Inflammatory changes in the aneurysm wall: a review

Characteristics of aneurysmal subarachnoid hemorrhage associated with rheumatic disease

Spontaneous subarachnoid hemorrhage (SAH) occurs due to intracranial aneurysm rupture in most cases. Rheumatic disease may cause vessel wall inflammation, which can increase the risk of rupture. However, the characteristics of SAH with rheumatic disease are unknown. This study aimed to evaluate SAH features in patients with rheumatic disease. We retrospectively analyzed clinical data of 5066 patients from the Nagasaki SAH Registry Study who had been diagnosed with aneurysmal SAH between 2001 and 2018. We evaluated the SAH characteristics in patients with rheumatic disease using multivariable logistic regression analysis. In total, 102 patients (2.0%, 11 men and 91 women, median age 69.0 [57.0-75.5]) had rheumatic disease. In these patients, univariate logistic regression analysis showed that sex, hypertension, family history of SAH, smoking history, World Federation of Neurosurgical Societies grade on admission, aneurysm size, multiple aneurysms, treatment, and symptomatic spasms were associated with SAH. Multivariable logistic regression analysis showed that characteristics independently associated with SAH in rheumatic disease were female sex (odds ratio [OR] 3.38; 95% confidence interval [CI] 1.81-6.93, P < 0.001), hypertension (OR 0.60; 95% CI 0.40-0.90, P = 0.012), family history of SAH (OR 0.18; 95% CI 0.01-0.80, P = 0.020), small ruptured aneurysms (OR 1.50; 95% CI 1.02-2.24, P = 0.048), and multiple aneurysms (OR 1.69; 95% CI 1.09-2.58, P = 0.021) in comparison with SAH without rheumatic disease. In conclusion, SAH in patients with rheumatic disease was characterized by small multiple aneurysms, regardless of the low incidence of hypertension and family history of SAH.

Giant intracranial aneurysm following radiation therapy: literature review with a novel case discussion

BACKGROUND

The aim of this paper is to report the results of our review of the literature of published cases of intracranial aneurysms appearing after radiotherapy, and to present our case to add it to the current literature, in order to discuss the role of inflammation.

METHODS

We searched the PubMed database using combinations of the following MeSH terms: intracranial aneurysm, radiosurgery, radiotherapy, inflammatory changes in aneurysmal walls from 1967 to 2019.

RESULTS

51 studies, for a total cohort of 60 patients, are described. The median latency between the radiation treatment and the diagnosis was 9,83 years, ranging from a minimum of 0,33 to a maximum of 33. The modality of rays' administration was variable, and the dosage ranged from a minimum of 12 grays to a maximum of 177,2 grays. The anterior circulation appeared to be more frequently involved, and the most compromised vessel was the internal carotid artery. Radiation-induced vascular diseases have already been described in literature as well as RT-induced cellular and structural changes such as necrosis, macrophage or mononuclear cell infiltration, and several data support the role of inflammation in the development and remodelling of intracranial aneurysms, that, on one hand, favours them and, on the other, is necessary to their healing after endovascular treatment.

CONCLUSIONS

Our team suggested a new insight in the management of these vascular lesions, which corresponds to a lower threshold when deciding whether or not to treat, and a longer and stricter follow-up.

Genetic polymorphisms and transcription profiles associated with intracranial aneurysm: a key role for NOTCH3

Intracranial aneurysm (IA) incidence is about 1~2%. However, the specific mechanisms of IA onset and development need further study. Our objective was to discover novel IA-related genes to determine possible etiologies further. We performed next-generation sequencing on nineteen Chinese patients with familial IA and one patient with sporadic IA. We obtained mRNA expression data of 129 samples from Gene Expression Omnibus (GEO) and made statistical computing to discover differentially expressed genes (DEGs). The screened IA-related gene NOTCH3 was determined by bioinformatic data mining. We verified the IA-related indicators of NOTCH3. Association was found between IA and the NOTCH3 SNPs rs779314594, rs200504060 and rs2285981. Levels of NOTCH3 mRNA were lower in IA tissue than in control tissue, but higher in peripheral blood neutrophils from IA patients than in neutrophils from controls. Levels of NOTCH3 protein were lower in IA tissue than in cerebral artery tissue. NOTCH3 also decreased the expression of angiogenesis factors in human umbilical vein endothelial cells. Variation in NOTCH3 and alteration of its expression in cerebral artery or neutrophils may contribute to IA. Our findings also describe a bioinformatic-experimental approach that may prove useful for probing the pathophysiology of other complex diseases.

