Ulceration location is associated with clinical course in carotid stenosis.

OBJECTIVE: Plaque ulceration in carotid artery stenosis is a risk factor for cerebral ischemic events; however, the characteristics that determine plaque vulnerability are not fully understood. We thus assessed the association between plaque ulceration sites and cerebrovascular ischemic attack. METHODS: We retrospectively collected the clinical data of 72 consecutive patients diagnosed with carotid artery stenosis with plaque ulcers. After excluding patients with pseudo-occlusion, a history of previous carotid endarterectomy or carotid artery stenting before the ulcer was first discovered, follow-up data of less than 1 month, or carotid endarterectomy or carotid artery stenting performed within 1 month after the ulcer was first discovered, 60 patients were ultimately included. Patients were divided into proximal and distal groups based on the ulcer location relative to the most stenotic point. The primary endpoints were ipsilateral cerebrovascular ischemic events ("ischemic events"), such as amaurosis fugax, transient ischemic attack, or ischemic stroke due to carotid artery stenosis with plaque ulceration. The association between ulcer location and ischemic events was also assessed. RESULTS: In the patients with plaque ulcer, more patients had proximal than distal plaque ulcers (39 vs 21; P = .028). The median follow-up duration was 3.8 years (interquartile range, 1.5-6.2 years). Nineteen patients (32%) experienced ischemic event. Ischemic events occurred more frequently in the distal than in the proximal group (18% vs 59%; P = .005). Kaplan-Meier curves demonstrated a significantly shorter event-free time in the distal group (log-rank P = .021). In univariate analysis, distal ulcer location was associated with ischemic events (odds ratio [OR], 2.94; 95% confidence interval [CI], 1.13-7.65; P = .03). Multivariate analysis using two different models also showed that distal ulcer location was independently associated with ischemic events (Model 1: OR, 3.85; 95% CI, 1.26-11.78; P = .03; Model 2: OR, 4.31; 95% CI, 1.49-12.49; P = .009). CONCLUSIONS: Patients with carotid artery stenosis and plaque ulcers located distal to the most stenotic point are more likely to experience cerebrovascular ischemic attacks. Therefore, carotid plaques with ulcers located distal to the most stenotic point may be a potential indication for surgical treatment.

Irreversible postoperative cognitive impairment after unruptured intracranial aneurysm treatment in the elderly.

PURPOSE: Postoperative cognitive dysfunction and recovery remain unclear in older patients undergoing interventional therapies for unruptured intracranial aneurysms (UIAs). This study aimed to compare changes in postoperative cognitive function between younger and older patients and to detect factors associated with non-recovery from postoperative cognitive dysfunction. METHODS: This study reviewed 59 consecutive patients with UIAs who underwent interventional therapies, including microsurgical clipping or endovascular treatment, from 2021 to 2022. All patients were divided into the older (aged ≥ 70 years) and younger (aged < 70 years) groups. Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) were performed within 2 months before interventions, at 1 week postoperatively (POW1), and 3-6 months postoperatively (POM3-6). RESULTS: MMSE and FAB scores decreased more frequently in the older group than in the younger group at POW1 (older vs. younger: MMSE: 48% vs. 21%, p < 0.05; FAB: 56% vs. 18%, p < 0.01). In the older group, the FAB Z-score decreased in POW1 and recovered by POM3-6 (p < 0.01), while the MMSE Z-score continued to decrease (p = 0.04). Age and the preoperative MSME Z-score were significantly associated with non-recovery from decreased MMSE score at POM3-6 (recovery vs. non-recovery, age: 62 years old vs. 72 years old, p = 0.03, preoperative MMSE Z-score: 0.16 vs. - 0.90, p < 0.01). CONCLUSIONS: This retrospective study found that older patients were more likely to have a postoperative cognitive decline after UIA treatment and implicated that global cognitive function tended to decline more than executive function in the long term. In addition, this study demonstrated that lower preoperative cognitive function was associated with inadequate postoperative cognitive recovery. The findings potentially contribute to the establishment of indications for treating UIAs in older patients.

