Pharmacological Inhibition of Epidermal Growth Factor Receptor Prevents Intracranial Aneurysm Rupture by Reducing Endoplasmic Reticulum Stress

BACKGROUND

Multiple pathways and factors are involved in the rupture of intracranial aneurysms. The EGFR (epidermal growth factor receptor) has been shown to mediate inflammatory vascular diseases, including atherosclerosis and aortic aneurysm. However, the role of EGFR in mediating intracranial aneurysm rupture and its underlying mechanisms have yet to be determined. Emerging evidence indicates that endoplasmic reticulum (ER) stress might be the link between EGFR activation and the resultant inflammation. ER stress is strongly implicated in inflammation and apoptosis of vascular smooth muscle cells, both of which are key components of the pathophysiology of aneurysm rupture. Therefore, we hypothesized that EGFR activation promotes aneurysmal rupture by inducing ER stress.

METHODS

Using a preclinical mouse model of intracranial aneurysm, we examined the potential roles of EGFR and ER stress in developing aneurysmal rupture.

RESULTS

Pharmacological inhibition of EGFR markedly decreased the rupture rate of intracranial aneurysms without altering the formation rate. EGFR inhibition also significantly reduced the mRNA (messenger RNA) expression levels of ER-stress markers and inflammatory cytokines in cerebral arteries. Similarly, ER-stress inhibition also significantly decreased the rupture rate. In contrast, ER-stress induction nullified the protective effect of EGFR inhibition on aneurysm rupture.

CONCLUSIONS

Our data suggest that EGFR activation is an upstream event that contributes to aneurysm rupture via the induction of ER stress. Pharmacological inhibition of EGFR or downstream ER stress may be a promising therapeutic strategy for preventing aneurysm rupture and subarachnoid hemorrhage.

Does the use of oral contraceptives or hormone replacement therapy offer protection against the formation or rupture of intracranial aneurysms in women?: a systematic review and meta-analysis

OBJECTIVE

The aim of this study was to carry out a systematic review of the literature with meta-analysis to evaluate the effect of using oral contraceptive and hormone replacement therapy as a protective factor in the formation of intracranial aneurysms and subarachnoid hemorrhage.

METHODS

This is a systematic review of the literature with meta-analysis, using PubMed and Embase as databases and the PRISMA method. Case-control and cohort studies published until December 2022 were included in this review.

RESULTS

Four studies were included in this review; three of which were eligible for meta-analysis. Regarding the use of oral contraceptive and the development of subarachnoid hemorrhage, there was a lower risk of aneurysm rupture with an odds ratio 0.65 (confidence interval 0.5-0.85). In the analysis of patients using hormone replacement therapy and developing subarachnoid hemorrhage, there was also a lower risk of aneurysm rupture with an OR 0.54 (CI 0.39-0.74). Only one article analyzed the formation of intracranial aneurysm and the use of hormone replacement therapy and oral contraceptive, and there was a protective effect with the use of these medications. oral contraceptive: OR 2.1 (CI 1.2-3.8) and hormone replacement therapy: OR 3.1 (CI 1.5-6.2).

CONCLUSION

The use of hormone replacement therapy and oral contraceptive has a protective effect in intracranial aneurysm rupture and formation.

Wheat ergot fungus-derived and modified drug for inhibition of intracranial aneurysm rupture due to dysfunction of TLR-4 receptor in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a form of dementia that strikes elderly people more frequently than it does younger people. The cognitive skills and memory of Alzheimer's sufferers continue to deteriorate over time. Recent studies have shown that patients with AD have greater amounts of inflammatory markers in their bodies, which suggests that inflammation occurs early on in the progression of the disease. There is a possibility that Aß oligomers and fibrils can be recognised by TLRs, in addition to the microglial receptors CD14, CD36, and CD47. When Aß binds to either CD36 or TLR4, it sets off a chain reaction of inflammatory chemokines and cytokines that ultimately results in neurodegeneration. Diabetes and Alzheimer's disease have both been recently related to TLR4. The activation of TLR4 has been connected to a variety of clinical difficulties that are associated with diabetes, in addition to the internal environment of the body and the microenvironment of the brain. TLR4 inhibitors have been shown in clinical investigations to not only lessen the likelihood of getting sick but also to increase the average longevity.

RESULT

In this work we used molecular docking and molecular dynamics modelling to investigate the effectiveness of FDA-approved antidiabetic plant derived drugs in combating the TLR4 receptor. Molecular docking experiments were used to make a prediction regarding the most important interactions involving 2-Bromoergocryptine Mesylate. With a binding affinity of -8.26 kcal/mol, it stood out from the other candidates as the one with the greatest potential. To verify the interaction pattern that takes place between 2-Bromoergocryptine Mesylate and the TLR4 receptor, a molecular dynamic simulation was run at a time scale of 150 nanoseconds. Because of this, 2-Bromoergocryptine Mesylate was able to make substantial contact with the active site, which led to increased structural stability during the process of the complex's dynamic development.

CONCLUSION

As a result of this, the results of our research may be relevant for future research into the efficacy of 2-bromoergocryptine mesylate as a potential lead treatment for TLR4 receptors in intracranial aneurysm rupture in AD.

Aspirin treatment prevents inflammation in experimental bifurcation aneurysms in New Zealand White rabbits

BACKGROUND

Aneurysm wall degeneration is linked to growth and rupture. To address the effect of aspirin (ASA) on aneurysm formation under various wall conditions, this issue was analyzed in a novel rabbit bifurcation model.