Pathophysiology of Intracranial Aneurysms

Background and Purpose:

The pathophysiology of development, growth, and rupture of intracranial aneurysms (IAs) is only partly understood. Cyclooxygenase 2 (COX-2) converts arachidonic acid to prostaglandin H 2 , which, in turn, is isomerized to prostaglandin E 2 . In the human body, COX-2 plays an essential role in inflammatory pathways. This explorative study aimed to investigate COX-2 expression in the wall of IAs and its correlation to image features in clinical (1.0T, 1.5T, and 3.0T) magnetic resonance imaging (MRI) and ultra-high-field 7T MRI.

Methods:

The study group comprised 40 patients with partly thrombosed saccular IAs. The cohort included 17 ruptured- and 24 unruptured IAs, which had all been treated microsurgically. Formaldehyde-fixed paraffin-embedded samples were immunohistochemically stained with a monoclonal antibody against COX-2 (Dako, Santa Clara, CA; Clone: CX-294). We correlated Perls Prussian blue staining, MRI, and clinical data with immunohistochemistry, analyzed using the Trainable Weka Segmentation algorithm.

Results:

Aneurysm dome size ranged between 2 and 67 mm. The proportion of COX-2 positive cells ranged between 3.54% to 85.09%. An upregulated COX-2 expression correlated with increasing IA dome size ( P =0.047). Furthermore, there was a tendency of higher COX-2 expression in most ruptured IAs ( P =0.064). At all field strengths, MRI shows wall hypointensities due to iron deposition correlating with COX-2 expression ( P =0.022).

Conclusions:

Iron deposition and COX-2 expression in IAs walls correlate with signal hypointensity in MRI, which might, therefore, serve as a biomarker for IA instability. Furthermore, as COX-2 was also expressed in small unruptured IAs, it could be a potential target for specific medical treatment.

Management of unruptured intracranial aneurysms: correlation of UIATS, ELAPSS, and PHASES with referral center practice

Concordance between the Unruptured Intracranial Aneurysm Treatment Score (UIATS), Earlier Subarachnoid Hemorrhage, Location, Age, Population, Size, Shape (ELAPSS) score, and Population, Hypertension, Age, Size, Earlier Subarachnoid Hemorrhage, Site (PHASES) score with real-world management decisions in unruptured intracranial aneurysms (UIAs) remains unclear, especially in current practice. This study aimed to investigate this concordance, while developing an optimal model predictive of recent decision practices at a quaternary referral center. A prospective database of patients presenting with UIAs to our institution from January 1 to December 31, 2018, was used. Concordance between the scores and real-world management decisions on every UIA was assessed. Complications and length of stay (LOS) were compared between aneurysms in the UIATS-recommended treatment and observation groups. A subgroup analysis of concordance was also conducted among junior and senior surgeons. An optimal logistic regression model predictive of real-world decisions was also derived. The cohort consisted of 198 patients with 271 UIAs, of which 42% were treated. The UIATS demonstrated good concordance with an AUC of 0.765. Of the aneurysms in the UIATS-recommended "observation" group, 22% were discordantly treated. The ELAPSS score demonstrated good discrimination (AUC = 0.793), unlike the PHASES score (AUC = 0.579). Endovascular treatment rates, complications, and LOS were similar between aneurysms in the UIATS-recommended treatment and observation groups. Similar concordance was obtained among junior and senior surgeons. The optimal predictive model consisted of several significantly associated variables and had an AUC of 0.942. Cerebrovascular specialists may be treating aneurysms slightly more than these scores would recommend, independently of years in practice. Wide variation still exists in management practices of UIAs.

