ARISE I Consensus Review on the Management of Intracranial Aneurysms.

BACKGROUND: Intracranial aneurysms (IAs) remain a challenging neurological diagnosis associated with significant morbidity and mortality. There is a plethora of microsurgical and endovascular techniques for the treatment of both ruptured and unruptured aneurysms. There is no definitive consensus as to the best treatment option for this cerebrovascular pathology. The Aneurysm, Arteriovenous Malformation, and Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts discussed best practices and the most promising approaches to improve the management of brain aneurysms. METHODS: A group of experts from academia, industry, and federal regulators convened to discuss updated clinical trials, scientific research on preclinical system models, management options, screening and monitoring, and promising novel device technologies, aiming to improve the outcomes of patients with IA. RESULTS: Aneurysm, Arteriovenous Malformation, and Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts suggested the incorporation of artificial intelligence to capture sequential aneurysm growth, identify predictors of rupture, and predict the risk of rupture to guide treatment options. The consensus strongly recommended nationwide systemic data collection of unruptured IA radiographic images for the analysis and development of machine learning algorithms for rupture risk. The consensus supported centers of excellence for preclinical multicenter trials in areas such as genetics, cellular composition, and radiogenomics. Optical coherence tomography and magnetic resonance imaging contrast-enhanced 3T vessel wall imaging are promising technologies; however, more data are needed to define their role in IA management. Ruptured aneurysms are best managed at large volume centers, which should include comprehensive patient management with expertise in microsurgery, endovascular surgery, neurology, and neurocritical care. CONCLUSIONS: Clinical and preclinical studies and scientific research on IA should engage high-volume centers and be conducted in multicenter collaborative efforts. The future of IA diagnosis and monitoring could be enhanced by the incorporation of artificial intelligence and national radiographic and biologic registries. A collaborative effort between academic centers, government regulators, and the device industry is paramount for the adequate management of IA and the advancement of the field.

Gadolinium-enhanced intracranial aneurysm wall imaging and risk of aneurysm growth and rupture: a multicentre longitudinal cohort study.

OBJECTIVES: In patients with an unruptured intracranial aneurysm, gadolinium enhancement of the aneurysm wall is associated with growth and rupture. However, most previous studies did not have a longitudinal design and did not adjust for aneurysm size, which is the main predictor of aneurysm instability and the most important determinant of wall enhancement. We investigated whether aneurysm wall enhancement predicts aneurysm growth and rupture during follow-up and whether the predictive value was independent of aneurysm size. MATERIALS AND METHODS: In this multicentre longitudinal cohort study, individual patient data were obtained from twelve international cohorts. Inclusion criteria were as follows: 18 years or older with ≥ 1 untreated unruptured intracranial aneurysm < 15 mm; gadolinium-enhanced aneurysm wall imaging and MRA at baseline; and MRA or rupture during follow-up. Patients were included between November 2012 and November 2019. We calculated crude hazard ratios with 95%CI of aneurysm wall enhancement for growth (≥ 1 mm increase) or rupture and adjusted for aneurysm size. RESULTS: In 455 patients (mean age (SD), 60 (13) years; 323 (71%) women) with 559 aneurysms, growth or rupture occurred in 13/194 (6.7%) aneurysms with wall enhancement and in 9/365 (2.5%) aneurysms without enhancement (crude hazard ratio 3.1 [95%CI: 1.3-7.4], adjusted hazard ratio 1.4 [95%CI: 0.5-3.7]) with a median follow-up duration of 1.2 years. CONCLUSIONS: Gadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not independent of aneurysm size. CLINICAL RELEVANCE STATEMENT: Gadolinium-enhanced aneurysm wall imaging is not recommended for short-term prediction of growth and rupture, since it appears to have no additional value to conventional predictors. KEY POINTS: • Although aneurysm wall enhancement is associated with aneurysm instability in cross-sectional studies, it remains unknown whether it predicts risk of aneurysm growth or rupture in longitudinal studies. • Gadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not when adjusting for aneurysm size. • While gadolinium-enhanced aneurysm wall imaging is not recommended for short-term prediction of growth and rupture, it may hold potential for aneurysms smaller than 7 mm.

Persistent intracranial hyper-inflammation in ruptured cerebral aneurysm after COVID-19: case report and review of the literature.