METHODS

Bifurcation aneurysms created in 45 New Zealand White rabbits were randomized to vital (n=15), decellularized (n=13), or elastase-degraded (n=17) wall groups; each group was assigned to a study arm with or without ASA. At follow-up 28 days later, aneurysms were evaluated for patency, growth, and wall inflammation at macroscopic and histological levels.

RESULTS

36 rabbits survived to follow-up at the end of the trial. None of the aneurysms had ruptured. Patency was visualized in all aneurysms by intraoperative fluorescence angiography and confirmed in 33 (92%) of 36 aneurysms by MRI/MRA. Aneurysm size was significantly increased in the vital (without ASA) and elastase-degraded (with and without ASA) groups. Aneurysm thrombosis was considered complete in three (50%) of six decellularized aneurysms without ASA by MRI/MRA. Locoregional inflammation of the aneurysm complex was significantly reduced in histological analysis among all groups treated with ASA.

CONCLUSION

ASA intake prevented inflammation of both the periadventitial tissue and aneurysm wall, irrespective of initial wall condition. Although ASA prevented significant growth in aneurysms with vital walls, this preventive effect did not have an important role in elastase-degraded pouches. In possible translation to the clinical situation, ASA might exert a potential preventive effect during early phases of aneurysm formation in patients with healthy vessels but not in those with highly degenerative aneurysm walls.

Roles of Phytoestrogen in the Pathophysiology of Intracranial Aneurysm

[Figure: see text].

Simvastatin increases circulating endothelial progenitor cells and inhibits the formation of intracranial aneurysms in rats with diet-induced hyperhomocysteinemia

BACKGROUND AND PURPOSE

Endothelial dysfunction triggers early pathological changes in artery, leading to the formation of intracranial aneurysm (ICA). Increase in plasma homocysteine (Hcy) impairs endothelium and endothelial progenitor cells (EPCs) are critical in repairing damaged endothelium. The aim of this study was to assess the impact of simvastatin on ICA formation in rats with hyperhomocysteinemia (HHcy).

METHODS

ICAs were induced in Male Sprague-Dawley rats after surgical induction in the presence of HHcy induced by a high L-methionine diet with or without oral simvastatin treatment. The size and media thickness of ICAs were evaluated 2 months after aneurysm induction. EPCs and serum vascular endothelial grow factor (VEGF) were measured be flow cytometry and ELISA respectively. Plasma Hcy levels and expression of VEGF, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), matrix metalloproteinase-2 (MMP-2), and MMP-9 in aneurysmal walls were examined and correlated with ICA formation.

RESULTS

HHcy accelerates ICA formation and rats treated with simvastatin exhibited a significant increase in media thickness and a reduction in aneurysmal size. Simvastatin increased levels of circulating EPCs and decreased iNOS, MMP-2, MMP-9 and VEGF mRNA levels, while increased eNOS mRNA in aneurysmal tissue.

CONCLUSION

In a rat model, HHcy reduces circulating EPCs and accelerates ICA formation. Simvastatin treatment increases circulating EPCs and inhabits the formation of ICA. We have shown a close association among circulating EPCs, biochemical markers related to vascular remodeling and the formation of ICA.

Candidate drugs for preventive treatment of unruptured intracranial aneurysms: A cross-sectional study

Background and purpose

Establishment of drug therapy to prevent rupture of unruptured intracranial aneurysms (IAs) is needed. Previous human and animal studies have gradually clarified candidate drugs for preventive treatment of IA rupture. However, because most of these candidates belong to classes of drugs frequently co-administered to prevent cardiovascular diseases, epidemiological studies evaluating these drugs simultaneously should be performed. Furthermore, because drugs included in the same class may have different effects in terms of disease prevention, drug-by-drug assessments are important for planning intervention trials.

Materials and methods

We performed a cross-sectional study enrolling patients diagnosed with IAs between July 2011 and June 2019 at our institution. Patients were divided into ruptured or unruptured groups. The drugs investigated were selected according to evidence suggested by either human or animal studies. Univariate and multivariate logistic regression analyses were performed to assess the association of drug treatment with rupture status. We also performed drug-by-drug assessments of the association, including dose-response relationships, with rupture status.

Results

In total, 310 patients with ruptured and 887 patients with unruptured IAs were included. Multivariate analysis revealed an inverse association of statins (odds ratio (OR), 0.54; 95% confidence interval (CI) 0.38–0.77), calcium channel blockers (OR, 0.41; 95% CI 0.30–0.58), and angiotensin II receptor blockers (ARBs) (OR, 0.67; 95% CI 0.48–0.93) with ruptured IAs. Moreover, inverse dose-response relationships with rupture status were observed for pitavastatin and rosuvastatin among statins, benidipine, cilnidipine, and amlodipine among calcium channel blockers, and valsartan, azilsartan, candesartan, and olmesartan among ARBs. Only non-aspirin non-steroidal anti-inflammatory drugs were positively associated with ruptured IAs (OR, 3.24; 95% CI 1.71–6.13).

Conclusions

The present analysis suggests that several types of statins, calcium channel blockers, and ARBs are candidate drugs for preventive treatment of unruptured IAs.

A novel application for bolus remifentanil: blunting the hemodynamic response to Mayfield skull clamp placement

OBJECTIVE

Neurosurgery often requires skull immobilization with a Mayfield clamp, which often causes brief intense nociceptive stimulation, hypertension and tachycardia. Blunting this response may help prevent increased intracranial pressure, cerebral aneurysm or vascular malformation rupture, and/or myocardial stress. While various interventions have been described to blunt this response, no reports have compared administration of a propofol versus a remifentanil bolus.

METHODS

We retrospectively analyzed the hemodynamic response to Mayfield placement in over 800 patients who received a prior propofol or remifentanil bolus from 2004 to 2010.