Infantile Giant Intracranial Aneurysm Resection and In Situ Anastomosis

BACKGROUND

Infantile intracranial aneurysms (IAs) are extremely rare. IA clipping and embolization have been the most common treatment options. Infantile giant IAs treated by surgical resection and in situ anastomosis have rarely been reported.

CASE DESCRIPTION

A 43-day-old female infant was admitted to our hospital because of abnormal crying and vomiting. Multimodal images showed a right temporal hematoma and a giant dissecting IA. With comprehensive preoperative management, IA resection and in situ anastomosis were successfully performed. Furthermore, intraoperative and postoperative multimodal images demonstrated that the parent vessel was patent. Pathological examination showed chronic inflammation of this IA wall. The infant had a favorable outcome during the 3-month follow-up period.

CONCLUSIONS

Infantile giant IAs are extremely rare. Chronic inflammation might be involved in the pathogenesis of infantile dissecting IAs. IA resection and in situ anastomosis could be a reasonable choice in the management of infantile giant IAs that cannot be completely clipped or embolized.

Ratio of IL-8 in CSF versus Serum Is Elevated in Patients with Unruptured Brain Aneurysm

Only scarce data pertaining to interleukin 8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) chemokines in human aneurysm can be found in the current literature. Therefore, the aim of this study was the evaluation of cerebrospinal fluid (CSF) and serum IL-8 and MCP-1 concentration in unruptured intracranial aneurysm (UIA) patients (n = 25) compared to the control group (n = 20). IL-8 and MCP-1 concentrations were measured with ELISA method. We demonstrated that CSF IL-8 concentration of UIA patients is significantly higher (p < 0.001) than that presented in the serum, which can indicate its local synthesis within central nervous system. CSF IL-8 concentration was also significantly related to aneurysm size, which may reflect the participation of IL-8 in the formation and development of brain aneurysms. IL-8 Quotient (CSF IL-8 divided by serum IL-8) in UIA patients was statistically higher compared to control individuals (p = 0.045). However, the diagnostic utility analysis did not equivocally indicate the diagnostic usefulness of the IL-8 Quotient evaluation in brain aneurysm patients. Nevertheless, this aspect requires further study.

The Bilateral Ovariectomy in a Female Animal Exacerbates the Pathogenesis of an Intracranial Aneurysm

Considering the poor outcome of subarachnoid hemorrhage (SAH) due to the rupture of intracranial aneurysms (IA), mechanisms underlying the pathogenesis of IAs, especially the rupture of lesions, should be clarified. In the present study, a rat model of IAs in which induced lesions spontaneously ruptured resulting in SAH was used. In this model, the combination of the female sex and the bilateral ovariectomy increased the incidence of SAH, similar to epidemiological evidence in human cases. Importantly, unruptured IA lesions induced in female animals with bilateral ovariectomy were histopathologically similar to ruptured ones in the presence of vasa vasorum and the accumulation of abundant inflammatory cells, suggesting the exacerbation of the disease. The post-stenotic dilatation of the carotid artery was disturbed by the bilateral ovariectomy in female rats, which was restored by hormone replacement therapy. The in vivo study thus suggested the protective effect of estrogen from the ovary on endothelial cells loaded by wall shear stress. β-estradiol or dihydrotestosterone also suppressed the lipopolysaccharide-induced expression of pro-inflammatory genes in cultured macrophages and neutrophils. The results of the present study have thus provided new insights about the process regulating the progression of the disease.

Peri-interventional Behavior of the Neutrophil to Lymphocyte Ratio in Patients with Intracranial Aneurysms

OBJECTIVE

The neutrophil-to-lymphocyte ratio (NLR) has been investigated as an independent predictive marker for clinical outcomes in vascular diseases. This study aimed to investigate the peri-interventional behavior of the NLR in patients with ruptured and unruptured intracranial aneurysms (IAs).

METHODS

A total of 117 patients with IAs, who were treated at our department and had available complete data, were retrospectively identified during a 10-year period. Routine laboratory parameters, including the neutrophil and lymphocytes counts, were evaluated before and after treatment.

