Computational Fluid Dynamics for Cerebral Aneurysms in Clinical Settings

Hemodynamics is thought to play an important role in the pathogenesis of cerebral aneurysms and recent development of computer technology makes it possible to simulate blood flow using high-resolution 3D images within several hours. A lot of studies of computational fluid dynamics (CFD) for cerebral aneurysms were reported; therefore, application of CFD for cerebral aneurysms in clinical settings is reviewed in this article.CFD for cerebral aneurysms using a patient-specific geometry model was first reported in 2003 and it has been revealing that hemodynamics brings a certain contribution to understanding aneurysm pathology, including initiation, growth and rupture. Based on the knowledge of the state-of-the-art techniques, this review treats the decision-making process for using CFD in several clinical settings. We introduce our CFD procedure using digital imaging and communication in medicine (DICOM) datasets of 3D CT angiography or 3D rotational angiography. In addition, we review rupture status, hyperplastic remodeling of aneurysm wall, and recurrence of coiled aneurysms using the hemodynamic parameters such as wall shear stress (WSS), oscillatory shear index (OSI), aneurysmal inflow rate coefficient (AIRC), and residual flow volume (RFV).

Can biomechanical analysis shed some light on aneurysmal pathophysiology? Preliminary study on ex vivo cerebral arterial walls

BACKGROUND

The pathophysiology of cerebral aneurysm is complex and poorly understood, and it can have the most catastrophic clinical presentation. Flow dynamics is a key player in the initiation and progression of aneurysm. Better understanding the interaction between hemodynamic loading and biomechanical wall responses can help to add the missing piece on aneurysmal pathophysiology. In this laboratory study we aimed to analyze the effect of the application of a mechanical force to cerebral arterial walls.

METHODS

Displacement control tests were performed on five porcine cerebral arteries. The test machine was the T150 Nanotensile. The stiffness variation with the increment of the strain level is modeled as the outcome of an isotropic hyperelastic material model.

FINDINGS

Through the application of an axial force we obtained Stress/Strain curves that showed a marked isotropic hyperelastic behavior, characterized by an increasing of stiffness with the level of strain. This behavior of the cerebral arterial wall is different from the well-established behavior of other arterial vessel (as the aortic vessel) characterized by a marked anisotropic behavior. Additionally, the data scattering observed for higher values of the applied stress are related to different individual packing of collagen fibers that represent the load-bearing mechanics at higher level of the strain.

INTERPRETATION

The data obtained by test in this paper represent a first step in our ongoing research about the mechanics of multi-axial loads on cerebral arterial walls, and in producing more comprehensive patient-specific calculations for potential applications on cerebral aneurysm management.

Twisting: Incidence and Risk Factors of an Intraprocedural Challenge Associated With Pipeline Flow Diversion of Cerebral Aneurysms

BACKGROUND

Pipeline Embolization Device (PED; Medtronic) "twisting" manifests with the appearance of a "figure 8" in perpendicular planes on digital subtraction angiography. This phenomenon has received little attention in the literature, requires technical precision to remediate, and has potential to cause ischemic stroke if not properly remediated.

OBJECTIVE

To report incidence, risk factors, and sequelae of PED twisting and to discuss techniques to remediate a PED twist.

METHODS

Case images were reviewed for instances of twisting from a prospectively-maintained, Institutional Review Board-approved cohort of patients undergoing flow diversion for cerebral aneurysm.

RESULTS

From August 2011 to December 2017, 999 PED flow diverting stents were attempted in 782 cases for 653 patients. A total of 25 PED twists were observed while treating 20 patients (2.50%, 25/999). Multivariate analysis revealed predictors of twisting to be: Large and giant aneurysms (odds ratio (OR) = 9.66, P = .005; OR = 27.47, P < .001), increased PED length (OR = 1.14, P < .001), and advanced patient age (OR = 1.07, P = .002). Twisted PEDs were able to be remediated 75% of the time, and procedural success was achieved in 90% of cases. PED twisting was not found to be a significant cause of major or minor complications. However, at long-term follow-up, there was a trend towards poor occlusion outcomes for the cases that encountered twisting.

CONCLUSION

Twisting is a rare event during PED deployment that was more likely to occur while treating large aneurysms with long devices in older patients. While twisting did not lead to major complications in this study, remediation can be challenging and may be associated with inferior occlusion outcomes.

Manejo bimodal de aneurismas asociados a malformaciones arteriovenosas cerebrales. Reporte de caso y breve revisión de la literatura

La patogénesis de los aneurismas intracraneales asociados a malformaciones arteriovenosas cerebrales no es bien entendida y es aún objeto de discusión. Las decisiones sobre cuándo y cómo tratar los aneurismas intracraneales de estas características siempre han sido un reto terapéutico tanto para neurocirujanos vasculares como para terapistas endovasculares neurológicos. Reportamos el caso de una paciente de 51 años con aneurismas múltiples asociados a una malformación arteriovenosa, así como su manejo neuroquirúrgico, con un análisis comparativo con lo publicado en la literatura médica y científica en los últimos 10 años.

The pathogenesis of intracranial aneurysms associated with arteriovenous malformations is not well understood and is still under discussion; the decisions about when and how to treat intracranial aneurysms of these characteristics have always been a therapeutic challenge for both, vascular neurosurgeons and endovascular neurological therapists. We report the case of a 51-year-old patient with multiple aneurysms associated with arteriovenous malformation, as well as her neurosurgical management, with a comparative analysis what has been published in the medical and scientific literature in the last 10 years.

Usefulness of Pointwise Encoding Time Reduction with Radial Acquisition and Subtraction-Based Magnetic Resonance Angiography after Cerebral Aneurysm Clipping

Objective

Time-of-flight magnetic resonance angiography (MRA) is limited by clip-induced artifacts after cerebral aneurysmal clipping. Recently, ultrashort echo time was shown to reduce metal artifacts. We assessed the pointwise encoding time reduction with radial acquisition (PETRA) sequence in subtraction-based MRA as an ultrashort echo time method during follow-up for clipping surgery.

Methods

We retrospectively evaluated 114 branches of 63 aneurysms in 56 patients treated with titanium clips using MRA and 3-dimensional computed tomography angiography. The appearance using each method was compared, and the associations between visibility on PETRA-MRA, clip number and shape, and amount of hematoma were examined. Furthermore, the visibility of the aneurysm remnants and 2 clipping cases with cobalt-chromium-nickel-molybdenum clips were evaluated.

Results

No branches were visible using time-of-flight-MRA, but 79 of 114 branches (69.3%) were visible on PETRA-MRA. PETRA-MRA was effective for follow-up imaging in 33 of 63 aneurysms (52.4%). The median vessel diameters were 1.67 mm (interquartile range, 1.24–2.62 mm) and 0.96 mm (interquartile range, 0.59–1.53 mm) in the visible and invisible groups, respectively. Only the vessel diameter correlated significantly (P < 0.001) with the visibility on PETRA-MRA. A receiver operating characteristic curve for the association between the vessel diameter and visibility on PETRA-MRA showed a cutoff value of 1.26 mm for vessel diameter. Cobalt-chromium-nickel-molybdenum clips produced a strong artifact, even on PETRA-MRA. All 4 residual aneurysms were visible on PETRA-MRA.

Conclusions

PETRA-MRA can be useful for follow-up aneurysm imaging when the diameter of vessels adjacent to the clip exceeds 1.26 mm. However, its usefulness is limited to titanium clips.

Y-Configuration Stenting for Coil Embolization of Complex Intracranial Aneurysms: Distinguishing Between Use of Crossing-Y and Kissing-Y

OBJECTIVE

Coil embolization with Y stenting is recognized as a suitable treatment for complex wide-necked aneurysms. Y stenting comprises crossing-Y stenting, in which a stent is passed through the interstices of another stent, and kissing-Y stenting, in which 2 stents are arranged in parallel. The purpose of this study was to elucidate how to distinguish between use of the 2 Y-stenting techniques.

METHODS

Clinical and angiographic data of patients who underwent coil embolization with Y stenting at our department from 2015 to 2019 were retrospectively analyzed. Basic characteristics, endovascular procedure, complications, and outcomes were compared between kissing-Y and crossing-Y stenting groups.

RESULTS

Thirty-eight intracranial aneurysms in 38 consecutive patients were included in this study. Nineteen patients (50%) were treated with coil embolization with kissing-Y stenting and 19 (50%) with crossing-Y. Endovascular procedures were successfully performed in all but 1 patient, in the kissing-Y group, who had stent migration. One hemorrhage (2.6%) recurred 12 months after coiling with kissing-Y stenting. Angiographic follow-up (mean, 15.8 months) was available in 35 patients. Adequate occlusion was shown in 14 patients (77.8%) and 13 patients (76.5%) in the kissing-Y and crossing-Y groups, respectively. Larger, wider-necked, and more proximal aneurysms were treated with kissing-Y stenting than with crossing-Y stenting, although there were no significant differences between the groups in complication rates or clinical outcomes.

CONCLUSIONS

Kissing-Y and crossing-Y stenting of intracranial aneurysms were both feasible and yielded reasonable angiographic and clinical results. The choice between the kissing-Y or crossing-Y-stenting technique should be decided according to the angioarchitecture of targeted aneurysms.

