Evaluation of the shrinkage process of a neck remnant after stent-coil treatment of a cerebral aneurysm using silent magnetic resonance angiography and computational fluid dynamics analysis: illustrative case.

BACKGROUND: Silent magnetic resonance angiography (MRA) mitigates metal artifacts, facilitating clear visualization of neck remnants after stent and coil embolization of cerebral aneurysms. This study aims to scrutinize hemodynamics at the neck remnant by employing silent MRA and computational fluid dynamics. OBSERVATIONS: The authors longitudinally tracked images of a partially thrombosed anterior communicating artery aneurysm's neck remnant, which had been treated with stent-assisted coil embolization, using silent MRA over a decade. Computational fluid dynamics delineated the neck remnant's reduction process, evaluating hemodynamic parameters such as flow rate, wall shear stress magnitude and vector, and streamlines. The neck remnant exhibited diminishing surface area, volume, neck size, dome depth, and aspect ratio. Its reduction correlated with a decline in the flow rate ratio of the remnant dome to the inflow parent artery. Analysis delineated regions within the contracting neck remnant characterized by consistently low average wall shear stress magnitude and variation, accompanied by notable variations in wall shear stress vector directionality. LESSONS: Evaluation of neck remnants after stent-coil embolization is possible through silent MRA and computational fluid dynamics. Predicting the neck remnant reduction may be achievable through hemodynamic parameter analysis.

Endovascular Treatment for Intracranial Artery Dissections in Posterior Circulation.

Intracranial artery dissections (IADs), although uncommon, are an important cause of cerebral infarction and subarachnoid hemorrhage (SAH). Some IADs can heal spontaneously after reconstitution of the vessel lumen with excellent prognosis. Meanwhile, others can progress to stroke that requires treatment. The incidence of IAD in the posterior circulation is higher than that in the anterior circulation. Anterior circulation dissections are more likely to develop into ischemia and posterior circulation lesions into hemorrhage. The mortality rate after IAD among patients with SAH is 19%-83%. Further, the mortality rate of IAD without SAH is 0%-3%. Patients with SAH commonly undergo surgery or receive neuroendovascular treatment (EVT) to prevent rebleeding. However, the treatment of IADs is empirical in the absence of data from randomized controlled trials. Recently, EVT has emerged and is considered for IADs because of its less invasiveness and perceived low rates of procedure-related morbidity with good efficacy. EVT strategies can be classified into deconstructive (involving sacrifice of the parent artery) and reconstructive (preserving blood flow via the parent vessel) techniques. In particular, the number of reports on reconstructive techniques is increasing. However, a reconstructive technique for ruptured IADs has not yet been established. This review aimed to provide an overview of IADs in the posterior circulation managed with EVT by performing a literature search.

[Preoperative Simulation of Neuroendovascular Therapy Using a Three-Dimensional Printer Model of a Tailor-Made Hollow Cerebral Aneurysm].

Several studies have reported the importance of preoperative simulations. This report describes the methods and utility of neuroendovascular treatment using a three-dimensional(3D)-printed hollow cerebral aneurysm model. This model was created using a stereolithography apparatus-type 3D printer with digital imaging and communications in medicine data from 3D digital subtraction angiograms. The 3D model was used to perform preoperative simulations of microcatheter placement in aneurysms, microguidewire manipulation, and stent deployment. We performed each simulated procedure during surgery. The hollow cerebral aneurysm 3D model can also be used as a training model for surgical trainees. Preoperative simulation using a high-precision hollow cerebral aneurysm model created using 3D printers enables the discussion of specific treatment strategies for each case, including new devices and device sizes, and is expected to develop into "tailor-made medicine" in the future, contributing to safe and reliable treatment implementation.

Power suppression in EEG after the onset of SAH is a significant marker of early brain injury in rat models.

