On the major role played by the lumen curvature of intracranial aneurysms walls in determining their mechanical response, local hemodynamics, and rupture likelihood

The properties of intracranial aneurysms (IAs) walls are known to be driven by the underlying hemodynamics adjacent to the IA sac. Different pathways exist explaining the connections between hemodynamics and local tissue properties. The emergence of such theories is essential if one wishes to compute the mechanical response of a patient-specific IA wall and predict its rupture. Apart from the hemodynamics and tissue properties, one could assume that the mechanical response also depends on the local morphology, more specifically, the curvature of the luminal surface, with larger values at highly-curved wall portions. Nonetheless, this contradicts observations of IA rupture sites more often found at the dome, where the curvature is lower. This seeming contradiction indicates a complex interaction between the hemodynamics adjacent to the aneurysm wall, its morphology, and mechanical response, which warrants further investigation. This was the main goal of this work. We accomplished this by analyzing the stress and stretch fields in different regions of the wall for a sample of IAs, which have been classified based on particular hemodynamics conditions and lumen curvature. Pulsatile numerical simulations were performed using the one-way fluid-solid interaction strategy implemented in OpenFOAM (solids4foam toolbox). We found that the variable best correlated with regions of high stress and stretch was the lumen curvature. Additionally, our data suggest a connection between the local curvature and particular hemodynamics conditions adjacent to the wall, indicating that the lumen curvature is a property that could be used to assess both mechanical response and hemodynamic conditions, and, moreover, suggest new rupture indicators based on the curvature.

Neurobrucellosis Mimicking Primary CNS Vasculitis-Should We Perform CSF Metagenomics Before Brain Biopsy?: A Case Report

Objective

To report a patient with neurobrucellosis mimicking primary CNS vasculitis (PCNSV) diagnosed by CSF metagenomic next-generation sequencing (mNGS).

Methods

A 32-year-old male patient with a prior stroke developed headache, dizziness, fever, and memory complaints in the past 30 days. Physical examination was unremarkable except for slight apathy. He was investigated with brain MRI, cerebral digital angiography, CSF analysis with mNGS, and brain biopsy.

Results

An examination of the brain MRI showed a left nucleocapsular gliosis compatible with prior stroke; MR angiogram showed circular enhancement of distal branches of the middle cerebral arteries. Digital angiogram revealed stenosis of intracranial carotid arteries and the left middle cerebral artery. The CSF disclosed 42 cells/mm³, 46 mg/dL of glucose, and 82 mg/dL of protein. Brain biopsy showed a chronic leptomeningeal inflammatory process, not fulfilling criteria for PCNSV. mNGS revealed the presence of Brucella sp. genetic material. He was treated with antibiotics with full remission of systemic and neurologic symptoms.

Discussion

Brucellosis is an endemic disease in developing countries and may mimic PCNSV. Our patient fulfilled the criteria for possible PCNSV; however, brain biopsy was inconsistent with PCNSV, and CSF mNGS disclosed neurobrucellosis. This case illustrates the importance of CSF mNGS in the differential diagnosis of CNS vasculitis.

Plasticity of the adult circle of Willis in response to flow diversion stents

Background

We present five patients with remodeling of the adult circle of Willis in response to flow diverter stents (FDSs) at the anterior communicating artery (AComA) and the posterior communicating artery (PComA). The observed changes provide a paradigm of how flow change can institute anatomic changes in the adult circle of Willis vasculature.

Case Description

In the first two cases, after placement of the FDS covering the AComA, there was an increase in size and flow of the contralateral A1-anterior cerebral artery which had previously been hypoplastic. In one of the cases, this led to the filling of the aneurysm and required placement of coils within the lesion which was curative. In case three, the FDS effect led to asymptomatic occlusion of the PComA and associated aneurysm without change of the ipsilateral P1-segement of posterior-cerebral-artery (P1-PCA) caliber. In the fourth case, the FDS covering an aneurysm with a fetal PCA arising from its neck resulted in significant reduction of the aneurysm size, persistent flow and caliber of the fetal PCA, and the hypoplastic ipsilateral P1-PCA. Finally, in the fifth case, after FDS occlusion of the PComA and aneurysm there was increasement in diameter of the ipsilateral P1-PCA that was previously hypoplastic.

