Moyamoya disease (MMD) is a chronic occlusive cerebrovascular disease which is characterized by the progressive stenosis at the internal carotid artery terminus and abnormal vascular network formation at the base of the brain. Although its etiology is still unknown, increasing evidence suggest the importance of the characteristic genetic variant of RNF213 p.R4810K polymorphism in its clinical presentation such as the early onset-age and/or clinical severity of MMD. More recently, MMD patients with RNF213 variant are shown to develop more neovascular pial synangiosis derived from encephalo-myo-synangiosis after combined revascularization surgery compared to non-variant patients, either in children or in adults. Alternatively, MMD patients with RNF213 variant are known to have potentially higher risk for delayed/prolonged cerebral hyperperfusion after combined revascularization surgery. The exact mechanism underlying such characteristic postoperative pathophysiology in RNF213 variant patients is undetermined, while modern high resolution magnetic resonance imaging vessel wall imaging studies may give clues to this mechanism by exploring the enhanced negative remodeling (medial layer thinness and outer diameter narrowing) of the intracranial arteries in MMD patients with RNF213 variant.

In recent years, the integration of high-resolution medical imaging with computational fluid dynamics (CFD) and computational structural mechanics (CSM) has allowed for the clinical application of various preoperative simulation techniques. This has enhanced the precision and efficacy of neurosurgical procedures. For coil embolization procedures, these advancements not only help to determine the ideal microcatheter position and coil selection but also enable the simulation of stent-assisted coil embolization. This includes the selection of stent size and deployment location. Similarly, for flow-diverter stent placement, these techniques allow the prediction of postimplantation elongation and contraction specific to braided stents, therefore enabling the development of highly accurate treatment strategies. Furthermore, using three-dimensional (3D) printing models for simulation has proven valuable in tailoring preoperative simulations and hands-on training for procedures involving intracranial stents and the Woven EndoBridge device. These simulation technologies may help to predict aneurysm rupture and guide retreatment decisions, as well as enable treatment planning program design through integration with artificial intelligence. The continued use of CFD, CSM, and 3D printing technologies in fields such as device training and treatment outcome prediction is expected to evolve and synergy between medicine and engineering is pivotal in this process. However, regulatory approval and appropriate commercialization strategies for software programs and 3D printers face challenges that must be addressed soon to fully harness the potential of innovative technologies for clinical practice and patient care.

Progressive worsening of atherosclerotic intracranial arterial stenosis is difficult to manage. When atherosclerotic plaques are severe and unstable, expansion using endovascular methods is unsafe. To restore hemodynamic insufficiency, placing a distal bypass without irritating the unstable plaques may be safer. We present seven cases of progressive atherosclerotic middle cerebral artery (MCA) stenosis treated with consecutive superficial temporal artery (STA)–MCA double-bypass. In all cases, mid- to long-term bypass patency without post-operative infarction was confirmed using MRA. Meticulous STA donor preparation and precise approximation of the intima of both donor and recipient during anastomosis are key.

Arteriovenous malformations (AVMs) are one of the cerebrovascular diseases that have benefited from advances in endovascular embolization and diagnostic equipment. At our institution, AVM treatment primarily involves surgical resection, and its evolution is reviewed in the current issue. We retrospectively assessed the progress and changes in AVM treatment strategies by comparing data between two time-periods: from the first half (before 2014, 30 cases) and the second half (after 2015, 35 cases). Cerebral hemorrhage occurred in 23 and 30 patients in the first and second halves, respectively. Although there was a higher proportion of cases in the second half, the difference was not statistically significant. Preoperative embolization was performed in 9 cases in the first half and 24 cases in the second half, showing a significant increase in the latter period. The proportion of high-grade cases (Grade 3 or higher) was significantly higher in the second half of the study period, indicating an increase in more challenging cases. A significantly higher number of cases were monitored in the second half. Treatment outcomes for eight cases of morbidity and one case of mortality were compared, with no significant difference between the first and second halves Multivariate analysis of the factors involved in morbidity and mortality risk indicated age (odds ratio 0.943, p=0.033) and high grade of AVM (odds ratio 16.728, p=0.006) to be significant factors. With increasing number of high-grade cases, surgical treatment with aggressive embolization and monitoring is becoming increasingly common. However, some cerebral hemorrhages have occurred after embolization, and the treatment protocol for staged embolization should be reconsidered. The treatment strategy now focuses more on brain function, and the safe and reliable resection of ruptured low-grade AVMs remains stable. However, the multimodal treatment for high-grade cases needs further improvement.

