There still remains uncertainty about the result of hemodynamic analysis of the intracranial aneurysm by computational fluid dynamics (CFD) because a variety of computational conditions are used by different analysts. In particular, the impact of the outflow boundary condition imposed at the outlets has not been fully elucidated, although it is considered to play an important role in determining the hemodynamic state in a bifurcation aneurysm. The purpose of this study is to discuss quantitative influences of different outflow boundary conditions on computed wall shear stress (WSS) in the aneurysm in terms of rupture risk assessment. Using three patient-specific models of aneurysms, the authors conducted hemodynamic analysis and compared the maximum, minimum and mean WSSs evaluated with seven outflow boundary conditions: the zero-pressure condition, five power laws with different exponents and Windkessel model. In one of the three models, even a slight difference in the power-law exponent caused a significant difference larger than 0.2 Pa in the minimum WSS, which could lead to misjudgement in rupture risk assessment. No particular outflow condition proved superior to the others. However, it was suggested that the Windkessel could perform better if the patient-specific information about the distal flow resistance were available.

The Windkessel model, which is known as a successful model for explaining the hemodynamic circulation, is a mathematical model with a direct correspondence with the electric circuit. We propose a theoretical model for the intracranial aneurysm based on the Windkessel-type steady blood flow. Intracranial aneurysms are well known vascular lesions, which cause subarachnoid hemorrhages. Since an aneurysm is an end-sack formed on the blood vessel, it functions as an unusual blood path that has characteristic features such as a reservoir and bottle neck orifice. We simulate an aneurysm by an electric circuit consisting of three different impedances, resistance, capacitance and inductance. A dumbbell-shaped aneurysm is the most dangerous aneurysm to easily rupture. Our aneurysmal model is created as a two-story aneurysm model for this point, thus namely the five-element Windkessel. Then, the mathematical formula was solved in numerical simulations by changing the size of the aneurysm and the elasticity of the aneurysm wall. An analysis of this model provided that the presence of the daughter aneurysm and the thinning of the aneurysm wall are positively correlated with a sharp increase in blood pressure in the aneurysm dome. Our mathematic aneurysm model proposes a good analogue to the real aneurysm and proved that this model includes soliton that is a non-decreasing wave propagation.

The Solitonic Windkessel model, which is successful for explaining the intracranial aneurysmal rupture based on the Windkessel-type hemodynamic circulation modelling, is employed for explaining unexpected and sudden intracranial aneurysmal rupture. In this paper, by focusing on the appearance of resonance, some aneurysmal ruptures are shown to possibly arise unexpectedly and suddenly as a resonance phenomenon.

A simple seesaw-type method using a sphere-shaped capsule as a blood testing container was developed, which is able to determine the time of onset of coagulation (coagulation time) of blood. The method is based on when a capsule containing a blood sample ceases rolling down a slope in a series of periodic, repetitive runs. From the elapsed time that the capsule stops rolling, the coagulation time can be determined. This method enables concurrent measurement of coagulation times for multiple blood samples. Optimal experimental conditions including the angle of slope and amount of blood were determined using cattle blood. The mean value of coagulation time for normal human donors was 19.6 ± 3.5 min, while that for patients taking direct oral anticoagulants (DOACs) was quite large. Addition of a coagulation accelerant (APTT reagent) to blood obtained from a normal donor and a DOAC-treated patient suffering from atrial fibrillation brought about dramatic shortening of the coagulation time. In addition, coagulation of the patient was slightly delayed compared with that of the normal donor. In this paper, it is shown that the present technique may be useful for assessing the anticoagulant effect of DOACs in patients as well as for determining the coagulation time of blood.

Infection control and protection from the emerging diseases should be rationally formulated and operated based on epidemiologically determined infection characteristics. In order to respond to this requirement, this study proposes a mathematical model of the progression of the spread of viral infection in the society. In addition, the model was applied to cases of transmission of the new coronavirus COVID-19. From the results, the following is clarified: the progress of the viral infection can be simply modeled by the daily-rate basic reproduction number r and the infection detection rate k; r is determined by the epidemiologically determined values of basic reproduction number Ro and the infection lifetime T of virus; the daily-rate effective reproduction number reff can be defined by reff = r(1 – k), and reff < 1 indicates that the infection is suppressed; the infection suppression can be realized to make k greater than the critical value kcr corresponding to the epidemiological parameters; this model fits well with the practical infection behavior of COVID-19 and enables the quantitative evaluation of infection suppress measures; In the case of China, thorough detecting and isolation would have improved the infection condition to the suppression phase after only 10 days.