Pathological changes in the lenticulostriate artery indicate the mechanisms leading to intracranial hemorrhage in Moyamoya disease: a case report.

This case report details the pathological findings of a vessel wall identified as the bleeding point for intracranial hemorrhage associated with Moyamoya disease. A 29-year-old woman experienced intracranial hemorrhage unrelated to hyperperfusion following superficial temporal artery-middle cerebral artery bypass surgery. A pseudoaneurysm on the lenticulostriate artery (LSA) was identified as the causative vessel and subsequently excised. Examination of the excised pseudoaneurysm revealed a fragment of the LSA, with a disrupted internal elastic lamina and media degeneration. These pathological findings in a perforating artery, akin to the circle of Willis, provide insights into the underlying mechanisms of hemorrhage in Moyamoya disease.

Impact of tailored multimodal treatment for unruptured brain arteriovenous malformation: comparison with a randomized trial of unruptured brain arteriovenous malformations.

PURPOSE: The first randomized controlled study on unruptured brain arteriovenous malformations (bAVM), the ARUBA trial, demonstrate the superiority of medical management; however, it failed to completely rule out the efficacy of therapeutic interventions due to several limitations. This study aimed to examine the outcomes of multimodal interventional treatment for bAVM in terms of safety and efficacy. METHODS: We reviewed 226 consecutive patients with unruptured bAVM admitted to our institute between 2002 and 2022. Treatment methods were divided into medical management and therapeutic intervention, including microsurgery, stereotactic surgery, and endovascular intervention. First, the choice of therapeutic modalities was assessed in the pre-ARUBA (before February 2014) and post-ARUBA (after March 2014) eras. Second, the incidence of symptomatic stroke or death and functional prognosis with a modified Rankin scale (mRS) score of ≥2 at 5 years was compared between the medical management and therapeutic intervention. RESULTS: In the pre- and post-ARUBA groups, 73% and 84% of patients underwent therapeutic interventions, respectively (p = 0.053). The rate of symptomatic stroke or death was lower in patients who underwent interventional therapies than in those who underwent medical management (9.7% vs. 22%, p = 0.022); however, the opposite was observed in the ARUBA trial (31% vs. 10%). The annual incidence of stroke or death was also lower in the interventional therapy group (4.3%/y vs. 1.8%/year, hazard ratio = 0.45, 95% confidence interval: 0.18-1.08, p = 0.032). The rate of mRS score of ≥2 after a 5-year follow-up was 18% and 6% in the medical treatment and intervention groups (p = 0.14). CONCLUSIONS: The therapeutic intervention rate did not decrease, even after the publication of the ARUBA trial. The rate of stroke or death was lower in the intervention group, indicating that a tailored choice of multimodality is safe and effective for managing unruptured bAVM.

[Changes in Gamma Knife Radiosurgery(GKRS)in Patients with Metastatic Brain Tumors before and after COVID-19].

The spread of coronavirus disease 2019(COVID-19)is a concern as it may delay the detection of malignant tumors due to delayed medical checkups. We examined changes in the treatment of metastatic brain tumors before and after COVID- 19. A retrospective review of 211 patients with metastatic brain tumors who underwent initial gamma knife radiosurgery between July 2019 and December 2021 was conducted. Data collected include patient age, gender, the Karnofsky performance status(KPS), primary tumor control, number, total volume, and outcome during the COVID-19 emergency declaration period and outside of it. The patient number was 164 outside of the emergency period and 47 during the period. Symptomatic cases(KPS<90)and poor control of the primary site increased during the COVID-19 period. The treatment number and volume of brain metastasis did not change. Metastatic control after 4 months of treatment also showed no difference. The number of symptomatic patients increased during the emergency declaration period, suggesting that COVID- 19 may have reduced the rate of asymptomatic patients being seen. However, these were not enough to affect the prognosis at 4 months. Overall, the COVID-19 pandemic had a small impact on the provision of stereotactic radiotherapy for metastatic brain tumors.

