Brain arteriovenous malformations (AVMs) are a major cause of hemorrhagic strokes; however, treating AVMs can be challenging. Identification and prediction of AVMs prone to rupture can help develop effective targeted treatments, which can improve patient outcomes. Stereotactic radiosurgery (SRS) is a minimally invasive standard treatment strategy for AVMs; however, its effects are not immediate, and there remains a risk of bleeding during the waiting period. Predicting the obliteration status of an AVM after SRS could enable guiding effective follow-up treatments. Phase contrast magnetic resonance imaging (PCMRI) is a non-invasive technique that utilizes phase shifts caused by applying magnetic fields of different polarities to measure fluid flow. In this review, we summarize findings from three studies conducted at our institution that performed PCMRI-based blood flow analysis. We focus on the relationship between AVM blood flow, hemorrhage, and treatment responsiveness. We also outline the current global status of this field. Recent advancements in PCMRI technology have lowered the barriers to its clinical application—the technique is increasingly used for elucidating the natural history of AVMs and optimizing treatment strategies. PCMRI is expected to enhance our understanding of and managing AVMs, particularly in improving prognostic predictions and treatment planning.

This study aimed to reform supply chain management in the field of neuroendovascular treatment. In endovascular treatment, expensive equipment such as microcatheters, coils, and stents are used once for each patient. Moreover, the surgeon learning curve is steep. As learning opportunities are rare in general facilities, treatment is often performed with the support of supervising surgeons from other hospitals. From a medicoeconomic perspective, the unnecessary inventory of treatment equipment and disposal costs due to sterilization are ultimately added to product costs. Additionally, devices are stored in small quantities at many hospitals and scattered across multiple vendor warehouses. Therefore, is difficult to quickly and accurately deliver equipment to hospitals for surgery. This study aimed to construct a system that uses artificial intelligence (AI) and telemedicine technologies to support treatment planning during neuroendovascular treatment, reduce physician workload, and improve medicoeconomics. Many treatment databases of two facilities will be used for AI analysis of device selection and surgical guidance. This information will be used to create a treatment planning support program (“AI system”) that will enable even inexperienced doctors to select appropriate devices. The telemedicine platform uses the Join mobile communication app, which has already been introduced to over 1,000 facilities in Japan and overseas. Using the app’s telemedicine system, it is now possible for senior supervising surgeons to provide remote guidance to inexperienced surgeons, thereby reducing the labor burden on doctors and providing highly medically and economically effective treatments.

Clazosentan is used to suppress the onset of cerebral vasospasm, delayed cerebral ischemia (DCI), and new cerebral infarctions after subarachnoid hemorrhage. Here we retrospectively examine our initial experience using this drug in our department. Evaluation items included patient background factors, clinical characteristics, spasms on imaging, DCI/new cerebral infarction, complications associated with fluid retention, and other complications. Thirty-two patients were included; among them, clazosentan was administered to 25. In the clazosentan group, 10 patients (31%) exhibited spasms on imaging, one (4%) experienced DCI, and four (16%) had a new cerebral infarction. Complications associated with fluid retention occurred in 13 patients (52%). Although differences were observed in the phase III study in patient background factors, clinical characteristics, and concomitant medications, clazosentan effectively prevented DCI and new cerebral infarctions. Additional cases should be examined to establish an ideal body fluid management protocol.

Background: Parent artery occlusion (PAO) is used to treat giant or large unruptured intracranial carotid artery aneurysms. Although PAO effectively cures aneurysms, long-term follow-up studies have demonstrated subsequent coexistent aneurysm enlargement and de novo aneurysm formation. This retrospective study examined the long-term outcomes of coexistent aneurysm enlargement and de novo aneurysm formation in patients treated with PAO using endovascular internal trapping.

Methods: We included patients with giant or large unruptured intracranial carotid artery aneurysms treated with PAO using endovascular internal trapping between January 2002 and March 2015 who were followed up for more than 12 months using magnetic resonance angiography or digital subtraction angiography.

