Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: Conventional time-of-flight (TOF) magnetic resonance angiography (MRA) failed to depict clear visualization of coiled cerebral aneurysms with PulseRider due to metal-induced susceptibility artifacts. Our aim was to overcome the metal artifact using a novel imaging technique of non-contrast-enhanced ultrashort echo-time magnetic resonance angiography (UTE-MRA). MATERIALS AND METHODS: Five unruptured intracranial aneurysms were treated using PulseRider and the patients underwent silent MRA (UTE-MRA). The images were compared with TOF-MRA and digital subtraction angiography (DSA). RESULTS: Silent MRA can visualize the residual cavity of the coiled aneurysms, which was not well visualized and rather defective when using TOF-MRA. While a segment of the proximal marker composed of stainless steel was poorly visualized, the other parts of the parent artery and the arteries of bifurcation, including the aneurysmal neck, were clearly visualized, equivalent to that of DSA. CONCLUSIONS: UTE-MRA achieves better visualization of cerebral aneurysms after PulseRider treatment than TOF-MRA.

DOI： 10.1007/s11604-022-01276-z

PubMed

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The selective provocative test (SPT) under local anesthesia aids in protecting against ischemic complications during endovascular treatment. However, the use of this test under general anesthesia is not well described. Herein, we present a case of a 51-year-old man with a ruptured fusiform aneurysm in the middle cerebral artery M4 segment, which was thought to possibly supply the motor cortex. Internal trapping of the affected vessel and aneurysm by endovascular intervention was successfully performed after SPT using transcranial motor evoked potential (MEP) monitoring under general anesthesia. Transcranial MEP is suitable for neurological assessment during SPT under general anesthesia.

DOI： 10.1007/s00701-021-05001-z

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.inat.2021.101118

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: Delayed bleeding of unruptured intracranial aneurysms (UIAs) after coil embolization is rare; this study aimed to analyze the occurrence of delayed bleeding of UIAs after coil embolization. METHODS: We retrospectively analyzed patients with UIAs after coil embolization between January 2002 and December 2018 and assessed the features of UIAs with delayed bleeding after coil embolization. RESULTS: Analysis included 307 patients with 335 UIAs. Mean follow-up was 7.1 ± 4.9 years, and total follow-up was 2365 aneurysm-years. There were 271 (80.9%) aneurysms located in the anterior circulation and 64 (19.1%) aneurysms located in the posterior circulation. Significant differences were observed between the 2 groups in terms of maximum size of the aneurysm (P < 0.01), width of the aneurysm neck (P < 0.01), and number of retreatment cases (P < 0.01). During the follow-up period, delayed bleeding occurred in 4 aneurysms (annual bleeding rate of 0.17%); all were located in the posterior circulation. The original size was not relatively large (mean 8.6 ± 2.4 mm). All aneurysms bled within 5 years (mean 35 ± 9.6 months) after the initial treatment. Two were de novo aneurysms that developed adjacent to the coiled aneurysms and were not detected on follow-up magnetic resonance angiography. CONCLUSIONS: Cautious follow-up of UIAs with digital subtraction angiography is important, articularly within the first 5 years after the procedure. If there are changes in the anatomic outcomes, short-term reassessment or additional treatment should be actively considered, particularly for aneurysms in the posterior circulation.

DOI： 10.1016/j.wneu.2021.02.061

PubMed

researchmap

Language：English  

BACKGROUND: Choroidal collaterals are a risk factor for hemorrhagic stroke, even in the nonhemorrhagic hemisphere, among patients with moyamoya disease (MMD). Peripheral choroidal aneurysms rupture in fragile collaterals; however, the development and natural course of these aneurysms remain elusive. OBSERVATIONS: A 51-year-old woman, who had experienced a right cerebral hemorrhage 3 years earlier, presented with asymptomatic minor bleeding from a left lateral choroidal artery aneurysm in a predeveloped choroidal anastomosis. Although the aneurysm spontaneously thrombosed within 2 months, the choroidal collaterals persisted. After bypass surgery, the choroidal anastomosis regressed, and neither a de novo aneurysm nor a hemorrhagic stroke occurred. A 75-year-old woman with MMD, who had experienced a left frontal infarction 6 years earlier, experienced recurrent right intraventricular hemorrhage from a ruptured lateral choroidal artery aneurysm that developed in the choroidal anastomosis. The aneurysm spontaneously regressed 3 days after the rebleeding with no recurrence over the following 7 years. LESSONS: Choroidal artery aneurysms may develop in the choroidal anastomosis and rupture in the nonsurgical or contralateral hemispheres. Patients with MMD who have a history of hemorrhagic or ischemic stroke and impaired cerebral blood flow require careful observation. Although aneurysms may rapidly regress spontaneously, bypass surgery can stabilize hemodynamic stress and prevent further hemorrhage.