RESULTS

Patients who received remifentanil experienced a 55% smaller increase in heart rate (p < 0.0001) and a 40% smaller increase in systolic blood pressure (p < 0.0001) after Mayfield placement than patients who received propofol. These data were retrospectively obtained from patients who were not randomized to receive remifentanil versus propofol, and hence these data could be subject to possible confounding. Nonetheless, these differences remained significant after multivariate analysis for possible confounding variables.

CONCLUSIONS

Thus, a remifentanil bolus is more effective than a propofol bolus in blunting hemodynamic responses to Mayfield placement, and possibly for other short, intense nociceptive stimuli.

Review of 2 decades of aneurysm-recurrence literature, part 1: reducing recurrence after endovascular coiling

SUMMARY

Angiographic recurrence following endovascular therapy is an indirect measure of the potential for hemorrhage. Because patients and physicians consider recurrence to be a suboptimal outcome with some chance of future hemorrhage, much effort has been expended to reduce the incidence of recurrence. The literature regarding aneurysm recurrence following endovascular therapy, spanning 2 decades, is extensive. We will review and summarize the effort to reduce recurrence following endovascular treatment of cerebral aneurysms.

Comparison of multislice computed tomography angiography and digital subtraction angiography in the detection of residual or recurrent aneurysm after surgical clipping with titanium clips

PURPOSE

To determine the diagnostic accuracy of 3D-CTA using volume rendering (VR) in the detection of residual or recurrent cerebral aneurysms after clipping.

MATERIAL AND METHODS

Between January 2006 and November 2007, 45 patients (20 female, 25 male) with 50 intracranial aneurysms treated using titanium clips were enrolled in this study. IADSA and 3D-CTA were performed within 1 month after surgery in 27 (60%) patients, after 1 year in 12 (26%) patients and after 5 years in six (13%) patients. In blinded fashion, CTA and DSA images were independently interpreted by two senior neuroradiologists with 7 years of experience in vascular diagnostic neuroradiology. The diagnostic performance of MDCTA compared with DSA for the detection of aneurysm remnants was measured by receiver operating characteristic (ROC) analysis. The area under the ROC curve, 95% confidence interval (CI), sensitivity, and specificity were calculated.

RESULTS

For the detection of residue-recurrent aneurysm; the sensitivity and specificity of MDCTA were 87.5% (95% CI = 52.9-97.8%) and 97.4% (95% CI = 86.5-99.5%) for the first reader and 87.5% (95% CI = 52.9-97.8%) and 100% (95% CI = 90.8-100%) for the second reader respectively. Receiver operating characteristic (ROC) analysis revealed good diagnostic performance for 3D-CTA (mean area under ROC curve (Az) = 0.98 and 0.99 for the first and the second observer, respectively) The kappa values extracted from the interobserver concordance analysis for agreement observers regarding the use of MDCTA for assessment of a remnant neck was 0.62.

CONCLUSION

Using MDCTA, it is possible to demonstrate the status of intracranial aneurysms after surgical clipping in the immediate postoperative period as well as long-term follow-up with an high sensitivity and specificity when comparing with the findings of DSA.

Intracerebral hemorrhage after prophylactic revascularization in a patient with adult moyamoya disease

BACKGROUND

The effect of revascularization surgery for a patient with moyamoya disease remains controversial.

CASE DESCRIPTION

A 60-year-old man presented with bleeding from asymptomatic moyamoya vessels 10 years after prophylactic revascularization surgery. Cerebral angiography 10 years after the surgery demonstrated that the bilateral direct anastomoses remained effective and a small aneurysm persisted in the anterior choroidal artery. The territories of perfusion through the anastomoses and the size of the aneurysm remained unchanged compared with the angiograms performed 10 years ago.

CONCLUSIONS

Direct revascularization surgery may not always resolve microaneurysms in the moyamoya vessels and prevent rebleeding in patients with hemorrhagic moyamoya disease or bleeding in the nonaffected side.

Collateral blood flow patterns in patients with unilateral ICA agenesis and cerebral aneurysm

BACKGROUND

Agenesis of one or both internal carotid arteries (ICA) is usually a benign congenital anomaly. Many patients are diagnosed incidentally and remain asymptomatic, however associated cerebral aneurysms can be life-threatening and result in high morbidity and mortality rates in this population.

MATERIAL & METHODS

Based on the timing of ICA agenesis, during the fetal life, we classified the collateral blood flow pattern into three major types; type I: Collateral blood flow via primitive vessels, type II: Collateral blood flow via ICA branches, and type III: collateral blood flow via branches of the external carotid artery (ECA). The type of collateral blood flow pattern in the reported patients with ICA agenesis and cerebral aneurysm was reviewed in order to determine the relation between the type of collateral blood flow and the development of CAs.

RESULTS

Twenty nine patients with ICA agenesis and CA were reported, of these 27 patients (93%) were found to have type II collateral blood flow, 2 patients (7%) had type I collateral blood flow pattern and none had type III collateral flow pattern. The majority of patients (79%) with CA secondary to ICA agenesis presented with subarachinoid hemorrhage (SAH).

CONCLUSION

Although ICA agenesis is a symptomatic in the majority of cases, it must be recognized because it promotes the development of CA and SAH. Our new classification system for collateral blood flow patterns is easy to use and can predict those at high risk to develop cerebral aneurysms and SAH, and therefore, need annual screening MRA.

The joint effect of oxidative stress and antioxidants on the risk of an aneurysmal rupture subarachnoid hemorrhage: a case-control study in Japan

PURPOSE

A case-control study was conducted in Japan to examine the joint effects of oxidative stress and antioxidants on the risk of subarachnoid hemorrhage (SAH).