Overview of Different Flow Diverters and Flow Dynamics

Over the past decade, flow diverter technology for endocranial aneurysms has seen rapid evolution, with the development of new devices quickly outpacing the clinical evidence base. However, flow diversion has not yet been directly compared to surgical aneurysm clipping or other endovascular procedures. The oldest and most well-studied device is the Pipeline Embolization Device (PED; Medtronic), recently transitioned to the Pipeline Flex (Medtronic), which still has sparse data regarding outcomes. To date, other flow diverting devices have not been shown to outperform the PED, although information comes primarily from retrospective studies with short follow-up, which are not always comparable. Because of this lack of high-quality outcome data, no reliable recommendations can be made for choosing among flow diversion devices yet. Moreover, the decision to proceed with flow diversion should be individualized to each patient. In this work, we wish to provide a comprehensive overview of the technical specifications of all flow diverter devices currently available, accompanied by a succinct description of the evidence base surrounding each device.

Bilateral Transradial Approach for Coil Embolization of Basilar Artery Aneurysms Associated with an Unfavorable Vertebral Artery Anatomy : Initial Experience with Role-sharing Technique

PURPOSE

An unfavorable vertebral artery (VA) anatomy occasionally inhibits a successful VA cannulation due to flow stagnation after catheterization. To preserve antegrade VA flow, we developed bilateral transradial catheter systems, referred to as the role-sharing technique, for coil embolization of basilar artery (BA) aneurysms associated with an unfavorable VA anatomy. This study aimed to evaluate the feasibility and safety of coil embolization using the role-sharing technique for BA aneurysms.

METHODS

We retrospectively analyzed an institutional database of consecutive patients with BA aneurysm who underwent coil embolization using the role-sharing technique between July 2019 and January 2020. The study included seven consecutive patients. Bilateral transradial VA cannulation was performed using 3.2F catheters (TACTICS; Technocrat Corporation, Aichi, Japan) via 4F guiding sheaths placed in the subclavian artery. The following catheter systems were used: the triaxial system (4F guiding sheath/TACTICS/coil or stent delivery microcatheter) that has a specialized role in embolization and the biaxial system (4F guiding sheath/TACTICS) that has a specialized role in contrast injection during embolization procedure. The procedural success and procedure-related or vascular access site complications were assessed.

RESULTS

All patients underwent a successful embolization procedure using the bilateral transradial catheter systems and none of them presented with flow stagnation, system instability, or other complications.

CONCLUSION

The role-sharing technique was shown to be a feasible and safe method for coil embolization of BA aneurysms associated with an unfavorable VA anatomy. This method may increase the success rate of transradial coil embolization for BA aneurysms.

The Modified Fisher Scale Lacks Interrater Reliability

BACKGROUND

The modified Fisher scale (mFS) is a critical clinical and research tool for risk stratification of cerebral vasospasm. As such, the mFS is included as a common data element by the National Institute of Neurological Disorders and Stroke SAH Working Group. There are few studies assessing the interrater reliability of the mFS.

METHODS

We distributed a survey to a convenience sample with snowball sampling of practicing neurointensivists and through the research survey portion of the Neurocritical Care Society Web site. The survey consisted of 15 scrollable CT scans of patients with SAH for mFS grading, two questions regarding the definitions of the scale criteria and demographics of the responding physician. Kendall's coefficient of concordance was used to determine the interrater reliability of mFS grading.

RESULTS

Forty-six participants (97.8% neurocritical care fellowship trained, 78% UCNS-certified in neurocritical care, median 5 years (IQR 3-6.3) in practice, treating median of 80 patients (IQR 50-100) with SAH annually from 32 institutions) completed the survey. By mFS criteria, 30% correctly identified that there is no clear measurement of thin versus thick blood, and 42% correctly identified that blood in any ventricle is scored as "intraventricular blood." The overall interrater reliability by Kendall's coefficient of concordance for the mFS was moderate (W = 0.586, p < 0.0005).

CONCLUSIONS

Agreement among raters in grading the mFS is only moderate. Online training tools could be developed to improve mFS reliability and standardize research in SAH.

Treatment of a middle cerebral artery aneurysm in the setting of Loeys-Dietz syndrome: Case report and review of literature

Loeys-Dietz syndrome (LDS) is a connective tissue disorder with associated systemic vasculopathies including intracranial arterial aneurysm formation and dissections. LDS is a relatively less well-known entity compared with other connective tissue disorders, such as Ehlers-Danlos or Marfan syndrome, and consequently experience in the management of the associated intracranial aneurysms is suboptimal. We present a case of surgical clipping of a middle cerebral artery aneurysm in a patient with LDS. A 46-year-old female with LDS (type III) was found to have a right middle cerebral artery (MCA) bifurcation aneurysm following vascular screening. The decision was made to surgically clip the aneurysm after consultation in our neurovascular multidisciplinary team meeting. A standard right pterional craniotomy was performed and the aneurysm was secured with 2 straight Sugita clips. The temporal M2 branch was noted to be thin walled and this prompted application of the second tandem clip, rather than risk re-positioning the initial clip. In our case, the MCA aneurysm neck was robust enough to take a clip without any complications, and therefore we suggest that the presence of LDS is not an absolute contra-indication to perform open craniotomy and clipping.

Diagnosis and Initial Emergency Department Management of Subarachnoid Hemorrhage

Atraumatic subarachnoid hemorrhage represents a small proportion of strokes, but is a true medical emergency that results in significant morbidity and mortality. Making the diagnosis can be challenging and misdiagnosis can result in devastating consequences. There are several time-dependent diagnostic and management considerations for emergency physicians and other frontline providers. This article reviews the most up-to-date literature on the diagnostic workup of subarachnoid hemorrhage, avoiding misdiagnosis, and initial emergency department management recommendations.

Endovascular treatment of patient with multiple extracranial large vessel stenosis and coexistent unruptured wide-neck intracranial aneurysm using a WEB device and Szabo-technique

The coexistence of severe extracranial large vessel stenosis and unruptured intracranial aneurysms is not rare. There are different treatment approaches for these conditions, such as initial treatment of the aneurysm before revascularization of the stenosis; single-stage endovascular treatment of both lesions; stenosis eliminating followed by treatment of the aneurysm, or without treating the aneurysm. But, taking into account the risk of aneurysm rupture on the one hand and the risk of ischemic stroke on the other, it is sometimes difficult to choose the right management strategy. Despite this fact, there are still no guidelines or consensus on the management of these coexistent lesions. The article describes a clinical case of endovascular treatment of multiple extracranial stenosis and coexistent unruptured wide-neck aneurysm of the middle cerebral artery. The endovascular treatment of the carotid stenosis and aneurysm using a woven endobridge device was performed in one session; endovascular treatment of vertebral artery stenosis with Szabo technique was performed in another session.

Relationship between aspirin use and subarachnoid hemorrhage: A systematic Review and meta-analysis

BACKGROUND

Aspirin has been associated with a decreasing risk of subarachnoid hemorrhage due to its anti-inflammatory mechanism of action and potential protective properties against aneurysm growth.

OBJECTIVE

To determine the association between aneurysmal subarachnoid hemorrhage and aspirin use.

METHODS

A systematic review of the literature and a meta-analysis were performed across the PubMed database. The following keywords were used: "aspirin, acetylsalicylic acid, 2-acetyloxy-benzoic acid, ruptured intracranial aneurysm, aneurysmal subarachnoid hemorrhage, spontaneous subarachnoid hemorrhage, intracerebral hemorrhage, spontaneous aneurysmal hemorrhage, spontaneous intracerebral bleeding". Studies that were performed with animals or analyzed patients with traumatic brain injury were excluded. A total of five studies were included in our meta-analysis, with a total of 19,222 patients evaluated. Statistical analysis was performed to determine the association between the use of aspirin and the risk of subarachnoid hemorrhage.

RESULTS

Aspirin use reduce the risk of subarachnoid hemorrhage (odds ratio [OR] 0.51, 95 % confidence interval [CI] 0.34-0.76).

CONCLUSION

Although some previous studies suggested that aspirin may potentially reduce the risk of subarachnoid hemorrhage, our meta-analysis found an association between the reduction of risk of aneurysmal subarachnoid hemorrhage.

Interleukin-6 Promotes Murine Estrogen Deficiency-Associated Cerebral Aneurysm Rupture

BACKGROUND

Estrogen deficiency is associated with cerebral aneurysm rupture, but the precise mechanism is unknown.

OBJECTIVE

To test the hypothesis that IL-6 is required for the increase in aneurysm rupture rate observed in estrogen-deficient mice.

METHODS

We analyzed IL-6 expression in human cerebral aneurysms. We induced cerebral aneurysms in estrogen-deficient female C57BL/6 mice that had undergone 4-vinylcyclohexene diepoxide (VCD) treatment or bilateral ovariectomy (OVE). Mice were blindly randomized to selective IL-6 inhibition (IL-6 receptor [IL-6R] neutralizing antibody, n = 25) or control (isotype-matched IgG, n = 28). Murine cerebral arteries at the circle of Willis were assessed for aneurysm rupture and macrophage infiltration.