DOI： 10.3171/CASE2110

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jnnfm.2021.104511

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

Computational fluid dynamics(CFD)is a useful tool for simulating blood flow and has been applied to hemodynamic analysis in cerebrovascular disease. Although CFD requires an engineering approach, it can potentially contribute to preoperative surgical simulation as an intraoperative aid. In this study, we describe the basic hemodynamic parameters for CFD analysis and demonstrate their effective practical use by focusing on intracranial aneurysms. A thinning cerebral aneurysmal wall indicates a rupture risk, and it cautions neurosurgeons of an intraoperative rupture. High pressure and low wall shear stress(WSS)have been proposed as hemodynamic parameters that are related to a thinning wall. However, an atherosclerotic region is occasionally observed, and a combination of low WSS and high oscillatory shear index characterizes these wall lesions. One representative case of ruptured middle cerebral artery aneurysm showed that high pressure and low WSS can lead to the identification of rupture points in pre-rupture analysis. Meanwhile, in endovascular surgery, we conducted flow analysis in the residual cavity after coil embolization via metal artifact reduction using silent MR angiography. With the development of imaging modalities, a combination with CFD analysis can lead to new findings. Thus, use of CFD software by neurosurgeons for clinical applications is important.

DOI： 10.11477/mf.1436204409

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Unilateral oculomotor nerve palsy, often caused by aneurysmal compression, is one of the decisive findings for confirming the site of a ruptured aneurysm. However, arterial compression can also cause unilateral oculomotor nerve palsy. Here, we present the case of a 59-year-old woman with a ruptured right internal carotid-posterior communicating artery aneurysm accompanied by contralateral oculomotor nerve palsy. The nerve was found to be compressed by the posterior cerebral artery and was isolated from the ruptured aneurysm. When confirming a ruptured aneurysm based on the evidence of unilateral oculomotor palsy, the arteries surrounding the nerve must be thoroughly assessed.

DOI： 10.1007/s00701-020-04633-x

PubMed

researchmap

Language：English  

BACKGROUND: Bow hunter's syndrome or stroke (BHS) is characterized by rotational vertebrobasilar insufficiency elicited by rotation of the neck. It is caused by dynamic and reversible occlusion of the vertebral artery (VA). Reversible symptoms of rotational vertebrobasilar insufficiency are described as bow hunter's syndrome, although brain infarction is rarely reported as bow hunter's stroke. OBSERVATIONS: A 70-year-old man experienced repeated cerebellar infarctions three times in the posterior inferior cerebellar artery (PICA) distribution of the nondominant right VA connecting the basilar artery. The onset of symptoms indicating cerebellar infarcts and the patient's head position changes were unrelated. Dynamic digital angiography (DA) revealed that the nondominant right VA was occluded by an osteophyte from the C4 vertebral body, and the right PICA branches were shown to be passing through the distal right VA from the left VA. These findings were observed when the patient's head was tilted to the right. An arterio-arterial embolic mechanism was suggested as the cause of repeated cerebellar infarctions. LESSONS: Transient nondominant VA occlusion has been rarely reported as a cause of BHS when the head is tilted. To confirm the diagnosis of BHS, additional head tilt is recommended when performing dynamic DA in patients with a cervical osteophyte.

DOI： 10.3171/CASE2061

PubMed

researchmap

Language：English  

Background: Perianeurysmal edema (PAE) has been suggested as an indicator of potential aneurysm rupture; however, the hemodynamic features of these aneurysms are still unknown. A computational fluid dynamic (CFD) analysis was performed to evaluate the hemodynamic features of a very rare case of a ruptured middle cerebral artery (MCA) aneurysm with PAE. Case Description: A 65-year-old woman presented with disturbed consciousness. A subarachnoid hemorrhage due to an azygos anterior cerebral artery (ACA) aneurysm rupture was suspected. An unruptured MCA aneurysm with PAE was identified in the left temporal lobe. Although the ACA aneurysm was clipped to prevent re-bleeding, the MCA aneurysm subsequently ruptured 6 days later. Clipping of the MCA aneurysm was performed, and hemosiderin deposits suggestive of sentinel bleeding were found on the surface of the aneurysm dome. CFD analysis revealed unstable hemodynamic stress at the expanded bleb area after rupture, localized to the rupture site. Moreover, this analysis revealed flow impingement with pressure elevation and low wall shear stress, which indicated increased inflammation and aneurysm wall thinning that likely led to rupture. Conclusion: Hemosiderin deposits at the aneurysm wall and PAE indicates leakage from a cerebral aneurysm. Hemodynamic stress at the aneurysm may promote an inflammatory response and lead to wall weakening accompanied by PAE. Based on our findings, we recommend that surgical intervention should be considered as the first line of treatment for such aneurysms to prevent rupture.