RESULTS

The baseline NLR showed significant differences between patients with ruptured and unruptured IAs (6.3 vs. 1.8; P < 0.001). In patients with ruptured IAs, the baseline NLR decreased significantly during the follow-up visits, whereas in unruptured IAs, the NLR remained low. Furthermore, higher baseline NLR values could also be observed in patients with ruptured IAs and fatal outcome than in surviving patients (8.0 vs. 5.4; P = 0.220). In patients with poor functional outcome, defined as modified Rankin score ≥3, the NLR was significantly higher before treatment (P = 0.047), at day 10 (P = 0.025), and 1 month after treatment (P = 0.001).

CONCLUSIONS

The peri-interventional NLR was significantly different between patients with ruptured and unruptured IAs. In patients with ruptured IAs, elevated baseline NLR levels were associated with poor postoperative functional outcomes and decreased postoperatively, implying the potential prognostic value of NLR in patients with IAs.

Flow-diverting stent and delayed intracranial bleeding: the case for discussing acquired von Willebrand disease

A unique feature of the flow-diverting stent (FDS) has rendered it useful in the endovascular treatment of selected intracranial aneurysms for the last decade. Delayed aneurysmal rupture and intracranial parenchymal bleeding are two leading hemorrhagic complications after FDS. It has recently been shown for the first time that there is a relationship between FDS and reduced level of vWF activity in patients undergoing endovascular cerebral aneurysm treatment. Here, the current literature is reviewed in the context of this novel finding to propose an illustrative scenario that conceptually links implantation of FDS to delayed intracranial bleeding, through the mechanism of shear-induced activation of vWF. In this scenario, after FDS implantation, sustained release of activated vWF in association with platelets plays a pivotal role in the mechanisms of delayed intracranial hemorrhages.

In the wall lies the truth: a systematic review of diagnostic markers in intracranial aneurysms

OBJECTIVE

Despite recent advances in molecular biology and genetics, the development of intracranial aneurysms (IA) is still poorly understood. Elucidation of the processes occurring in the IA wall is essential for a better understanding of IA pathophysiology. We sought to analyze the current evidence from histological, molecular and genetic studies of IA.

METHODS

We systematically searched PubMed, Scopus, Web of Science and Cochrane Library for articles published before Mar 1, 2019 reporting on different diagnostic markers in human IA specimens. Expression of the markers in IA wall (vs. healthy arterial wall) and association with the rupture status were analyzed. The quality of the included studies and the level of the evidence for the markers were incorporated into the final data assessment.

RESULTS

We included 123 studies reporting on analyses of 3476 IA (median 19 IA/study) published between 1966 and 2018. Based on microscopic, biochemical, genetic and biomechanical analyses, data on 358 diagnostic targets in the IA wall were collected. We developed a scale to distribute the diagnostic markers according to their specificity for IA or healthy arterial wall, as well as for ruptured or unruptured IA. We identified different functional pathways, which might reflect the intrinsic and extrinsic processes underlying IA pathophysiology.

CONCLUSIONS

Multiple histological and molecular markers and the related functional pathways contributing to the development of IA might present promising targets for future therapeutic interventions. Because of small numbers of IA samples in each study, 89% of the analyzed diagnostic markers presented with the lowest level of evidence. This underlines the need for the initiation of a multi-centric prospective histological IA register for pooled data analysis.

Persistence of Intraluminal Thrombus Makes Saccular Aneurysm More Biologically Active than Fusiform in an Experimental Rat Model

INTRODUCTION

Saccular aneurysms are thought to have a worse prognosis than fusiform aneurysms in humans, due to hemodynamic reasons. However, data comparing hemodynamic and biology in saccular and fusiform aneurysms are lacking. The main objective was to evaluate the impact of aneurysm morphology on intra-luminal thrombus (ILT) formation and activity.

METHODS

Forty Lewis rats were ran-domly divided into 2 groups of 20: "saccular" (Group A) and "fusiform" (Group B) aneurysms. Decellularized thoracic aortas from guinea pigs were xenografted to create saccular or fusiform aneurysms. Final imaging evaluation of the aneurysms was carried out during the third week, by quantitative Doppler ultrasound and magnetic resonance imaging. Assays of myeloperoxidase (MPO), platelet factor 4 (PF4), advanced oxidation protein products (AOPPs) iron and matrix metallopeptidase-9 (MMP-9) were performed as biological criteria.