Seizures are observed in 6–30% of patients after subarachnoid hemorrhage (SAH) and are associated with poor functional outcomes; however, the use of prophylactic anti-seizure medications (ASM) for SAH is controversial. Between 2015 and 2020, 190 patients with SAH were treated at our hospital. We retrospectively surveyed the current ASM prescription practices, incidence of seizures, and risk factors for seizures in patients after SAH. The clinical variables were compared based on their association with the occurrence of seizures. Seizures occurred in 40 patients (21.1%) and were correlated with a higher WFNS grade, clipping, intracranial hematoma, middle cerebral aneurysm, and delayed cerebral ischemia. The timing of seizures was as follows: onset seizure (OS) in 5 patients, early seizures (ES) in 13 patients, ES and delayed seizures (LS) in 9 patients, and only LS in 13 patients. Twelve patients (51.9 %) with OS or ES developed LS, and prophylactic ASM was administered to 47 (25.4 %) patients. Levetiracetam was the most widely used ASM, and no patient discontinued treatment owing to ASM-induced side effects within one month of onset. For patients with SAH who are judged to be at a high risk of seizures, the prophylactic use of new-generation ASM seemed acceptable. Additionally, patients had a relatively high rate of symptomatic epilepsy if they experienced seizures, even in the acute phase.

Objective: Stereotactic radiosurgery (SRS) is a minimally invasive treatment option for intracranial dural arteriovenous fistulas (DAVF). To further improve radiosurgical outcomes, we started integrating high spatial resolution images obtained by 3-dimensional rotational angiography (3DRA) into SRS (3DRA-SRS) for DAVF in 2015. This study aimed to validate its efficacy in comparison to that of MRI-based conventional SRS (c-SRS). Methods: Sixty-five patients who underwent SRS for DAVF at our hospital between June 1990 and May 2023 were retrospectively enrolled. The primary outcome was DAVF obliteration, and the secondary outcomes included post-SRS hemorrhage, symptom improvement, and adverse radiation events. Results: 3DRA-SRS was performed in 30 patients and c-SRS in 35 underwent c-SRS. The cumulative DAVF obliteration rates in the 3DRA-SRS group were significantly higher than those in the c-SRS group (72% vs. 31% at 2 years and 83% vs. 69% at 5 years; log-rank test; p = 0.010). Multivariable Cox proportional hazard analysis showed 3DRA-SRS was significantly associated with higher DAVF obliteration rate (hazard ratio [HR] 2.09, 95% confidence interval [CI] 1.09–4.00, p = 0.026), and absence of CVR was marginally associated (HR 1.90, 95% CI 0.99–3.63, p = 0.053). Additionally, the cumulative hemorrhagic stroke-free survival was 96% over 10 years in the entire cohort, with no significant difference between the two groups. The cumulative symptom improvement rates in the 3DRA-SRS group were significantly higher than those in the c-SRS group (80% vs. 39% at one year and 100% vs. 54% at two years, respectively; log-rank test; p = 0.002). Conclusions: 3DRA-SRS provides better radiosurgical outcomes for DAVF. Further research is required to confirm these long-term benefits.