DOI： 10.25259/SNI_780_2020

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

BACKGROUND AND PURPOSE: Metal artifacts limit computational fluid dynamics analysis after coil embolization. Silent magnetic resonance angiography reduces metal artifacts and improves visualization of the residual cavity of coil-embolized aneurysms. This study investigated the flow dynamics of the residual cavity after coil embolization using silent magnetic resonance angiography and computational fluid dynamics to elucidate the hemodynamic characteristics of recanalization. METHODS: Twenty internal carotid-posterior communicating aneurysm cases treated with coil embolization and without stent assistance were followed up (mean±standard deviation, 13.0±6.1 months) and assessed using silent magnetic resonance angiography. The hemodynamic characteristics of the residual cavities in both types of aneurysms were compared between neck remnants, which persisted for >12 months (NR group), and those treated with coil compaction-induced body filling (BF group). Computational fluid dynamics analysis of each aneurysm was performed using morphological data obtained from silent magnetic resonance angiography. Pressure, pressure difference, normalized wall shear stress, and flow velocity were measured. RESULTS: The residual cavity was well-visualized using silent magnetic resonance angiography and compared with those imaged using conventional time-of-flight magnetic resonance angiography, and eight internal carotid-posterior communicating aneurysms with neck remnants and body filling were investigated. The maximum pressure area was localized to the aneurysm wall in the NR group (n=4) and to sides of the coil surface in the BF group (n=4). No significant differences were observed for each hemodynamic parameter. CONCLUSIONS: Combination of silent magnetic resonance angiography and computational fluid dynamics helps to understand the hemodynamic characteristics of residual cavity in coil- embolized aneurysms. The flow-impingement zone at the coil surface (maximum pressure area) may influence the risk for future coil compaction.

DOI： 10.1016/j.jstrokecerebrovasdis.2020.105290

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：{SAGE} Publications  

PURPOSE: We aimed to evaluate the safety and feasibility of the distal transradial approach (DTRA) as a novel technique for cerebral angiography based on our institutional initial experience. METHODS: We retrospectively analyzed our institutional database of consecutive diagnostic cerebral angiographies performed with DTRA from December 2018 to August 2019. Patient demographics and clinical and procedural data were recorded. RESULTS: In total, 51 diagnostic cerebral angiographies in 51 patients (age, 15-83 years; mean age, 59.4 years, SD 13.5; 35 (69%) females) were performed or attempted with DTRA. Ultrasound evaluation showed that the mean inner distal radial artery diameter was significantly smaller than the mean inner forearm radial artery diameter (2.19 mm vs. 2.56 mm, P < 0.001). Cannulation via the distal radial artery was successful in 47 (92%) procedures. In the four procedures that failed, operators converted to the ipsilateral transradial approach without repositioning or redraping. Selective catheterization of the intended vessel was achieved in 64 (91%) of 70 vessels. In the remaining six, operators achieved the objective of the examination with angiography injecting from proximal and conversion to another approach was not required. One patient experienced temporary numbness around the puncture site after the procedure. No radial artery occlusion was identified in the patients who underwent ultrasound evaluation. CONCLUSION: Our results demonstrate that DTRA could become a standard approach for diagnostic cerebral angiography owing to the low complication rate and the high cannulation success rate.

DOI： 10.1177/1591019920925709

PubMed

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Ovid Technologies (Wolters Kluwer Health)  

BACKGROUND AND PURPOSE: Intracranial aneurysm formation and rupture risk are, in part, determined by genetic factors and sex. To examine their role, we compared 3 mouse strains commonly used in cerebrovascular studies in a model of intracranial aneurysm formation and rupture. METHODS: Intracranial aneurysms were induced in male CD1 (Crl:CD1[ICR]), male and female C57 (C57BL/6NCrl), and male 129Sv (129S2/SvPasCrl or 129S1/SvImJ) mice by stereotaxic injection of elastase at the skull base, combined with systemic deoxycorticosterone acetate-salt hypertension. Neurological deficits and mortality were recorded. Aneurysms and subarachnoid hemorrhage grades were quantified postmortem, either after spontaneous mortality or at 7 to 21 days if the animals survived. In separate cohorts, we examined proinflammatory mediators by quantitative reverse transcriptase-polymerase chain reaction, arterial blood pressure via the femoral artery, and the circle of Willis by intravascular latex casting. RESULTS: We found striking differences in aneurysm formation, rupture, and postrupture survival rates among the groups. 129Sv mice showed the highest rates of aneurysm rupture (80%), followed by C57 female (36%), C57 male (27%), and CD1 (21%). The risk of aneurysm rupture and the presence of unruptured aneurysms significantly differed among all 3 strains, as well as between male and female C57. The same hierarchy was observed upon Kaplan-Meier analysis of both overall survival and deficit-free survival. Subarachnoid hemorrhage grades were also more severe in 129Sv. CD1 mice showed the highest resistance to aneurysm rupture and the mildest outcomes. Higher mean blood pressures and the major phenotypic difference in the circle of Willis anatomy in 129Sv provided an explanation for the higher incidence of and more severe aneurysm ruptures. TNFα (tumor necrosis factor-alpha), IL-1β (interleukin-1-beta), and CCL2 (chemokine C-C motif ligand 2) expressions did not differ among the groups. CONCLUSIONS: The outcome of elastase-induced intracranial aneurysm formation and rupture in mice depends on genetic background and shows sexual dimorphism.