RESULTS

IL-6 is expressed in human cerebral aneurysms, but not in control arteries. Serum IL-6 is elevated in ovariectomized female mice compared to sham control (14.3 ± 1.7 pg/mL vs 7.4 ± 1.5 pg/mL, P = .008). Selective IL-6R inhibition suppressed cerebral aneurysm rupture in estrogen-deficient mice compared with control (VCD: 31.6% vs 70.0%, P = .026; OVE: 28.6% vs 65.2%, P = .019). IL-6R inhibition had no effect on formation or rupture rate in wild-type mice. IL-6R neutralizing antibody significantly reduced macrophage infiltration at the circle of Willis (1.9 ± 0.2 vs 5.7 ± 0.6 cells/2500 μm2; n = 8 vs n = 15; P < .001).

CONCLUSION

IL-6 is increased in the serum of estrogen-deficient mice and appears to play a role in promoting murine estrogen deficiency-associated cerebral aneurysm rupture via enhanced macrophage infiltration at the circle of Willis. Inhibition of IL-6 signaling via IL-6 receptor neutralizing antibody inhibits aneurysm rupture in estrogen-deficient mice. IL-6 receptor inhibition had no effect on aneurysm formation or rupture in wild-type animals.

Nimodipine after aneurysmal subarachnoid hemorrhage: Fourteen-day course for patients that meet criteria for early hospital discharge

BACKGROUND

Randomized-controlled trials and meta-analyses showed nimodipine use after aneurysmal subarachnoid hemorrhage (aSAH) leads to reduction in incidence of cerebral infarction, persistent neurological deficits, and poor outcomes. Trials administered it for 21 days; however, we assessed whether a shorter duration might be reasonable for a subset of patients.

METHODS

We performed a retrospective single-center study to compare outcomes between patients who received ≤14 days, 15-20 days or ≥21 days of nimodipine. Primary outcome was defined as rate of good functional outcome at final follow-up, assessed using dichotomized modified Rankin Score (mRS). Secondary outcomes included median mRS at follow-up, discharge disposition, and readmission for stroke or vasospasm.

RESULTS

195 patients were included: 101 patients received nimodipine for ≤14 days, 72 patients for 15-20 days, and 22 patients for ≥21 days. There were differences in baseline characteristics of the groups. The shorter duration groups had higher admission GCS score (GCS 15 for ≤14 days, GCS 13 for 15-20 days, GCS 8 for ≥21 days, p = 0.003) and lower Hunt-Hess grade (2 for ≤14 days, 3 for 15-20 days, 4 for ≥21 days, p = 0.001). Of the group of patients that received ≤14 days of nimodipine, 3 patients (3%) were readmitted for concerns for possible stroke or vasospasm, but they did not experience worsening of their functional status related to this.

CONCLUSION

Our data suggests a more limited 14-day course of nimodipine therapy after aSAH may be reasonable and efficacious in patients with higher GCS and lower Hunt-Hess grade on presentation.

Effect of Neck Size on the Inflow Magnitude Evaluated on 4D Flow MRI in Unruptured Internal Carotid Artery Aneurysms

BACKGROUND

A neck size >4.0 mm is a risk factor for recanalization after coil embolization. The high inflow magnitude of pretreatment wide-neck aneurysms may be correlated to recanalization. We aimed to elucidate the effect of the neck size on the inflow magnitude evaluated on four-dimensional (4D) flow magnetic resonance imaging (MRI) in pretreatment unruptured internal carotid artery (ICA) aneurysms.

METHODS

Thirty-three untreated ICA aneurysms were subjected to 4D flow MRI to evaluate the inflow magnitude parameters including the maximum spatially-averaged inflow velocity (MSAIV), maximum inflow velocity, maximum inflow rate (MIR), and their ratios to each corresponding flow parameter in the parent artery.

RESULTS

The neck size was linearly correlated to all inflow parameters investigated in this study. A strong correlation was observed between the neck size and the following: MSAIV (r = .755, p < .0001), MIR (r = .715, p < .0001), MSAIV ratio (r = .724, p < .0001), and MIR ratio (r = .741, p < .0001). The predicted value of MIR ratio of an aneurysm with the neck size of 4.0 mm was 23.0% and 20.6%, based on the linear regression equation of all aneurysms and on that of aneurysms with the neck size >4.0 mm, respectively.

CONCLUSIONS

The neck size was linearly correlated with the inflow magnitude of unruptured ICA aneurysms. Inflow magnitude evaluation using 4D flow MRI may help to hemodynamically identify aneurysms with a high risk of recanalization after endovascular coil embolization.

Low-dose adenosine-induced transient asystole during intracranial aneurysm surgery

Background

Few studies have evaluated the adenosine dose that induces cardiac arrest during intracranial aneurysm surgery. We present our experiences with adenosine-induced transient asystole (AiTA) during intracranial aneurysm surgery and dosage recommendations.

Methods

We retrospectively reviewed the medical records of all patients who underwent intracranial aneurysm surgery between July 2016 and December 2018. Patients who experienced AiTA during intracranial aneurysm surgery were included in the study.

Results

Our study included nine intracranial aneurysm surgeries performed in eight patients. Thirteen episodes of AiTA were reported. Five of these were performed to facilitate bleeding control due to intraoperative aneurysm rupture (IAR), and adenosine doses were 9 mg (0.20 mg/kg), 12 mg (0.25 mg/kg), 12 mg (0.26 mg/kg), 18 mg (0.34 mg/kg), and 18 mg (0.39 mg/kg), resulted in transient asystole for 12, 14, 9, 44, and 18 s, respectively. For episodes without IAR, adenosine doses ranging from 6 to 18 mg (0.11-0.39 mg/kg) caused asystole for 8-33 s. In five episodes without IAR, low-dose adenosine (lower than 0.2 mg/kg) was used and caused asystole ranging from 8 to 12 s. Postoperatively, two patients had elevated cardiac troponin T levels but normal electrocardiograms.

Conclusion

AiTA can facilitate the clipping of intracranial aneurysms at low-risk of serious cardiac complications. An adenosine dose of 0.2-0.4 mg/kg is safe and effective in both IAR and non IAR situations. In non IAR cases, we propose that low-dose AiTA is an option to facilitate aneurysm clipping. A starting dose of 6 mg or 0.1-0.2 mg/kg can adequately induce brief asystole by softening the aneurysmal sac during clip application.

Long-Term Outcome of Endovascular Therapy for Large or Giant Thrombosed Intracranial Aneurysms

OBJECTIVE

Large or giant thrombosed intracranial aneurysms (LGTIAs) are highly associated with poor prognosis and remain a challenging disease to treat by either surgery or endovascular treatment (EVT). EVT is considered more difficult for complicated aneurysm like LGTIAs. To understand long-term clinical and angiographic outcomes of EVT for LGTIAs, we retrospectively analyzed our single-center data on multimodality EVT for patients with LGTIAs.

METHODS

From the data of 35 EVT procedures performed in 31 consecutive patients with LGTIAs at our institution between December 2004 and December 2018, the rate of periprocedural complications, clinical outcomes at 12 months after EVT, and the rate of aneurysm recurrence were analyzed, and their related factors were evaluated.

RESULTS

Initial EVTs were performed by deconstructive (n = 10) or reconstructive (n = 21) techniques. Although 5 patients (16%) died during the periprocedural period, 23 (74%) had good outcome at 12 months after the procedures. Among 26 patients with long-term follow-up, aneurysm recurrence was observed in 6 patients (23.1%; median time from treatment, 33.2 months). Aneurysm recurrence was significantly higher in patients with basilar artery aneurysm (P = 0.0421) and stroke (P = 0.0307); however, there was no significant difference between the procedures and devices used.

CONCLUSIONS

Multimodality EVT for LGTIAs was performed with similar clinical outcomes and better radiologic outcomes compared with previous reports. New innovative techniques and devices are expected to be helpful for long-term aneurysm occlusion.

Long-Term Outcomes of Cerebral Blood Flow and Neurotransmitter Receptor Function on Iodine-123-Iomazenil Single-Photon Emission Computed Tomography and Cognitive Assessments After Parent Artery Occlusion Combined with Cerebral Revascularization for Internal Carotid Artery Aneurysms

OBJECTIVE

Many studies of external-internal carotid artery (EC-IC) bypass as cerebral revascularization for unclippable internal carotid artery (ICA) aneurysms have reported surgical outcomes, including bypass patency and aneurysm resolution. However, no previous studies have assessed the long-term outcomes of cerebral blood flow (CBF), brain neural density, and cognition. The purpose of the present study was to evaluate the long-term outcomes of CBF and neurotransmitter receptor function using early and late images of iodine-123 (¹²³I)-iomazenil (IMZ) single-photon emission computed tomography (SPECT) and the cognitive function of patients who had undergone EC-IC bypass for symptomatic aneurysms in the cavernous portion of the ICA.

METHODS

We performed a prospective observational study of 11 patients who had undergone superficial temporal artery-middle cerebral artery bypass or bypass using a saphenous vein graft for symptomatic aneurysms in the cavernous portion of the ICA. One patient experienced extensive infarction and, therefore, did not undergo postoperative testing. ¹²³I-IMZ SPECT was performed with scanning at 23 minutes (early) and 180 minutes (late) after tracer administration before and after surgery. The preoperative and follow-up neuropsychological test scores from 6 patients were also analyzed.

