Published papers

【背景および目的】近年,高齢化に伴う高齢者ドライバーの増加,および高齢者ドライバーが運転中に脳卒中に罹患することによる自動車事故の増加が社会的に懸念されている.今回,「慶應義塾大学脳動脈瘤共同研究」データベース解析により,運転中発症くも膜下出血(aneurysmal SAH:aSAH)の全体に占める比率および特徴を解析した.【結果】発症時行動様式が記録されていた623名中,発症時運転中だったのは10名(1.6%).623名を発症時運転群(n=10)と非運転群(n=613)とに分け,臨床因子を比較した.運転時発症群は有意に男性比率が高かったが,それ以外の臨床因子(来院時aSAH重症度,退院時予後等)では有意差を認めなかった.【結論】自動車運転とaSAH発症との因果関係については否定できず,また,運転時に発症した場合事故につながる確率は低くないため,研究継続されるべき課題である.(著者抄録)

Purpose: Bridging veins (BVs) serve as a route of pial venous reflux, and its anatomy is essential to understand the pathophysiology of dural arteriovenous shunts (dAVSs) around the craniocervical junction (CCJ) (from the jugular foramen level to the atlantal level). However, the anatomical variations of the BVs and their proximal connections remained poorly elucidated. This study aimed to radiologically investigate the anatomy of the bridging veins around CCJ and discuss the clinical significance of these BVs in the dAVS. Methods: We investigated normal venous anatomy of the BVs from the jugular foramen level to the atlantal level using preoperative computed tomography digital subtraction venography in patients undergoing elective neurosurgery. BVs affected by the dAVSs in the same region were also evaluated. The three types of dAVS, craniocervical junction, anterior condylar, and proximal sigmoid sinus, were investigated. Results: We identified six BV groups: superolateral, anterolateral, lateral, posterior, inferolateral, and inferoposterior. The superolateral and inferolateral groups, connected with the proximal sigmoid sinus and suboccipital cavernous sinus, respectively, were the largest groups. Each group has a specific downstream venous connection. The association with dVASs was observed only in the inferolateral group, which was typically the sole venous drainage in most dAVSs at the CCJ. Conclusion: We reported detailed anatomy of BVs from the jugular level to the atlantal level, which enhanced our understanding of the pathophysiology of dAVSs in the corresponding region.

BACKGROUND: Pial arteriovenous fistula (AVF) is a vascular fistulous disease in which the cerebral pial artery and vein are directly connected without the intervening nidus within a sub-pial space. Multi-hole pial AVFs, wherein multiple feeders flow into one drainer, are usually formed with complex angioarchitecture and are difficult to treat. METHODS: A rare case of an adult patient with hereditary hemorrhagic telangiectasia and multi-hole pial AVF was described. A 23-year-old woman was referred to our hospital. She was previously diagnosed with left cerebellar pial AVF with multiple feeders (bilateral superior cerebellar artery and common trunk of the left anterior inferior cerebellar artery and posterior inferior cerebellar) and large varix that had been untreated for 9 years. The enlargement of the large varix with the new second varix formation was revealed by angiography. Although asymptomatic, considered to be a risk for future hemorrhage was the continuous high hemodynamic stress. RESULTS: Endovascular embolization was performed by securing safe transarterial n-butyl-2-cyanoacrylate injection by transarterial and transvenous coil placement to the shunt points and feeders, resulting in total occlusion of the fistula without any complications. Extensive transvenous coil placement inside the varix allowed safe embolization of the entire fistula with multiple high-flow feeders. Moreover, bidirectional (transarterial and transvenous) retrograde coil embolization enabled firm obliteration of the shunt points. CONCLUSIONS: Performing combined transarterial and transvenous embolization in a well-balanced manner was considered to treat multi-hole pial AVF to provide a safe and effective embolization.