DOI： 10.1161/STROKEAHA.120.029651

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：{SAGE} Publications  

Cortical spreading depolarization (CSD) induces pro-inflammatory gene expression in brain tissue. However, previous studies assessing the relationship between CSD and inflammation have used invasive methods that directly trigger inflammation. To eliminate the injury confounder, we induced CSDs non-invasively through intact skull using optogenetics in Thy1-channelrhodopsin-2 transgenic mice. We corroborated our findings by minimally invasive KCl-induced CSDs through thinned skull. Six CSDs induced over 1 h dramatically increased cortical interleukin-1β (IL-1β), chemokine (C-C motif) ligand 2 (CCL2), and tumor necrosis factor-α (TNF-α) mRNA expression peaking around 1, 2 and 4 h, respectively. Interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) were only modestly elevated. A single CSD also increased IL-1β, CCL2, and TNF-α, and revealed an ultra-early IL-1β response within 10 min. The response was blunted in IL-1 receptor-1 knockout mice, implicating IL-1β as an upstream mediator, and suppressed by dexamethasone, but not ibuprofen. CSD did not alter systemic inflammatory indices. In summary, this is the first report of pro-inflammatory gene expression after non-invasively induced CSDs. Altogether, our data provide novel insights into the role of CSD-induced neuroinflammation in migraine headache pathogenesis and have implications for the inflammatory processes in acute brain injury where numerous CSDs occur for days.

DOI： 10.1177/0271678X19859381

PubMed

researchmap

Language：Japanese   Publisher：金原出版(株)  

researchmap

Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2020&ichushi_jid=J01565&link_issn=&doc_id=20200512110004&doc_link_id=10.18888%2Frp.0000001194&url=https%3A%2F%2Fdoi.org%2F10.18888%2Frp.0000001194&type=%88%E3%8F%91.jp_%83I%81%5B%83%8B%83A%83N%83Z%83X&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00024_2.gif

Language：English  

BACKGROUND: Granulomatous amoebic encephalitis (GAE) is a rare and mostly fatal disease. Without specific symptoms, laboratory findings, or radiologic characteristics, establishing a correct diagnosis is challenging. In many cases of GAE, multiple ring-enhancing lesions with perifocal edema are observed on magnetic resonance imaging (MRI); a solitary and homogeneously enhancing mass masquerading as a malignant lymphoma that evolved into multiple hemorrhagic and necrotic lesions has rarely been reported in GAE. CASE DESCRIPTION: An immunocompetent 68-year-old man presented with transient right hemiparesis due to epilepsy. MRI revealed a well- and homogeneously enhancing mass with perifocal edema and restricted diffusion in the left parietal subcortical region. As malignant lymphoma was suspected based on MRI findings and an elevated β2-microglobulin level in the cerebrospinal fluid, an open biopsy was performed; the pathological diagnosis was inconclusive but suggested a granulomatous disease. Although steroid therapy was administrated, subsequently the mass lesion gradually enlarged. After a second surgery for removal of the mass lesion, multiple hemorrhagic and necrotic lesions developed at the primary site and additionally in the brainstem. The patient entered a comatose state and died 3 months after admission. Histopathological examination and polymerase chain reaction analysis of the specimen revealed posthumously GAE caused by Balamuthia mandrillaris with necrotizing vasculitis. CONCLUSION: A solitary mass lesion initially mimicked a malignant lymphoma, and subsequently evolved into multiple hemorrhagic and necrotic lesions detected on T2*-weighted and susceptibility-weighted imaging. Such serial changes noted on MRI seem characteristic and suggestive of necrotizing vasculitis of GAE.