RESULTS

None of 10 patients who had undergone EC-IC bypass showed reductions in CBF and brain neural density. In addition, the neuropsychological test scores had not changed significantly from preoperatively to postoperatively.

CONCLUSION

Using early and late ¹²³I-IMZ SPECT, the present study has demonstrated that patients undergoing uncomplicated cerebral revascularization for unclippable ICA aneurysms will not experience reductions in CBF or neurotransmitter receptor function, and their cognitive function was not impaired.

An Aneurysm at the Origin of a Duplicated Middle Cerebral Artery Treated by Stent-Assisted Coiling Using the "Wrapped-Candy" Low-Profile Visualized Intraluminal Support (LVIS) Technique: A Technical Case Report and Review of the Literature

BACKGROUND

Aneurysms at the origin of a duplicated middle cerebral artery (DMCA) are quite rare. Here, we report a patient with such an aneurysm successfully treated endovascularly using our novel "wrapped-candy" low-profile visualized intraluminal support (LVIS) technique.

CASE DESCRIPTION

A 44-year-old woman underwent endovascular treatment for an unruptured wide-necked aneurysm at the origin of a DMCA that incorporated the origin of the DMCA into its neck. Stent-assisted coiling was performed using our newly developed "wrapped-candy" LVIS technique. To protect the origin of the DMCA and increase the stent metal density at the neck, an LVIS blue 3.5-mm × 22-mm stent was deployed by pushing the delivery wire aggressively to transform the visible wire components of the LVIS into a shape like "wrapped candy," maximizing the strut compaction at the neck of the aneurysm. Subsequently, the aneurysm component was coiled using a jailed microcatheter. The final procedural angiography demonstrated almost complete aneurysm occlusion with DMCA preservation.

CONCLUSIONS

Stent-assisted coiling can be a feasible treatment for an unruptured, usually wide-necked, aneurysm at the origin of a DMCA. The wrapped-candy LVIS technique may be useful in more challenging morphologies such as wide-necked aneurysms that incorporate the branch origin into the aneurysm neck.

Three tesla magnetic resonance angiography with ultrashort echo time describes the arteries near the cerebral aneurysm with clip and the peripheral cerebral arteries

Background:

The assessment of the clipped cerebral aneurysm and the cerebral arteries after the treatment of subarachnoid hemorrhage (SAH) is important to find aneurysm regrowth or postoperative cerebral vasospasm. Usually, contrast-enhanced computed tomography angiography is performed for the evaluation of the arteries, but it has side effects of contrast medium. Time-of-flight magnetic resonance angiography (MRA) is a fast and non-invasive method, but clip-induced artifact limits assessment of the artery in the vicinity of the clip. 1.5T MRA with ultrashort echo time (UTE) reduces metal artifact, but the obtained image is too rough to evaluate the aneurysm remnant, and the description range is too narrow to assess the cerebral vasospasm. We routinely use SIGNA Pioneer 3.0T (GE Healthcare Life Sciences, Buckinghamshire, England) and perform SILENT SCAN with UTE-MRA for the postoperative assessment of the clipped aneurysm and cerebral arteries for SAH patients treated by clipping. It has better image quality and describes arteries with a wide description range, so it possesses the potential to overcome the disadvantages of 1.5T UTE-MRA.

Case Description:

We presented a representative SAH patient who postoperatively underwent 3.0T UTE- MRA after clipping. The artery near the clipped aneurysm was evaluated in detail, and the cerebral arteries were described from the main trunk to the peripheral parts with a wide description range, which enabled the assessment of cerebral vasospasm.

Conclusion:

3.0T UTE-MRA may be helpful for the usual assessment of the arteries after clipping and cerebral vasospasm in the future.

Internal Maxillary to Middle Cerebral Artery Bypass Using an Anterior Tibial Artery Graft, Performed Using a 3-Dimensional Exoscope: 2-Dimensional Operative Video

Fusiform aneurysms remain challenging entities to treat, as maintenance of flow and prevention of branch occlusion are concerns. Use of endovascular stents may risk nearby branch occlusion. We present a 31-yr-old male with a prior subarachnoid hemorrhage from a left middle cerebral artery (MCA) M1 aneurysm. Informed consent for use of the operative video and information was obtained from the patient. Initially, open clipping was performed with noted residual because of risk of nearby branches. On angiography, a growing fusiform segment distal to the initial aneurysm was noted. The patient was referred to our institution for this finding, and a multidisciplinary team reviewed the case. Endovascular treatment was felt to be risky, as stenting could jail nearby MCA branches. Clipping would also risk occlusion because of scaring from previous hemorrhage. Sufficient flow would be needed, and because the ipsilateral superficial temporal artery was sacrificed in the initial craniotomy, the internal maxillary artery (IMAX) was chosen as the bypass source. A cerebrovascular neurosurgeon, skull base otolaryngologist, and vascular surgeon worked together to perform a left-side IMAX to MCA bypass using an anterior tibial artery graft under 3-dimensional exoscopic visualization. Specifically, a 9-0 nylon suture on a BV-130 needle along with straight and tying forceps were used along with heparinized saline. The bypass was noted to be of robust flow, and the patient did very well on postoperative follow-up. The utilization of an anterior tibial artery graft, IMAX exposure, and corresponding bypass provides educational value, as there are only a limited number of videos on this topic.

Early strategy of scepter XC balloon angioplasty and simultaneous Nimodipine infusion for vasospasm following ruptured aneurysm

Background

Cerebral vasospasm still results in high morbidity and mortality rates in patients after aneurysmal subarachnoid hemorrhage (SAH). The aim of this study was to establish a protocol for the management of vasospasm and demonstrate our experience of angioplasty using the Scepter XC balloon catheter.

Methods

In this retrospective study, a computed tomography angiography and perfusion image was arranged if early symptoms occurred or on the 7th day following aneurysmal SAH. In patients with clear consciousness, balloon angioplasties were performed for symptomatic vasospasms, which were not improved within 6–12 h after maximal medical treatments. In unconscious patients, balloon angioplasties were performed for all patients with angiographic vasospasms.

Results

Fifty patients underwent Scepter XC balloon angioplasty among 396 consecutive patients who accepted endovascular or surgical treatments for ruptured aneurysms. All angioplasty procedures were successful without complications. 100% angiographic improvement and 94% clinical improvement were reached immediately after the angioplasties. A favorable functional outcome (modified Rankin Score of ≤2) could be achieved in 82% of patients. Even in patients with poor clinical grading (Hunt–Hess grade 4–5), a clinical improvement rate of 87.5% and favorable outcome rate was 70.8% could be achieved.

Conclusion

Balloon angioplasty with Scepter XC balloon catheter is safe and effective for post-SAH vasospasm. This device’s extra-compliant characteristics could considerably improve the quality of angioplasty procedures. For all patients, even those with poor neurological status, early treatment with combined protocol of nimodipine and angioplasty can have good clinical outcomes.

Treatment of Acutely Ruptured Cerebral Aneurysms With the Woven EndoBridge Device: Experience Post-FDA Approval

BACKGROUND

Coil embolization of ruptured bifurcation aneurysms is challenging and often necessitates adjunctive stenting, which requires antiplatelet therapy in the setting of subarachnoid hemorrhage (SAH). The Woven EndoBridge (WEB; Terumo) device is an alternative self-expanding 3D mesh that does not require antiplatelet agents. However, its use has been mostly reserved for unruptured aneurysms.

OBJECTIVE

To assess the safety and feasibility of ruptured aneurysm treatment with the WEB.

METHODS

Retrospective analysis of 9 SAH patients with 11 aneurysms that were treated with the WEB device at 2 institutions after FDA approval.

RESULTS

Hunt and Hess grades were III and IV in 4 (44%) each and V in 1 (11%). All patients were treated within 24 h of hospitalization, and a single WEB was used in all but one aneurysm. Aneurysms treated were 3 basilar tip, 2 anterior communicating artery, 2 posterior inferior cerebellarartery, 1 middle cerebral artery, 1 carotid-ophthalmic artery, 1 posterior communicating artery, and 1 vertebrobasilar junction. Mean aneurysm height and width were 6.2 ± 2.2 mm (range: 3-10) and 5.6 ± 3.0 mm (range: 3.3-14), respectively. Mean dome-to-neck ratio was 1.7 ± 0.8 (range: 1.0-3.8). There was one intraoperative rupture that occurred because of device dislodgement and was managed with embolization. There were no treatment-related mortalities and no re-rupture after securement of the aneurysms with the WEB.

CONCLUSION

Our preliminary experience indicates that the WEB device can be used safely for ruptured aneurysms of various sizes in the anterior and posterior circulation. Larger series with long-term follow-up are necessary to confirm our findings.

External validation demonstrated the Ottawa SAH prediction models can identify pSAH using health administrative data

OBJECTIVES

The objective of the study is to externally validate three primary subarachnoid hemorrhage (pSAH) identification models.

STUDY DESIGN AND SETTING

We evaluated three models that identify pSAH using recursive partitioning (A), logistic regression (B), and a prevalence-adjusted logistic regression(C), respectively. Blinded chart review and/or linkage to existing registries determined pSAH status. We included all patients aged ≥18 in four participating center registries or whose discharge abstracts contained ≥1 administrative codes of interest between January 1, 2012 and December 31, 2013.