METHODS

The study included 201 consecutive patients with first spontaneous SAH aged 30 to 79 years who had aneurysm(s) confirmed by angiography and/or computed tomographic scan and were admitted to two medical hospitals in Nagoya, Japan, from April 1992 to March 1997. Community control subjects were identified and matched to each case by gender and age (+/-2 years). Conditional logistic regression modeling was used to compute odds ratios (ORs) adjusted for body mass index, physical activity, family history of SAH, a history of hypertension, drinking habit, and frequency of green-yellow vegetables and fruits, and tea consumption.

RESULTS

The greatest risk for SAH was posed by combination of current smoking and a less frequent intake of soy products (adjusted OR = 5.3; 95% confidence interval [CI], 2.0 to 14.3). Less frequent intake of soy products significantly elevated SAH risk, independent of smoking habits.

CONCLUSION

These data suggested that enhancement of the antioxidant defense system such as much intake of soy products may be important in preventing SAH rather than the reduction of such oxidants as smoking. Our findings should prove useful for targeting individuals/populations in programs for primary prevention of SAH.

Cerebral aneurysm progression suppressed by blockage of endothelin B receptor

OBJECT

Cerebral aneurysm is a major cause of subarachnoid hemorrhage, but the mechanisms of its development remain unclear. Mechanical stretch has been reported to induce vascular smooth-muscle cell apoptosis via endothelin B receptors (ETBRs). The objectives of this study were to clarify the expression and localization of ETBR in cerebral aneurysms and to examine the effect of ETBR blockage on the development of experimental cerebral aneurysms.

METHODS

Seventy-two rats underwent a cerebral aneurysm induction procedure and were divided into four groups according to the duration of postoperative study periods. Expression of ETBR was confirmed by reverse transcription-polymerase chain reaction and immunohistochemical analysis. The authors also studied the effect of K-8794, an oral selective antagonist of ETBR, to see whether it would influence the formation of cerebral aneurysms. Two weeks after the aneurysm induction procedure, ETBR was rarely detected in anterior cerebral artery-olfactory artery bifurcations, but it was weakly expressed in experimental cerebral aneurysms at 1 month after the procedure, and markedly expressed at 3 months. The administration of K-8794 for 1 month after the procedure significantly reduced the number of advanced aneurysms and the number of apoptotic smooth-muscle cells.

CONCLUSIONS

These results suggest that ETBR might play a significant role in the progression of cerebral aneurysms and have the potential to improve prevention and treatment of cerebral aneurysms.

Sentinel Headache and the Risk of Rebleeding After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

The clinical significance of sentinel headaches in patients with subarachnoid hemorrhage (SAH) is still unknown. We investigated whether patients with a sentinel headache (SH) have a higher rate of rebleeding after SAH.

METHODS

An SH was defined as a sudden, severe, unknown headache lasting >1 hour with or without accompanying symptoms, not leading to a diagnosis of SAH in the 4 weeks before the index SAH. Age, sex, smoking status, clinical grade, computed tomography (CT) findings, angiographic findings, placement of an external ventricular drain, and time to aneurysm obliteration were prospectively recorded. All rebleeding events were confirmed by CT. Outcome was assessed at 6 months according to the modified Rankin Scale.

RESULTS

Of 237 consecutive patients with SAH, 41 (17.3%) had an SH. Rebleeding occurred in 23 (9.7%) of all patients. Patients with an SH had a 10-fold increased odds of rebleeding compared with patients without SH. Aneurysm size and the total number of aneurysms were also significantly associated with rebleeding. There were no differences in age, sex, smoking, CT or angiographic findings, external ventricular drain placement, or time to aneurysm obliteration between groups. Patients with rebeeding had a significantly worse outcome. Logistic regression revealed the presence of an SH as an independent risk factor for rebleeding.

CONCLUSIONS

In our study, patients with SAH who had an SH constituted a special group of patients with a 10-fold odds for early rebleeding. The presence of an SH may select candidates for ultraearly aneurysm obliteration or drug treatment.

Growth factor receptor expression and remodeling of saccular cerebral artery aneurysm walls: implications for biological therapy preventing rupture

OBJECTIVE

Remodeling of the saccular cerebral artery aneurysm (SCAA) wall, known to be associated with rupture, might be modified with bioactive endovascular implants or systemic drug therapy targeted at growth factor receptors to prevent rupture. The receptors regulating SCAA wall remodeling are, however, unknown.

MATERIALS AND METHODS

Immunostaining for 12 growth factor receptors, and markers for matrix synthesis, proliferation, and inflammatory cell infiltration, were analyzed in 21 unruptured and 35 ruptured aneurysm fundi resected after microsurgical clipping of the aneurysm neck. The results were compared with clinical and radiological data.

RESULTS

Eleven of the 12 receptors studied were expressed at varying intensities in the 56 SCAA walls. Only transforming growth factor (TGF)beta-R2 and vascular endothelial growth factor (VEGF)-R1 were associated with rupture and basic fibroblast growth factor-R1 with minor leaks (P = 0.018). TGFbeta-R3 and VEGF-R1 was associated with wall remodeling (P = 0.043 and 0.027), and VEGF-R1 was associated with T-cell and macrophage infiltration as well as organization of luminal thrombosis (P = 0.019). VEGF-R2 was associated with myointimal hyperplasia (P = 0.017) and proliferation (P < 0.001).