DOI： 10.1016/j.clinimag.2019.10.015

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Background: Morphological changes of a stented artery can cause a flow diversion effect to reduce intra-aneurysmal flow; however, there is a potential for the negative effect of increased intra-aneurysmal flow. We present cases with multiple overlapping stents for a partially thrombosed vertebral artery aneurysm and characterize the hemodynamic properties of a recurrent case by focusing on the morphological changes of the stented artery. Methods: Between October 2017 and April 2019, four consecutive cases of symptomatic unruptured large and giant partially thrombosed vertebral artery aneurysms were treated with multiple overlapping low-profile visualized intraluminal support stents and no coils. Both angiographic and clinical outcomes were assessed. Computational fluid dynamics analysis was performed to clarify hemodynamic features. The degree of pressure elevation was calculated as the pressure difference (Pd). Wall shear stress (WSS) was also calculated. Results: In three of the four cases, successful flow reduction was achieved with no morphological change of the stented arteries. The patients' symptoms were gradually improved. The remaining case required additional stents after the initial treatment. In the recurrent case, Pd was noticeably elevated at the aneurysm neck after treatment, and WSS was generally increased in the area due to altered blood flow into the aneurysm dome caused by morphological changes of the stented artery. Conclusion: Overlapping stents can be used for the treatment of large and giant thrombosed vertebral artery aneurysms with flow diversion effect; however, morphological changes of the stented artery requires careful attention as it may lead to an increase in the intra-aneurysmal flow, causing negative outcomes.

DOI： 10.3389/fneur.2020.611124

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：{SAGE} Publications  

DOI： 10.1177/0271678X19870583

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: The authors reviewed the clinical role of computational fluid dynamics (CFD) in assessing the risk of intracranial aneurysm rupture. METHODS: A literature review was performed to identify reports on CFD assessment of aneurysms using PubMed. The usefulness of various hemodynamic parameters, such as wall shear stress (WSS) and the Oscillatory Shear Index (OSI), and their role in aneurysm rupture risk analysis, were analyzed. RESULTS: The authors identified a total of 258 published articles evaluating rupture risk, growth, and endovascular device assessment. Of these 258 articles, 113 matching for CFD and hemodynamic parameters that contribute to the risk of rupture (such as WSS and OSI) were identified. However, due to a lack of standardized methodology, controversy remains on each parameter's role. CONCLUSIONS: Although controversy continues to exist on which risk factors contribute to predict aneurysm rupture, CFD can provide additional parameters to assess this rupture risk. This technology can contribute to clinical decision-making or evaluation of efficacy for endovascular methods and devices.

DOI： 10.3171/2019.4.FOCUS19189

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Background and Purpose- Inflammation is a critical determinant of aneurysmal wall destabilization, growth, and rupture risk. Targeting inflammation may suppress aneurysm rupture. Vagus nerve stimulation (VNS) has been shown to suppress inflammation both systemically and in the central nervous system. Therefore, we tested the effect of a novel noninvasive transcutaneous VNS approach on aneurysm rupture and outcome in a mouse model of intracranial aneurysm formation with wall inflammation. Methods- Aneurysms were induced by a single stereotaxic injection of elastase into the cerebrospinal fluid at the skull base, combined with systemic deoxycorticosterone-salt hypertension, without or with high-salt diet, for mild or severe outcomes, respectively. Cervical VNS (two 2-minute stimulations 5 minutes apart) was delivered once a day starting from the day after elastase injection for the duration of follow-up. Transcutaneous stimulation of the femoral nerve (FNS) served as control. Multiple aneurysms developed in the circle of Willis and its major branches, resulting in spontaneous ruptures and subarachnoid hemorrhage, neurological deficits, and mortality. Results- In the milder model, VNS significantly reduced aneurysm rupture rate compared with FNS (29% versus 80%, respectively). Subarachnoid hemorrhage grades were also lower in the VNS group. In the more severe model, both VNS and FNS arms developed very high rupture rates (77% and 85%, respectively). However, VNS significantly improved the survival rate compared with FNS after rupture (median survival 13 versus 6 days, respectively), without diminishing the subarachnoid hemorrhage grades. Chronic daily VNS reduced MMP-9 (matrix metalloproteinase-9) expression compared with FNS, providing a potential mechanism of action. As an important control, chronic daily VNS did not alter systemic arterial blood pressure compared with FNS. Conclusions- VNS can reduce aneurysm rupture rates and improve the outcome from ruptured aneurysms.

