frontotemporal craniotomy for clipping of an unruptured cerebral aneurysm. A small defect was accidentally created in the orbital roof intraoperatively. The patient developed left eyelid edema and ocular pain after recovery from anesthesia. The following day, the eyelid edema worsened, and she had difficulty opening her eyes. On the 9

A 69-year-old woman presented on an emergency basis, with headache and left hemiparesis. Initial head CT at the time of admission revealed a large subcortical hematoma with perihematomal edema extending from the right parietal to the occipital lobe. A small part of the hematoma extended toward the trigone of the right lateral ventricle. CT angiography revealed no vascular abnormalities. Emergency craniotomy was erformed, and the patient's initial postoperative course was unremarkable. However, the patient's neurological symptoms worsened 10 days postoperatively, and CT revealed a new low-density cystic lesion with perifocal edema at the site of hematoma removal, in addition to severe cerebral compression. We performed a reoperation, and intraoperatively we observed hematoma fluid mixed with cerebrospinal fluid without any abnormal blood vessels or neoplastic lesions in the hematoma cavity. We identified the choroid plexus deep within the surgical field, and slight leakage of cerebrospinal fluid was detected from the ventricular aspect, indicating the formation of a small passage between the hematoma cavity and the ventricle. After the second operation, her postoperative course was uneventful without recurrent cyst formation. An early symptomatic expanding porencephalic cyst in the hematoma cavity after removal of an intracerebral hematoma is rare, and only a few cases have been reported in the literature. Based on literature review and considering the likely mechanism of cyst development, we speculated that progressive cyst expansion could be attributed to a check valve mechanism between the ventricle and the cavity from which the hematoma was removed, as observed in the present case.

Cerebral aneurysms and arachnoid cysts are relatively common cerebral malformations and the use of recent modalities has increased their detection rates. However, cerebral aneurysms associated with arachnoid cysts are unusual. We describe two cases of ruptured cerebral aneurysms associated with arachnoid cysts. According to previous reports, clinical presentation may sometimes be unusual, as cysts can prevent subarachnoid hemorrhage. Moreover, in some cases, CT may reveal typical arachnoid cysts without subarachnoid hemorrhage, without intracystic hematoma, or with subdural hematoma alone. These clinical presentations and radiologic findings can lead to delayed diagnosis of subarachnoid hemorrhage. Therefore, we should consider the coexistence of arachnoid cyst in case of a warning sign of aneurysm rupture.

Cervical carotid disease is typical atherosclerosis, which is responsible for ischemic stroke. The effectiveness of carotid endarterectomy (CEA) for advanced carotid stenosis has been established in many large studies, and CEA is the gold standard in surgical treatment. On the other hand, endovascular carotid artery stenting (CAS) has become increasingly popular recently. It is very important to avoid any complications to maintain the effectiveness of CEA. The retractor device is important for the exposure of carotid arteries and for the safe surgical manipulation. We have started to use lone star retractor system (LSRS) to deploy the surgical field. LSRS provides the usability to handle and a shallower surgical field without the disturbance of surgical manipulation. And it can facilitate exposure of the distal internal carotid artery because surgeon can retract freely in whole circumference by towing with moderate strength. LSRS may bring the smoother and easier surgical manipulations in CEA.

Intracranial germinomas are considered one of the most radiosensitive tumors and are curable by radiotherapy alone. Although patients can expect long-term survival, the adverse effects of radiotherapy and late sequelae in survivors are a major concern. Radiation-induced secondary neoplasms are one of those sequelae and are a serious concern because they are often connected directly with life prognosis. We describe a case of radiation-induced glioblastoma after radiotherapy for germinoma. An 11-year-old boy with basal ganglia germinoma was successfully treated with postoperative cranial irradiation. At the age of 40 years, he was admitted to our hospital for aphasia and memory disturbance. CT and MRI revealed a tumor in the left parietal lobe with dissemination. The tumor of the parietal lobe was removed surgically, and pathohistologically, it was diagnosed as glioblastoma. Long-term survivors who receive radiotherapy for germinomas in childhood are at risk for late complications, including radiation-induced neoplasms. Therefore, careful follow-up neurological examinations are recommended in these patients, even 20-30 years after radiotherapy.