We analyzed the correlation between the duration of electroencephalogram (EEG) recovery and histological outcome in rats in the acute stage of subarachnoid hemorrhage (SAH) to find a new predictor of the subsequent outcome. SAH was induced in eight rats by cisternal blood injection, and the duration of cortical depolarization was measured. EEG power spectrums were given by time frequency analysis, and histology was evaluated. The appropriate frequency band and recovery percentage of EEG (defined as EEG recovery time) to predict the neuronal damage were determined from 25 patterns (5 bands × 5 recovery rates) of receiver operating characteristic (ROC) curves. Probit regression curves were depicted to evaluate the relationships between neuronal injury and duration of depolarization and EEG recovery. The optimal values of the EEG band and the EEG recovery time to predict neuronal damage were 10-15 Hz and 40%, respectively (area under the curve [AUC]: 0.97). There was a close relationship between the percentage of damaged neurons and the duration of depolarization or EEG recovery time. These results suggest that EEG recovery time, under the above frequency band and recovery rate, may be a novel marker to predict the outcome after SAH.

Short- versus long-term Dual AntiPlatelet Therapy for Stent-Assisted treatment of CErebral aneurysm (DAPTS ACE): a multicenter, open-label, randomized clinical trial.

BACKGROUND: The optimal duration of dual antiplatelet therapy (DAPT) after stent-assisted coil embolization (SACE) for cerebral aneurysm remains uncertain. This randomized trial of short- versus long-term Dual AntiPlatelet Therapy for Stent-Assisted treatment of CErebral aneurysm (DAPTS ACE) aimed to clarify whether long-term DAPT can reduce the occurrence of ischemic stroke in patients with cerebral aneurysms treated by SACE compared with short-term DAPT. METHODS: Patients treated for cerebral aneurysm with SACE were enrolled from 17 hospitals in Japan. Patients were enrolled within 30 days after SACE and assigned in a 1:1 ratio to receive long-term (12 months) or short-term (3 months) DAPT with aspirin and clopidogrel. Randomization was performed centrally through a web-based system. The primary outcome was the time to ischemic stroke event during 3 to 12 months after SACE. This trial was registered with the Japan Registry of Clinical Trials (jRCTs051180141). RESULTS: A total of 142 patients were recruited from November 4, 2016 to January 7, 2019. Among them, 65 and 68 patients assigned to the long- and short-term DAPT groups, respectively, were included in the full analysis set. Ischemic stroke occurred in no patients in the long-term DAPT group and in one patient in the short-term DAPT group. The incidence rate did not differ between the groups (0.0 vs 2.1/100 person-years; log rank test, P=0.33). CONCLUSIONS: In this multicenter randomized controlled trial, there was not a statistically significant difference in the rate of ischemic strokes between long- and short-term DAPT.

Questionnaire Survey of Neurointerventional Simulation Training in the Japanese Society for Neuroendovascular Therapy.

Objective: Simulation training has focused on education and practical training. However, the adoption rate of neurointerventional simulation training in Japan is unknown. Therefore, we sent a questionnaire survey form to consulting specialists from the Japanese Society for Neuroendovascular Therapy (JSNET) to clarify the actual simulation training situation and compare the differences between university hospitals and general hospitals in Japan. Methods: The questionnaire survey was conducted in 243 neurosurgical training facilities that had JSNET consulting specialists between May 31, 2021 and July 31, 2021. The questionnaire survey forms were distributed by Google Forms. Results: A total of 162 facilities responded to the survey (response rate: 66.7%; 35.2% from university hospitals and 64.8% from general hospitals). The adoption rate for simulation training was 53.7%, and it was significantly higher in the university hospitals than in the general hospitals (64.9% vs. 47.6%, p = 0.035). On the simulation effectiveness survey, more than 80% of respondents answered that the simulation training was a useful tool for upskill training. The open-ended question on interventional simulation training showed that there are limiting factors such as financial constraints. Additionally, respondents expressed a desire for a standard neurointerventional simulation training and education program. Conclusion: The adoption rate for simulation training was 53.7% in the training facilities of JSNET, and it was higher in the university hospitals than in the general hospitals. Most of the respondents answered that simulation training is an effective tool to improve neurointerventional skills. They also requested the establishment of simulation training programs and simulation tools.

Relation between duration of dual antiplatelet therapy and risk of ischemic stroke after stent-assisted treatment of cerebral aneurysm (DAPTS ACE-registry).