Conclusion

The use of FDS can affect vessels covered by the device and other arteries of the circle of Willis adjacent to the FDS. The phenomena illustrated in the hypoplastic branches appear to be a compensatory response to the hemodynamic changes induced by the divertor and to the altered flow in the circle of Willis.

A numerical investigation of the mechanics of intracranial aneurysms walls: Assessing the influence of tissue hyperelastic laws and heterogeneous properties on the stress and stretch fields

Numerical simulations have been extensively used in the past two decades for the study of intracranial aneurysms (IAs), a dangerous disease that occurs in the arteries that reach the brain and affect overall 3.2% of a population without comorbidity with up to 60% mortality rate, in case of rupture. The majority of those studies, though, assumed a rigid-wall model to simulate the blood flow. However, to also study the mechanics of IAs walls, it is important to assume a fluid-solid interaction (FSI) modeling. Progress towards more reliable FSI simulations is limited because FSI techniques pose severe numerical difficulties, but also due to scarce data on the mechanical behavior and material constants of IA tissue. Additionally, works that have investigated the impact of different wall modeling choices for patient-specific IAs geometries are a few and often with limited conclusions. Thus our present study investigated the effect of different modeling approaches to simulate the motion of an IA. We used three hyperelastic laws - the Yeoh law, the three-parameter Mooney-Rivlin law, and a Fung-like law with a single parameter - and two different ways of modeling the wall thickness and tissue mechanical properties - one assumed that both were uniform while the other accounted for the heterogeneity of the wall by using a "hemodynamics-driven" approach in which both thickness and material constants varied spatially with the cardiac-cycle-averaged hemodynamics. Pulsatile numerical simulations, with patient-specific vascular geometries harboring IAs, were carried out using the one-way fluid-solid interaction solution strategy implemented in solids4foam, an extension of OpenFOAM®, in which the blood flow is solved and applied as the driving force of the wall motion. We found that different wall morphology models yield smaller absolute differences in the mechanical response than different hyperelastic laws. Furthermore, the stretch levels of IAs walls were more sensitive to the hyperelastic and material constants than the stress. These findings could be used to guide modeling decisions on IA simulations, since the computational behavior of each law was different, for example, with the Yeoh law being the fastest to converge.

Blood pressure behavior during mechanical thrombectomy and drugs used for conscious sedation or general anesthesia

BACKGROUND

The optimal blood pressure (BP) during mechanical thrombectomy for acute ischemic stroke is currently unclear.

OBJECTIVE

To investigate BP behavior during mechanical thrombectomy in patients with acute ischemic stroke and its relationship with drugs used for sedation or general anesthesia. Additionally, we investigated the association between BP oscillation during mechanical thrombectomy and recanalization status, and with functional outcome at discharge.

METHODS

Consecutive patients treated with mechanical thrombectomy for acute ischemic stroke were evaluated in a tertiary hospital from December/2009 to December/2015. Maximum, minimum, and mean systolic and diastolic BP, and mean arterial pressures were collected during the procedure. Sedative drugs were also reviewed.

RESULTS

Fifty-three patients with a mean age of 71.9 years (60.4% men) were treated with mechanical thrombectomy. The mean reduction in systolic BP and mean arterial pressure from hospital admission to mechanical thrombectomy were respectively 42 and 36 mmHg. During the procedure, oscillations were 50.4 mmHg for systolic, and 33.2 mmHg for diastolic BP. Patients treated with neuromuscular blocking drugs had more oscillation in systolic BP from hospital admission to procedure (51.1 versus 26.2 mmHg, P=0.06). The use of cisatracurium (43.9 versus 29.6 mmHg, P=0.02) and succinylcholine (44.7 versus 29.3 mmHg, P=0.01) were associated with a significant drop in BP during the procedure.