RESULTS

A total of 3,262 of 193,190 admissions underwent chart review (n = 2,493) or registry linkage (n = 769). A total of 657 had pSAH confirmed (20·1% sample, 0·34% admissions). The sensitivity, specificity, and positive predictive value (PPV) were as follows: i) model A: 98·3% (97·0-99·2), 53·5% (51·5-55·4), and 34·8% (32·6-37·0); ii) model B (score ≥6): 98·0% (96·6-98·9), 47·4% (45·5-49·4), and 32·0% (30·0-34·1); and iii) model C (score ≥2): 95·7% (93·9-97·2), 85·5% (84·0-86·8), and 62·3 (59·3-65·3), respectively. Model C scores of 0, 1, 2, 3, or 4 had probabilities of 0·5% (0·2-1·5), 1·5% (1·0-2·2), 24·8% (21·0-29·0), 90·0% (86·8-92·0), and 97·8% (88·7-99·6), without significant difference between centers (P = 0·86). The PPV of the International Classification of Diseases code (I60) was 63·0% (95% confidence interval: 60·0-66·0).

CONCLUSIONS

All three models were highly sensitive for pSAH. Model C could be used to adjust for misclassification bias.

Intraoperative neurophysiological monitoring in aneurysm clipping: Does it make a difference? A systematic review and meta-analysis

The use of intraoperative neurophysiological monitoring (IOM) has been proposed to prevent new neurological deficit during aneurysm clipping. The purpose of this meta-analysis was to evaluate if IOM can prevent neurological injury during clipping of intracranial aneurysm. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews and meta-analysis, we reviewed clinical comparative studies who evaluate the rate of new neurological deficit in patients who had a surgical clipping with and without IOM. Of the 268 citations screened, four studies (including 873 patients) met the inclusion criteria and were included in the meta-analysis. Patients who received surgery with IOM had less new neurological deficit than those who underwent surgery without it (p = 0,04). This finding was more significant in the subgroup analysis of two studies focused on middle cerebral artery (MCA) aneurysm (p = 0,02). However, a specific analysis of the three studies reporting the results of IOM to prevent permanent deficit revealed that there is only a trend for less neurological events in monitored patients without statistically significance (p = 0,05). The use of IOM during clipping of intracranial aneurysm was associated with less new neurological deficit with the obtained evidence of the included studies. However, at long-term follow-up the use of IOM did not correlate with a significant improvement in neurological outcome.

Automated computer-assisted detection system for cerebral aneurysms in time-of-flight magnetic resonance angiography using fully convolutional network

Background

As the rupture of cerebral aneurysm may lead to fatal results, early detection of unruptured aneurysms may save lives. At present, the contrast-unenhanced time-of-flight magnetic resonance angiography is one of the most commonly used methods for screening aneurysms. The computer-assisted detection system for cerebral aneurysms can help clinicians improve the accuracy of aneurysm diagnosis. As fully convolutional network could classify the image pixel-wise, its three-dimensional implementation is highly suitable for the classification of the vascular structure. However, because the volume of blood vessels in the image is relatively small, 3D convolutional neural network does not work well for blood vessels.

Results

The presented study developed a computer-assisted detection system for cerebral aneurysms in the contrast-unenhanced time-of-flight magnetic resonance angiography image. The system first extracts the volume of interest with a fully automatic vessel segmentation algorithm, then uses 3D-UNet-based fully convolutional network to detect the aneurysm areas. A total of 131 magnetic resonance angiography image data are used in this study, among which 76 are training sets, 20 are internal test sets and 35 are external test sets. The presented system obtained 94.4% sensitivity in the fivefold cross-validation of the internal test sets and obtained 82.9% sensitivity with 0.86 false positive/case in the detection of the external test sets.

Conclusions

The proposed computer-assisted detection system can automatically detect the suspected aneurysm areas in contrast-unenhanced time-of-flight magnetic resonance angiography images. It can be used for aneurysm screening in the daily physical examination.

Morphological Change of Cerebral Aneurysm with Possible Pseudoaneurysm at A2/3 of the Anterior Cerebral Artery on Three-dimensional Computed Tomographic Angiography

Intracranial pseudoaneurysm formation due to a ruptured nontraumatic aneurysm is rare. We describe a case of ruptured aneurysm, which showed morphological change on radiological examinations. An 83-year-old woman developed subarachnoid hemorrhage (SAH) with ventricular rupture and intracerebral hematoma in the corpus callosum. Contrast-enhanced computed tomography (CE-CT) demonstrated an aneurysm at the right A2/3 junction of the anterior cerebral artery. CE-CT repeated 17 h after the initial one showed shortening of the lesion on both three-dimensional and raw images. The aneurysm was surgically clipped. In cases of SAH with a hematoma or thick SAH, there is a possibility that a pseudoaneurysm will form at the tip of the true aneurysm in an adjacent thrombus or existence of intraluminal thrombus. The morphology may change during the period between initial radiological evaluation and the operation in these cases. We should be aware that the intraoperative findings or subsequent radiological findings might be different from those observed on preoperative radiological examinations.

Computational fluid dynamics simulations of cerebral aneurysm using Newtonian, power-law and quasi-mechanistic blood viscosity models

Cerebral aneurysm is a fatal neurovascular disorder. Computational fluid dynamics simulation of aneurysm haemodynamics is one of the most important research tools which provide increasing potential for clinical applications. However, computational fluid dynamics modelling of such delicate neurovascular disorder involves physical complexities that cannot be easily simplified. Recently, it was shown that the Newtonian simplification used to close the shear stress tensor of the Navier-Stokes equation is not sufficient to explore aneurysm haemodynamics. This article explores the differences between the latter simplification, non-Newtonian power-law model and a newly proposed quasi-mechanistic model. The modified Krieger model, which treats blood as a suspension of plasma and particles, was implemented in computational fluid dynamics context here for the first time and is made available to the readers in a C# code in the supplementary material of this article. Two middle-cerebral artery and two anterior-communicating artery aneurysms, all ruptured, were utilized here as case studies. It was shown that the modified Krieger model had higher sensitivity for wall shear stress calculations in comparison with the other two models. The modified Krieger model yielded lower wall shear stress values consistently in comparison with the other two models. Moreover, the modified Krieger model has generally predicted higher pressure in the aneurysm models. Based on published aneurysm rupture studies, it is believed that ruptured aneurysms are usually correlated with lower wall shear stress values than unruptured ones. Therefore, this work concludes that the modified Krieger model is a potential candidate for providing better clinical relevance to aneurysm computational fluid dynamics simulations.

Temporal muscle thickness and area with various characteristics data of the patients with aneurysmal subarachnoid hemorrhage who underwent endovascular coiling

These data present the characteristics of patients with subarachnoid hemorrhage who underwent endovascular coiling. We retrospectively collected data from the medical records of Iwaki City Medical Center including physiological symptoms, laboratory data, radiological data on admission, and modified Rankin Scale scores at 6 months. Our article entitled “Temporal Muscle as an Indicator of Sarcopenia is Independently Associated with Hunt and Kosnik Grade on Admission and the Modified Rankin Scale at 6 Month of Patients with Subarachnoid Hemorrhage Treated by Endovascular Coiling” was based on these data [1]. We previously reported similar small dataset of elderly patients with subarachnoid hemorrhage who underwent surgical clipping [2], [3]. However, remarkably, this is the largest and the first dataset on temporal muscle thickness or area of patients of all ages with subarachnoid hemorrhage who underwent endovascular coiling, not surgical clipping.

Discrepancy between two-dimensional and three-dimensional digital subtraction angiography for the planning of endovascular coiling of small cerebral aneurysms <5 mm

BACKGROUND

To investigate the discrepancy between two-dimensional digital subtraction angiography and three-dimensional rotational angiography for small (<5 mm) cerebral aneurysms and the impact on decision making among neuro-interventional experts as evaluated by online questionnaire.

MATERIALS AND METHODS

Eight small (<5 mm) ruptured aneurysms were visually identified in 16 image sets in either two-dimensional or three-dimensional format for placement in a questionnaire for 11 invited neuro-interventionalists. For each set, two questions were posed: Question 1: "Which of the following is the preferred treatment choice: simple coiling, balloon remodeling or stent assisted coiling?"; Question 2: "Is it achievable to secure the aneurysm with pure simple coiling?" The discrepancies of angio-architecture parameters and treatment choices between two-dimensional-digital subtraction angiography and three-dimensional rotational angiography were evaluated.

RESULTS

In all eight cases, the neck images via three-dimensional rotational angiography were larger than two-dimensional-digital subtraction angiography with a mean difference of 0.95 mm. All eight cases analyzed with three-dimensional rotational angiography, but only one case with two-dimensional-digital subtraction angiography were classified as wide-neck aneurysms with dome-to-neck ratio < 1.5. The treatment choices based on the two-dimensional or three-dimensional information were different in 56 of 88 (63.6%) paired answers. Simple coiling was the preferred choice in 66 (75%) and 26 (29.6%) answers based on two-dimensional and three-dimensional information, respectively. Three types of angio-architecture with a narrow gap between the aneurysm sidewall and parent artery were proposed as an explanation for neck overestimation with three-dimensional rotational angiography.

CONCLUSIONS

Aneurysm neck overestimation with three-dimensional rotational angiography predisposed neuro-interventionalists to more complex treatment techniques. Additional two-dimensional information is crucial for endovascular treatment planning for small cerebral aneurysms.