PURPOSE: The venous plexus of Rektorzik (VPR), first described by Rektorzik in 1858, is a venous plexus around the internal carotid artery in the carotid canal. However, the VPR has never been investigated using the recently developed imaging modalities. In this study, we analyzed the VPR using computed tomography-digital subtraction venography (CT-DSV). METHODS: This study included 253 patients who had undergone head CT-DSV. The presence or absence of the right and left VPRs and their connecting veins were visually examined by two researchers. RESULTS: The VPR was observed in 60 patients (24%), 39 of which showed VPR only on the right side, 10 only on the left side, and 11 on both sides. VPR was significantly more common on the right side (p = 0.0002) and was observed more frequently around the horizontal segment of the internal carotid artery than around the vertical segment. The most common veins identified as distal and proximal VPR connections were the cavernous sinus (63/71, 89%) and the anterior condylar confluence (27/71, 38%), respectively. The mean age was significantly lower in patients with the VPR than in those without (53 vs. 57 years, p = 0.02). CONCLUSION: The VPR was significantly more frequent on the right side and in younger patients but was not a radiographically constant structure. In most cases, the VPR connected the cavernous sinus and anterior condylar confluence. Preoperative evaluation of VPR may lead to refined surgical procedures.

Ruptured aneurysms at the craniocervical junction (CCJ) involving the anterior spinal artery (ASA) are rare and consist of heterogenous lesions with variable clinical entities. However, the standard therapeutic strategy for the lesions has not been well-established. Moreover, despite advances in modern neurointervention, reports describing endovascular treatment for this specific lesion have been few. Here, we report three cases of ruptured aneurysms on the pial tributary of the ASA at the CCJ, which were subsequently treated by transarterial glue injection or coil embolization. Endovascular treatment can be a therapeutic option, particularly for these ruptured aneurysms. Either transarterial glue injection or coil embolization can be effective depending on the type of etiology and the surrounding vasculature anatomy.

Background and Purpose: Information on the clinical picture of aneurysmal SAH (aSAH) occurring while driving may be useful to strokologists. A retrospective study was conducted using the Keio Brain Aneurysm Registry database. Methods: We used a dataset of 623 aSAH patients (204 men and 419 women) registered on the database between January 2019 and December 2021. Demographic variables were compared between patients who sustained aSAH while driving (Driving group) and those who sustained aSAH during other activities. Results: Ten patients (7 men and 3 women) sustained an aSAH while driving, with an overall frequency of 1.6%. Although male:female ratio was significantly higher in the Driving group, there were no significant intergroup differences, including the aSAH severity and outcomes at discharge. The frequency in the hospitals located in the metropolitan areas was lower than that in those located in the suburban/rural areas; the difference was not significant (1.0% vs. 2.0%, p=0.36). Conclusion: This study is one of the first studies to report the frequency of aSAH occurring while driving. Car drivers may experience stress-induced blood pressure elevation, and it remains to be observed closely whether causal relationship between driving and aSAH exists or not.

PURPOSE: Although the craniocervical junction has a complex anatomical structure associated with clinical diseases, its ventral venous network has not been well studied. This study aimed to clarify the extracranial ventral venous structure at the craniocervical junction. METHODS: Head computed tomography digital subtraction venography (CT-DSV) images of 273 patients (age 6 months to 93 years) taken at our department were retrospectively analyzed. We analyzed the frequency and anatomical features of the venous channels, as well as their upstream and downstream connections with the surrounding channels at the ventral craniocervical junction, from the level of the hypoglossal canal to the second cervical vertebra. RESULTS: In 54% of the cases, the vein descended from the anterior condylar confluence, running medially along the basioccipital and fusing with its counterpart in the midline at the level of the atlanto-occipital membrane. Furthermore, 24% of this vein was connected caudally to the anterior external vertebral venous plexus. We also identified venous channels, either as a sole vein or venous plexus, on the tip of the odontoid process (10%), which has not been well described previously. The vein around the odontoid process was connected to several veins, including the aforementioned vein anterior to the condyle and the anterior internal vertebral venous plexus. CONCLUSIONS: CT-DSV analysis revealed a detailed venous architecture ventral to the craniocervical junction. Venous structures identified in this study may be involved in diseases in this area.