Our hospital serves as the main hub for eight remote island hospitals(RIHs)in Nagasaki Prefecture, Japan. The shortage of stroke physicians, which has led to overwork, is a major concern. Several "task-shifting" systems were adopted to avoid physician burnout. First, the emergency department established a hotline system for receiving emergency calls regarding a stroke, and which managed initial care until the stroke physicians arrived(called the Nagasaki Medical Center stroke hotline system: N-SHOT)in 2014. The rt-PA administration rate increased from 3.3% in the Pre-N-SHOT group to 6.7% in the N-SHOT group. Second, the 'isolated islands stroke hotline system(I-SHOT)', with which physicians in RIHs participate in cooperation with N-SHOT, was started in 2017. After I-SHOT was introduced, the number of patients treated with the drip and ship method using teleradiology and 24-h helicopter transportation increased from 20(2010-2016)to 29 cases in 2017-2018. Additionally, new information and communication technology(ICT)using smart devices was introduced into the teleradiology system for task support. Third, on behalf of stroke physicians, nurse practitioners(NP)helped bedridden patients who had been delivered from RIHs and who had received acute treatment, and returned to their islands by helicopter or airplane as transitions of care. N-SHOT is smoothly operated by each hospital department without reducing the quality of the stroke hotline. It has contributed to an increase in rt-PA and mechanical thrombectomy cases; I-SHOT has had the same effect. Task-shifting and task support with N-I-SHOT, the smooth transfer system by NP, and the new ICT are considered to be useful for reducing the overall burden of stroke physicians.

A 59-year-old woman suffering from memory impairment visited our hospital. She was discharged nine years ago without complications after undergoing neck clipping surgery for intracranial aneurysm rupture and a right ventricular peritoneal shunt using the CODMAN

A 68-year-old male with a sudden headache while defecation was transferred to our hospital. He was initially diagnosed with intracerebral hemorrhage in the right occipital lobe and acute subdural hematoma(ASDH)in the right interhemispheric fissure. A CT angiography(CTA)showed stenosis in the superior sagittal sinus(SSS)and the vein of Galen(VG)near the hematoma, which were considered to be due to compression of the hematoma. In the source image of CTA, the enhancement effect of the hematoma part was not clear. MRI revealed a heterogeneous mixed signal intensity in the hematoma area, suggesting a mixture of hematoma components that had bled at different times. Cerebral angiography performed two weeks after onset showed a tumor shadow imaged from the middle meningeal artery. Therefore, the presence of hemorrhagic meningioma was suspected. This was confirmed by contrast-enhanced MRI. One month after the onset, tumor resection was performed after the embolization of the feeding artery. Part of the tumor around the SSS and VG was left due to severe adhesion. Postoperatively, stenosis of the SSS and VG significantly improved. In this case, the increase in venous pressure may be related to the bleeding mechanism. Hemorrhagic onset meningioma with interhemispheric ASDH is extremely rare, and only 4 cases have been reported. It is easy to misdiagnose if only non-contrast CT is used. It should be noted that in cases of intratumoral hemorrhage, CTA may not show an enhancing effect in the acute phase. Since contrast-enhanced MRI may be useful for a definitive diagnosis, it should be performed at the time of initial imaging.

A 17-year-old female in a lethargic state with mild dysarthria was transferred to our hospital after experiencing a generalized tonic seizure immediately after giving birth. Head CT showed a cortical subarachnoid hemorrhage(cSAH)in the left frontoparietal convexity. Three-dimensional rotational angiography(3D-RA)revealed multifocal narrowing of the cortical branches of the left middle cerebral artery(MCA)and severe stenosis of the left M1 segment with plexiform collateral networks, suggesting the presence of reversible vasoconstriction syndrome(RCVS)and aplastic or twig-like MCA(Ap/T-MCA). When 3D-RA was repeated on day 17, the narrowing of the cortical artery had resolved, and a new constriction of more proximal blood vessels was observed. The arterial spasm disappeared within 3 months, confirming the diagnosis of RCVS and Ap/T-MCA. Although non-aneurysmal SAH due to Ap/T-MCA is extremely rare, RCVS often complicates cSAH in the frontal/parietal region. It is suggested that RCVS triggers cSAH in the presence of incidental Ap/T-MCA. Ap/T-MCA is thought to be caused by developmental abnormalities during the embryonic period, but only 11 cases in children or adolescents have been reported. This suggests that there are a considerable number of asymptomatic young patients whose condition has not been detected. The majority of patients with Ap/T-MCA are from East Asia, suggesting that racial and genetic background differences are a factor. As this anomaly is more likely to present as a stroke in adulthood, long-term follow-up is recommended if it is found at a young age. There is no evidence that revascularization is effective in preventing stroke. Further studies are needed on how to manage this condition appropriately.