Results: Thirty patients were included (median age, 64 years [interquartile range [IQR], 57–70 years], 93% women). The median time to diagnosis was 130 months (IQR, 94–163 months). The median maximum diameter of the aneurysms treated with PAO was 25 mm (IQR, 20–32 mm). Seven patients had nine coexistent aneurysms, including two with enlargement. Additionally, two de novo aneurysms were identified. Enlarged coexistent aneurysms were detected in the posterior communicating and cavernous segments of the contralateral internal carotid artery at 14 and 110 months post-PAO, respectively. Two de novo aneurysms were detected at the paraclinoid segment of the contralateral internal carotid artery and ipsilateral posterior cerebral artery at 50 and 91 months post-PAO, respectively. Four patients with enlarged coexistent or de novo aneurysms were significantly younger at the time of PAO (44 vs. 66 years, p=0.01).

Conclusions: Younger age is a risk factor for coexistent aneurysm enlargement or de novo aneurysm formation post-PAO. Therefore, careful follow-up is necessary, especially in younger patients.

Introduction: Arteriosclerosis in the intracranial internal carotid artery (iIC) must be evaluated during aneurysm neck clipping for internal carotid artery-posterior communicating artery aneurysm (IC-PC An), when we control the proximal artery to the aneurysm. Here, we investigated the usefulness of iIC by the MRI contrast-enhanced motion-sensitized driven equilibrium (CE-MSDE). Method: We enrolled 12 patients (mean age, 63.0±12.3 years; range, 32–78 years) who underwent neck clipping for IC-PC An from January 2019 to March 2023. Of them, 10 were unruptured cases and 2 were impending ruptured cases. The average size of the aneurysm was 7.2±2.2 mm, the average distance from the anterior clinoid process to the proximal neck of the aneurysm was 4.4 mm, and the average surgical time was 5 hours and 10 minutes. We performed preoperative computed tomography (CT) angiography, MRI, and CE-MSDE. The results were retrospectively compared and evaluated its usefulness.

Results: Six patients had atherosclerotic changes in iIC intraoperatively (50.0%); one (16.7%) had calcification on CT, and all six had positive findings on CE-MSDE on iIC. In the six patients (50.0%), no arteriosclerotic changes were observed in the iIC during surgery. Of them, one (16.7%) showed calcification on CT, and none were CE-MSDE-positive. The sensitivity and specificity of iIC for predicting arteriosclerosis were 16.7% and 83.3% for CT, whereas for CE-MSDE, both were 100%.

Conclusion: MRI CE-MSDE could be a predictor of atherosclerosis changes in iIC. When we consider the surgical strategies for IC-PC An, CE-MSDE should be confirmed preoperatively.

Despite being classified as a high Spetzler & Martin grade, therapeutic intervention is indicated for arteriovenous malformations (AVMs) with a history of bleeding due to their high rebleeding rate. A combination of surgical resection and endovascular therapy is most effective to treat high-grade AVM. However, the corresponding strategy must be designed in a way that ensures procedural risks are minimized. When endovascular procedures are combined, avoiding complications and maximizing surgical safety should be prioritized. To achieve this goal, injecting excessive embolic materials into the nidus should be avoided, as well as aggressive embolization of associated aneurysms and deep feeders. In contrast, intraoperative angiography is crucial for assessing blood flow and identifying residual nidus.

Background: The precise prevalence of in-hospital ischemic stroke (IHIS) may vary among healthcare institutions, but it is universally recognized as a significant concern within medical care settings. Patients with IHIS exhibit severe clinical comorbidities, such as chronic heart failure or active cancer. We aimed to investigate the clinical characteristics and outcome indicators among patients with IHIS using a multicenter stroke registry (The Hiroshima Acute Stroke Retrospective and Prospective Registry Study: HARP study) in Hiroshima city, Japan.

Methods: Patients with consecutive acute ischemic stroke within 7 days of stroke onset were enrolled in five primary stroke centers in Hiroshima city from July 2020 to March 2022. The patients were categorized into two groups: those with IHIS and those with community-onset ischemic stroke (COIS). Stroke outcomes, namely a 3-month modified Rankin Scale score (mRS) indicative of poor functional outcome (mRS score of 3–6), were assessed.