CONCLUSION

VEGF, TGFbeta, and basic fibroblast growth factor receptors were associated with SCAA wall remodeling, making them potential targets for bioactive endovascular implants or drug therapy aiming to reinforce the SCAA wall.

A mathematical model of the natural history of intracranial aneurysms: quantification of the benefit of prophylactic treatment

Object

The International Study of Unruptured Intracranial Aneurysms (ISUIA) data raised new controversy regarding the threshold size that requires treatment. In particular, this study has been criticized for disagreeing with previous epidemiological data.

Methods

The author first used a Markov model to simulate the natural history of intracranial aneurysms, making three key assumptions based on prospective ISUIA data and other recent reports: that the rate of de novo aneurysm formation is constant after the age of 20 years; that unruptured aneurysms gain volume at a constant rate; and that unruptured aneurysms rupture at a volume-dependent rate. Next, he expressed outcomes for patients with unruptured aneurysms in terms of expected number of quality-adjusted life years (QALY) and compared two hypothetical cohorts, one receiving treatment and the other not being treated. These assumptions enabled the construction of a mathematical model with epidemiologically compatible findings. The benefits of treatment for unruptured aneurysms were highly influenced by aneurysm size and were calculated as −0.28, 0.25, and 1.07 QALY for patients having unruptured aneurysms with diameters of 7, 10, and 13 mm, respectively.

Conclusions

Under the author’s assumptions, the prospective ISUIA data may be consistent with epidemiological findings. Prophylactic treatment for unruptured aneurysms may produce some benefits in large aneurysms if acceptable treatment risks can be assured, but it is not likely to offer improvement over the natural history for patients with small aneurysms.

Role of estrogen deficiency in the formation and progression of cerebral aneurysms. Part II: experimental study of the effects of hormone replacement therapy in rats

OBJECT

The increased incidence of cerebral aneurysms in postmenopausal women appears to be related to low levels of circulating estrogen. Using a rat model of aneurysm induction, the authors found that oophorectomy increased the incidence of experimental cerebral aneurysms (Part I in this issue). In the current study they examined the effects of hormone replacement therapy (HRT) on the formation of cerebral aneurysms in rats.

METHODS

Forty-five female Sprague-Dawley rats were divided into three equal groups. The animals in Groups A and B were subjected to a cerebral aneurysm induction procedure (renal hypertension and right common carotid artery ligation) followed 1 month later by bilateral oophorectomy. After an additional week the rats in Group A received 17beta estradiol continuous-release pellets. The rats in Group C served as controls. Three months after the aneurysm induction procedure, all the rats were killed and vascular corrosion casts of their cerebral arteries were prepared and checked for aneurysmal changes. Using a scanning electron microscope, the authors recorded aneurysmal changes as endothelial changes alone (Stage I), endothelial changes with intimal pad elevation (Stage II), and saccular aneurysm formation (Stage III). Aneurysmal changes (Stages I, II, and III) occurred in one third of rats that had undergone oophorectomy and were receiving HRT (Group A), compared with 87% of the rats that had undergone oophorectomy but did not receive HRT (Group B). Although most of the aneurysmal changes identified in Group A rats were limited to Stage I or II, most changes in Group B animals were identified as saccular dilation (Stage III).

CONCLUSIONS

The findings demonstrated the significant protective role of estrogen against the formation and progression of cerebral aneurysms. It appears to be related to the beneficial effects of estrogen on the function and growth of endothelial cells, which play a major role in preserving the integrity of the vascular wall.

A failure of matrix metalloproteinase inhibition in the prevention of rat intracranial aneurysm formation

We tested the hypothesis that nonspecific matrix metalloproteinase (MMP) inhibition with doxycycline would decrease the incidence of intracranial aneurysm formation in a rat aneurysm model. We performed common carotid artery ligation on 96 Long-Evans rats. A treatment group of 48 animals was chosen at random to receive oral doxycycline (3 mg/kg) in addition to standard rat chow, and the control group of 48 animals received standard rat chow only. The major circle of Willis arteries was dissected at 1 year following carotid ligation, and the proportions of animals with aneurysms were compared between groups using Fisher's exact test. Four animals given oral doxycycline and ten control animals expired before 1 year. Of the examined animals, eight saccular intracranial aneurysms were found in 8 of 45 animals which had received doxycycline (17.8%) and seven saccular intracranial aneurysms were found in 7 of 37 control animals (18.9%). There was no significant difference in aneurysm formation between the doxycycline-treated and control groups (P=0.894). Nonspecific MMP inhibition with doxycycline is not effective in preventing intracranial aneurysm formation in a rat model.

Predictors and impact of aneurysm rebleeding after subarachnoid hemorrhage

BACKGROUND

Aneurysm rebleeding has historically been an important cause of mortality after subarachnoid hemorrhage (SAH).

OBJECTIVE

To describe the frequency and impact of rebleeding in the modern era of aneurysm care, which emphasizes early surgical or endovascular treatment.

DESIGN

Inception cohort.

SETTING

Tertiary care medical center.

PATIENTS

A total of 574 patients enrolled in the Columbia University SAH Outcomes Project between August 1996 and June 2002. Early aneurysm repair was performed whenever feasible.

MAIN OUTCOME MEASURES

Rebleeding was defined by prespecified clinical and radiographic criteria, excluding prehospital, intraprocedural, and postrepair events. Functional outcome was assessed at 3 months with the modified Rankin Scale. Multiple logistic regression was used to identify predictors of rebleeding, poor functional outcome, and mortality.