BACKGROUND: The optimal duration of dual antiplatelet therapy (DAPT) in patients with cerebral aneurysm who undergo stent-assisted coil embolization (SACE) has not been established. We aimed to clarify the association between duration of DAPT and incidence of ischemic stroke in patients with cerebral aneurysm. METHODS: We registered patients with cerebral aneurysm who underwent SACE in 27 hospitals in Japan. Those treated with DAPT (aspirin and clopidogrel) were eligible for inclusion in a previously reported randomized control trial (RCT). Patients who were ineligible or refused to participate to the RCT were followed-up for 15 months after SACE as the non-RCT cohort. Our study examined both the RCT and non-RCT cohorts. The primary and secondary outcomes were ischemic stroke and hemorrhagic events. RESULTS: Among the 313 patients registered, 296 were included for analysis (of these, 136 were RCT patients and 160 were non-RCT patients). Patients who were treated with DAPT for more than 6 months (n=191) were classified as the long-term DAPT group. Those treated less than 6 months (n=105) were classified as the short-term group. The incidence of ischemic stroke did not significantly differ between the long-term group (2.5 per 100 person-years) and the short-term group (3.2 per 100 person-years); nor did incidence of hemorrhagic events (0.8 and 3.2 per 100 person-years, respectively). The period of DAPT was not significantly associated with incidence rates of ischemic stroke or hemorrhagic events. CONCLUSIONS: Duration of DAPT was not associated with the incidence of ischemic stroke in the first 15 months after SACE.

Transvenous embolization of the direct carotid-cavernous fistula via the pterygoid plexus: illustrative case.

BACKGROUND: Endovascular treatment is the mainstay of treatment for carotid-cavernous fistulas, but endovascular approaches vary widely. The authors report a rare case of a direct carotid-cavernous fistula with cranial nerve symptoms caused by rupture of a giant aneurysm in which selective transvenous embolization via the pterygoid plexus was performed. OBSERVATIONS: An 81-year-old man presented with headache and various progressive cranial nerve symptoms due to a direct carotid-cavernous fistula caused by a ruptured giant aneurysm. All the draining veins visualized on preoperative examination immediately before the treatment were occluded except for the pterygoid plexus. Therefore, the authors chose the dilated pterygoid plexus to approach the shunted pouch at the cavernous sinus and achieve shunt obliteration by selective embolization with coils and n-butyl cyanoacrylate. LESSONS: Careful study of the three-dimensional rotational images in the preoperative examination is important when considering the various approaches to surgery. The pterygoid plexus can be an effective venous approach route to reach the cavernous sinus area.

Angioarchitecture of the Normal Lateral Spinal Artery and Craniocervical Junction Arteriovenous Fistula Using Contrast-enhanced Cone-beam CT.

BACKGROUND AND PURPOSE: The lateral spinal artery (LSA) perfuses the dorsolateral part of the spinal cord at the craniocervical junction (CCJ). We analyzed the angioarchitecture of the normal LSA and CCJ arteriovenous fistula (AVF). METHODS: The first study included 26 patients with a cerebral aneurysm of the posterior circulation. Using slab maximum intensity projection (MIP) images from three-dimensional rotational angiography (3D-RA) and contrast-enhanced cone-beam CT (CE-CBCT), we analyzed the origin of the LSA, its anastomosis with the posterior inferior cerebellar artery (PICA), the point where it reaches the spinal cord, and the visualized range. In the second study, we analyzed the angioarchitecture and treatment results of 7 CCJAVF lesions treated in our department between 2016 and 2021. RESULTS: We visualized the normal LSA for all patients. In 23 patients with an intradural origin PICA, all LSAs originated from the C1 or C2 radicular artery, and 8 patients had an anastomosis with the PICA. In three patients with a C1 level origin PICA, all LSAs originated from the PICA. All LSAs reached the dorsolateral part of the spinal cord. The mean visualized range of the LSA was 27.4 mm. The LSA was involved in five of seven CCJAVF lesions (71%). There was one lesion with a spinal infarction after LSA embolization. Other lesions were treated by direct interruption of the AVF, and the ASA and LSA were preserved. CONCLUSION: This is the first report that visualized the LSA's normal anatomy using slab MIP images from 3D-RA and CE-CBCT. Knowledge of LSA anatomy is critical to avoid complications during the treatment of CCJAVF.

[Visualization of Cerebrospinal Micro-Angioarchitecture].