DOI： 10.1161/STROKEAHA.118.023928

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: Degenerative cerebral aneurysm walls are associated with aneurysm rupture and subarachnoid hemorrhage. Thin-walled regions (TWRs) represent fragile areas that may eventually lead to aneurysm rupture. Previous computational fluid dynamics (CFD) studies reported the correlation of maximum pressure (Pmax) areas and TWRs; however, the correlation with aneurysm rupture has not been established. This study aims to investigate this hemodynamic correlation. METHODS: The aneurysmal wall surface at the Pmax areas was intraoperatively evaluated using a fluid flow formula under pulsatile blood flow conditions in 23 patients with 23 saccular middle cerebral artery (MCA) bifurcation aneurysms (16 unruptured and 7 ruptured). The pressure difference (Pd) at the Pmax areas was calculated by subtracting the average pressure (Pave) from the Pmax and normalized by dividing this by the dynamic pressure at the aneurysm inlet side. The wall shear stress (WSS) was also calculated at the Pmax areas, aneurysm dome, and parent artery. These hemodynamic parameters were used to validate the correlation with TWRs in unruptured MCA aneurysms. The characteristic hemodynamic parameters at the rupture points in ruptured MCA aneurysms were then determined. RESULTS: In 13 of 16 unruptured aneurysms (81.2%), Pmax areas were identified that corresponded to TWRs. In 5 of the 7 ruptured cerebral aneurysms, the Pmax areas coincided with the rupture point. At these areas, the Pd values were not higher than those of the TWRs in unruptured cerebral aneurysms; however, minimum WSS, time-averaged WSS, and normalized WSS at the rupture point were significantly lower than those of the TWRs in unruptured aneurysms (p < 0.01). CONCLUSIONS: At the Pmax area of TWRs, decreased WSS appears to be the crucial hemodynamic parameter that indicates the risk of aneurysm rupture.

DOI： 10.3171/2018.12.JNS182897

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Peripheral anterior inferior cerebellar artery (AICA) aneurysms are rare and commonly associated with vascular malformations, such as cerebellar arteriovenous malformations (AVMs). We present a case wherein multiple AICA feeding aneurysms on the subarcuate artery as a feeding artery of a Borden type I transverse-sigmoid dural arteriovenous fistula (dAVF) manifested as subarachnoid hemorrhage. CASE DESCRIPTION: A 67-year-old woman presented with acute severe headache. Brain computed tomography (CT) demonstrated subarachnoid hemorrhage mainly in the posterior fossa. A transverse-sigmoid dAVF was detected on magnetic resonance angiography (MRA) and three-dimensional-CT angiography (3D-CTA), with no cortical venous reflex. The patient underwent conventional angiography, which showed multiple aneurysms on a small branch of the AICA, feeding a transverse-sigmoid dAVF (Borden type I). The AICA aneurysms seemed flow dependent and ruptured owing to high-flow arteriovenous shunts through the dAVF. Based on the source images of the MRA, the small artery arising from the AICA was considered the subarcuate artery, and it was confirmed on 3D-CTA after the artery was successfully embolized with Onyx without any complications. Multiple aneurysms on the subarcuate artery are extremely rare, and the artery has not been identified as a feeding artery of the transverse-sigmoid dAVF. CONCLUSION: A rare case of multiple ruptured aneurysms on the subarcuate artery was reported in a patient with a Borden type I dAVF at the transverse-sigmoid sinuses manifesting as subarachnoid hemorrhage. Onyx embolization of the parent artery occlusion was feasible and useful in treating this type of feeding artery aneurysm of the AICA with a dAVF.

DOI： 10.1177/1591019918799299

PubMed

researchmap

Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society for Neuroendovascular Therapy  

DOI： 10.5797/jnet.oa.2018-0095

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Magnetic resonance image (MRI) is now widely used for imaging follow-up for post coiling brain aneurysms. However, the accuracy on the estimation of residual aneurysm, which is crucial for the retreatment planning, remains to be controversial. The purpose of this study is to evaluate a new post-processing technique that provides improved estimation of the residual aneurysm after coil embolization. One hundred aneurysms on 93 patients who underwent coil embolization for brain aneurysm were evaluated using the 1.5 Tesla time-resolved magnetic resonance angiography (TR-MRA) one year after the treatment. To minimize the inter-observer variability caused by the window level adjustment, an automatic post processing protocol using the full-width at half-maximum (FWHM) value was utilized. The result was then compared with that from the conventional cerebral angiography. Of the 97 aneurysms that underwent both TR-MRA and DSA, 23 (23.7%) showed residual neck / dome during follow-up. After window level adjustment, the size of the parent artery in the TR-MRA was consistent with that in the DSA. The reconstructed Volume Rendering images provided clear contours of the residual aneurysms and contributed to the understanding the configuration of residual aneurysm. The largest and the smallest diameter of the residual aneurysms was larger in the TR-MRA than in the DSA (8.05 vs. 7.72 mm, p = 0.0004; 4.99 vs. 4.19 mm, p = 0.007 respectively). The sensitivity, specificity, and positive and negative predictive values of TR-MRA compared to DSA were 100%, 97%, 73%, and 100%, respectively. Using the FWHM value to optimize the window level adjustment, the size of the residual component observed in the TR-MRA was larger compared to that in the DSA whereas the size of neck and the parent artery showed consistency between the two modalities. This image processing technique can be used as an effective screening tool for evaluating residual component in post-coiling brain aneurysms.