BACKGROUND: The systemic manifestations of coronavirus disease 2019 (COVID-19) include hyperinflammatory reactions in various organs. Recent studies showed evidence for the frequent involvement of central nervous system in affected patients; however, little is known about clinical features of cerebrovascular diseases in childhood-onset COVID-19. CASE PRESENTATION: A 10-year-old boy recovered from SARS-CoV-2 infection without complication. On 14 days after infection, he presented with loss of consciousness. A head computed tomography detected a ruptured cerebral aneurysm at the left posterior cerebral artery accompanying subarachnoid hemorrhage (SAH). Immediate surgical intervention did not rescue the patient, resulting in the demise 7 days after admission. Serological and genetic tests excluded the diagnosis of vasculitis and connective tissue disorders. Retrospective analysis showed markedly higher levels of interleukin (IL)-1ß, IL-6 and IL-8 in the cerebrospinal fluid than the serum sample concurrently obtained. A review of literature indicated that adult patients with COVID-19 have a risk for the later development of SAH during the convalescent phase of COVID-19. CONCLUSIONS: SAH is a severe complication of COVID-19 in children and adults who have asymptomatic cerebrovascular aneurysms. The markedly high levels of cytokines detected in the cerebrospinal fluid suggested that intracranial hyperinflammatory condition might be one of the possible mechanisms involved in the rupture of a preexisting cerebrovascular aneurysms.

Study on prognosis of acutely ruptured intracranial aneurysms (SPARTA): a protocol for a multicentre prospective cohort study.

BACKGROUND: Ruptured intracranial aneurysms resulting in subarachnoid haemorrhage can be treated by open surgical or endovascular treatment. Despite multiple previous studies, uncertainties on the optimal treatment practice still exists. The resulting treatment variation may result in a variable, potentially worse, patient outcome. To better inform future treatment strategies, this study aims to identify the effectiveness of different treatment strategies in patients with ruptured intracranial aneurysms by investigating long-term functional outcome, complications and cost-effectiveness. An explorative analysis of the diagnostic and prognostic value of radiological imaging will also be performed. METHODS: This multi-centre observational prospective cohort study will have a follow-up of 10 years. A total of 880 adult patients with a subarachnoid haemorrhage caused by a ruptured intracranial aneurysm will be included. Calculation of sample size (N = 880) was performed to show non-inferiority of clip-reconstruction compared to endovascular treatment on 1 year outcome, assessed by using the ordinal modified Rankin Scale. The primary endpoint is the modified Rankin Scale score and mortality at 1 year after the initial subarachnoid haemorrhage. Patients will receive 'non-experimental' regular care during their hospital stay. For this study, health questionnaires and functional outcome will be assessed at baseline, before discharge and at follow-up visits. DISCUSSION: Despite the major healthcare and societal burden, the optimal treatment strategy for patients with subarachnoid haemorrhage caused by ruptured intracranial aneurysms is yet to be determined. Findings of this comparative effectiveness study, in which in-between centre variation in practice and patient outcome are investigated, will provide evidence on the effectiveness of treatment strategies, hopefully contributing to future high value treatment standardisation. TRIAL REGISTRATION NUMBER: NCT05851989 DATE OF REGISTRATION: May 10th, 2023.

Infectious endocarditis complicated with intracranial infected aneurysm rupture and sinus of valsalva aneurysm rupture.

BACKGROUND: Infectious endocarditis (IE) is an infectious disease caused by direct invasion of the heart valve, endocardium, or adjacent large artery endocardium by pathogenic microorganisms. Despite its relatively low incidence, it has a poor prognosis and a high mortality. Intracranial infectious aneurysms (IIA) and ruptured sinus of Valsalva aneurysm (RSVA) are rare complications of IE. CASE PRESENTATION: We report a young male patient with symptoms of respiratory tract infection, heart murmurs and other symptoms and signs. The patient also had kidney function impairment and poor response to symptomatic therapy. Blood culture was negative, but echocardiography was positive, which met the diagnostic criteria for infective endocarditis. Moreover, an echocardiography showed a ruptured sinus of Valsalva aneurysm with a ventricular septal defect. Finally, secondary rupture of an IIA with multiple organ damage led to a poor clinical outcome. CONCLUSION: Therefore, in the clinical setting, for young patients with unexplained fever, chest pain, or palpitations, we need to be highly vigilant, considering the possibility of infective endocarditis and promptly performing blood culture, echocardiography, cerebrovascular imaging and so on, in order to facilitate early proper diagnosis and treatment.

Bifurcation dissecting aneurysm: tips and tricks to differentiate from saccular aneurysm.