Intracranial arterial stenosis associated with Hashimoto's disease: angiographic features and clinical outcomes.

BACKGROUND: Hashimoto's disease has reportedly been associated with stroke; however, cerebrovascular morphology and clinical course remain poorly documented. The present study aimed to determine the angiographic features and clinical outcomes of intracranial arterial stenosis (IAS) associated with Hashimoto's disease in a retrospective cohort. METHODS: Overall, 107 adult patients with IAS were screened for anti-thyroid antibodies; of these, 26 patients tested positive. The 42 affected hemispheres were classified into subgroups according to the steno-occlusion site and the development of abnormal collateral (moyamoya) vessels. These subgroups were dichotomized into moyamoya vessels positive (MM type) and negative (non-MM type). The initial presentation, IAS progression, and vascular events during the follow-up period were compared. RESULTS: The following sites of stenosis were identified: the bifurcation of the internal carotid artery in 11 (26.2%), M1 or A1 in 29 (69.0%), and more distal (M2-M4/A2-A4) in 2 (4.8%) hemispheres. Further, 17 hemispheres were categorized into the MM type and 25 were classified into the non-MM type. During the follow-up period (mean 2.5 years), IAS progression was identified in 8 (32%) hemispheres of the non-MM type and 0 (0%) hemispheres of the MM type (p = 0.041). Ischemic attacks occurred in 5 (20.0%) hemispheres of the non-MM type (4.6%/year) and 0 hemispheres of the MM type (p = 0.08). Further, 4 (23.5%) hemispheres of the MM type experienced intracerebral hemorrhage, whereas none of the non-MM type hemorrhaged (p = 0.012). CONCLUSIONS: Hashimoto's disease-associated IAS exhibits various angiographic morphologies, resulting in different clinical presentations. Screening for anti-thyroid antibodies and careful management based on vascular morphology appears important in adults with IAS.

[Actual status of children with food allergies and food provision at residential nurseries and children's care homes: Comparison of groups using and not using guidelines or manuals].

Objectives　To elucidate the actual status of children with food allergies and the measures of allergy-appropriate food provisions at residential nurseries and children's care homes. We also compared institutions that used guidelines, manuals, etc. with those that did not.Methods　Self-administered questionnaires were administered to residential nurseries and children's care homes in Japan. Responses were received from 394 institutions, yielding a response rate of 53.6%. The prevalence of food allergies was assessed in 392 institutions. To investigate the relationship between using guidelines and the status of the children, the analysis included 230 institutions where there were children with food allergies. The relationships between the presence or absence of guidelines and (i) occurrence or non-occurrence of anaphylactic shock or other allergy-related events and (ii) each step of food service were evaluated.Results　The prevalence of food allergies at the 392 institutions was found to be 3.31%. It was difficult to obtain information concerning food allergies at admission to the institutions because a high proportion of children were reported as "children with no physician's diagnostic record," "children admitted without confirmation of allergy information," or "children with discrepancies between the information at admission and actual state."　Of the 230 institutions studied, guidelines were followed at 25.0% of the institutions. Even when institutions with other written rules were included, this proportion only increased to 32.1%. The statistical analysis involved adjustments for different types of institutions. A multivariate logistic regression analysis showed that the odds ratio for institutions where treatment was based on guidelines were significant for the following items: children with no physician's diagnostic record (0.35), existence of a consistent documentation method for collection of information (5.04), regular revisions of information being made (2.85), and reports being submitted when mistakes in food provided to children with allergies were made or narrowly avoided (2.49). In addition, strong correlations were found for the following: children who experienced anaphylactic shock during the previous 3 years (9.72) and children admitted without confirmation of a food allergy (3.12).Conclusions　When rule-based approaches were established, the preparation of information collection forms, revision of information, and reporting of food provision mistakes proceeded more efficiently than when rule-based approaches were not used. Although the prevalence of children experiencing anaphylactic shock and the cases in which information was not confirmed at admission were higher in the institutions using guidelines, this survey revealed that when guidelines were followed, appropriate measures were taken after the admission of children to the institution and that physicians' medical diagnoses were obtained.