Background: Middle cerebral artery (MCA) has a significantly lower incidence of anatomical variations than other intracranial arteries. We present an extremely rare case of unruptured aneurysms with the segmental duplicated MCA (d-MCA) formed a fenestrated structure at origin. Case Description: A 55-year-old female underwent direct surgery for the unruptured aneurysms at the top of the right internal cerebral artery with d-MCA. The d-MCA branches separated at the right internal cerebral artery top and had comparable with that of the main MCA trunk. Moreover, there was an anastomosis between the d-MCA branches. We diagnosed this anastomosis as segmental d-MCA. Two aneurysmal domes were identified during surgery at the origin of the d-MCA, which the main dome protruding backward was wide necked and another small one was collapsed or thrombosed protruding forward. We used a fenestrated clip for the posterior projecting dome, and the aneurysms were successfully obliterated. Conclusion: Although cerebral aneurysms associated with d-MCA are rare, there are technical difficulties in the surgical management. A fenestrated clip might be most reasonable to obtain patency of the parent arteries for the posterior projecting aneurysms if the perforators can be avoided.

We report a rare case of the endovascular treatment of a ruptured aneurysm of the right vertebral artery with an aberrant right subclavian artery(ARSA). A 60-year-old woman was urgently admitted because of consciousness disturbance. Brain CT showed subarachnoid hemorrhage, and CT angiography showed a right vertebral ruptured aneurysm. Endovascular treatment of the aneurysm was performed via a transfemoral approach. During the endovascular treatment, the right subclavian artery was found to diverge from the descending aorta on the periphery of the left subclavian artery. An ARSA was detected, and the right vertebral artery(VA)originated from the ARSA. The guiding catheter was passed through the right VA via an ARSA, and the aneurysm was completely embolized. The patient was transferred to another hospital on day 44 without any motor weakness. To our knowledge, this is the first case of an ARSA with a ruptured aneurysm in the right VA for which endovascular treatment was successfully performed via the ARSA. In patients with an ARSA or aberrant left subclavian artery, the artery could merge with Kommerell's diverticulum(KD)at its origin and be histologically fragile. Thus, in patients with an ARSA, attention should be paid to catheterization to avoid injuring the KD. CT angiography of the aortic arch might be considered before endovascular treatment.

We report two rare cases of late-onset brain edema after craniotomy for clipping or coating of unruptured intracranial aneurysms, possibly due to an allergic reaction to topically applied fibrin glue or gelatin sponge used for arachnoid plasty to cover the opened sylvian cistern. Both patients were women in their 60s with an allergic predisposition and both followed a similar clinical course. A slight fever and headache persisted during the postoperative period. Five to six weeks after surgery without complications, MR images showed an extensive T2 prolongated region in the white matter around the operative field, indicative of vasogenic edema, with mass effect and meningeal enhancement around the sylvian fissure that had been covered with gelatin sponge and sprayed fibrin glue. Swelling of the cerebral cortex around the sylvian fissure subjected to arachnoid plasty was also observed. Blood tests showed the absence of an inflammatory reaction and cerebrospinal fluid examination showed lymphocytosis that was considered to be due to an aseptic meningeal reaction or meningitis. Clinical symptoms and imaging findings steadily improved with the administration of steroids and antiallergic agents. Delayed brain edema may occur around the arachnoid plasty area despite an uneventful chronic postoperative period, which could be due to an allergic reaction to locally administered fibrin glue or gelatin sponge. Thus, the application of arachnoid plasty using fibrin glue and gelatin sponge in patients with a predisposition to allergies needs to be carefully considered.