Objective: The goal of schwannoma resection is to control the tumor while preserving neurological function. Schwannomas have a variable postoperative growth pattern, therefore preoperative prediction of a schwannoma’s growth pattern is favorable. This study aimed to examine the relationship between preoperative neutrophil-to-lymphocyte ratio (NLR) and postoperative recurrence and retreatment in patients with schwannoma. Methods: We retrospectively examined 124 patients who underwent schwannoma resection in our institution. Associations between preoperative NLR, other patient and tumor characteristics, and tumor recurrence and retreatment were analyzed. Results: Median follow-up was 2569.5 days. Postoperative recurrence occurred in 37 patients. Recurrence that required retreatment occurred in 22. Treatment-free survival (TFS) was significantly shorter in patients with NLR ≥2.21 (P = 0.0010). Multivariate Cox proportional hazards regression showed that NLR and neurofibromatosis type 2 were independent predictors of retreatment (P = 0.0423 and 0.0043, respectively). TFS was significantly shorter in patients with NLR ≥2.21 in the following subgroups: sporadic schwannoma, primary schwannoma, schwannoma ≥30 mm in size, subtotal resection, vestibular schwannoma, and postoperative recurrence. Conclusions: Preoperative NLR ≥2.21 before surgery was significantly associated with retreatment after schwannoma resection. NLR may be a novel predictor of retreatment and assist surgeons in preoperative surgical decision making.

Objective: To elucidate the genetic etiology of sporadic vestibular schwannomas (VSs) and investigate the correlation between NF2 inactivation mechanisms and preoperative clinical characteristics, including hearing function and tumor growth. Methods: Nineteen patients who underwent VS resection at our otorhinolaryngology or neurosurgery department between June 2020 and March 2022 were included in this study. Whole-exome sequencing (WES) was performed to detect somatic changes in NF2. Additionally, NF2 promoter methylation status and copy number changes were evaluated using methylation analysis and multiple ligation-dependent probe amplification (MLPA). Preoperative clinical data, including pure tone audiometry, speech discrimination scores, and tumor growth rates, were collected and analyzed for correlations with genetic findings. Results: WES identified somatic alterations in both NF2 alleles in 16 cases (84.2%). The addition of methylation analysis and MLPA confirmed biallelic NF2 inactivation in all cases. NF2 promoter methylation was suggested to be associated with hearing loss and tumor progression. A weak correlation between NF2 expression levels and tumor growth rate was observed (r = 0.21), while no significant correlation was found between NF2 expression and pure tone audiometry or speech discrimination scores. Conclusion: Comprehensive genetic analyses, including WES, methylation analysis, and MLPA, are essential for identifying NF2 inactivation mechanisms in sporadic VSs. The findings suggest that NF2 methylation may contribute to variations in clinical presentation. Further studies with larger cohorts are necessary to clarify the role of epigenetic modifications in disease progression and their potential impact on patient management strategies. Level of Evidence: 4.

To clarify the optimal timing of surgical or endovascular treatment for patients with small-sized (<5 mm) unruptured intracranial aneurysms (UIA) with conventional follow-up, we retrospectively evaluated the characteristics of UIA that ruptured or enlarged during observation. From 1999 to 2014, 316 UIA (271 cases) were initially treated without surgical or endovascular intervention. Four ruptured and 17 grown UIAs were treated with clipping or coil embolization. In these cases, the ratio of the internal carotid to the posterior communicating artery and that of the anterior cerebral artery to the anterior communicating artery was 71%. Intraoperative findings revealed that the bleb formed during follow-up was observed as a very thin wall. Ruptured UIAs are prone to rapid growth. We conclude that location, growth rate, and bleb formation are useful to estimate the risk of rupture of smallsized UIAs during follow-up.

The greater superficial petrosal nerve (GSPN) is especially important in anterior transpetrosal approach (ATPA) as the most reliable superficial landmark of Kawase's triangle. The GSPN can be considered as the superficial lateral border of anterior petrosectomy on the middle fossa to avoid internal carotid artery (ICA) injury. Although experienced operators can find the GSPN, its confirmation is not always easy to achieve. We introduce our recent GSPN confirmation methods using facial nerve monitoring. In 10 recent cases, antidromic GSPN stimulation and free-running facial muscle electromyography (EMG) monitoring were performed. Facial nerve evoked-EMG by antidromic GSPN stimulation confirmed the location of the GSPN course with precision in all cases. Free-running facial muscle EMG informed the mechanical stress of facial nerves through the GSPN. There was no postoperative facial palsy or dry eye in these cases. GSPN confirmation and preservation are not always easy to achieve. These monitoring methods are useful for the confirmation of the GSPN, which is a landmark for safe extradural anterior petrosectomy, and for the preservation of the GSPN itself.