[Analysis of Post-Recurrence Survival of Resected Lung Cancer with Brain Metastasis].

METHODS: We retrospectively evaluated the post-recurrence survival of 37 cases with brain metastases out of 439 consecutive resected cases of primary lung cancer between 2001 and 2017. FINDINGS: There was no difference in survival according to tumor size but survival was significantly shorter in patients with larger numbers of tumors. Patients initially treated with stereotactic radiosurgery(SRS)or surgical resection survived longer than those with whole-brain irradiation(WBI)(median survival: 23 months for SRS, 17 months for surgical resection, and 4 months for WBI: p<0.001 between SRS and WBI). CONCLUSIONS: As SRS is recommended for 1-4 tumors with maximum diameters ofC3 cm and surgical resection is recommended for tumors larger than 3 cm, these effective locoregional therapies should be aggressively adopted for local control of brain metastases with the aim of improved QOL and prolonged survival. Due to the deterioration of neurocognitive function, WBI should be avoided as initial treatment for brain metastases when effective locoregional therapy or systemic chemotherapy is available and reserved for leptomeningeal dissemination or miliary metastases.

Multimodal Interventional Treatment and Outcomes for Unruptured Arteriovenous Malformations.

BACKGROUND: This study aimed to evaluate the selection and outcomes of multimodal interventional treatment for unruptured brain arteriovenous malformations (uAVMs) in ARUBA-eligible patients in a single institution. METHODS: We retrospectively reviewed the data of 94 patients with uAVMs treated between 2002 and 2014. They were divided into an intervention group and a conservative group. The primary outcome was defined as the composite of death or symptomatic stroke. Functional outcome was assessed using the modified Rankin Scale (mRS). RESULTS: The intervention and conservative groups included 75 and 19 patients, respectively, with mean follow-up periods of 59.2 ± 41.6 and 72.8 ± 39.2 months (P = 0.20), among whom the primary outcome occurred in 9 (12.3%) and 3 (17.6%) patients, respectively (P = 0.91). The proportion of patients with an mRS score ≥ 2 at last follow-up was not significantly different between the two groups (6.9% vs. 11.7%). In the intervention group, the incidence of death or stroke was lower and functional outcomes were better among patients with grade I/II AVMs than among patients with grade III AVMs. CONCLUSION: For patients with uAVMs, interventional treatment is not inferior to medical treatment alone, and careful selection should be made for patients with grade III AVMs.

Superselective Provocative Test with Propofol Using Motor-Evoked Potential Monitoring for Managing Cerebral Arteriovenous Malformations Fed by the Anterior Choroidal Artery.

When feeder artery obliteration is performed via an endovascular procedure to treat cerebral arteriovenous malformation (AVM), it is important to prevent the ischemic complications that are associated with feeder occlusion. A provocative test may be beneficial in some cases to protect against ischemic complications. We report the case of a 57-year-old man who developed an intracerebral hematoma in the left internal temporal lobe and who had an AVM with a varix in the ambient cistern, which was primarily fed by a branch of the left anterior choroidal artery (AChA) and the posterior lateral choroidal artery, and drained into the basal vein. Therefore, we planned endovascular obliteration of the AChA, followed by gamma knife radiosurgery for the residual posterior component. The patient underwent a superselective provocative test with a 3 mg of propofol under general anesthesia using motor-evoked potential monitoring. The feeder embolization was performed as planned after the provocative test, and the patient exhibited no neurological deficits, such as hemiparesis, during the procedure.

The impact of comprehensive stroke care capacity on the hospital volume of stroke interventions: a nationwide study in Japan: J-ASPECT study.