We report a rare case of pediatric clinically mild encephalitis/encephalopathy with a reversible splenial lesion(MERS)associated with transient ischemic attack(TIA)-like symptoms. A 13-year-old boy who presented with transient left hemiparesis and dysarthria was transferred to our hospital. He had experienced similar symptoms at the age of nine years and was diagnosed with MERS type 2 due to the typical clinical course and MR imaging findings. His elder brother showed a similar clinical history at the age of eight years. DW-MR images on admission revealed high signal intensity areas in the splenium of the corpus callosum and deep white matter. The territories were depicted as low intensity on apparent diffusion coefficient maps and slightly high intensity on T2-weighted images. Recurrence of MERS type 2 was considered because the symptoms of the patient disappeared within several hours and the abnormal signal intensities markedly decreased on the follow-up DWI performed eight days after initial MR imaging. The abnormal MR imaging findings completely disappeared after five weeks. After discharge, the patient experienced eight TIA-like episodes with a similar clinical course and MR imaging findings over a period of six years. MERS associated with TIA-like episodes is extremely rare, especially MERS associated with recurrent episodes in multiple phases over a long period, as seen in the present case. In addition, the findings in the last two MR imaging scans involving the internal capsule, thalamus, and midbrain were highly unusual and maybe considered to be indicative of an advanced form of MERS type 2, as reported in other familial cases.

We report a rare case of perianeurysmal edema(PAE)around the dome of a usual intracranial aneurysm. A 79-year-old woman who presented with a dull headache that had become stronger from a month before was referred to our hospital for further examination of an aneurysm. MR angiogram had detected the aneurysm, having a dumbbell shape and arising from the M2 bifurcation of the right middle cerebral artery. Initial fluid attenuated inversion recovery and T2 weighed images revealed a slightly high intensity area in the brain around the dome of the aneurysm buried in the right temporal lobe, suggesting the presence of PAE possibly due to a preceding minor leak or partial thrombosis or impending rupture of the aneurysm. A CT angiogram revealed bleb formation of the aneurysm(size:10×6 to 4mm)without definite intraluminal thrombosis. The patient and her family consented to emergency craniotomy. During the microsurgical approach, thickening of the arachnoid membrane on the right sylvian fissure was observed. The subarachnoid space between the right frontal and temporal lobes was turbid/adhesive, and deposition of hemosiderin was observed around the aneurysm, indicating a preceding minor bleeding. The aneurysm was successfully clipped, and the postoperative course was uneventful. The present case showed that PAE could be observed even in a usual aneurysm. This finding might be an indirect sign of a preceding minor leak from the aneurysm, particularly when the dome is buried in brain parenchyma or is in close contact with the surrounding brain surface.

We report a rare case of reversible cerebral vasoconstriction syndrome(RCVS)with cortical subarachnoid hemorrhage(cSAH)associated with a fresh cortical infarction beneath the sulcus with thick cSAH. A 34-year-old woman presented with history of thunderclap headache. She was transferred to our hospital for further examination of a cSAH in the left frontal lobe. Results of the cerebrospinal fluid examination were unremarkable, but three-dimensional rotational angiography revealed multiple instances of narrowing of the cortical branches of the anterior and middle cerebral arteries, suggesting the diagnosis of RCVS. Diffusion weighted imaging(DWI)demonstrated a small cortical area with high-signal intensity around the sulcus , where a thick cSAH clot was observed. This cortical lesion appeared as low-signal intensity on the apparent diffusion coefficient maps, and the follow-up T2-weighted images(obtained 3 months after onset)demonstrated a residual lesion that was smaller than the initial DWI abnormality with high-signal intensity;thus indicating the presence of a coincident fresh cortical infarction. The position of the infarct next to the thickest portion of cSAH suggested that it was the bleeding source of the cSAH. Ten days after onset, the cerebral blood flow and volume in the cortex around the cSAH increased as compared to the same area on the contralateral side. These findings suggested that at least one of the bleeding mechanisms of the cSAH was related to the hemorrhagic infarction or subpial hemorrhage resulting from the "ischemia-reperfusion injury" due to the acute disturbance of the pial vessel microcirculation with subsequent rapid resolution of the blood flow during the early phases of RCVS. These dynamics could not be demonstrated with contemporary angiographic imaging.