The purpose of this study was to evaluate the usefulness of CT digital subtraction angiography (CTDSA) by using 320-detector row CT in the diagnosis and classification of cerebral dural arteriovenous fistula (dAVF) and comparing it with DSA as the standard reference. A total of 29 CTDSA/DSA from 25 patients with dAVF were retrospectively evaluated by two neuroradiologists. The presence, Cognard classification, and feeding arteries of dAVFs on CTDSA were assessed according to DSA. DSA depicted 33 dAVFs in 28 cases. By consensus reading, CTDSA correctly detected 32 dAVFs in 27 cases and properly graded 31 lesions. The intermodality agreement for the presence and classification of dAVFs was excellent (kappa = 0.955 and 0.921, respectively). CTDSA detected 77 of 109 feeding arteries (70.6 %) in 25 cases. The intermodality agreement for the feeding arteries was good (kappa = 0.713). Although CTDSA is limited in temporal and spatial resolution in comparison with DSA, it is an effective non-invasive tool for the detection and classification of dAVF.

A 23-year-old male with non-communicating hydrocephalus caused by intraventricular hemorrhage from an arteriovenous malformation was treated by endoscopic third ventriculostomy (ETV) after repeated ventricular cerebrospinal fluid drainage and removal of ventriculoperitoneal shunt due to infection. Postoperatively, the patient developed robust rigidity and akinesia with mutism, suggesting secondary parkinsonism. These symptoms showed marked improvement after administration of levodopa, and were not aggravated after discontinuation. The pathophysiology of this case might involve dysfunction of the dopaminergic system caused by repeated compression and release of the paraventricular white matter. Careful perioperative management not leading to excessive dilation of the the ventricles should be considered for ETV for non-communicating hydrocephalus to avoid this unexpected complication.

Lip protrusion requires bilateral symmetrical movements of the facial muscles, but the laterality of the activated sensorimotor cortex corresponding to the area of the face activated during lip protrusion remains under discussion. In this study, blood-oxygenation-level-dependent (BOLD) responses in the sensorimotor cortex during non-verbal lip protrusion were evaluated in a 3T magnetic field in twenty healthy right-handed subjects. The results showed that the activated sensorimotor area on the left side was larger than that on the right side, and there was a statistically significant difference in the number of activated voxels between the left and right sensorimotor cortex in an individual study of the male group, although approximately symmetrical motor action potentials of facial muscles were recorded during lip protrusion. There was a statistically significant difference in interaction between the hemisphere (right and left) and sex (men and women) and multiple comparison test showed statistical significant differences between "men and right" and "men and left", and between "men and left" and "women and left". The peak value of the percent changes in BOLD signal responses on the left side was approximately twice as high as that on the right side in the males of the group, though the bilateral sensorimotor cortex was almost equally activated in the females in the group. In addition, the left primary sensory area related to the face area was significantly activated as a region where Male was more active than Female in a general linear model (multi-study, multisubject) analysis. This study revealed the possibility that the left sensorimotor cortex was more closely involved in non-verbal mouth movement in men, suggesting sex-related differences in sensorimotor cortex activation.

Objective: The aim of this study is to investigate a source of cortical magnetic fields evoked by index finger movements. Methods: We analysed both movement-related cortical fields (MRCFs) and somatosensory-evoked fields (SEFs) by single equivalent current dipole (ECD) method in six healthy subjects. Dipole locations were superimposed on MR images of each individual subject. Results: The first component after finger movement (movement-evoked field I, MEFI) was observed in all subjects. The dipole of MEFI was oriented posteriorly, and was located on the posterior wall of the central sulcus of the hemisphere contralateral to the movement. The SEFs showed three major components: N20m, P30m and P60m. The dipoles of P30m and P60m were orientated posteriorly, similarly to the MEFI dipole, while that of N20m was orientated anteriorly. The dipole location of MEFI was closely located to P60m, not to N20m and P30m. The mean location of the MEFI dipole was significantly (p < 0.05) superior to N20m. Conclusion: These findings suggest that MEFI would be generated in the sensory area ( area 3b) affected by multiple afferents and activities, and that the source of the MEFI is not identical to that of the N20m component.