BACKGROUND: The association between comprehensive stroke care capacity and hospital volume of stroke interventions remains uncertain. We performed a nationwide survey in Japan to examine the impact of comprehensive stroke care capacity on the hospital volume of stroke interventions. METHODS: A questionnaire on hospital characteristics, having tissue plasminogen activator (t-PA) protocols, and 25 items regarding personnel, diagnostic, specific expertise, infrastructure, and educational components recommended for comprehensive stroke centers (CSCs) was sent to 1369 professional training institutions. We examined the effect of hospital characteristics, having a t-PA protocol, and the number of fulfilled CSC items (total CSC score) on the hospital volume of t-PA infusion, removal of intracerebral hemorrhage, and coiling and clipping of intracranial aneurysms performed in 2009. RESULTS: Approximately 55% of hospitals responded to the survey. Facilities with t-PA protocols (85%) had a significantly higher likelihood of having 23 CSC items, for example, personnel (eg, neurosurgeons: 97.3% versus 66.1% and neurologists: 51.3% versus 27.7%), diagnostic (eg, digital cerebral angiography: 87.4% versus 43.2%), specific expertise (eg, clipping and coiling: 97.2% and 54% versus 58.9% and 14.3%, respectively), infrastructure (eg, intensive care unit: 63.9% versus 33.9%), and education (eg, professional education: 65.2% versus 20.7%). On multivariate analysis adjusted for hospital characteristics, total CSC score, but not having a t-PA protocol, was associated with the volume of all types of interventions with a clear increasing trend (P for trend < .001). CONCLUSION: We demonstrated a significant association between comprehensive stroke care capacity and the hospital volume of stroke interventions in Japan.

A Review of Current Flow Diverters.

Flow diverter (FD) devices are new-generation stents placed in the parent artery at the aneurysmal neck to obstruct intra-aneurysmal blood flow, thus favoring intra-aneurysmal thrombosis. In Japan, about eight years have passed since health insurance approval was granted for FD devices, and FD placement to treat aneurysms has become widespread. Treatment indications have also been expanded with the introduction of novel devices. At present, three types of FD (Pipeline, FRED, and Surpass Streamline) are available in Japan. This report represents a compilation of available FD technologies and describes the current consensus on this treatment.

Comparative analysis of peri-nidal cerebral blood flow and metabolism using a novel quantitative 15O-PET method in patients with arteriovenous malformations.

To effectively treat cerebral arteriovenous malformations (AVMs), peri-nidal flow regulation and metabolic status must be understood. In this study, we used 15O-oxygen positron emission tomography (PET) post-processing analysis to investigate vascular radioactivity in the nidal region of AVMs. Single-dynamic PET imaging was performed on seven unruptured AVM patients during the sequential inhalation of 15O2 and C15O2. A previously validated dual-tracer basis function method (DBFM) was employed to calculate parametric images. The results of our study were as follows. First, in remote and contralateral AVM regions, DBFM and a previous approach of dual-tracer autoradiography (DARG) showed strong positive correlations in cerebral blood flow (CBF), cerebral oxygen metabolism rate (CMRO2), and oxygen extraction fraction. Second, peri-nidal CBF and CMRO2 correlation was lower, and overestimation occurred with DARG compared to with DBFM. Third, on comparing DBFM to quantitative 123I-iodoamphetamine single-photon emission computed tomography (SPECT), CBF correlated significantly. In contrast, the correlation between DARG and quantitative 123I-iodoamphetamine-SPECT was weaker in the peri-nidal regions. Fourth, analysis of tissue time-activity curves demonstrated good reproducibility using the novel formulation in the control, peri-nidus, and core nidal regions, indicating the adequacy of this approach. Overall, the DBFM approach holds promise for assessing haemodynamic alterations in patients with AVMs.

Preoperative Simulation of Intraoperative Findings in Surgical Clipping of Posterior Communicating Artery Aneurysms Using T2-Weighted 3D Images.