We report an extremely rare case of dural arteriovenous fistula(DAVF)involving the superior sagittal sinus(SSS)that presented as a primary intraventricular hemorrhage(PIVH). A 79-year-old man who presented with disturbance of consciousness and vomiting was transferred to our hospital. The initial head CT revealed an intraventricular hemorrhage in the lateral, third, and fourth ventricles, predominantly involving the right lateral ventricle associated with obstructive hydrocephalus. CT angiography and three-dimensional rotational angiography(3D-RA)revealed SSS-DAVF with retrograde venous drainage from the cortical venous system to the subependymal venous system through engorged superficial/anastomotic/deep medullary or transcerebral veins, showing a pseudophlebitic pattern. A severe stenosis of the SSS was observed at the site just proximal to the shunting point. A varix of the right transvers caudate vein(TCV)was observed within the thickest portion of the hematoma in close contact with the wall of the right lateral ventricle. A stenosis of the branching point of the right TCV was detected on the 3D-RA image. The DAVF was completely cured after transarterial embolization. The varix gradually shrank and finally disappeared after 2 months. This is the first report of a case of PIVH due to SSS-DAVF with a subependymal varix considered as the bleeding point. Serial gadolinium-enhanced MR images clearly showed the shrinking of the varix. Our case is the second reported case of spontaneous resolution of the varix after embolization of the DAVF. The obstructive changes of the two venous outflow pathways(SSS/TCV)might further worsen the state of venous congestion in the deep medullary venous system and eventually lead to formation and rupture of the varix.

The incidence of spontaneous thrombosis of intracranial aneurysm ranges from 1% to 2% of ruptured aneurysms. Most of them are giant or large aneurysms, and various factors have been discussed in previous literatures. Recanalization of thrombosed aneurysms may be rare, but its mechanism is poorly understood. Reports on recanalization of small aneurysms after spontaneous thrombosis are rare, and the natural history is still unknown. We describe a rare case of spontaneous thrombosis and recanalization of a ruptured small aneurysm of the distal posterior inferior cerebellar artery. Spontaneous aneurysmal thrombosis should not always be considered as a good or safe sign, as it may recanalize in a short time, resulting in re-rupture. In the acute stage, periodic follow-up of patients with a spontaneously thrombosed aneurysm is important.

The term "carotid web" was first used in 1973 and is considered a rare form of fibromuscular dysplasia(FMD). A carotid web was reported to produce thrombus formation and cause of ischemic events. However, it is rarely reported because of its low incidence. As for the diagnosis, noninvasive routine radiological modalities such as ultrasonography or magnetic resonance angiography may have very low sensitivity due to the subtle nature of the entity. Therefore, these types of lesions may be often underdiagnosed. We describe three cases that presented with minor and recurrent major ischemic strokes resistant to medical management. All 3 cases had a good course with no recurrence after carotid endarterectomy. On pathological examination, all specimens revealed mild atherosclerotic change, although FMD was known to be a non-inflammatory and non-atherosclerotic angiopathy. Early detection of a carotid web is highly important. Three-dimensional CT angiography(3D-CTA)maximum intensity projection(MIP)imaging seems to be a reliable noninvasive technique, although catheter angiography is considered as the gold standard. The cases with carotid web have characteristics such as more recurrent ischemic stroke and resistance to medical management. Surgical treatment should be considered if medical management in unsuccessful. Moreover, even if asymptomatic, it might also be considered for cases with a growing web or with blood stasis behind the web.

We report an extremely rare case of a fenestration in the infracallosal(A2)segment of the right anterior cerebral artery(ACA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion. A 70-year-old man was referred to our hospital for further examination and treatment of unruptured aneurysms at the A1/A2 junction of the right ACA and the distal end of the right vertebral artery that were incidentally detected on MR angiography. CT angiography and 3D-rotational angiography revealed a fenestration in the proximal A2 segment of the right ACA with a small(3.6×3.8mm)aneurysm arising from the proximal end of the fenestration. The dome of the aneurysm projected to the left anterior/inferior direction. He underwent aneurysm neck clipping surgery via the right pterional approach without complications, while the vertebral artery aneurysm was managed conservatively. An extensive review of the literature revealed that only a small number of cases of A2 fenestration have been reported to date. To our knowledge, this is the first report of an A2 fenestration associated with an aneurysm at the fenestrated segment. Embryologically, the A2 fenestration may represent a remnant of plexiform arterial channels that constitute the primitive ACA system including the primitive olfactory artery, median artery of the corpus callosum and anterior communicating plexus.