RESULTS

Quantitatively, saccular aneurysms are characterized by a more thicker ILT, lower inflow velocities and more important relative backflow velocities as compared to fusiform aneurysms. Compared to fusiform, saccular aneurysms released significantly more MPO (p = 0.004), PF4 (p = 0.02), AOPPs (p < 0.002), iron (p < 0.0001) and MMP-9 (p < 0.04).

CONCLUSION

Experimental saccular and fusiform aneurysms show differential specific hemodynamics, which seem to impact the histology and the biology of the ILT in each type of aneurysm.

Is the unruptured intracranial aneurysm treatment score (UIATS) sensitive enough to detect aneurysms at risk of rupture?

To evaluate if the unruptured intracranial aneurysm treatment score (UIATS) is a sensitive tool to detect aneurysms at risk of rupture, we conducted an a posteriori retrospective study on ruptured intracranial aneurysms. We performed a retrospective analysis of adult patients admitted to our center from January 2010 to April 2016 with aneurysmal subarachnoid hemorrhage. The UIATS was applied to all ruptured aneurysms. Patients for whom the UIATS recommended treatment were labeled as “true positives,” whereas patients for whom the UIATS recommended observation were labeled as “false negatives.” Patients for whom the UIATS was inconclusive were excluded from the final analysis. Based on the UIATS recommendation, a sensitivity analysis was performed. A total of 262 patients with aneurysmal subarachnoid hemorrhage were screened. Of these, 212 were included in our analysis. Median age was 53 years (23–90). Most patients were females (n = 134, 63%), with an equal distribution between low-grade and high-grade hemorrhages (Hunt & Hess ≥ 3 n = 107, 50%). UIATS recommended treatment in n = 52, 25% cases (TP), was inconclusive in n = 93, 44% (excluded), and recommended observation in n = 67, 32% (FN). Based on these data, the UIATS showed a sensitivity of 44% (CI 35–53%). The UIATS exhibits rather low sensitivity for detecting aneurysms at risk of rupture.

A two-miRNA signature (miR-21 and miR-92) in peripheral whole blood as a potential biomarker for diagnosis of human cerebral aneurysms

Introduction

microRNAs (miRs) have been reported as blood-based noninvasive indicators for the diagnosis of various diseases. However, the utility of whole blood-based miRs in the diagnosis of intracranial aneurysm (IA) is still not clear. The present study aimed to examine miR expression profiling in the peripheral whole blood of IA patients and healthy controls.

Material and methods

Seventy-three IA patients, including 34 unruptured and 39 ruptured, and 28 healthy subjects, were recruited for diagnostic analysis. microRNA (miR) expression profiling in whole blood from healthy controls and IA patients was evaluated using miRNA microarray assay. RT-qPCR was used to evaluate miR expression. Receiver operating characteristics (ROC) curves and the area under the ROC curves (AUC) were used to calculate the diagnostic power of miRs in whole blood of IA.

Results

We observed significantly higher miR-21 and miR-92 expression levels in aneurysmal tissues and whole blood of IA patients as compared to healthy subjects. miR-21 expression level was significantly positively correlated with miR-92 in IA tissues and whole blood of IA patients. ROC analysis revealed that miR-21 (AUC = 0.843, sensitivity = 0.849, specificity = 0.750) and miR-92 (AUC = 0.892, sensitivity = 0.945, specificity = 0.786) were promising in diagnosis of IA with high detectability. Intriguingly, miR-21 combined with miR-92 markedly improved the diagnostic power of IA (AUC = 0.920, sensitivity = 1.000, specificity = 0.786).

Conclusions

miR-21 combined with miR-92 could be considered as a potential biomarker for IA screening.