DOI： 10.1371/journal.pone.0203615

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: In most simulations of intracranial aneurysm hemodynamics, blood is assumed to be a Newtonian fluid. However, it is a non-Newtonian fluid, and its viscosity profile differs among individuals. Therefore, the common viscosity assumption may not be valid for all patients. OBJECTIVE: This study aims to test the suitability of the common viscosity assumption. METHODS: Blood viscosity datasets were obtained from two healthy volunteers. Three simulations were performed for three different-sized aneurysms, two using measured value-based non-Newtonian models and one using a Newtonian model. The parameters proposed to predict an aneurysmal rupture obtained using the non-Newtonian models were compared with those obtained using the Newtonian model. RESULTS: The largest difference (25%) in the normalized wall shear stress (NWSS) was observed in the smallest aneurysm. Comparing the difference ratio to the NWSS with the Newtonian model between the two Non-Newtonian models, the difference of the ratio was 17.3%. CONCLUSIONS: Irrespective of the aneurysmal size, computational fluid dynamics simulations with either the common Newtonian or non-Newtonian viscosity assumption could lead to values different from those of the patient-specific viscosity model for hemodynamic parameters such as NWSS.

DOI： 10.3233/THC-161245

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Stabilization of microcatheters during coiling after their optimal shaping are key factors for successful endovascular coil embolization of cerebral aneurysms. However, stabilization and optimal shaping of microcatheters are sometimes difficult. Our aim was to introduce "tailor-made" microcatheter shapes for coil embolization using three-dimensional (3D) printed vessel models. METHOD: Since August 2014, we have been investigating the use of 3D printed models of intracranial arterial aneurysms to produce optimally shaped microcatheters for endovascular coil embolization. Using Digital Imaging and Communication in Medicine data obtained from preoperative cerebral angiography, a vessel model was produced with a 3D printer using acrylic resin. Preoperative planning of microcatheter navigation and shaping were performed using the 3D vessel models. Before the procedure, microcatheter mandrels were bent manually to the intended angle, referring to the vessel model, and then sterilized. The 3D vessel models were also sterilized with plasma and used during the procedure. RESULTS: Twenty-six patients (27 aneurysms) were treated using a total of 48 microcatheters shaped while referring to the 3D printed vessel model. Of the 48 catheters, only 9 (19%) required modification of the initial shape due to inappropriate positioning of the catheter. Only 29% of the catheter placements required repositioning due to catheter kick back. There were no procedure-related complications, including aneurysm rupture. The responses from assistants to a questionnaire administered after the embolizations on the usefulness of the technique were favorable. CONCLUSIONS: Tailor-made shaping of microcatheters may facilitate easier and safer procedures in coil embolization of intracranial aneurysm.

DOI： 10.1016/j.compbiomed.2016.07.005

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Thin-walled regions (TWRs) of cerebral aneurysms are at high risk of rupture, and careful attention should be paid during surgical procedures. Despite this, an optimal imaging technique to estimate TWRs has not been established. Previously, pressure elevation at TWRs was reported with computational fluid dynamics (CFD) but not fully evaluated. OBJECTIVE: To investigate the possibility of predicting aneurysmal TWRs at high-pressure areas with CFD. METHODS: Fifty unruptured middle cerebral artery aneurysms were analyzed. Spatial and temporal maximum pressure (Pmax) areas were determined with a fluid-flow formula under pulsatile blood flow conditions. Intraoperatively, TWRs of aneurysm domes were identified as reddish areas relative to the healthy normal middle cerebral arteries; 5 neurosurgeons evaluated and divided these regions according to Pmax area and TWR correspondence. Pressure difference (PD) was defined as the degree of pressure elevation on the aneurysmal wall at Pmax and was calculated by subtracting the average pressure from the Pmax and dividing by the dynamic pressure at the aneurysm inlet side for normalization. RESULTS: In 41 of the 50 cases (82.0%), the Pmax areas and TWRs corresponded. PD values were significantly higher in the correspondence group than in the noncorrespondence group (P = .008). A receiver-operating characteristic curve demonstrated that PD accurately predicted TWRs at Pmax areas (area under the curve, 0.764; 95% confidence interval, 0.574-0.955; cutoff value, 0.607; sensitivity, 66.7%; specificity, 82.9%). CONCLUSION: A high PD may be a key parameter for predicting TWRs in unruptured cerebral aneurysms. ABBREVIATIONS: CFD, computational fluid dynamicsMCA, middle cerebral arteryPave, average pressurePD, pressure differencePmax, maximum pressureTWR, thin-walled regionWSS, wall shear stress.