Researchers have been trying to visualize fine angioarchitecture in cerebrospinal vascular lesions and the positional relationship between vascular lesions and surrounding structures. The aim of this article was to introduce the usefulness of imaging in visualizing the microvascular anatomy in cerebrospinal vascular lesions, such as aneurysm, arterial dissection, arteriovenous malformation, dural arteriovenous fistula(AVF), spinal dural and epidural AVF, and craniocervical junction AVF. For the imaging modality, we used high-resolution magnetic resonance imaging, three-dimensional rotational angiography(3D-RA), slab maximum intensity projection image from 3D-RA, cone-beam computed tomography, and fusion imaging. If fully exploited, imaging can contribute to clinical analysis and surgical treatment and be an essential tool for achieving maximum therapeutic effect without complications.

Treatment outcome of coil embolization for distal anterior cerebral artery aneurysms: A single-center experience.

OBJECTIVE: In recent years, endovascular treatment has become the treatment of choice for distal anterior cerebral artery (DACA) aneurysms. In this study, we report the outcomes of coil embolization for DACA aneurysms. METHODS: Eighteen DACA aneurysms in 16 patients treated with endovascular treatment between January 2010 and December 2020 were included in this study. We retrospectively analyzed patient characteristics, data on aneurysms, the reason for the selection of endovascular treatment, treatment technique, and treatment outcomes. RESULTS: There were 18 procedures in 16 patients. The average age was 65.7 years and 56% of patients were male. The average diameter of the dome was 5.5 mm, and the location of aneurysm was A3 in 83% and A4 in 17%. We mainly selected endovascular treatment for patients with a past history of craniotomy and head trauma, or with systemic comorbidities. The technical success rate was 94%, and adequate obliteration immediately after treatment was achieved in 72%. There were no symptomatic periprocedural complications. The retreatment rate was 11.1%. CONCLUSION: Coil embolization for DACA aneurysms yielded good treatment outcomes. Endovascular treatment for DACA aneurysms will become more common with advances in endovascular devices and the establishment of stable perioperative antiplatelet therapy.

[Neuroendovascular Therapy and Infection].

In this paper, we will discuss the relationship between neuroendovascular therapy and infection in two parts: the risk of infectious complications in neuroendovascular therapy and neuroendovascular therapy for infectious diseases. The risk of infectious complications associated with neuroendovascular therapy is rare but should not be ignored. We must comply with clean procedures and consider prophylactic antibiotic administration in selected cases. Neuroendovascular therapy for infectious diseases is a high-risk treatment, and a safer treatment strategy should be considered for each case.

Hemifacial spasm due to vertebral artery dissecting aneurysm treated with stent-in-stent placement; Pre- and post-treatment evaluation by 3D multifusion imaging using silent MR angiography.

Background: Hemifacial spasm (HFS) due to vertebral artery (VA) dissecting aneurysm (VADA) is rare and endovascular treatment has been performed in selected cases. Case Description: We encountered a case of HFS caused by VADA that was managed with endovascular stent placement and additional stent-in-stent placement. Therapeutic strategies and benefits based on pre- and post-treatment evaluation by 3D multifusion imaging using silent MRA were discussed. Conclusion: This is the first case report of stent-in-stent placement in successful treatment of HFS caused by VADA, in which relief of neurovascular contact was demonstrated by multifusion imaging.

Depolarization time and extracellular glutamate levels aggravate ultraearly brain injury after subarachnoid hemorrhage.

Early brain injury after aneurysmal subarachnoid hemorrhage (SAH) worsens the neurological outcome. We hypothesize that a longer duration of depolarization and excessive release of glutamate aggravate neurological outcomes after SAH, and that brain hypothermia can accelerate repolarization and inhibit the excessive release of extracellular glutamate and subsequent neuronal damage. So, we investigated the influence of depolarization time and extracellular glutamate levels on the neurological outcome in the ultra-early phase of SAH using a rat injection model as Experiment 1 and then evaluated the efficacy of brain hypothermia targeting ultra-early brain injury as Experiment 2. Dynamic changes in membrane potentials, intracranial pressure, cerebral perfusion pressure, cerebral blood flow, and extracellular glutamate levels were observed within 30 min after SAH. A prolonged duration of depolarization correlated with peak extracellular glutamate levels, and these two factors worsened the neuronal injury. Under brain hypothermia using pharyngeal cooling after SAH, cerebral perfusion pressure in the hypothermia group recovered earlier than that in the normothermia group. Extracellular glutamate levels in the hypothermia group were significantly lower than those in the normothermia group. The early induction of brain hypothermia could facilitate faster recovery of cerebral perfusion pressure, repolarization, and the inhibition of excessive glutamate release, which would prevent ultra-early brain injury following SAH.