Natural Y-shaped radial artery graft bypass for a complex middle cerebral artery aneurysm: A case report

Giant thrombosed middle cerebral artery (MCA) aneurysms are difficult to treat and sometimes require complex revascularization using allografts. We describe a technical method using revascularization with a natural Y-shaped graft that provides a normal variation for a complex MCA aneurysm. A 65-year-old man with a giant thrombosed MCA aneurysm presented with right hemiparesis and aphasia. The patient had a history of clipping surgery for the ipsilateral side of the MCA aneurysm 25 years before, and a de novo aneurysm developed over the previous 18 years. For the giant thrombosed aneurysm, trapping and revascularization were performed. A natural radial artery Y-graft was used as the graft and anastomosed to both M2 trunks. The symptoms improved after surgery, and the patient was discharged 3 weeks later. This is the first report of a double-barrel bypass using a natural Y-graft. This method attained a normal variation, and the flow of the Y-graft was physiological. For the radical cure of giant thrombosed MCA aneurysms, multiple revascularizations might be required. With this natural Y-graft, complex transpositions could be avoided.

Stent-Assisted Coiling Using Leo+ Baby Stent : Immediate and Mid-Term Results

Background

Stent-assisted coiling is well-established for treatment of cerebral aneurysms. The technique enables treatment of wide-neck, bifurcation and recurrent aneurysms with high packing rates. While described in extenso for laser cut stents, the results of patients treated with the Leo+ Baby (Balt, Montmorency, France) braided microstent are presented.

Material and Methods

Patients were included if treated with a Leo+ Baby and with digital subtraction angiography (DSA) follow-up available of at least 6 months. Data were evaluated for successful deployment, aneurysm occlusion according to the modified Raymond-Roy classification (MRRC), stent patency and procedure-related morbidity and mortality.

Results

A total of 81 patients were included and Leo+ Baby deployment was successful in all cases. Coils were used in 80 cases. In 1 case 2 stents were used stent-in-stent without additional coiling. Initial aneurysm occlusion rates were MRRC_i1 51.9%, MRRC_i2 11.1%, MRRC_i3a 24.7% and MRRC_i3b 12.3%. Occlusion rates after 6 months were MRRC_6m1 78.9%, MRRC_6m2 3.9%, MRRC_6m3a 6.6% and MRRC_6m3b 10.5%. Procedure-related morbidity was 1 case of acute stent thrombosis successfully treated with tirofiban and 1 case with transient hemiparesis due to stent thrombosis after 4 months. There was 1 case of coil-associated subarachnoid hemorrhage (SAH) which caused prolonged hospitalization. No procedure-related mortality was observed.

Conclusion

The results confirm that stent-assisted coiling with the Leo+ Baby stent is safe and efficient for treatment of wide neck or recurrent cerebral aneurysms. Spontaneous progressive aneurysm occlusion over 6 months supports the theory of considerable flow-modulating effects of Leo+ Baby.

Does Systemic Lupus Erythematosus Increase the Risk of Procedure-Related Complication in Endovascular Treatment of Intracranial Aneurysm?

Cerebral aneurysms associated with systemic lupus erythematosus (SLE) are more likely to grow rapidly and rupture, compared to those found in the general population. The main underlying pathology of intracranial aneurysm and its rupture is presumed to be SLE-related intracranial vasculitis and fragility of blood vessels due to prolonged use of steroid. For these reasons, both surgical and endovascular options are challenging. On the other hand, given the possibility that SLE may predispose to growth and rupture of intracranial aneurysm, early intervention for cerebral aneurysms associated with SLE may be more necessary and beneficial than other cerebral aneurysms in the general population. Here we would like to report on the unexpected complications that occurred during or after endovascular treatment of an SLE patient with multiple aneurysms. The complications include intraprocedural rupture of unruptured aneurysm, coil stretching, contrast-induced encephalopathy, and delayed ipsilateral intraparenchymal hemorrhage after stent-assisted coiling. Our unique case highlights that the SLE patient with multiple intracranial aneurysms had a higher risk of endovascular procedure-related complications, which might be due to the increased bleeding tendency and fragility of blood vessels.

What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review

Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier-Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.

Magnetic resonance angiography with ultrashort echo time evaluates cerebral aneurysm with clip

Contrast-enhanced computed tomography angiography is usually valuable for the evaluation of clipped cerebral aneurysm, but it has side effects of contrast medium. Time-of-flight magnetic resonance angiography (MRA) is a non-invasive and fast method. However, clip-induced artifact limits assessment of the artery in the vicinity of a clip. MRA with ultrashort echo time (TE) reduces metal artifact. We use MAGNETOM Aera 1.5T (SIEMENS, München, Germany) and perform pointwise encoding time reduction with radial acquisition (PETRA)-MRA using ultrashort TE for the assessment of the cerebral aneurysm after clipping. We, herein, presented two representative cases with a clipped aneurysm which could be evaluated by PETRA- MRA. Especially in one of them, the neck remnant was revealed by PETRA-MRA. PETRA-MRA can reduce the time and the invasiveness and may be helpful for the usual follow-up of the clipped aneurysm with the development of MRA technology in the future.

Relationshıp of spontaneous subarachnoid haemorrhage and cerebral aneurysm to serum Visfatin and Nesfatin-1 levels

OBJECTIVES

Visfatin and nesfatin are recently discovered peptides that play a role in various metabolic reactions exhibiting inflammatory and neuroprotective effects, and their levels are known to increase in cerebral ischaemia and haematomas. Inflammation plays a role in the development of aneurysm, and spontaneous subarachnoid haemorrhage (SAH) is typically caused by rupture of the aneurysmal sac because of the increased inflammation. In the present study, we investigated the relationship between serum visfatin and nesfatin levels and the clinical and radiological findings in patients with SAH.

PATIENTS AND METHOD

Overall, 62 patients with spontaneous SAH who were followed-up in our clinic between September 2018 and July 2019 and 35 healthy patients who presented to our outpatient clinic with complaints of back, lumbar and neck pain were included in the study. ELISA method was used to study the visfatin and nesfatin levels in the serum samples of both groups. The visfatin and nesfatin levels of patients with spontaneous SAH were compared with the healthy population. In addition, the relationship between visfatin and nesfatin levels and the radiological and clinical findings of patients with spontaneous SAH were also investigated. All findings were evaluated statistically.

RESULTS

The median nesfatin and mean visfatin levels were higher in patients with SAH compared with the control group. The median nesfatin and mean visfatin levels were higher in patients with aneurysm than those without aneurysm. A positive correlation was observed between aneurysm length and nesfatin and visfatin levels. In patients with perimesencephalic haemorrhage, the mean visfatin level was determined to be lower compared with patients with classical aneurysmatic SAH, and the median nesfatin level did not differ significantly. The cut-off value of nesfatin for predicting SAH in patients compared with controls was >598.4 with 82.8 % sensitivity and 80 % specificity (P <  0.001). The cut-off value of visfatin for predicting SAH was >10.3 with 85.3 % sensitivity and 91.4 % specificity (P <  0.001). The diagnostic performance of visfatin and nesfatin levels was similar in predicting SAH.

CONCLUSION

In the present study, we demonstrated that the presence of aneurysm, size of aneurysm, number of aneurysms correlate with visfatin and nesfatin levels in patients with SAH, and visfatin and nesfatin may be biomarkers for predicting SAH and presence of aneurysm. Nonetheless, future studies can include patients with unruptured aneurysm and investigate their serum visfatin and nesfatin levels to prove whether visfatin and nesfatin can serve as biomarkers in the follow-up of these patients.

Simultaneous neck coverage and branch preservation using the proximal portion of a self-expandable open-cell stent for embolization of distal internal carotid artery aneurysms: multi-center, long-term results

PURPOSE

We report the long-term results of a modified stent-assisted coil embolization technique using the far proximal part of a self-expanding open-cell stent. The technique was used to cover the neck of the aneurysm while simultaneously preserving the branches of the distal internal carotid artery in patients with aneurysms of the posterior communicating (Pcom) and anterior choroidal arteries (AchA).

METHODS

We performed a retrospective review of the prospectively maintained databases at two tertiary neurosurgical centers to identify all patients who underwent embolization of Pcom or AchA aneurysms using this technique between January 2014 and July 2019. Postoperative and follow-up clinical and radiological results for initial (n = 16) or re-do (n = 4) embolizations were analyzed.

RESULTS

We identified 19 patients with 20 (16 Pcom and 4 AchA) unruptured (n = 19) or ruptured (n = 1) aneurysms. Eighteen among 20 stents (90.0%) were deployed successfully, and complete occlusions were initially attained in 18 aneurysms (90.0%). At follow-up examinations 8 to 56 months later, 6 of 14 aneurysms (42.8%) showed neck remnants. All of the branches were saved and no thromboembolic event, rupture, or sequelae were noted during or after the procedures.

CONCLUSION

These results suggest that this modified stent-assisted technique is a feasible and reasonable alternative to conventional stent deployment for coil embolization of wide-necked sidewall aneurysms in the distal ICA.