DOI： 10.1227/NEU.0000000000001232

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Combined extra- and intracranial carotid artery stenoses, particularly involving multiple lesions, show complex hemodynamic properties and represent a therapeutic dilemma. We used computational fluid dynamics (CFD) to investigate whether insufficient cerebral blood flow (CBF) in a 70-year-old man with tandem stenoses was the cause of aphasia and right hemiparesis after carotid artery stenting (CAS) of the extracranial stenosis. METHOD: Three-dimensional digital subtraction angiography (3D-DSA) was performed before and after balloon angioplasty and CAS in the patient. The geometrical and rheological conditions of the carotid arteries were determined, and computational meshes were generated from the patient-specific 3D-DSA datasets. CFD analysis was performed, and hemodynamic parameters such as mass flow, pressure, fractional flow reserve, and streamlines were calculated. RESULTS: Post-CAS simulations showed that the percentage of internal carotid artery mass flow from common carotid artery mass flow increased from 9% to 14% and CBF improved by only 5%. CONCLUSIONS: CFD analysis suggested that the neurological complications were caused by insufficient CBF rather than embolic events, and in tandem carotid stenoses, CAS for an extracranial lesion alone may not always sufficiently increase CBF. CFD enabled the noninvasive quantitative estimation of the effects of CAS of each stenotic segment on carotid flow.

DOI： 10.3233/THC-161217

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Neuroradiology ({ASNR})  

BACKGROUND AND PURPOSE: Combination of high-resolution C-arm CT and novel metal artifact reduction software may contribute to the assessment of aneurysms treated with stent-assisted coil embolization. This study aimed to evaluate the efficacy of a novel Metal Artifact Reduction prototype software combined with the currently available high spatial-resolution C-arm CT prototype implementation by using an experimental aneurysm model treated with stent-assisted coil embolization. MATERIALS AND METHODS: Eight experimental aneurysms were created in 6 swine. Coil embolization of each aneurysm was performed by using a stent-assisted technique. High-resolution C-arm CT with intra-arterial contrast injection was performed immediately after the treatment. The obtained images were processed with Metal Artifact Reduction. Five neurointerventional specialists reviewed the image quality before and after Metal Artifact Reduction. Observational and quantitative analyses (via image analysis software) were performed. RESULTS: Every aneurysm was successfully created and treated with stent-assisted coil embolization. Before Metal Artifact Reduction, coil loops protruding through the stent lumen were not visualized due to the prominent metal artifacts produced by the coils. These became visible after Metal Artifact Reduction processing. Contrast filling in the residual aneurysm was also visualized after Metal Artifact Reduction in every aneurysm. Both the observational (P < .0001) and quantitative (P < .001) analyses showed significant reduction of the metal artifacts after application of the Metal Artifact Reduction prototype software. CONCLUSIONS: The combination of high-resolution C-arm CT and Metal Artifact Reduction enables differentiation of the coil mass, stent, and contrast material on the same image by significantly reducing the metal artifacts produced by the platinum coils. This novel image technique may improve the assessment of aneurysms treated with stent-assisted coil embolization.

DOI： 10.3174/ajnr.A4509

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Cranial nerve palsy caused by aneurysmal compression has not been fully evaluated. The main causes of symptoms are considered to be direct mechanical compression and aneurysm pulsations. Recent studies indicate that nerve dysfunction is mainly induced by pulsation rather than by direct compression, and successful cases of endovascular surgery have been reported. We describe a patient with an unruptured vertebral artery-posterior inferior cerebellar artery (VA-PICA) aneurysm compressing the facial nerve at the root exit zone (REZ). The patient presented with peripheral facial nerve palsy but not hemifacial spasm and was successfully treated by coil embolization. To investigate the mechanisms underlying peripheral facial nerve palsy, fluid structure interaction (FSI) analysis can approximate displacement and the magnitude of aneurysmal wall motion due to hemodynamic forces. In our case, maximum mesh displacement was observed at the aneurysmal wall attached to the facial nerve inside the pons rather than the REZ, which explains the clinical manifestation of facial nerve palsy in the absence of hemifacial spasm. This preliminary report demonstrates the utility of FSI analysis for investigating cranial nerve neuropathy.

DOI： 10.1016/j.compbiomed.2015.09.016

PubMed

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap

Language：Japanese   Publisher：(NPO)日本脳神経血管内治療学会  

researchmap