A case of delayed foreshortening and disconnection of pipeline embolization device detected by chronological cone-beam computed tomography fusion image.

OBJECTIVE: The morphological changes of the pipeline embolization device (PED; Medtronic, Minneapolis, MN, USA), such as delayed migration or foreshortening, can relate to the incomplete occlusion of aneurysms. CASE PRESENTATION: A 30-year-old man with a giant cavernous carotid artery aneurysm was treated with two PEDs using the overlapping technique. Six months after treatment, follow-up angiography showed morphological changes of the PEDs and residual flow into the aneurysm. Chronological cone-beam computed tomography fusion imaging clearly revealed the dynamic foreshortening of the first PED and the disconnection of both PEDs, so we decided to implant an additional PED. CONCLUSION: This case illustrates that a three-dimensional understanding can be useful for assessing the cause of treatment failure or recurrence.

Association of bleb formation with peri-aneurysmal contact in unruptured intracranial aneurysms.

The mechanism of bleb formation in unruptured intracranial aneurysms (UIAs) remains unclear. This study aimed to investigate the association between peri-aneurysmal contact (PAC) and bleb formation. Forty-five aneurysms were classified depending on the presence of blebs and PAC using computed tomographic angiography and magnetic resonance imaging. Aneurysmal hemodynamics were assessed using computational fluid dynamics. The independent variables associated with bleb formation were statistically assessed. Fourteen aneurysms (31.1%) had blebs, all of which were located at the site of PAC (group A). Thirty-one aneurysms (68.9%) had no bleb, of which 13 had a PAC (group B) and 18 had no PAC (group C). PAC was the only independent variable associated with bleb formation (p < 0.05). Aneurysmal volumes were significantly higher in group A, followed by groups B and C in series. Aneurysmal wall shear stress (WSS) tended to be lowest in group A, followed by groups B and C in series. The maximum WSS at the blebs was only 17% of the maximum WSS at the aneurysmal domes. This study demonstrated that bleb formation in UIAs was associated with the establishment of PAC during their growth, which may have more detrimental effects on bleb formation than hemodynamics.

Incidence and clinical characteristics of spinal arteriovenous shunts: hospital-based surveillance in Okayama, Japan.

OBJECTIVE: There have been no accurate surveillance data regarding the incidence rate of spinal arteriovenous shunts (SAVSs). Here, the authors investigate the epidemiology and clinical characteristics of SAVSs. METHODS: The authors conducted multicenter hospital-based surveillance as an inventory survey at 8 core hospitals in Okayama Prefecture between April 1, 2009, and March 31, 2019. Consecutive patients who lived in Okayama and were diagnosed with SAVSs on angiographic studies were enrolled. The clinical characteristics and the incidence rates of each form of SAVS and the differences between SAVSs at different spinal levels were analyzed. RESULTS: The authors identified a total of 45 patients with SAVSs, including 2 cases of spinal arteriovenous malformation, 5 cases of perimedullary arteriovenous fistula (AVF), 31 cases of spinal dural AVF (SDAVF), and 7 cases of spinal epidural AVF (SEAVF). The crude incidence rate was 0.234 per 100,000 person-years for all SAVSs including those at the craniocervical junction (CCJ) level. The incidence rate of SDAVF and SEAVF combined increased with advancing age in men only. In a comparative analysis between upper and lower spinal SDAVF/SEAVF, hemorrhage occurred in 7/14 cases (50%) at the CCJ/cervical level and in 0/24 cases (0%) at the thoracolumbar level (p = 0.0003). Venous congestion appeared in 1/14 cases (7%) at the CCJ/cervical level and in 23/24 cases (96%) at the thoracolumbar level (p < 0.0001). CONCLUSIONS: The authors reported detailed incidence rates of SAVSs in Japan. There were some differences in clinical characteristics of SAVSs in the upper spinal levels and those in the lower spinal levels.

Mobile endovascular therapy for acute treatment of ruptured vertebral artery dissecting aneurysm in multiple hospitals.