Intracranial aneurysm (IA) is a socially important disease as a major cause of subarachnoid hemorrhage. Recent experimental studies mainly using animal models have revealed a crucial role of macrophage-mediated chronic inflammatory responses in its pathogenesis. However, as findings from comprehensive analysis of unruptured human IAs are limited, factors regulating progression and rupture of IAs in humans remain unclear. Using surgically dissected human unruptured IA lesions and control arterial walls, gene expression profiles were obtained by RNA sequence analysis. RNA sequencing analysis was done with read count about 60~100 million which yielded 6~10 billion bases per sample. 79 over-expressed and 329 under-expressed genes in IA lesions were identified. Through Gene Ontology analysis, ‘chemokine activity’, ‘defense response’ and ‘extracellular region’ were picked up as over-represented terms which included CCL3 and CCL4 in common. Among these genes, quantitative RT-PCR analysis using another set of samples reproduced the above result. Finally, increase of CCL3 protein compared with that in control arterial walls was clarified in IA lesions. Findings of the present study again highlight importance of macrophage recruitment via CCL3 in the pathogenesis of IA progression.

出血発症の椎骨動脈解離(vertebral artery dissection: VAD)において，前脊髄動脈(anterior spinal artery: ASA)が解離側VA から2 本分岐しY 字型にfusion している症例を経験したので報告する．症例は43 歳男性．くも膜下出血（subarachnoid hemorrhage: SAH）で発症した破裂VAD で，解離部から1本，解離部より末梢の正常部位から1 本ASA が分岐し，fusion 後に下行していた．マイクロカテーテルを3 本使用しASA を温存しVAD のinternal trapping を行った．片側VA から2 本のASA が分岐しfusion するタイプの血管走行は今まで報告がなく本症例が初めてである．ASA の起始部にはvariationがあり，VA union 近くの塞栓術では脳幹への穿通枝とともにASA 分岐の詳細な観察が必要である．

トラスツズマブは，ヒト上皮成長因子受容体2 型蛋白のモノクローナル抗体であり，エピルビシンはアントラサイクリン系抗生物質で，どちらも乳癌の治療に用いられる．今回，両者による高度な心不全が原因で脳塞栓を起こした症例を経験した．症例は50 歳，女性．乳癌で乳房全摘出術を受け，術後エピルビシン投与後にトラスツズマブ治療を受けていた．就寝中に息苦しさ，意識レベル低下，右片麻痺を呈し当院に搬送された．来院時，失語，右上肢麻痺を認め，MRI で左頭頂葉に新鮮梗塞，MRA で左M2 閉塞を認め，アルテプラーゼ投与で改善した．心エコーでLVEF(left ventricular ejection fraction)が23.8％と低値を示した．入院2 日目にJCS 200 まで意識レベル低下し，MRA で右M1 閉塞を認め，カテーテル血栓除去術でThrombolysis In Cerebral Infarction(TICI) 3 の再開通を得た．第16 病日にも脳塞栓を再発した．本症例は，両薬剤による高度な心不全が主な原因で脳塞栓を繰り返したと考えられ，稀な症例と思われた．

症例は既往症のない56 歳，女性．意識障害および右片麻痺を認め，当院へ救急搬送後に左被殻出血と診断．血腫拡大傾向のため，症状改善目的で神経内視鏡下血腫除去術を施行した．術後は発語可能となったが，重度右片麻痺は継続し，弾性ストッキンングおよび間欠的空気圧迫装置を使用して血栓症予防をしながらリハビリを継続した．術後7～8 日目に血圧低下と酸素飽和度低下を認め，血漿D-dimer の急激な上昇を認めた．下肢静脈エコーで右膝窩静脈の深部静脈血栓症を認め，胸部造影CT で両側肺動脈に巨大血栓を確認し，重症肺塞栓症の診断に至った．また，経胸壁心エコーで三尖弁に付着する右房内血栓の存在を確認したため，開胸下で血栓除去術を緊急で施行し，救命に至った．肺塞栓症は脳卒中患者において注目すべき合併症であり，発症予防だけでなく，早期診断および迅速な治療開始が重要である．

Bilateral traumatic carotid-cavernous fistula(CCF)is rare. It is most commonly caused by a direct head or face injury involving the cavernous sinus and develops immediately after trauma. We report a case of bilateral traumatic CCF that occurred as an intracerebral hematoma(ICH)mimicking apoplexy 5 months later. We treated the patient with point occlusion of venous reflux causing an ICH using coil embolization to remove the hematoma. Three days after we performed trans-venous occlusion of the intercavernous connection and right cavernous sinus using coil embolization through the right inferior petrosal vein, it was identified that the left CCF was occluded after first embolization into the left sylvian vein. The mechanism of delayed development of traumatic CCF and spontaneous disappearance of CCF after occlusion of venous reflux are discussed.