Bifurcations are a common site for saccular aneurysms, but rarely can be a site for dissecting aneurysms. Identification of these aneurysms is extremely important because the management plan depends on it. We describe a rare case of a ruptured dissecting aneurysm at the right ICA bifurcation in a pre-teen child which posed a diagnostic dilemma but ultimately was successfully managed with flow diversion.

Clinical and radiological features associated with rupture of pulmonary artery pseudoaneurysm: a retrospective study.

BACKGROUND: Hemoptysis resulting from rupture of the pulmonary artery pseudoaneurysm (PAP) is massive and fatal, while factor contributing to the rupture of pseudoaneurysm remains elusive. This study aimed to elucidate the clinical and radiological features of PAP and identify the risk factors associated with rupture. METHODS: Patients who developed hemoptysis with PAP were collected from January 2019 to December 2022 retrospectively. Clinical data of the demographic characteristics, radiological findings, treatment strategies, and prognosis were collected. A comparative analysis was performed on the characteristics in the ruptured and non-ruptured cases. RESULTS: A total of 58 PAPs were identified in the 50 patients. The most common causes were infection (86%) and cancer (8%). The PAPs were located predominantly in the upper lobes of both lungs, and 57 (99.3%) were distributed in the segmental or subsegmental pulmonary arteries. The median diameter was 6.1(4.3-8.7) mm. A total of 29 PAPs were identified adjacent to pulmonary cavitations, with the median diameter of the cavity being 18.9 (12.4-34.8) mm. Rupture of pseudoaneurysm occurred in 21 cases (42%). Compared to unruptured group, the ruptured group had a significantly higher proportion of massive hemoptysis (57.1% vs. 6.9%, p < 0.001), larger pseudoaneurysm diameter (8.1 ± 3.2 mm vs. 6.0 ± 2.3 mm, p = 0.012), higher incidence of pulmonary cavitation (76.2% vs. 44.8%, p = 0.027), and larger cavitation diameters (32.9 ± 18.8 mm vs. 15.7 ± 8.4 mm, p = 0.005). The mean pulmonary artery pressure (mPAP) in the ruptured group was also significantly higher than that in the unruptured group [23.9 ± 7.4 mmHg vs. 19.2 ± 5.0 mmHg, p = 0.011]. Endovascular treatment was successfully performed in all 21 patients with ruptured PAP, of which the clinical success rate was 96.0%. Five patients experienced recurrent hemoptysis within one year. CONCLUSIONS: Massive hemoptysis, pseudoaneurysm diameter, pulmonary cavitation, and elevated mPAP were the risk factors for rupture of pseudoaneurysm. Our findings facilitate early identification and timely intervention of PAP at high risk of rupture.

Internal carotid artery-persistent primitive anterior choroidal artery aneurysms: report of two cases and literature review.

PURPOSE: Persistent primitive anterior choroidal artery (PPAChA) is a rare vascular anomaly. The clinical course of internal carotid artery (ICA)-PPAChA aneurysms has not been well described. CASE REPORTS: We report two patients with an ICA-PPChA aneurysm and summarize previously reported cases. RESULTS: Including our two, a total of 10 patients with an ICA-PPAChA aneurysm have been reported. Data were not described for one. Among the remaining nine, five patients (56%) experienced aneurysmal rupture. Five patients underwent surgical clipping and four underwent endovascular coiling. The procedure was completed in all but one patient who had a tiny branch artery adherent to the aneurysm; this patient was converted from clipping to aneurysm coating with a cotton sheet. Among the other eight patients, one who underwent coiling experienced an internal capsule infarction. The remaining seven had a satisfactory postoperative course; however, an asymptomatic occlusion of the PPAChA at its origin was noted on postoperative angiography in one. CONCLUSION: PPChA is associated with a high incidence of aneurysm formation and rupture. During treatment of ICA-PPAChA aneurysms, obstruction of the PPAChA and any surrounding perforating arteries should be avoided to prevent ischemic stroke.

Spontaneous occlusion of ruptured microaneurysm formed on postoperative transosseous anastomosis after indirect revascularization in a patient with moyamoya disease.

A 40-year-old female with a history of ischemic moyamoya disease treated with indirect revascularization at ages 12 and 25 years presented with a sudden severe headache. Imaging studies revealed focal parenchymal hemorrhage and acute subdural hematoma, confirming a microaneurysm formed on the postoperative transosseous vascular network as the source of bleeding. Conservative management was performed, and no hemorrhage recurred during the 6-month follow-up period. Interestingly, follow-up imaging revealed spontaneous occlusion of the microaneurysm. However, due to the rarity of this presentation, the efficacy of conservative treatment remains unclear. Further research on similar cases is warranted.