In patients with a high-degree of internal carotid artery stenosis, cerebral hemodynamics and metabolism are compromised during ischemia. Revascularization improves cortical hemodynamics and oxygen metabolism during functional activity, but the process by which it occurs is still controversial. Therefore, using functional near-infrared spectroscopy (fNIRS), we investigated the process by which cerebral hemodynamics improve after revascularization surgery. Eight patients with severe carotid artery stenosis were examined using fNIRS during a motor task before and after surgery. We evaluated postoperative changes in total hemoglobin and deoxyhemoglobin (HbR), at 2 weeks after surgery, and again at 3 months after surgery. Parameters measured were the TTP0.7 (time to peak) value, defined as the time taken to reach 70% of the maximum total hemoglobin concentration, and the increase in HbR during the motor task. TTP0.7 was higher in four patients preoperatively, but this was no longer evident in two of the patients at 2 weeks after surgery. An increase in HbR during the task was observed in six patients before surgery, and was maintained at 2 weeks after surgery. However, in three of these patients, this increase was no longer evident 3 months later. These changes observed using fNIRS suggest that the increase in cerebral blood flow after revascularization surgery is followed by improvement in parenchymal vasodilation and neuronal oxygen metabolism. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved.

PURPOSE: MR angiography using the silent MR angiography algorithm (silent MRA), which combines arterial spin labeling and an ultrashort time echo, has not been used for the evaluation of cerebral arteriovenous malformations (CAVMs). We aimed to determine the usefulness of silent MRA for the evaluation of CAVMs. METHODS: Twenty-nine CAVMs of 28 consecutive patients diagnosed by 4D CT angiography or digital subtraction angiography, who underwent both time-of-flight (TOF) MRA and silent MRA, were enrolled. Two observers independently assessed the TOF-MRA and silent MRA images of CAVMs. Micro AVM was defined as AVM with a nidus diameter less than 10 mm. The detection rate, visualization of the components, and accuracy of Spetzler-Martin grade were evaluated with statistical software R. RESULTS: For all 29 CAVMs, 23 (79%) lesions were detected for TOF-MRA and all for silent MRA. Of 10 micro AVMs, only 4 (40%) lesions were detectable on TOF-MRA and all (100%) on silent MRA. The visibility of the nidus and drainer was significantly better for silent MRA than TOF-MRA (p < 0.001), while there was no significant difference in the feeder between the two sequences. The accuracy rates of the Spetzler-Martin grade for the TOF and silent MRA were 38% (11/29) and 79.3% (23/29), respectively (p < 0.001). CONCLUSIONS: Silent MRA is useful for evaluating CAVM components and detecting micro AVM.

BACKGROUND: Spinal arteriovenous shunts are a common spinal vascular disorder. However, they can have a misleading clinical presentation and poor prognosis. They are classified into 4 types according to shunt points and drainage route, among which extradural arteriovenous fistula (eAVF) is the most rare, comprising only 1% of all spinal arteriovenous shunts. We report an extremely rare case of coexistent eAVF at the craniocervical junction and soft tissue arteriovenous malformation within the same metamere. CASE DESCRIPTION: A 30-year-old man presented with neck pain. T2-weighted magnetic resonance imaging revealed a flow void at the right craniocervical junction compressing the spinal cord. Angiography revealed eAVF at the craniocervical junction. The patient was treated via transvenous embolization. After the procedure, shunt flow and symptoms markedly decreased. During the operation, an extracranial arteriovenous malformation under the occipital skin was detected immediately after occluding the shunt point. CONCLUSIONS: This case indicates that transvenous embolization can be an effective treatment for eAVF and supports some hypotheses of arteriovenous malformation development. Additionally, it emphasizes the importance of examining a lesion with multiple modalities, including angiography, three-dimensional angiography, and cone-beam computed tomography, to understand the anatomy of the lesion.

BACKGROUND: The endoscopic transclival approach is a method for reaching the anterior side of the brainstem. In making this approach, bleeding from the basilar plexus is often observed when cutting the dura overlying the clivus. Controlling such bleeding is essential. CASE DESCRIPTION: We performed a transvenous embolization of the basilar plexus before making the transclival approach. After embolization, bleeding from the basilar plexus during the operation decreased considerably. CONCLUSIONS: To our knowledge, this is the first report of transvenous embolization of the basilar plexus. If the basilar plexus is well developed on preoperative computed tomographic venography or digital subtraction angiography, this procedure is useful for controlling bleeding during endoscopic transclival surgery.