Plasmacytomas are characterized by a monoclonal proliferation of plasma cells, and constitute the bulk of multiple myeloma. A solitary plasmacytoma is a rare entity, and is even more unlikely to occur intracranially. Here we present a 62-year-old man with an intracranial tumor. Magnetic resonance imaging revealed a large mass on the surface of the right fronto-parieto-temporal region, with extradurally directed growth. The tumor was enhanced homogenously by gadolinium, with dural tail-like findings, which resembled a meningioma. Head computed tomography scan showed osteolytic changes of the calvarium. Tumor removal following intravascular embolization was performed. The tumor seemed to have developed from the dura mater because it was firmly adhered to the dura but not to the calvarium. Histopathological analysis revealed monoclonal proliferation of plasma cells, which were positive for CD56, CD138, and lambda chain, on immunostaining. Since a systemic examination showed no evidence of other lesions, we diagnosed the tumor as a solitary dural plasmacytoma. There was no recurrence after postoperative radiotherapy. Rare entities, such as a solitary plasmacytoma, should be considered when an intracranial lesion with atypical radiological features is observed. If the lesion is anatomically resectable, histopathological evaluation is essential.

Accurate and long-term transposition of offending vessels is required in microvascular decompression (MVD) for the treatment of hemifacial spasm (HFS) and trigeminal neuralgia (TN). We created ion-beam implanted of an expanded-polytetrafluoroethylene (i-ePTFE) surface to transpose offending vessels in MVD. In 13 patients with MVD, we concealed and transposed offending vessels with tape-shaped i-ePTFE, and relieved facial and trigeminal nerve compression by attaching the i-ePTFE to the dura with fibrin glue. After surgery, none of the patients reported further symptoms or experienced recurrence of symptoms up to 12 months post-surgery. Favorable surgical outcomes are obtainable, since i-ePTFE has high tissue affinity and is easy to manipulate, even under a narrow and deep operative field. Our results suggested that i-ePTFE is very useful for transposition in MVD.

We reviewed basic considerations in fluid dynamics of cerebral aneurysms and applied these in surgery on the three most common types: internal carotid-posterior communicating artery, middle cerebral artery, and anterior communicating artery. It was found that aneurysmal initiation and growth do not occur at symmetric bifurcations. As blood flow always obeys the law of inertia, jet flow into the aneurysm will disperse along the wall; assuming the aneurysmal wall strength is even, the shape of the aneurysm becomes round or oval. When neurosurgeons encounter an aneurysm that is not round or oval, the wall may be fragile and requires great care during surgical manipulation.

The effect of a simple bare metal stent on repression of wall shear stress inside a model cerebral aneurysm was experimentally investigated by two-dimensional particle image velocimetry in vitro. The flow model simulated a cerebral aneurysm induced at the apex of bifurcation between the anterior cerebral artery and the anterior communicating artery. Wall shear stress was investigated using both stented and non-stented models to assess the simple stent characteristics. The flow behavior inside the stented aneurysm sac was unusual and wall shear stress was much smaller inside the aneurysm sac. Stent placement effectively repressed the temporal and spatial variations and the magnitude of wall shear stress. Hence, there is an effective possibility that would retard the progress of cerebral aneurysms by even simple stent.

Background: Mucoepidermoid carcinoma (MEC) is a rare tumor of the lung that accounts for 0.1–0.2% of all pulmonary tumors. To the best of our knowledge, brain metastasis from lung MEC is rare and magnetic resonance imaging (MRI) findings of this lesion have not been documented. Case Description: We herein report the case of a 72-year-old male. MRI revealed a left parietal tumor showing ring enhancement with medium gadolinium contrast and an evident high intensity area in the nonenhanced central portion on diffusion-weighted images (DWI) mimicking a brain abscess. Histologically, MEC is composed of a mixture of different cell types including mucin-secreting glandular cells and squamous cells. Accordingly, we suggest that the high DWI signal can be explained by the development of intracellular and intraluminal mucin, which have a high viscosity. Conclusion: Further accumulation of cases with brain metastasis from MEC is needed to establish the characteristic image findings, which would lead to prompt and adequate treatment.

We experienced a case with a synovial cyst accompanied by asymptomatic lumbar vertebral fracture that required differentiation from spinal metastasis. An 82-year-old man suffered from right leg and anal pain. Computed tomography (CT) showed L5 spondylolysis. Magnetic resonance images (MRI) revealed an intra spinal cyst and acute lumbar vertebral fracture of L5 vertebral body. The surrounding area of the cyst presented contrast enhancement, and the extradural mass compressed the dural sac. Bone scintigraphy with 99m technetium-MDP demonstrated intense uptake on the right first, fourth, fifth, and seventh ribs and L2, L3, and L5 vertebra. The F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) image demonstrated an increased radiotracer uptake in the L5 vertebra(standardized uptake value(SUV) max=3.5). Spinal metastasis was suspected. Because of the cauda equina compression syndrome, it was surgically removed. Intraoperatively, a well-demarcated extradural cyst was found and compressed the dural sac markedly. The cyst capsule was thin and contained clear, thin fluid with no signs of bleeding. The histological diagnosis was a synovial cyst. His neurological symptoms improved after the surgery. The synovial cyst may enlarge after asymptomatic vertebral fractures.