Surgical repair of torn base of ruptured middle cerebral artery trifurcation aneurysm.

BACKGROUND: Treating complex middle cerebral artery (MCA) trifurcation aneurysms requires a delicate balance between achieving aneurysm obliteration and preserving vascular integrity. Various cerebral revascularization techniques, including bypass, and clip reconstruction are considered individually or in combination. METHODS: This case report outlines a successful repair of a ruptured neck and base of MCA trifurcation aneurysm using a suturing-clip reconstruction technique. Temporary aneurysm trapping was implemented, with maintained elevated blood pressure to ensure collateral perfusion during repair of ruptured base and neck of MCA aneurysm. CONCLUSION: The suturing-clip reconstruction exhibited long-term radiological stability, emerging as a valuable alternative for managing challenging MCA trifurcation aneurysms.

Ruptured aneurysm in collateral arteries with blood-flow impairment of posterior inferior cerebellar artery: a report of three cases.

Herein, we report three cases of cerebellar hemorrhage due to a ruptured small aneurysm located on a collateral artery compensating for one or more stenotic or occluded major cerebellar arteries. In each case, endovascular distant parent artery occlusion of both the collateral artery and aneurysm was performed to prevent rebleeding. A ruptured small aneurysm in a collateral artery may be observed in patients with hemorrhage in an atypical cerebellar region, especially in cases of stenosis or occlusion of the vertebral artery or posterior inferior cerebellar artery. Thus, cerebral angiography is recommended to rule out collateral artery aneurysm.

Basilar artery perforator aneurysms: a comparison with non-perforator saccular aneurysms.

BACKGROUND: Basilar artery perforator aneurysms (BAPAs) are rare. There is no systematic description of their presentation, imaging, natural history and outcomes and how these compare to conventional non-perforator aneurysms. Thus, the authors in this study aimed to compare BAPAs to non-perforator aneurysms. METHODS: Cases were identified from a prospective neurovascular database, notes and imaging retrospectively reviewed and compared to a consecutive series of patients with non-perforator aneurysms. Blood volume on CT and vessel wall imaging (VWI) were compared to controls. RESULTS: 9/739 patients with aneurysmal subarachnoid haemorrhage (aSAH) harboured BAPAs. Compared to 103 with aSAH from posterior circulation aneurysms, they were more likely to be male (6/9, p = 0.008), but of equal severity (4/9 poor grade, p = 0.736) and need of CSF drainage (5/9, p = 0.154). Blood volume was similar to controls (30.2 ml vs 26.7 ml, p = 0.716). 6/9 BAPAs were initially missed on CTA. VWI showed thick (2.9 mm ± 2.7) bright enhancement (stalk ratio 1.05 ± 0.12), similar to controls with ruptured aneurysms (0.95 ± 0.23, p = 0.551), and greater than unruptured aneurysms (0.43 ± 0.11, p < 0.001). All were initially managed conservatively. Six thrombosed spontaneously. Three grew and had difficult access with few good endovascular options and were treated through a subtemporal craniotomy without complication. None rebled. At 3 months, all presenting in poor grade were mRS 3-4 and those in good grade mRS 1-2. CONCLUSIONS: Despite their small size, BAPAs present with similar volume SAH, WFNS grade and hydrocephalus to other aneurysms. They are difficult to identify on CTA but enhance strikingly on VWI. The majority thrombosed. Initial conservative management reserving treatment for growth was associated with no rebleeds or complications.

Hemosuccus pancreaticus - Multidisciplinary therapy for a splenic artery aneurysm, ruptured into the pancreatic duct.