In Moyamoya disease, cortical venous reddening (CVR) is occasionally observed immediately after direct revascularization and is thought to reflect an increase in cerebral blood flow. However, whether CVR is also observed in superficial temporal artery-middle cerebral artery anastomosis (STA-MCA bypass) for atherosclerotic steno-occlusive lesions has not been fully studied. We retro-spectively reviewed 29 patients who underwent STA-MCA bypass for symptomatic internal carotid artery, middle cerebral artery occlusion, or stenosis secondary to atherosclerosis at our institution between June 2019 and May 2023. Twenty-nine patients (21 males, median age 69 years) were divided into a CVR group (3 patients) and a non-CVR group (26 patients), and their backgrounds and outcomes were examined. No significant differences were observed in age, sex, atherosclerotic factors, cardiac disease, renal function, clinical presentation, bypass patency rate, or pre-and postoperative modified Rankin Scale scores between the two groups. The incidence of postoperative hyperperfusion syndrome (two patients [67%] in the CVR group and two patients [7.7%] in the non-CVR group, p=0.042) and cerebral infarction (three [100%] patients in the CVR group and one [3.8%] in the non-CVR group, p=0.001) was significantly higher in the CVR group. All patients in the CVR group had cerebral infarction in areas distant from the craniotomy field (remote infarction). However, none of the patients in the non-CVR group had remote infarction (3 [100%] in the CVR group and 0 [0%] in the non-CVR group, p<0.001). These results suggest a relationship between the occurrence of CVR and postoperative remote infarction after STA-MCA bypass for atherosclerotic lesions. In conclusion, the CVR may be an important predictor of remote infarction after STA-MCA bypass in atherosclerotic lesions.

Sufficient evidence has not yet been established for mechanical thrombectomy in middle cerebral artery M2 segment occlusion, unlike in the case of M1 occlusion. This study aimed to compare the treatment results of M2 and M1 segment occlusions in our cases. We retrospectively investigated cases in which mechanical thrombectomy was performed for occlusion of the middle cerebral artery segments M1 and M2 from July 2014 to April 2021. They were divided into cases with M1 segment occlusion (M1 group) and cases with M2 segment occlusion (M2 group), and patient background, preoperative NIHSS, use of rt-PA, treatment time, recanalization rate as TICI score, frequency of intracranial hemorrhage, and modified Rankin scale (mRS) after 3 months were compared. In addition, factors contributing to an mRS 3-6 after three months were examined using logistic regression analysis. During the study period, 128 patients (mean age 75.9 years, male 52.3%) were enrolled in this study, the M1 group was 86 cases (67.1%) in the M2 group and 42 (32.9%). There was no difference in age between the two groups, and the patients in the M2 group were older (74.5 years vs. 78.7 years, P = 0.03). Onset to recanalization time (259.5 minutes vs 235.5 minutes; P = 0.25), recanalization rate (TICI 2b ≤; 89.5% vs 83.3%; P = 0.4) and hemorrhagic transformation (34.9% vs 28.6%; P = 0.24) were no difference. In multivariate analysis, age (OR 1.08, 95% CI 1.03 – 1.13; P<0.01), preoperative mRS (OR 3.53, 95% CI 1.84 – 6.78; P<0.01), hemorrhagic transformation (OR 7.62, 95% CI 2.51 – 23.20; P<0.01) were associated with mRS 3-6 after 3 months and the occlusion arteries were not associated. In mechanical thrombectomy for M2 segment occlusion, the recanalization rate and hemorrhagic complications are equivalent to M1 segment occlusion. In the multivariate analysis, the difference in occluded arteries was not associated with poor prognosis. According to our results, mechanical thrombectomy for M2 segment occlusion appears to be a useful treatment option.