Spreading Depolarizations and Subarachnoid Hemorrhage

Cortical spreading depolarizations (SD) are strongly associated with worse tissue injury and clinical outcomes in the setting of aneurysmal subarachnoid hemorrhage (SAH). Animal studies have suggested a causal relationship, and new therapies to target SDs are starting to be tested in clinical studies. A recent set of single-center randomized trials assessed the effect of the phosphodiesterase inhibitor cilostazol in patients with SAH. Cilostazol led to improved functional outcomes and SD-related metrics in treated patients through a putative mechanism of improved cerebral blood flow. Another promising therapeutic approach includes attempts to block SDs with, for example, the NMDA receptor antagonist ketamine. SDs have emerged not only as a therapeutic target but also as a potentially useful biomarker for brain injury following SAH. Additional clinical and preclinical experimental work is greatly needed to assess the generalizability of existing therapeutic trials and to better delineate the relationship between SDs, SAH, and functional outcome.

Cerebral Aneurysms in Autosomal Dominant Polycystic Kidney Disease: A Comparison of Management Approaches

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is a risk factor for formation of intracranial aneurysms (IAs), though the ideal screening and treatment strategies in this population are unclear.

OBJECTIVE

To report outcomes of observation, open surgical, or endovascular management of ruptured and unruptured aneurysms in patients with ADPKD.

METHODS

We performed a retrospective analysis of all patients with ADPKD and IAs at a single center from 2000 to 2016.

RESULTS

Forty-five patients with ADPKD harboring 71 aneurysms were identified, including 11 patients with subarachnoid hemorrhage (SAH). Of 22 aneurysms managed with observation, none ruptured in 136 yr of clinical follow-up. Thirty-five aneurysms were treated with open surgery and 14 with an endovascular approach. Among treated aneurysms, poor neurologic outcome (modified Rankin scale >2) was seen only in patients presenting with SAH (17% SAH vs 0% elective, P = .06). Acute kidney injury (AKI) was also significantly associated with SAH presentation (22% SAH vs 0% elective, P = .05). Neither procedural complications nor AKI were associated with treatment modality. Among 175 yr of radiographic follow-up in patients with known IAs, 8 de novo aneurysms were found, including 3 that were treated. Of 11 patients with SAH, 7 ruptured in the setting of previously known ADPKD, including 2 with prior angiographic screening and 5 without screening.

CONCLUSION

Poor outcomes occurred only with ruptured presentation but were equivalent between treatment modalities. Screening is performed only selectively, and 64% (7 of 11) of patients presenting with SAH had previously known ADPKD.

Vascular Ehlers-Danlos Syndrome: Literature review and surgical management of intracranial vascular complications

Vascular Ehlers-Danlos (vEDS) is a rare form of the Ehlers-Danlos Syndrome (EDS) where arterial fragility results from mutations in the gene that encodes type III collagen. The disease can lead to major neurological complications including carotico-cavernous fistulae (CCF), aneurysms of the Circle of Willis and endovascular procedures have an increased risk profile due to the delicate vasculature. Management of intracranial disease in vEDS requires an intricate understanding of the syndrome but is still associated with significant complications that lead to morbidity and mortality. As well as providing an approach to the management of neurovascular complications in vEDS, the relevant literature regarding nosology, aetiology and genetics of the condition is summarised here. Particular emphasis is placed on the two most common intracranial complications, namely carotico-cavernous fistulas and and cerebral aneurysms. Pros and cons of surgical and endovascular interventions are discussed and a technical discussion is concentrated on the surgical aspects of management.

WEB as a combined support and embolization device in a giant partially thrombosed donut-shaped aneurysm

BACKGROUND

Giant partially thrombosed aneurysms are challenging lesions for which treatment can be difficult due to their unfavourable anatomical configuration and abnormal flow conditions.

CASE DESCRIPTION

The patient presented in this report suffered from a symptomatic giant partially thrombosed donut-shaped aneurysm of the left-sided supraophthalmic internal carotid artery. Due to the location and the size of the aneurysm, endovascular treatment was performed. Navigation of the microcatheter-microwire-system distal to the aneurysm for stent deployment was technically not possible due to limited support, caused by the large aneurysm. Therefore, a WEB device was placed in the distal leg of the donut-shaped aneurysm. Additionally to the occlusion of this part of the aneurysm, the WEB device enabled enough support to navigate the microcatheter-microwire-system distal to the aneurysm. After deployment of a flow-diverting stent, coiling of the aneurysm was performed. Follow-up angiography showed complete occlusion of the aneurysm. The patient suffered from severe headaches which were no longer present 6 months after treatment.

CONCLUSIONS

The WEB intraaneurysmal flow diverter can be effectively used as combined support and embolization device for the treatment of complex aneurysms in selective cases where other catheterization and embolization strategies have failed.

Lattice-Boltzmann interactive blood flow simulation pipeline

PURPOSE

Cerebral aneurysms are one of the prevalent cerebrovascular disorders in adults worldwide and caused by a weakness in the brain artery. The most impressive treatment for a brain aneurysm is interventional radiology treatment, which is extremely dependent on the skill level of the radiologist. Hence, accurate detection and effective therapy for cerebral aneurysms still remain important clinical challenges. In this work, we have introduced a pipeline for cerebral blood flow simulation and real-time visualization incorporating all aspects from medical image acquisition to real-time visualization and steering.

METHODS

We have developed and employed an improved version of HemeLB as the main computational core of the pipeline. HemeLB is a massive parallel lattice-Boltzmann fluid solver optimized for sparse and complex geometries. The visualization component of this pipeline is based on the ray marching method implemented on CUDA capable GPU cores.

RESULTS

The proposed visualization engine is evaluated comprehensively and the reported results demonstrate that it achieves significantly higher scalability and sites updates per second, indicating higher update rate of geometry sites' values, in comparison with the original HemeLB. This proposed engine is more than two times faster and capable of 3D visualization of the results by processing more than 30 frames per second.

CONCLUSION

A reliable modeling and visualizing environment for measuring and displaying blood flow patterns in vivo, which can provide insight into the hemodynamic characteristics of cerebral aneurysms, is presented in this work. This pipeline increases the speed of visualization and maximizes the performance of the processing units to do the tasks by breaking them into smaller tasks and working with GPU to render the images. Hence, the proposed pipeline can be applied as part of clinical routines to provide the clinicians with the real-time cerebral blood flow-related information.

Incorporating variability of patient inflow conditions into statistical models for aneurysm rupture assessment

BACKGROUND

Hemodynamic patterns have been associated with cerebral aneurysm instability. For patient-specific computational fluid dynamics (CFD) simulations, the inflow rates of a patient are typically not known. The aim of this study was to analyze the influence of inter- and intra-patient variations of cerebral blood flow on the computed hemodynamics through CFD simulations and to incorporate these variations into statistical models for aneurysm rupture prediction.

METHODS

Image data of 1820 aneurysms were used for patient-specific steady CFD simulations with nine different inflow rates per case, capturing inter- and intra-patient flow variations. Based on the computed flow fields, 17 hemodynamic parameters were calculated and compared for the different flow conditions. Next, statistical models for aneurysm rupture were trained in 1571 of the aneurysms including hemodynamic parameters capturing the flow variations either by defining hemodynamic "response variables" (model A) or repeatedly randomly selecting flow conditions by patients (model B) as well as morphological and patient-specific variables. Both models were evaluated in the remaining 249 cases.

RESULTS

All hemodynamic parameters were significantly different for the varying flow conditions (p < 0.001). Both the flow-independent "response" model A and the flow-dependent model B performed well with areas under the receiver operating characteristic curve of 0.8182 and 0.8174 ± 0.0045, respectively.

CONCLUSIONS

The influence of inter- and intra-patient flow variations on computed hemodynamics can be taken into account in multivariate aneurysm rupture prediction models achieving a good predictive performance. Such models can be applied to CFD data independent of the specific inflow boundary conditions.

Can sectioning the posterior communicating artery be predicted with computed tomography angiography in the microsurgical clipping of basilar apex aneurysms?

BACKGROUND

Microsurgical clipping is a viable option for managing high-riding basilar apex aneurysms (BAXs) using a transsylvian approach. Cutting the posterior communicating artery (PCoA) at the perforator-free zone provides sufficient exposure of BAX, although it is not always safe. The aim was to qualitatively predict sectioning of the interfering PCoA by using preoperative computed tomographic angiography (CTA).

METHODS

A virtual trajectory from the lesser sphenoid wing to the neck of the aneurysm was simulated on CTA in 19 consecutive patients operated on BAX aneurysms from 2013 to 2018. The angles on CTA resembled the typical view through the extended pterional craniotomy. Next, the ipsilateral PCoA was tracked from the internal carotid to its end at the posterior cerebral artery in the trajectory.

RESULTS

The opticocarotid and carotid-oculomotor window served as the corridors for entering the interpeduncular fossa in 16 patients (84.2%) and in 3 patients (15.8%), respectively. The PCoA was intentionally cut during nine surgeries and preserved in 10 of them. The PCoA was cut more often when positioned toward the cranial base and more medially in the corridor; both the Kernel density analysis and the data points representing the position of the PCoA supported this finding (p < 0.01). The CTA-based position of either ends of the PCoA in the trajectory did not differ between cut and not-cut groups (p = 0.19-0.96). Aneurysm projection, rupture, size, PCoA diameter, length, and other distances on CTA were not related to the sectioning of PCoA (p > 0.05).