BACKGROUND: Numerous conditions may lead to gastrointestinal bleeding (GIB). Compared with common causes, hemosuccus pancreaticus (HP) is a scarce and potentially life-threatening condition. CASE PRESENTATION: We report the case of a 45-year-old female patient who suffered from hematemesis and subsequent hemorrhagic shock. In repeat esophagogastroduodenoscopies, bleeding from the major duodenal papilla was detected. To stop the acute bleeding, an ERCP was performed, and a plastic stent was inserted into the pancreatic duct (PD). Subsequently, MR and CT scans demonstrated a pseudoaneurysm of the splenic artery (SA) with a fistula to the PD. An interventional therapy approach failed due to a highly twisted course of the SA. Thus, the patient underwent surgery with ligation of the SA. The stent from the PD was removed postoperatively, and the patient recovered well. A histological examination of the SA revealed fibromuscular dysplasia. A lifelong ASA therapy was prescribed, and the patient was discharged on the 14th postoperative day in good condition. CONCLUSION: The diagnosis and treatment of HP might be impeded due to its multiple causes, ambiguous symptoms, and challenging diagnostic verification. Being a potentially life-threatening condition, the knowledge of this rare entity and the provision of multidisciplinary and multimodal therapy are mandatory for the successful treatment of patients with obscure GIB and proven HP.

Follow-up care compliance among patients diagnosed with unruptured intracranial aneurysms.

OBJECTIVES: Periodic imaging follow-up for patients with unruptured intracranial aneurysms (UIA) is crucial, as studies indicate higher rupture risk with aneurysm growth. However, few studies address patient adherence to follow-up recommendations. This study aims to identify compliance rates and factors influencing follow-up adherence. METHODS: Patients with a UIA were identified from our institution's database from 2011-2021. Follow-up imaging (CT/MR Angiogram) was advised at specific intervals. Patients were categorized into compliant and non-compliant groups based on first-year compliance. Factors contributing to compliance were assessed through multivariate logistic regression. Phone interviews were conducted with non-compliant patients to understand reasons for non-adherence. RESULTS: Among 923 UIA diagnosed patients, 337 were randomly selected for analysis. The median follow-up period was 1.4 years, with a 42% first-year compliance rate. The mean aneurysm size was 3.3 mm. Five patients had a rupture during follow-up, of which 4 died. Compared with patients consulting specialists at the initial diagnosis, those seen by non-specialists exhibited lower compliance (OR 0.25, p < 0.001). Loss to follow-up was greatest during transition from emergency service to specialist appointments. Patients who spoke languages other than English exhibited poorer compliance than those speaking English (OR 0.20, p = 0.01). CONCLUSIONS: Significant amounts of UIA patients at low rupture risk were lost to follow-up before seeing UIA specialists. Main non-compliance factors include inadequate comprehension of follow-up instructions, poor care transfer from non-specialists to specialist, and insurance barriers.

Bivalirudin as a substitute for heparin in neurointervention for patients with heparin-induced thrombocytopenia.

OBJECTIVES: Heparin-induced thrombocytopenia is a known complication of heparin exposure with potentially life-threatening sequelae. Direct thrombin inhibitors can be substituted for heparin in patients with heparin-induced thrombocytopenia that require anticoagulation. However, the use of direct thrombin inhibitors as a substitute for heparin has not been widely reported in the neuroendovascular literature. MATERIALS AND METHODS: Here we report the first use of the direct thrombin inhibitor bivalirudin in a neuroendovascular procedure as a substitute for heparin in a patient with a ruptured pseudoaneurysm and heparin-induced thrombocytopenia, and review the literature on the use of bivalirudin and argatroban for such patients. RESULTS: Bivalirudin was safely and effectively used in the case reported, with no thrombotic or hemorrhagic complications. Our literature review revealed a paucity of studies on the use of heparin alternatives, including bivalirudin, in neuroendovascular procedures in patients with heparin-induced thrombocytopenia. CONCLUSIONS: Heparin-induced thrombocytopenia is an important iatrogenic disease process in patients undergoing neuroendovascular procedures, and developing protocols to diagnose and manage heparin-induced thrombocytopenia is important for healthcare systems. While further research needs to be done to establish the full range of anticoagulation options to substitute for heparin, our case indicates bivalirudin as a potential candidate.

Effects of induced arterial hypertension for vasospasm on unruptured and unsecured cerebral aneurysms (growth and rupture). A retrospective case-control study.