RESULTS

Rebleeding occurred in 40 (6.9%) of the 574 patients; most cases (73%) occurred within 3 days of ictus. Hunt-Hess grade on admission (odds ratio [OR], 1.92 per grade; 95% confidence interval [CI], 1.33-2.75; P<.001) and maximal aneurysm diameter (OR, 1.07/mm; 95% CI, 1.01-1.13; P = .005) were independent predictors of rebleeding. After controlling for Hunt-Hess grade and aneurysm size, rebleeding was associated with a markedly reduced chance of survival with functional independence (modified Rankin Scale score, </=4; OR, 0.08; 95% CI, 0.02-0.34) at 3 months.

CONCLUSIONS

Despite an aggressive management strategy, rebleeding still occurred in 6.9% of patients and was associated with a dismal outcome. Poor Hunt-Hess grade and larger aneurysm size are related to rebleeding. Pharmacologic therapy to reduce the risk of rebleeding before aneurysm repair, particularly in patients with poor grade neurologic status and large aneurysms, deserves renewed attention.

Role of the endothelial lining in recurrences after coil embolization: prevention of recanalization by endothelial denudation

BACKGROUND AND PURPOSE

Endovascular treatment can improve the outcome of patients treated for ruptured intracranial aneurysms as compared with surgical clipping, but angiographic recurrences are frequent. Endothelial denudation before coil embolization may prevent recanalization and improve results of endovascular treatment.

METHODS

We compared angiographic and pathological results 3 months after coil occlusion of paired canine arteries (n=16), with or without previous denudation of the endothelial lining using an endovascular device. The technique was then used to denude the neck of carotid venous pouch bifurcation aneurysms before coil embolization in 8 dogs, and the angiographic evolution at 12 weeks was compared with 7 control aneurysms treated by coiling only. Qualitative scoring systems were used to compare angiographic results with time and neointimal coverage at the neck of aneurysm after necropsy. The evolution of angiographic scores was analyzed using Wilcoxon signed rank tests whereas angiographic and neointimal scores of the 2 groups were compared using the Mann-Whitney test.

RESULTS

All arteries embolized with platinum coils recanalized, whereas most arteries (12/16 or 75%) denuded before coil embolization remained occluded at 3 and 12 weeks (P<0.001). Aneurysms treated with coils without previous denudation tended to recur, with angiographic scores significantly worse at 12 weeks as compared with T(0) (P=0.015). Median angiographic and neointimal scores were significantly better at 12 weeks with endothelial denudation (P=0.011 and 0.026, respectively).

CONCLUSIONS

Endothelial denudation can prevent recanalization after coil embolization.

A therapeutic dilemma: atrial fibrillation, transient ischaemic attacks and an unruptured intracranial aneurysm

Within 1 month, a 69-year-old right-handed man had three episodes of weakness of sudden onset affecting the left arm and face, followed by complete recovery within 10 minutes to 2 hours. He was a non-smoker, but had been diagnosed with hypertension 4 months earlier, treated with bendrofluazide. The neurological examination was normal, but he was in atrial fibrillation (ventricular rate >100/min) with a blood pressure of 160/70 mmHg. There were no carotid bruits. Transthoracic echocardiogram, carotid doppler ultrasonography and computed tomography (CT) of the brain were all normal. A diagnosis of transient ischaemic attacks (TIAs) was made, probably caused by emboli of cardiac origin. He was commenced on sotalol (40 mg twice daily) to attempt to prevent further attacks of atrial fibrillation. The use of anticoagulation was also considered.

In the past medical history, an episode of right-sided weakness of sudden onset, lasting 5 hours with complete recovery, had occurred 8 years earlier. CT brain scan at that time showed a high density lesion in the left internal capsule; it was not possible to decide whether this was haemorrhage into an infarct or a primary intracerebral haemorrhage from a left middle cerebral artery aneurysm. Cerebral angiography showed a small saccular aneurysm close to the trifurcation of the right (sic) middle cerebral artery. This lesion was thought incidental to the clinical history and, because of its size, surgery was not advised. Interval magnetic resonance angiography 3 and 6 years later showed no change in aneurysm size (<2 mm) and management remained conservative.

Despite the evidence supporting anticoagulation to prevent stroke in patients with atrial fibrillation, it was initially thought that this treatment would be contraindicated by the presence of an unruptured intracranial aneurysm. However, in the absence of evidence specific to this clinical situation (see discussion), the available data suggested that benefits of anticoagulation (stroke prevention) outweighed (haemorrhagic) risk in this patient. These issues were discussed with the patient who decided to opt for anticoagulation. Close monitoring to maintain an international normalized ratio between 2.0 and 2.5 was the aim. After 12 months of follow up the patient remained well with no further TIAs and no complications.

In situ beta radiation to prevent recanalization after coil embolization of cerebral aneurysms

BACKGROUND AND PURPOSE

Endovascular treatment of cerebral aneurysms, a minimally invasive alternative to surgery, is too often followed by recanalization and recurrences. The purpose of this work was to assess if in situ beta radiation can inhibit recanalization after coil embolization.

METHODS

Radioactive platinum coils (32P-coils) were produced by ion implantation of 32P. A single-coil arterial occlusion model was used to compare angiographic and pathological results at 1 to 12 weeks after nonradioactive and 32P-coil embolization of maxillary, cervical, and vertebral arteries in 26 dogs. Coils of varying activities were used and results compared to define the minimal activity required to inhibit recanalization. Similar experiments were performed in 16 porcine maxillary and lingual and 8 rabbit axillary arteries. Results of 32P-coil embolization of bifurcation aneurysms were then compared with embolization with nonradioactive coils in 12 dogs at 3 months.