CONCLUSIONS

Significant BP oscillation occurs during mechanical thrombectomy. Drugs used for conscious sedation or general anesthesia, specifically neuromuscular blocking agents, might have an influence upon BP levels.

Safety and Effectiveness of the Pipeline Flex Embolization Device With Shield Technology for the Treatment of Intracranial Aneurysms: Midterm Results From a Multicenter Study

BACKGROUND

The safety and efficacy of the first generation of the Pipeline Embolization Device (PED; Medtronic Inc) have been proven in large case series. Ischemic events are one of the most common complications following treatment of aneurysms with flow diverters. The new PED Flex with Shield technology (PED Shield; Medtronic Inc) was introduced to minimize the rate of complications.

OBJECTIVE

To evaluate the outcomes of patients harboring aneurysms treated with the PED Shield.

METHODS

This was an observational, prospective, single-arm multicenter study of patients treated with the PED Shield. The primary safety endpoint was the absence of major neurological complications and death. The secondary effectiveness endpoint was angiographic occlusion at 6 and 12 mo. Technical complications were also reported.

RESULTS

Between November 2017 and December 2018, 151 patients from 7 centers with 182 aneurysms were enrolled. The mean aneurysm size was 7.0 mm; 27 (14.8%) aneurysms were large, and 7 (3.8%) were giant. In 141 of 151 patients (93.4%), the primary endpoint was reached. The overall rate of periprocedural complications was 7.3%. Of the aneurysms, 79.7% met the study's secondary endpoint of complete occlusion at 6 mo and 85.3% at 12 mo.

CONCLUSION

The PED Shield is a safe and effective treatment for intracranial aneurysms. The results regarding total occlusion and ischemic complications did not differ from those obtained in case series using previous versions of the PED. Long-term follow-up and comparative studies are required to provide stronger conclusions regarding the reduced thrombogenicity of this device.

Derivo Embolization Device for the Treatment of Intracranial Aneurysms

Background and Purpose—

Flow diverter technology improvements are necessary to provide safe and good results and enable the treatment of a larger variety of aneurysms. We report a nationwide experience with the Derivo Embolization Device in the treatment of intracranial aneurysms.

Methods—

BRAIDED (Brazilian Registry of Aneurysms Assigned to Intervention With the Derivo Embolization Device) is a multicenter, prospective, interventional, single-arm trial of the Derivo Embolization Device for the treatment of intracranial aneurysms. The primary effectiveness end point was total aneurysm occlusion at 6- and 12-month angiographies. The secondary safety end point was the absence of serious adverse events during follow-up. Univariable and multivariable logistic regression was performed to identify predictors of aneurysm persistence, periprocedural complications, and adverse events during follow-up.

Results—

Between December 2016 and October 2018, 146 patients harboring 183 intracranial aneurysms were treated in 151 interventions at 7 centers. Derivo Embolization Device placement was technically successful in all patients. Most aneurysms (86.9%) were located at the internal carotid artery, and the mean diameter was 6.7 mm. At 6 months, 113 of 140 (80.7%) aneurysms met the study’s primary end point, and 74 of 83 (89.2%) met the study’s primary end point at 12 months. Saccular morphology of the aneurysm (odds ratio, 5.66; 95% CI, 1.01–31.77) and the presence of a branch arising from the sac (odds ratio, 6.36; 95% CI, 2.11–22.36) predicted persistence. A long duration of follow-up (odds ratio, 0.86; 95% CI, 0.78–0.95) predicted total occlusion. Of the 146 enrolled patients, 138 (94.5%) were treated without serious adverse events during follow-up. In the multivariable analysis, aneurysms located at a sidewall were less likely to experience these events than those located at bifurcations (odds ratio, 0.07; 95% CI, 0.01–0.51).

Conclusions—

The Derivo Embolization Device is a safe and effective treatment for intracranial aneurysms.