BACKGROUND: Tentorium resection and detachment from the oculomotor nerve are sometimes required for surgical clipping of unruptured posterior communicating artery (PCoA) aneurysms. Using T2-weighted 3D images, we aimed to identify the preoperative radiological features required to determine the necessity of these additional procedures. METHODS: We reviewed 30 patients with unruptured PCoA aneurysms who underwent surgical clipping and preoperative simulation using T2-weighted 3D images for measurement of the distance between the tentorium and aneurysm. Aneurysms were classified into superior type (superior to the tentorium) and inferior type (inferior to the tentorium). RESULTS: Seven patients (23%) underwent tentorium resection; all had the inferior type (superior vs. inferior, 0% vs. 33%, p = 0.071). In the 21 patients with the inferior type, the distance from the tentorium to the aneurysmal neck was 2.2 ± 1.1 mm and 0.0 ± 0.5 mm without and with tentorium resection (p < 0.01), respectively. An optimal cutoff value of ≤ +0.84 mm was identified for tentorium resection (area under the curve (AUC) = 0.96). Furthermore, 17 patients (57%) showed tight aneurysm attachment to the oculomotor nerve; all had the inferior type (0% vs. 81%, p < 0.01). The distance from the aneurysm tip to the tentorium was 1.1 ± 1.2 mm and -1.7 ± 1.4 mm without and with attachment (p < 0.01). The optimal cutoff value was ≤ +0.45 mm (AUC = 0.92). CONCLUSIONS: Measurement of the distance between the tentorium and aneurysmal neck or tip with T2-weighted 3D images is effective for preoperative simulation for surgical clipping of PCoA aneurysms.

Plaque Ulcerations are Associated with Recurrence in Symptomatic Low-Grade Carotid Stenosis.

OBJECTIVE: Surgical indications for low-grade carotid stenosis have not yet been established. This study aimed to clarify the characteristics of low-grade carotid stenosis refractory to medical treatment. METHODS: We retrospectively analyzed 48 patients with symptomatic low-grade carotid stenosis (<50%). Recurrence was defined as an ipsilateral ischemic event in the symptomatic lesions during the follow-up period. Patient demographics and imaging findings were compared between the recurrence and nonrecurrence groups to investigate risk factors associated with medical treatment. RESULTS: The mean age was 74.1 (58-90 years), and the mean follow-up period was 35.4 months (2.0-97 months). Recurrence occurred in 15 of the symptomatic patients. Ulceration was significantly associated with recurrence under medical treatment (P = 0.001). The median time to recurrence was 26.1 months in patients with ulcers and 54.3 months in those without ulcers (P = 0.04). Pathological study with recurrence showed plaque rupture with multilayered lesions, indicating lesions refractory to medical treatment. CONCLUSIONS: In cases of low-grade carotid stenosis, lesions with ulcerations are likely refractory to medical therapy. Consideration of the indications for surgical treatment may be warranted for lesions with ulceration, even if the degree of stenosis is low.

Treatment Outcome of Flow Diverter Device for Medium-Sized Cerebral Aneurysms: A Single-Center Report.

Objective: Flow diverters (FDs), first introduced in Japan in 2015, were initially limited to wide-necked large cerebral aneurysms, which pose a high treatment risk. However, based on the results of the PREMIER study, the indications have expanded since 2020, and the number of treatment cases is increasing in Japan. At our hospital, FD placement with adjunctive coil embolization has been actively performed for medium-sized cerebral aneurysms, as indicated in the PREMIER study; herein, we report the outcomes of this treatment. Methods: Of the 25 patients with 28 aneurysms who underwent FD placement at our institution between April 2022 and June 2023, 15 with 17 wide-necked unruptured cerebral aneurysms with a maximum diameter of <12 mm in the internal carotid artery (ICA) or vertebral artery (VA) were included. Postoperative complications were investigated in each case, and the aneurysm occlusion status was assessed using ultrashort echo time (UTE)-MRA at 3 months postoperatively and angiography at 6 months postoperatively. Fifteen patients who underwent coiling or stent-assisted coiling (SAC) for the same criteria during the same period were compared. Baseline characteristics and treatment results were compared between FD and coiling/SAC cases. Results: Four males and 11 females with a mean age of 61.7 ± 12.8 years were included, and the median follow-up period was 9 months (6-18 months). There were 14 aneurysms of the ICA and 3 of the VA, and the mean maximum aneurysm diameter was 7.9 ± 1.7 mm. All patients were treated using the Pipeline Flex with Shield Technology (Medtronic, Minneapolis, MN, USA), and 14 aneurysms (82.4%) were treated with adjunctive coil embolization. There were no symptomatic strokes in the perioperative period; only one patient receiving corticosteroid therapy for thyroid eye disease had asymptomatic ICA occlusion at 3 months. Fifteen aneurysms (88.2%) were not visible on UTE-MRA at 3 months postoperatively, and angiography at 6 months showed complete occlusion in 16 (94.1%) aneurysms. The coiling/SAC group had a smaller neck size and higher volume embolization ratio than the FD group; however, complete occlusion was higher in the FD group. Conclusion: FD placement with adjunctive coil embolization for medium-sized cerebral aneurysms is expected to result in good occlusion rates in the early postoperative period.