CONCLUSIONS

The probability of PCoA sectioning is higher when the PCoA is positioned medially and closer to the cranial base. If the anatomical course of the PCoA is recognized beforehand, it can contraindicate surgery. Preoperative CTA-based planning facilitates the surgery of BAX aneurysms. Therefore, CTA can make microsurgical clipping planning more predictable for the neurosurgeon and safer for the patient.

Make Clipping Great Again: Microsurgery for Cerebral Aneurysms by Dual-Trained Neurosurgeons

OBJECTIVE

Despite an increasing focus on endovascular treatment of cerebral aneurysms, microsurgical clipping remains an integral part of management. We evaluated the safety and effectiveness of microsurgical clipping performed by dual-trained neurosurgeons at our institute, which has adopted an endovascular first approach.

METHODS

We retrospectively reviewed clinical and radiographic data of 412 aneurysms in 375 patients treated with microsurgical clipping. Univariate and multivariate analyses were performed to identify predictive outcome factors. We defined favorable outcome as a modified Rankin Scale (mRS) score of 0-2 at last clinical follow-up; unfavorable outcome was an mRS score of 3-6. We compared outcomes in our series with those of seminal aneurysm clipping series.

RESULTS

Clipping of 330 of 351 unruptured aneurysms (94.01%) was associated with favorable outcome during the follow-up period (mean, 26.5 months). On univariate analysis, older patient age, intraoperative rupture, and higher baseline mRS scores were associated with unfavorable outcome in the unruptured cohort. On multivariate analysis, older age, higher baseline mRS scores, and posterior circulation aneurysm location were predictive of unfavorable outcome. Clipping of 46 of 61 ruptured aneurysms (75.4%) was associated with favorable outcome during the follow-up period (mean, 23.1 months). On univariate analysis, left-sided aneurysms, intraoperative rupture, and large aneurysm size were associated with unfavorable outcome in the ruptured cohort. On multivariate analysis, female sex was predictive of unfavorable outcome.

CONCLUSIONS

Our ruptured and unruptured cohort results compared favorably with those in seminal series. Treatment by neurosurgeons adept at both endovascular and microsurgical techniques may improve clinical outcomes.

Temporal Muscle as an Indicator of Sarcopenia is Independently Associated with Hunt and Kosnik Grade on Admission and the Modified Rankin Scale Score at 6 Months of Patients with Subarachnoid Hemorrhage Treated by Endovascular Coiling

OBJECTIVE

Sarcopenia is defined as the loss of skeletal muscle mass and is considered an important factor for clinical outcomes in various diseases. Recent studies have shown that temporal muscle thickness (TMT) and area (TMA) can be novel indicators of sarcopenia. We examined clinical characteristics, including TMT and TMA, of patients with subarachnoid hemorrhage (SAH) treated by endovascular coiling.

METHODS

A retrospective analysis of 298 patients with SAH who were treated with endovascular coiling from 2009 to 2019 was conducted. Their premorbid modified Rankin Scale (mRS) score was 0-2. The association between the factors and Hunt and Kosnik (H-K) grades on admission and that between the clinical variables and mRS scores 6 months after the operation were analyzed.

RESULTS

In all 298 patients with SAH, Fisher group 4 and TMA <200 mm² were independently associated with H-K grade III-V on admission in the multivariate analysis. In 254 patients with H-K grades I-III on admission, age, H-K grade III, presence of ventriculoperitoneal shunt, presence of postoperative complications, and TMA <200 mm² were independent factors related to poor outcomes in the multivariate analysis.

CONCLUSIONS

The H-K grade on admission was independently associated with TMA. The mRS score 6 months after aneurysm treatment in patients with H-K grades I-III was also independently associated with TMA. Sarcopenia could be one of a few modifiable factors that prevent severe symptoms of SAH and improve outcomes after coiling by strengthened nutrition and physical activity.

Factors affecting recurrence and management of recurrent cerebral aneurysms after initial coiling

OBJECTIVE

To investigate factors affecting recurrence and effects and safety of endovascular retreatment for aneurysms recurrent after embolization.

METHODS

Among 815 aneurysms treated with embolization, recurrence was in 114 aneurysms (14.0%). Forty-three recurrent aneurysms were managed with re-embolization. Procedural complications, angiographic, and clinical results of retreatment were analyzed.

RESULTS

Patients with recurrent aneurysms were significantly (P < 0.01) younger than without recurrence (51.09 ± 10.46 vs. 53.88 ± 9.61 years). Recurrent aneurysms (n = 114) were significantly (P = 0.00) greater (11.12 ± 8.35 vs. 5.81 ± 3.44 mm) with a significantly (P = 0.00) greater neck (4.34 ± 2.26 vs. 2.90 ± 1.44 mm) than without recurrence. The rupture status of aneurysms significantly (P = 0.00) affected recurrence at follow-up. Significantly (P = 0.00) more aneurysms without recurrence were treated with advanced embolization techniques (81.0% vs. 62.3%) and got complete occlusion at the first embolization than those with recurrence (93.7% vs. 36.8%). In treating 43 recurrent aneurysms, stent-assisted recoiling was used in 48.8% in the first retreatment and 50% in the second and third retreatment procedures. Angiographic follow-up in 38 (88.4%) cases showed complete or near complete occlusion in 30 aneurysms, with the rest eight aneurysms experiencing a second recurrence (21.1%). Of the eight aneurysms with the second recurrence, five underwent the second endovascular retreatment, with complete aneurysm occlusion achieved in three cases (60%), near-complete occlusion in one (20%), and incomplete occlusion in one case at immediate angiography and six-month follow-up. Procedure-related complications occurred in three patients.

CONCLUSIONS

Endovascular retreatment of recurrent previously coiled aneurysms is safe and effective even though advanced embolization techniques are frequently involved especially for large and giant aneurysms.

Cerebral arterial infundibula are preaneurysmal lesions caused by direct flow impact

PURPOSE

To investigate whether arterial infundibular widening is a preaneurysmal lesion or not.

METHODS

Two hundred and nine patients with cerebral angiography were enrolled. The morphology, size and location of infundibula and cerebral aneurysms were studied in two-dimensional angiography and three-dimensional software space. Computational fluid dynamics (CFD) analysis was performed.

RESULTS

234 infundibula and 129 infundibulum-like aneurysms (IFAs) were detected. In two-dimensional space, the typical morphology of an infundibulum was a symmetric dilatation at the arterial branch origin with a small vessel branch emanating from the tip and a wide base connecting the parent artery. In three-dimensional space, the infundibulum was dissymmetric with always one side longer than the other side. Furthermore, the infundibulum tilted upstream rather than downstream, with the longer side located downstream and the shorter side upstream in all cases. All the 129 IFAs occurred on the distal wall of the vessel branch origin, and no IFAs grew from the proximal wall of the branch origin. The possible development process of an infundibulum to an IFA was described in four development stages. The CFD analysis revealed that these lesions were associated with direct flow impingement in all cases. All the hemodynamic parameters on the distal wall of infundibula and IFAs were significantly (P<0.0001 or P<0.05) decreased compared with on the distal wall after virtual lesion removal.

CONCLUSION

The infundibulum is a preaneurysmal lesion associated with high total pressure and high wall shear stress resulted from direct flow impingement and will progress to an aneurysm with time.

Common Data Elements for Unruptured Intracranial Aneurysm and Subarachnoid Hemorrhage Clinical Research: Recommendations from the Working Group on Long-Term Therapies

OBJECTIVES

The goal for the long-term therapies (LTT) working group (WG) of the Unruptured Intracranial Aneurysm (UIA) and Subarachnoid Hemorrhage (SAH) common data elements (CDEs) was to develop a comprehensive set of CDEs, data definitions, case report forms, and guidelines for use in UIA and SAH LTT clinical research, as part of a new joint effort between the National Institute of Neurological Disorders and Stroke (NINDS) and the National Library of Medicine of the US National Institutes of Health. These UIA and SAH CDEs will join other neurological disease-specific CDEs already developed and available for use by research investigators.

METHODS

The eight LTT WG members comprised international UIA, and SAH experts reviewed existing NINDS CDEs and instruments, created new elements when needed, and provided recommendations for future LTT clinical research. The recommendations were compiled, internally reviewed by the all UIA and SAH WGs and steering committee members. The NINDS CDE team also reviewed the final version before posting the SAH Version 1.0 CDE recommendations on the NINDS CDE website.

RESULTS

The NINDS UIA and SAH LTT CDEs and supporting documents are publicly available on the NINDS CDE ( https://www.commondataelements.ninds.nih.gov/#page=Default ) and NIH Repository ( https://cde.nlm.nih.gov/home ) websites. The subcommittee members discussed and reviewed various parameters, outcomes, and endpoints in UIA and SAH LTT studies. The following meetings with WG members, the LTT WG's recommendations are incorporated into the disease/injury-related events, assessments and examinations, and treatment/intervention data domains.

CONCLUSIONS

Noting gaps in the literature regarding medication and rehabilitation parameters in UIA and SAH clinical studies, the current CDE recommendations aim to arouse interest to explore the impact of medication and rehabilitation treatments and therapies and encourage the convergence of LTT clinical study parameters to develop a harmonized standard.