Clinical Trial Registration—

URL: http://plataformabrasil.saude.gov.br/login.jsf . Unique identifier: CAAE 77089717.7.1001.5125.

Tips and tricks in the diagnosis of intracranial dural arteriovenous fistulas: A pictorial review

Dural arteriovenous fistulas (DAVFs) are complex vascular abnormalities that account for 10-15% of intracranial vascular malformations. DAVFs are typically encountered in middle-aged adults, with a slightly female predominance. The causative factors are still uncertain; however, abnormal local hemodynamics and neoangiogenesis related to dural sinus or venous thrombosis can contribute to DAVF occurrence. The diagnosis is dependent on a high level of clinical suspicion and high-resolution imaging techniques. Computed tomography and/or magnetic resonance imaging aid in the diagnosis, but conventional angiography remains the most accurate method for the complete characterization and classification of DAVFs. The therapeutic approach can be conservative or more aggressive, based on symptom severity, sequelae risk and patient characteristics. This article is a pictorial review of adult intracranial DAVFs that highlights some tips and tricks for recognizing useful red flags in the suspicion of DAVFs.

Growth and rupture mechanism of partially thrombosed aneurysms

SUMMARY

Within the group of giant and large aneurysms the subgroup of the so-called "partially thrombosed" aneurysms can be differentiated according to clinical and neuroimaging findings. The present study was carried out to determine the site of bleeding of these aneurysms and what implications concerning their pathomechanism can be drawn from these findings. Twenty patients aged two to 77 (mean 44) years who exhibited a partially thrombosed aneurysm that had recently bled were included. Images (MRI including T1 pre- and postcontrast and T2 weighted images in multiple planes, CT and digital subtraction angiography) and patients' charts were reviewed. MRI showed an onion-skin appearance of the thrombus in 19 patients, rim enhancement of the aneurysm wall (either partial or complete) in 17, and a perifocal edema in 16 patients. The acute hemorrhage was typically crescent-shaped and located at the periphery of the aneurysm, distant from the perfused lumen of the aneurysm within the thrombosed part of the aneurysm. The current denomination "partially thrombosed" intracranial arterial aneurysms leads to the presumption that thrombus is present endoluminal whereas in fact the site of hemorrhage is within the vessel wall. A more accurate nomination would, therefore, be "aneurysms with intramural hemorrhage". The enhancing wall and the edematous reaction of the adjacent brain parenchyma might be a sign for an inflammatory pathomechanism which is reinforced by histological and pathophysiological studies. This disease should be regarded as a clinical entity separate from saccular or non-thrombosed giant or large aneurysms.

Segmental unfused basilar artery with kissing aneurysms: report of three cases and literature review

Basilar artery "fenestration" is the result of a failed fusion of the bilateral longitudinal neural arteries and can be associated with a saccular aneurysm, which typically arises at the proximal juncture of the unfused segment. "Kissing" aneurysms at this site, i.e. two aneurysms arising from the proximal junction of the unfused segment of the basilar artery pointing anteriorly and posteriorly are reported to be exceedingly rare. We present three patients with this rare condition, all of them being treated by endovascular techniques.

Use of risperidone in children with epilepsy

OBJECTIVE

Although the atypical antipsychotic medications appear to be safe in patients with epilepsy, few studies have specifically addressed the use of risperidone in children with seizures. The objective of this study was to evaluate behavior improvement and seizure outcome in children with epilepsy and behavioral disorders (self-injurious, aggressive, or destructive behavior) after introduction of risperidone.

METHODS

In this prospective study, 54 patients were evaluated, 38 boys and 16 girls, aged 2-18 (mean=10). The dose of risperidone ranged from 0.01 to 0.14 mg/kg/day (mean=0.038 mg/kg/day). Risperidone was introduced gradually. The titration rate was determined by clinical response. The data were collected from patients' follow-up visits and clinical files. Exacerbation of seizures was established as an increase in seizure frequency after introduction of risperidone, with return to baseline seizure frequency after risperidone withdrawal.