A persistent primitive olfactory artery (PPOA) is a rare anomaly of anterior cerebral artery (ACA), which generally arises from the internal carotid artery (ICA), runs along the olfactory tract, and makes a hairpin bend to supply the territory of the distal ACA. PPOA is also associated with cerebral aneurysms. An accessory MCA is a variant of the middle cerebral artery (MCA) that arises from either the proximal or distal portion of the A1 segment of the ACA, which runs parallel to the course of the MCA and supplies some of the MCA territory. We experienced a rare case of coexistence of PPOA with an unruptured aneurysm and accessory MCA. Three-dimensional computed tomographic angiography (3D-CTA) has an excellent picture of the spatial relationship of the surrounding bony and vascular structure.

We report an extremely rare case of a fenestration in the cavernous segment of the left internal carotid artery(ICA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion. A 44-year-old woman with a dull headache was referred to our hospital for further evaluation of a suspected aneurysm in the right ICA on MR angiography(MRA). CT angiography and 3D-rotational angiography revealed no aneurysm in the right ICA;however, an intracavernous fenestration with an incidental aneurysm was observed in the left ICA. The aneurysm was small(5×3mm)with a wide neck arising from the origin of the ventral limb of the duplicated vessels, in association with a tiny bulge projecting medially. She requested conservative management and periodic follow-up with MRA. After 18 months, no structural change in the aneurysm was observed. To our knowledge, including our patient, only three cases of this type of ICA fenestration have been published, and this is the first report of an ICA fenestration with an unruptured aneurysm at the fenestrated segment. It is presently unknown whether the intracavernous fenestration has the potential to form an aneurysm within the proximal end of the duplicated segment, as reported in cases of supraclinoid ICA fenestrations.

We report a rare case of an unruptured aneurysm arising from the junction between the internal carotid artery(ICA)and duplicate origin of the middle cerebral artery(MCA). A 49-year-old man who presented with vertigo was admitted to our hospital. Subsequent MR and CT angiograms revealed an incidental aneurysm arising from the proximal end of the duplicate origin of the left MCA. He underwent clipping via the distal transsylvian approach. The aneurysm projected to the posterior direction and several perforators from the two M1 segments were attached to the neck of the aneurysm, which made neck dissection very difficult. Approaching the space from the posterior/lateral direction to reach the M1 segment, the aneurysm neck was successfully dissected and clipped without sacrificing any perforators or stenosis of parent vessels. The postoperative course was uneventful, and the patient was discharged within 2 weeks. Duplicate origin of the MCA has been confused with a fenestration of the proximal M1 segment or terminal segment of the ICA. In this condition, two MCA branches arise separately from the terminal segment of the ICA and fuse early to form an arterial ring at the proximal M1 segment. An aneurysm originating from this anomaly has never been described. However, some aneurysms associated with this type of origin may have incorrectly been reported as those associated with proximal MCA or terminal ICA fenestrations. We summarize the cases that are similar to our case of duplicate origin of the MCA with an aneurysm, and discuss the precise diagnosis and significant intraoperative problems that were described in the literature.

Distal anterior cerebral artery(DACA)aneurysms have a low incidence. Particularly, DACA mirror aneurysms are extremely rare, although DACA multiple aneurysms are not rare. Generally, it is said that tiny aneurysms have a low risk of rupture. However, we sometimes encounter cases of ruptured tiny aneurysm. We describe a rare case of a mirror image of DACA ruptured tiny aneurysm. A tiny aneurysm can rupture if the aneurysmal wall is fragile. Detection of the aneurysm may often be difficult with a single modality, even if the modality is digital subtraction angiography. Moreover, the distribution of subarachnoid hemorrhage may not be typical. It might be important to capture a slight change of aneurysm in follow-up imaging to detect a ruptured aneurysm over multiple iterations of imaging.