OBJECTIVES: Unruptured cerebral aneurysms (UCAs) often coexist with the ruptured one but are typically left unsecured during the weeks following aneurysmal subarachnoid hemorrhage (aSAH). We compared the rate of UCAs rupture or volume growth (≥5 mm3) between patients exposed to induced arterial hypertension (iHTN) for vasospasm and those not exposed (control group). MATERIALS AND METHODS: From 2013 to 2021, we retrospectively included consecutive adult patients with aSAH who had ≥1 UCA. Custom software for digital subtraction angiography (DSA) image analysis characterized UCAs volume, going beyond merely considering UCAs long axis. RESULTS: We analyzed 118 patients (180 UCAs): 45 in the iHTN group (64 UCAs) and 73 in the control group (116 UCAs). Systolic blood pressure in the iHTN group was significantly higher than in the control group for several days after aSAH. During the 107 day-monitoring period [interquartile range(IQR):92;128], no UCA rupture occurred in either group. UCA volume analysis was performed in 44 patients (60 UCAs): none of the UCAs in the iHTN group and 3 out of 42 (7%) in the control group had a >5 mm3 volume growth (p=0.55). Other morphologic parameters did not exhibit any variations that might indicate an increased risk of rupture in the iHTN group compared to the control group. CONCLUSION: iHTN did not increase the risk of rupture or volume growth of UCAs within several weeks following aSAH. These reassuring results encourage not to refrain, because of the existence of UCAs, from iHTN as an option to prevent cerebral infarction during cerebral vasospasm.

[Update on Vessel Wall Imaging of Intracranial Aneurysm].

Intracranial aneurysms occur frequently; however, only a few of these rupture to cause subarachnoid hemorrhage. This presents a dilemma regarding the course of appropriate treatment. In the last decade, the wide utilization of magnetic resonance imaging-based vessel wall imaging(VWI) has facilitated the assessment of aneurysm wall enhancement(AWE), which has garnered significant attention. In 2013, initial reports highlighted that AWE was characteristic of ruptured aneurysms whereas, in 2014, AWE was identified as a characteristic feature of unruptured aneurysms with a high risk of rupture. Several studies have supported these findings since then. VWI, a novel modality that visualizes the inflammation of the aneurysmal wall, is considered highly useful for the diagnosis of aneurysms. This review discusses the key literature on AWE. Long-term prospective studies are warranted to determine whether AWE is an independent risk factor for aneurysmal progression.

[Basic Setup and Coil Embolization Technique for Ruptured Cerebral Aneurysms].

For treating ruptured cerebral aneurysms, it is important to understand the setup and basic technique of coil embolization. Safe and effective embolization relies on preoperative considerations that determine the treatment strategy, guide the optimization of the therapeutic environment, and help in the selection of appropriate device systems. Moreover, during aneurysmal embolization, basic techniques for microcatheter shaping and navigation, safe coil introduction, and precise use of occlusion balloons are indispensable. Microcatheter shaping should be based on three-dimensional digital subtraction angiography findings as well as the axes of the parent artery and aneurysm. The operator must understand the advantages and disadvantages of the two methods for navigating the microcatheter into the aneurysm. Furthermore, it is essential to preoperatively simulate and understand the approaches for managing aneurysmal embolization-related complications, such as intraoperative aneurysmal rupture and thromboembolism. Mastery of these steps is mandatory before undertaking embolization of ruptured cerebral aneurysms.

[Endovascular Treatment Strategies for Ruptured Vertebral Artery Dissecting Aneurysms].

Ruptured vertebral artery dissecting aneurysms(VADA) carry a poor prognosis owing to the high rates of rebleeding, stroke, and mortality without appropriate treatment. Various endovascular techniques are employed to treat these aneurysms. Deconstructive techniques, involving internal trapping with coils, often achieve complete angiographic occlusion at higher rates; however, they carry a risk of medullary infarction. Reconstructive techniques using neck-bridge stents preserve the parent vessel and reduce perioperative morbidity. Nevertheless, these techniques are associated with a higher rate of aneurysmal rebleeding or recurrence. Optimal treatment modalities should be chosen based on the anatomical characteristics of the aneurysm and the trade-off between risks and benefits.

[Interhemispheric Approach for Ruptured Anterior Communicating Artery Aneurysms].

The interhemispheric approach is very useful for the safe and reliable clipping of ruptured anterior communicating aneurysms. This approach enables surgeons to directly visualize the aneurysm and the surrounding vessels, including perforators, and provides a wide surgical corridor for clip insertion from multiple directions. Furthermore, in challenging situations, this approach facilitates vascular reconstruction without the need for graft harvesting. However, because of the procedural difficulty, many young and inexperienced neurosurgeons may hesitate to perform this technique. Therefore, this study aimed to provide useful tips, based on intraoperative photography, for skin and dural incisions, prevention of cerebrospinal fluid leakage and olfactory impairment, and fundamental steps for opening tight interhemispheric fissures. Finally, representative challenging cases that were adequately managed using the advantages of this approach are presented.