Hemodynamic differences determining rupture and non-rupture in middle cerebral aneurysms after growth.

BACKGROUND AND PURPOSE: Intracranial aneurysm growth is a significant risk factor for rupture; however, a few aneurysms remain unruptured for long periods, even after growth. Here, we identified hemodynamic features associated with aneurysmal rupture after growth. MATERIALS AND METHODS: We analyzed nine middle cerebral artery aneurysms that grew during the follow-up period using computational fluid dynamics analysis. Growth patterns of the middle cerebral artery aneurysms were divided into homothetic growth (Type 1), de novo bleb formation (Type 2), and bleb enlargement (Type 3). Hemodynamic parameters of the four ruptured aneurysms after growth were compared with those of the five unruptured aneurysms. RESULTS: Among nine aneurysms (78%), seven were Type 1, one was Type 2, and one was Type 3. Three (43%) Type 1 aneurysms ruptured after growth. Maximum oscillatory shear index after aneurysmal growth was significantly higher in ruptured Type 1 cases than in unruptured Type 1 cases (ruptured vs. unruptured: 0.455 ± 0.007 vs. 0.319 ± 0.042, p = 0.003). In Type 1 cases, a newly emerged high-oscillatory shear index area was frequently associated with rupture, indicating a rupture point. Aneurysm growth was observed in the direction of the high-pressure difference area before enlargement. In Types 2 and 3 aneurysms, the maximum oscillatory shear index decreased slightly, however, the pressure difference values remain unchanged. In Type 3 aneruysm, the maximum OSI and PD values remained unchanged. CONCLUSIONS: This study suggests that hemodynamic variations and growth pattern changes are crucial in rupture risk determination using computational fluid dynamics analysis. High-pressure difference areas may predict aneurysm enlargement direction. Additionally, high maximum oscillatory shear index values after enlargement in cases with homothetic growth patterns were potential rupture risk factors.

Ruptured brainstem arteriovenous malformation associated with a thalamoperforating artery aneurysm arising from the P1 segment of the right posterior cerebral artery: illustrative case.

BACKGROUND: Cerebral aneurysms of perforating arteries are rare and can be difficult to detect on computed tomography angiography (CTA) and digital subtraction angiography. Treatment is challenging and associated with a significant risk of morbidity. Endovascular treatment of a thalamoperforating artery (TPA) aneurysm within the midbrain has not previously been reported. OBSERVATIONS: A 13-year-old girl with no previous medical history presented with unconsciousness and anisocoria. Head computed tomography showed a right midbrain hemorrhage. CTA showed a midbrain arteriovenous malformation fed by a TPA aneurysm arising from the P1 segment of the right posterior cerebral artery. The feeder had a small distal aneurysm, which increased in size over time. Endovascular embolization was then performed. LESSONS: Cerebral aneurysms of perforating arteries are rare and can be difficult to treat. This is the first report of the endovascular treatment of a TPA aneurysm within the midbrain. Understanding the individual patient's brainstem perforator anatomy and the associated blood flow is essential before occluding a TPA aneurysm to avoid causing ischemia or infarction. Arteriovenous malformation embolization within the brainstem should be avoided because of interperforator anastomoses.