We report a rare case of a de novo ruptured aneurysm arising from the twig-like networks(TLN)of an anomalous collateral artery associated with an aplastic or twig-like middle cerebral artery(Ap/T-MCA). A 65-year-old woman with a decreased level of consciousness, who had been diagnosed with a right Ap/T-MCA and was treated with coil embolization for a ruptured A1 aneurysm at the origin of the anomalous collateral artery 4 years ago, was transferred to our hospital. Head CT revealed an intracerebral hematoma extending from the right frontal lobe to the caudate nucleus with intraventricular hemorrhage. Subsequent 3D-rotational angiograms revealed a ruptured de novo aneurysm arising from the TLN and regrowth of the residual neck of the coiled aneurysm. The two aneurysms were successfully treated by surgical clipping combined with superficial temporal artery middle cerebral artery anastomosis in the subacute phase. To our knowledge, only 11 cases of this type of aneurysm have been reported, including our case, and this is the first report of a de novo aneurysm within the TLN so far. Although all previously reported aneurysms were small(5-6mm), 10 of them(91%)ruptured. These data may indicate the vulnerability of this type of aneurysm to rupture despite their small size, probably due to hemodynamic stress and the fragile nature of their immature walls. To prevent recurrence of hemorrhage in these cases, revascularization may be necessary in addition to surgical clipping. Whether this concept is correct is an open question. Further studies are necessary to examine this issue.

A 65-year-old woman was transferred to our hospital because of loss of consciousness along with a right hemiplegia due to an intracerebral hematoma(ICH)that extended from the left temporal lobe to the lateral part of the basal ganglia. CT angiograms(CTA)and 3D-rotational angiograms showed an absence of the distal C1 segment of the left internal carotid artery(ICA), and an anomalous collateral vessel arising from the proximal end of the left A2 with plexiform(twig-like)arterial networks, supplying antegrade blood flow to the left middle cerebral artery territory. The caliber of the left carotid arterial system decreased from the origin to the terminal end. The source images of CTA revealed that the plexiform arteries were very close to the ICH, suggesting that the vessels might have caused the bleeding. Because a hypoplastic left carotid canal was observed, the segmental dysgenesis of the C1 portion of the left ICA seemed to have occurred during the early embryonic period. T2-weighted DRIVE images of MRI demonstrated the presence of a cord-like rudimentary structure corresponding to the distal C1 and proximal M1 portions. The patient was managed conservatively and was transferred to another hospital for subsequent rehabilitation. Segmental dysgenesis of the C1 portion is extremely rare. To our knowledge, only a single report has been published. The present findings suggest that 1)an anomalous collateral vessel corresponding to Heubner's artery evolved with residual primitive plexiform(twig-like)arterial networks and 2)this anomalous structure has not been proposed as a type of collateral systems for ICA dysgenesis.

We report the first case of two de novo miniature aneurysms(ruptured/unruptured)emerging from the infundibular dilatation(ID)of the callosomarginal artery, which branches from the infracallosal(A2)segment of the azygos anterior cerebral artery(AACA), in a 36-year-old woman. The patient had previously been diagnosed with a miniature, unruptured aneurysm, occurring in the A2 segment of the AACA, detected by CT angiography(CTA)at another hospital two years ago, and had been followed up with MR angiography(MRA)every 6 months. Three months after the final check-up with MRA, which did not indicate a significant change in the aneurysm, the patient presented with subarachnoid hemorrhage. Subsequent CTA and digital subtraction angiograms revealed that the right callosomarginal artery, originating from the apex of the aneurysmal bulge, had a maximal diameter of 3mm, indicating an ID of the artery. Additionally, two miniature bleb-like aneurysms emerged from the ID, projecting in opposite directions:one projecting to the right-posterior/superior direction and the other to the left-anterior/inferior direction. Both aneurysms were successfully clipped via a right pterional approach with partial resection of the gyrus rectus, and the right-projecting aneurysm was confirmed to be ruptured during surgery. In the current report, we review previously reported cases of AACA with aneurysms, and discuss their clinical characteristics, and the possible mechanisms underlying the formation of the ID and de novo aneurysms in this extremely rare case.