Introduction: We investigated the value of low-cost screening for patients at risk for stroke, cerebral aneurysm, or carotid stenosis who need lifestyle improvements. Methods: We created a pamphlet to raise awareness among people with risk factors for cerebral aneurysm and carotid artery stenosis. The pamphlet was distributed to small organizations, such as nursing departments, and was publicized in local newspapers. Candidate patients underwent magnetic resonance imaging and carotid ultrasonography. We investigated risk factors, imaging abnormalities, surgical interventions, and lifestyle improvements among these patients. Results: 1: No patients had received a brain dock within the last 5 years. Overall, women received approximately twice as many screenings as men. Many individuals with hypertension and dyslipidemia were screened. 2: Twelve percent of screened patients had image abnormalities, and screening for cerebral aneurysm and carotid artery stenosis led to four surgical interventions (1.2%) in three patients, all of whom were restored to their pretreatment quality of life. 3: One stroke (0.24% per year) occurred during follow-up. This patient had uncontrolled diabetes and was a smoker. Conclusion: Imaging abnormalities discovered via low-cost cerebral aneurysm and carotid artery stenosis screening effectively identify critical health risk factors. It is thus necessary to increase patient screening to reduce the complication rate associated with surgical interventions. Precise risk factor control information to at risk patients is important.

Background: Direct surgery for recurrent aneurysms after coil embolization or clipping is difficult owing to various factors, such as adhesions to surrounding structures, fragility of the aneurysm wall, and mobility of previous coils or clips. Here, we report the surgical strategies and results for recurrent aneurysms after coil embolization or clipping.

Patients and methods: Sixteen patients with recurrent aneurysms, with a median age of 64 years (range, 46–80 years; seven females), were surgically treated between April 2012 and March 2019. The treatment results and clinical outcomes at six months were retrospectively analyzed.

Results: Among the aneurysms, 3 (19%), 4 (25%), 4 (25%), and 5 (31%) originated from the anterior, middle, internal carotid, and posterior circulation, respectively. Presentations at initial treatment included subarachnoid hemorrhage (SAH) in 14 (88%) cases and oculomotor nerve palsy in two (13%) cases. Presentations at retreatment were SAH in 5 (31%) cases, mass effect in 2 (13%) cases, and asymptomatic in 9 (56%) cases. The average period between the initial and final treatments was 52 (1–192) months. Surgical retreatment was performed using clipping in 11 cases (69%) and trapping of the aneurysm combined with extracranial-intracranial bypass in 5 (31%) cases. In three cases, the previous clip was removed; in two cases, the previous coil was partially removed; however, there were no cases in which the previous coil was completely removed. The elimination of blood flow into the aneurysm was confirmed in all patients after treatment. At 6 months, the modified Rankin scale score improved in 2 (13%) cases, remained unchanged in 13 (81%) cases, and worsened in 1 (6%) case.

Conclusions: In direct surgery for recurrent aneurysms, simple clipping can be performed without directly manipulating the aneurysm wall, which is weakened by inflammation around the coil or clip. However, since curability is strongly required in retreatment, aggressive treatment such as deconstructive methods or removal of the initial clip should be performed as needed, and it is important to make an accurate intraoperative judgment and prepare in advance.

Takotsubo cardiomyopathy (TTC) is a cardiac dysfunction with uncertain pathophysiology. Approximately 1.2% of subarachnoid hemorrhage (SAH) cases are associated with TTC. Due to cardiac dysfunction, surgical and medical treatment of SAH in the acute phase is often difficult. Clazosentan (CLZ) is a newly approved drug for treating delayed cerebral vasospasm. Fluid retention is a serious secondary effect of CLZ, and it is uncertain whether CLZ is useful and safe in patients with complications that cause heart failure, such as TTC.

Here, we report a case of SAH associated with TTC treated with CLZ and discuss the safety and efficacy of CLZ for TTC following SAH.

The patient was a 79-year-old woman transported to our hospital with impaired consciousness. She was diagnosed with SAH due to rupture of a right middle cerebral artery bifurcation aneurysm. Transient cardiac dysfunction caused by TTC was also observed. After conservative treatment, her cardiac function improved, and neck clipping was performed on the third day. We began CLZ administration on the fifth day. No delayed cerebral vasospasm or cardiac failure was observed, and CLZ was discontinued on the 15th day. Furthermore, no deficits were observed. However, because of disuse syndrome, the patient was transferred to a different hospital for rehabilitation at an modified Rankin Scale score of 2.

Due to the surgery and CLZ administration after the improvement of cardiac function, as well as fluid balance management, CLZ use was deemed safe in this case.