BACKGROUND: The patients with ruptured vertebral artery dissecting aneurysm (rVADA) should be treated as early as possible because VADA carries extremely high risk of rebleeding in the acute phase. We have established a mobile endovascular strategy for the patients with rVADA between our flagship center and its affiliated local hospitals. We introduced and reviewed our mobile endovascular therapy in this study. METHODS: We retrospectively evaluated 98 consecutive patients who underwent endovascular surgery for rVADA from 2000 to 2018 at our institution or five affiliated hospitals. When each patient was initially transported to the local affiliated hospitals, neuroendovascular surgeons traveled directly to the affiliated hospital from the flagship center in order to treat the patient there. Clinical outcomes using modified Rankin Scale at 6 months after treatment, radiological results, and procedure-related complications were reviewed to justify our mobile endovascular strategy. RESULTS: All aneurysms were cured successfully by internal trapping. Favorable outcome was achieved in 61 patients (62.2%) even though 53 patients (54.1%) had presented with severe subarachnoid hemorrhage. Overall mortality rate, treatment-related mortality rate, and treatment related complication rate were 18.4% (18/98), 0%, and 16% (16/98), respectively. There were no differences in clinical and radiological outcomes between the patients treated in the flagship center and those who treated in the affiliated hospitals. Treatment in the affiliated hospital was not a predictive factor of unfavorable outcome in our multivariate analysis, and elderly age (≥ 60) was negatively associated with favorable outcome. CONCLUSIONS: Our results prove the efficacy and safety of mobile endovascular therapy for the treatment of rVADA in the ultra-acute stage. Mobile endovascular therapy may work well in the acute treatment of rVADAs in the certain circumstance.

A New Method of Intracranial Aneurysm Modeling for Stereolithography Apparatus 3D Printer: The "Wall-Carving Technique" Using Digital Imaging and Communications in Medicine Data.

OBJECTIVE: To assess the ability of the "wall-carving (WC) image technique", which uses vascular images from 3-dimensional digital subtraction angiograms (3DDSAs). Also, to verify the accuracy of the resulting 3D-printed hollow models of intracranial aneurysms. METHODS: The 3DDSA data from 9 aneurysms were processed to obtain volumetric models suitable for the stereolithography apparatus. The resulting models were filled with iodinated contrast media. 3D rotational angiography of the models was carried out, and the aneurysm geometry was compared with the original patient data. The accuracy of the 3D-printed hollow models' sizes and shapes was evaluated using the nonparametric Wilcoxon signed-rank test and the Dice coefficient index. RESULTS: The aneurysm volumes ranged from 34.1 to 4609.8 mm3 (maximum diameters 5.1-30.1 mm), and no statistically significant differences were noted between the patient data and the 3D-printed models (P = 0.4). Shape analysis of the aneurysms and related arteries indicated a high level of accuracy (Dice coefficient index value: 88.7%-97.3%; mean ± SD: 93.6% ± 2.5%). The vessel wall thickness of the 3D-printed hollow models was 0.4 mm for the parent and 0.2 mm for small branches and aneurysms, almost the same as the patient data. CONCLUSIONS: The WC technique, which involves volume rendering of 3DDSAs, can provide a detailed description of the contrast enhancement of intracranial vessels and aneurysms at arbitrary depths. These models can provide precise anatomic information and be used for simulations of endovascular treatment.

An Evaluation of the Safety and Feasibility of Adenosine-assisted Clipping Surgery for Unruptured Cerebral Aneurysms: Study Protocol.

The effectiveness of adenosine-induced flow arrest in surgical clipping for the cerebral aneurysms with difficulties in temporary clip placement to the proximal main trunk has been reported. This is the first clinical trial to evaluate the safety and feasibility of adenosine-assisted clipping surgery for unruptured cerebral aneurysms (UCAs) in Japan. The inclusion criteria are as follows: patients over 20 years old, patients who agree to be enrolled in this study after providing informed consent, patients who undergo clipping surgery for UCA in our institute, and patients in whom the surgeons (T.H. or I.D.) judge that decompression of the aneurysm is effective. The primary endpoint is a modified Rankin Scale (mRS) score 30 days after surgery. We plan to enroll 10 patients in this study. The original protocol of adenosine administration was established in this trial. Herein, we present the study protocol.