RESULTS

Nonradioactive coil embolization of canine arteries led to occlusion at 1 week, followed by recanalization at 2 weeks, which persisted at 3 months in all cases. 32P-coils, ion-implanted with activities above 0.13 microCi/cm, led to persistent occlusion at 3 months in 80% of arteries. 32P-coils ion-implanted with the same activity inhibited recanalization in porcine and rabbit arteries. Bifurcation aneurysms treated with 32P-coils had better angiographic results at 3 months (P=0.006) than aneurysms treated with nonradioactive coils. Arteries occluded were filled with fibrous tissue at 3 months. Aneurysms embolized with 32P-coils showed more complete neointimal coverage of the neck, without recanalization, as compared with aneurysms treated with nonradioactive coils.

CONCLUSION

In situ low-dose beta radiation inhibits recanalization after coil embolization and may improve long-term results of endovascular treatment of aneurysms.

Epidemiology of intracranial aneurysm and subarachnoid hemorrhage

Intracranial aneurysmal hemorrhage is a common but devastating condition associated with significant morbidity and mortality. Epidemiologic studies have identified risk factors associated with this condition. Genetic factors involve family history and the presence of certain heritable connective tissue disorders such as Ehlers-Danlos syndrome, Marfan's syndrome, neurofibromatosis, and polycystic kidney disease. Acquired factors include traumatic brain injury, sepsis, smoking, and hypertension. Management of these patients consists of prevention, patient screening, and prophylactic aneurysm repair.

Mechanism and prevention of enlargement or new development of aneurysm following treatment by clipping or coiling

The mechanisms of cerebral aneurysm recurrence and enlargement were investigated in 11 patients: two with dissecting aneurysms, six with fully grown aneurysms after neck clipping, one with enlarged aneurysm after dome clipping, and two with enlarged aneurysm due to recanalization after GDC coil embolization. We concluded that it is fundamentally important to ensure complete attachment of the internal elastic lamina around the aneurysm neck by precise neck clipping and effective embolization, with accurate positioning of remaining internal elastic lamina.

Prevention of rat cerebral aneurysm formation by inhibition of nitric oxide synthase

BACKGROUND

Cerebral saccular aneurysm is a major cause of subarachnoid hemorrhage, one of the cerebrovascular diseases with the highest mortality. The mechanisms underlying the development of aneurysms, however, still remain unclear. We have made a series of reports on an animal model of experimentally induced cerebral aneurysms that resemble human cerebral aneurysms in their location and morphology, suggesting that the arterial wall degeneration associated with aneurysm formation develops near the apex of arterial bifurcation as a result of an increase in wall shear stress. Using the animal model and human specimens, we examined the role of nitric oxide (NO) in the degenerative changes and cerebral aneurysm formation.

METHODS AND RESULTS

Inducible NO synthase (iNOS) was immunohistochemically located at the orifice of human and rat aneurysms. Nitrotyrosine distribution was also seen in the human aneurysm. Although no iNOS immunostaining was found in normal arteries, iNOS immunoreactivity was observed in parallel with the development of early aneurysmal changes in rats. In contrast, during the early development of aneurysm, endothelial NOS immunostaining in the endothelium was weakened compared with that in the control arteries. An NOS inhibitor, aminoguanidine, attenuated both early aneurysmal changes and the incidence of induced aneurysms. A defibrinogenic agent, batroxobin, which may diminish shear stress by reduction of blood viscosity, prevented iNOS induction as well as early aneurysmal changes.

CONCLUSIONS

The evidence suggests that NO, particularly that derived from iNOS, is a key requirement for the development of cerebral aneurysm. The iNOS induction may be caused by an increase in shear stress near the apex.

Screening for cerebral aneurysm in patients with polycystic liver disease

BACKGROUND

Polycystic liver disease (PCLD) is an autosomal dominant disease characterized by multiple macrocystic lesions throughout the liver. The association between PCLD and cerebral aneurysm is well documented, and approximately 20% of patients with PCLD have demonstrable cerebral aneurysms at autopsy. The prevalence reported from autopsy series, however, may not reflect the true prevalence in patients with PCLD. We undertook this study to evaluate the prevalence and diagnosis of cerebral aneurysms in screening cerebral studies in patients with PCLD.

METHODS

Patients were identified by searching the hepatobiliary surgical service data base and hospital medical records. Hospital charts were reviewed to confirm presence of PCLD and to identify screening studies for cerebral aneurysms.

RESULTS

Ten patients with PCLD received screening studies of the cerebral vasculature during a 10 1/2-year period. One patient was found to have an asymptomatic cerebral aneurysm. A 45-year-old woman with no other significant medical history was referred for evaluation of PCLD. Screening magnetic resonance angiography (MRA) revealed a 5 mm aneurysm extending anteriorly near the origin of the right ophthalmic artery, without evidence of rupture. Cerebral angiography confirmed these findings, and the aneurysm was clipped.

CONCLUSIONS

Because cerebral aneurysms can be an important source of morbidity and mortality in PCLD, we recommend screening by MRA or by computed tomographic angiography (CTA) of the cerebral vasculature in all patients who have PCLD.

Coiling of recurrent and residual cerebral aneurysms after unsuccessful clipping

We treated four patients with 3 recurrent and 1 residual aneurysm after surgical clipping by using Guglielmi detachable coils (GDCs). Three subjects presented after a second subarachnoid hemorrhage (SAH) occurring between 10 and 25 years after the first bleeding. Early postoperative angiography of the fourth patient showed an incompletely clipped aneurysm. In three poor grade patients we observed one good outcome, one fair result and one death due to the sequelae of SAH. One good grade patient remained in excellent condition postoperatively. Three aneurysms were totally occluded and in one a more than 90% occlusion was achieved with GDCs. We consider the treatment with GDC a viable alternative to reoperation in all patients with recurrent or residual aneurysms following failed attempt at surgical obliteration.