Results: Of the 2,470 patients with consecutive acute ischemic stroke, 103 (4.2%) were categorized into the IHIS group. The patients with IHIS had higher prevalence of diabetes mellitus (p=0.004), atrial fibrillation (p=0.025), coronary heart disease (p=0.007), chronic heart failure (p＜0.001), and hemodialysis (p=0.024) than did those with COIS. The patients with IHIS exhibited severe neurological deficits at stroke onset compared with those with COIS (median 7 vs. 3, p＜0.001). Of the 2,470 patients, 385 (15.6%) had reperfusion therapy (intravenous thrombolysis or/and endovascular therapy). The rates of reperfusion therapy were higher among those with IHIS than among those with COIS (35.9% vs. 14.7%, p＜0.001). For the 1,210 patients with premorbid mRS 0–2, multivariable analysis revealed that the presence of IHIS was independently associated with poor stroke outcomes after adjusting for several confounding factors (odds ratio: 2.20, 95% CI: 1.05–4.62).

Conclusion: IHIS cases often involve severe comorbidities and neurological conditions, and reperfusion procedures are frequently necessary. The clinical outcomes of IHIS tend to be unfavorable.

During clipping of an unruptured, right middle cerebral artery aneurysm in a 58-year-old woman, motor-evoked potential (MEP) findings were inconsistent with intraoperative indocyanine green (ICG) fluorescence angiography and Doppler results. After the first clipping, the MEP disappeared but the ICG and Doppler results appeared normal. As a result, a decision was made to perform cranial closure on the patient. Recognizing these discrepancies, the medical team shared the information and the anesthesiologist suspected left hemiparesis during the wake-up test. The anesthesiologist promptly adjusted the anesthetic depth, following which, the neurosurgeons performed a repeat craniotomy to remove the clip, resulting in normalization of the MEP. Reorienting the clip resolved the aneurysm and rectified the abnormal monitoring findings. The patient was then discharged without complications. This case highlights the possible challenges when subjective ICG and Doppler evaluations take precedence over objective MEP evaluations. To prevent complications, it is crucial to not only utilize various monitoring methods, but also share results across the medical team to implement appropriate treatments.

Reversible cerebral vasoconstriction syndrome (RCVS) is a group of disorders characterized by a thunderclap headache and reversible multifocal and segmental arterial constriction that resolve within 3 months. Here we report a case of suspected RCVS that developed after the surgical clipping of an unruptured aneurysm. The patient was a 61-year-old woman with no history of hypertension, migraines, or smoking. A 5-mm unruptured anterior communicating artery aneurysm was discovered incidentally for which surgical clipping was performed using the left pterional approach. The patient's postoperative course was uneventful, but she presented with a thunderclap headache and mild aphasia on the 8th postoperative day. Magnetic resonance imaging (MRI) revealed a slight left frontal cortical subarachnoid hemorrhage, while magnetic resonance angiography (MRA) revealed vasospasms of the bilateral middle cerebral arteries and the left anterior cerebral artery consistent with RCVS. The vasospasms were treated with hypervolemia and calcium channel blockers. At 2 weeks after symptom onset, MRA demonstrated alleviation of the vasospasms accompanied by progressive improvement in the patient's headache and aphasia. Although MRI revealed small infarcts in the insula, the patient was discharged without neurological deficits. This case demonstrates that RCVS may occur despite the surgical clipping of an unruptured aneurysm. Although early detection and prompt treatment are important for RCVS, its exact pathophysiology remains unknown. Further experimental and clinical studies are needed to better understand its pathophysiology.

Giant thrombosed internal carotid artery (ICA) aneurysms are difficult to treat with neck clipping or aneurysmal coiling. Parent artery occlusion (PAO) of the ICA is an alternative treatment that requires a balloon test occlusion (BTO) to evaluate the ischemic tolerance and need for various types of bypass surgeries. However, the BTO evaluation methods vary according to the facility, and no guidelines are available. The indication for revascularization is important when selecting the necessary bypass surgery using multimodality evaluation with BTO before the treatment of cerebral aneurysms requiring PAO.