Lessons from Vessel Wall Imaging of Intracranial Aneurysms: New Era of Aneurysm Evaluation beyond Morphology

Recent basic studies have clarified that aneurysmal wall inflammation plays an important role in the pathophysiology of intracranial aneurysms. However, it remains an interdisciplinary challenge to visualize aneurysm wall status in vivo. MR-vessel wall imaging (VWI) is a current topic of advanced imaging techniques since it could provide an additional value for unruptured intracranial aneurysms (UIAs) risk stratification. With regard to ruptured intracranial aneurysms, VWI could identify a ruptured aneurysm in patients with multiple intracranial aneurysms. Intraluminal thrombus could be a clue to interpret aneurysm wall enhancement on VWI in ruptured intracranial aneurysms. The interpretation of VWI findings in UIAs would require much caution. Actually aneurysm wall enhancement in VWI was significantly associated with consensus morphologic risk factors. However, aneurysmal wall with contrast enhancement oftentimes associated with atherosclerotic, degenerated and thickened wall structure. It remains ill defined if thin wall without wall enhancement (oftentimes invisible in VWI) could be actually safe or look over wall vulnerability. We reviewed currently available studies, especially focusing on VWI for intracranial aneurysms and discussed the clinical utility of VWI.

Vessel wall imaging in intracranial aneurysms

High-resolution vessel wall imaging (HR-VWI) is becoming a useful tool in the characterization and identification of unstable unruptured brain aneurysms. However, it has not been validated for clinical use. The current evidence on HR-VWI techniques for characterization of brain aneurysms is described in this review. Specific imaging approaches such as aneurysm wall contrast enhancement, MRI-quantitative susceptibility mapping, and 7T MRI are described in detail.

Shear stress and aneurysms: a review

Wall shear stress, the frictional force of blood flow tangential to an artery lumen, has been demonstrated in multiple studies to influence aneurysm formation and risk of rupture. In this article, the authors review the ways in which shear stress may influence aneurysm growth and rupture through changes in the vessel wall endothelial cells, smooth-muscle cells, and surrounding adventitia, and they discuss shear stress–induced pathways through which these changes occur.

Delayed development of a de novo contralateral middle cerebral artery aneurysm in a patient with hyperimmunoglobulin E syndrome: A case report

A 50-year-old female patient with hyperimmunoglobulin E syndrome (HIES) presented initially at the age of 48 years with subarachnoid hemorrhage (SAH) from a ruptured left middle cerebral artery (MCA) bifurcation aneurysm, which was treated successfully with coiling and microsurgical clipping. Angiography and cross-sectional imaging did not indicate evidence of any additional intracranial aneurysm. However, the patient presented two years later with SAH secondary to a new ruptured right MCA bifurcation aneurysm, which was treated successfully with microsurgical clipping. This case provides further evidence that HIES places the cerebral vasculature at increased risk for cerebral aneurysm formation and that special considerations are indicated in managing and monitoring these patients.

A Study of the Sagittal Angle of Lumbar Bicortical Pedicle Screws from the Anatomic Perspective of the Lumbar Artery

OBJECTIVE

To observe anatomic relationships between lumbar bicortical pedicle screws (BPSs) at 2 sagittal section angles (SSAs) and lumbar artery (LA).

METHODS

We observed 2 SSAs, vertical angle and cephalic angle, of the BPS. The positions at which the BPS breaks through the anterior vertebral cortex were defined as point A and point B. Distances from point A and point B to LAs were measured. The percentage of risk of injury to LAs was calculated according to these distances.

RESULTS

At the same transverse section angle on the left and right side in L1 and L2, distance from point A to LA was significantly greater than distance from point B to LA (P < 0.001) except at a transverse section angle of 0° on the right side in L2 (P > 0.05). At the same transverse section angle on the left in L3 and L4, distance from point B to LA was significantly greater than distance from point A to LA (P < 0.001). The percentages of high risk of injury to the LA resulting from BPSs at the vertical angle in L1 and L2 were 0%-6.2%. The percentages of high risk of injury to the LA resulting from BPSs at the cephalic angle on the left side in L3 and L4 were 0%-18.5%.

CONCLUSIONS

Lumbar BPSs present a risk of injury to the LA. The vertical angle is the recommended SSA for BPSs in L1 and L2, and the cephalic angle is the recommended SSA in L3 and L4.