RESULTS

Seizure frequency was not affected by risperidone in 51 patients (94.5%). Only two (4%) patients experienced seizure exacerbation after the introduction of risperidone. In one patient, the effect of risperidone on seizure control could not be established. After introduction of the risperidone, 38 (70.4%) patients manifested improvement in behavior.

CONCLUSION

Our data suggest that risperidone can be used in pediatric patients with epilepsy and that seizure outcome is not changed in most children with epilepsy and psychiatric comorbidity. In addition, behavior improvement is usually achieved in most patients.

What about us?

RATIONALE

It is known that epilepsy has a severe impact in the quality of life of the patients; however, it affects the lives of all family members. The psychosocial repercussions of epilepsy are often of greater significance than the seizures themselves.

METHODS

This was a prospective study, conducted from January 2005 to December 2005 at the pediatric epilepsy clinic of our University Hospital. Parents were interviewed by one of the authors according to a structured questionnaire about the impact of epilepsy in the life of the siblings of children with epilepsy.

RESULTS

One hundred and twenty-seven children, siblings of 78 patients with epilepsy were evaluated. From the 127 siblings of children with epilepsy, 60 were girls and 67 were boys. Ages ranged from 5 to 18 years old (mean=11.7 years). After the diagnosis of epilepsy, the siblings had only negative feelings toward the disease, mostly sadness and fear.

CONCLUSION

Our data showed that the impact of epilepsy in the lives of siblings of children with epilepsy is much more severe than previously suspected.

Multiple mirror-like intracranial aneurysms. Report of a case and review of the literature

While multiple intracranial arterial aneurysms occur in 26.4% of patients with aneurysms, in our practice bilateral mirror-like aneurysms are encountered in 9.4% of patients. Multiple mirror aneurysms in the same patient are exceedingly rare. We report a case of mirror-like middle cerebral artery aneurysms associated with mirror-like posterior inferior cerebellar arteries aneurysms and discuss their significance. Although an exceptional finding, multiple mirror-like aneurysms may shed light on the vulnerability of different arterial segments to specific diseases.

Comparison of Magnetic Resonance Imaging Sequences With Computed Tomography to Detect Low-Grade Subarachnoid Hemorrhage

OBJECTIVES

To compare computed tomography (CT) with magnetic resonance imaging (MRI) for the presumptive diagnosis and localization of acute and subacute low-grade subarachnoid hemorrhage (SAH).

METHODS

We consecutively enrolled 45 patients clinically suspected of low-grade SAH, comparing them with a control group. We obtained axial nonenhanced CT scans as well as fluid-attenuated inversion recovery (FLAIR) and T2-weighted gradient echo (T2*) MRI sequences at 1.0 T. Two neuroradiologists scrutinized the presence of blood at 26 different regions in the intracranial subarachnoid space (SAS).

RESULTS

Three of 45 patients had normal CT and MRI scans, and SAH was excluded by lumbar puncture. We demonstrated SAH on CT scans in 28 of 42 (66.6%) patients, T2* sequences in 15 of 42 (35.7%) patients, and FLAIR sequences in 42 of 42 (100%) patients. Fluid-attenuated inversion recovery sequences were superior to CT in 16 of the 26 evaluated regions.

CONCLUSIONS

The FLAIR sequence was superior for presumptive diagnosis and localization of acute and subacute low-grade SAH, representing a potential tool in this setting.

Traumatic carotid-cavernous fistula: endovascular treatment with onyx and coils

SUMMARY

Carotid cavernous fistulas (CCF) are mostly post-traumatic and are due to a tear of the internal carotid artery (ICA) inside the cavernous sinus. The improvement of endovascular techniques with venous approach enables the preservation of internal carotid artery patency in most cases when detachable balloons fail in order to reconstruct and repair the tear in the ICA. The case described here has a giant aneurysmatic dilatation of the cavernous sinus and inferior petrosal sinus. We associate coils and Onyx to occlude the lesion preserving and repairing the large hole of the fistula.