Cost-effective screening for cerebral aneurysms

The advent of accurate, noninvasive angiography has raised hopes that premorbid screening for cerebral aneurysm will soon be possible. This article discusses the medical and economic issues which will determine the appropriate conditions for, and cost-effectiveness of, large-scale aneurysm screening.

Risk of harboring an unruptured intracranial aneurysm

BACKGROUND AND PURPOSE

The purpose of the present study was to calculate the prevalence and relative risk of unruptured incidental intracranial aneurysms (IAs) among families with IA case(s) compared with the general population in one geographically defined area in East Finland and to identify the risk group that could benefit most from screening for IAs. We compared these results with our earlier study results of familial IA (FIA) cases, with two or more known IA cases in the same family.

METHODS

The study groups were collected from the catchment area of the University Hospital of Kuopio in East Finland. The inclusion criteria were age 30 to 70 years and unruptured incidental IAs > or =3 mm. Patients with previous subarachnoid hemorrhage or in whom a ruptured IA was found to be the cause of death were excluded from all study groups. During routine forensic autopsies the circle of Willis was studied for IAs to estimate the number of IAs in the general population. In the families with one known IA case and in FIA families, MR angiography was used as a preliminary screening method for IAs, followed by intra-arterial angiography to verify suspected IAs. Study populations were age and sex adjusted for the statistical calculations.

RESULTS

The relative risk for IAs among first-degree relatives in FIA families was 4.2 (95% confidence interval, 2.2 to 8.0) and among first-degree relatives in families with only one affected family member was 1.8 (95% confidence interval, 0.7 to 4.8) compared with the general population in East Finland.

CONCLUSIONS

First-degree relatives in FIA families constitute a high-risk group for incidental IAs, and this group would benefit from screening studies for IAs. Screening for IAs in families with only one affected member or in the general population is not recommended.

[A new technique of extubation using laryngeal mask in the neurosurgical anesthesia]

Recently we experienced two cases of multiple cerebral aneurysms for the aneurysmal neck clipping operation. In these cases, as these aneurysms can not be clipped primarily, the patient may still be susceptible to the rupture of remaining aneurysm after operation. Frequent bucking and hypertension occurring during extubation and emergence from anesthesia, can lead to intracranial hemorrhage and increases of intracranial pressure. To reduce this hemodynamic responses, several studies have been reported, but techniques in those papers are not sufficient to prevent the bucking perfectly, and the anesthesiologist has to hold the face mask forcefully for a long time after operation. The laryngeal mask airway (LM) seemed preferable for prevention of bucking and attenuation of cardiovascular response. Therefore, we tried to use LM at the emergence from anesthesia. After surgery, tracheal tube was removed at the deep level of anesthesia, and LM was inserted. After muscle relaxant was reversed, oxygen, nitrous oxide, and 0.3-0.5% sevoflurane were administered until spontaneous breathing became adequate. When sufficient breathing volume was confirmed, all anesthetic agents were terminated, and LM was removed after ascertaining swallowing motion. No bucking and serious hypertension were seen during the procedures, and the patient recovered uneventfully.

[Effectiveness of magnetic resonance angiography for mass screening of unruptured intracranial aneurysms]

Magnetic resonance angiography (MRA) is widely used in screening for unruptured intracranial aneurysm (UIA) in the prevention of onset of subarachnoid hemorrhage (SAH) in Japan. However, the clinical efficacy of mass screening of UIA using MRA has not been established. This study aims to establish the clinical efficacy of mass screening of UIA using MRA by decision-making. The decision tree is constructed simulating a flow of population (100,000 persons, aged 50-59) starting from the MRA screening until the final outcomes of quality adjusted life or death in ten years. In order to estimate the numerical values various parameters were used as follows, prevalence rate: 1%; sensitivity of MRA: 74%; specificity of MRA: 76%; death rate by intracranial angiography: 0.1%; rupture rate of UIA: 2%/year; death rate of SAH: 57%; and death rate for surgery for UIA: 0.0%. The following results were obtained: 1. The number of lives saved by the MRA screening was 760, while the number saved without MRA was 79. 2. The number of deaths in those receiving the MRA screening was 52, while the number of deaths without MRA was 104. 3. The level of quality adjusted life with the MRA screening was higher than that without MRA in all cases. In conclusion, mass screening of UIA using MRA appears to be effective.

Risk factors and solutions for the development of neurobehavioral changes after coronary artery bypass grafting

BACKGROUND

As operative mortality for coronary artery bypass grafting has decreased, greater attention has focused on neurobehavioral complications of coronary artery bypass grafting and cardiopulmonary bypass.

METHODS

To assess risk factors and to evaluate changes in surgical technique, between 1991 and 1994 we evaluated 395 patients undergoing coronary artery bypass grafting with an 11-part neurobehavioral battery administered preoperatively and at 1 and 6 weeks postoperatively. Patients were instrumented with 5-MHz focused continuous-wave carotid Doppler transducers intraoperatively to estimate cerebral microembolism as an instantaneous perturbation of the velocity signal. Microembolism data were quantitated and compared with surgical technical maneuvers during operation and with neurobehavioral deficit (> or = 20% decline from preoperative performance on two or more neurobehavioral tests) postoperatively. These data and patient demographics were statistically analyzed (chi2, t test) and the results at 2 years (1991 and 1992; group A) were used to influence surgical technique in 1993 and 1994 (group B).

RESULTS

Significantly associated with new neurobehavioral deficits were increasing patient age (p < 0.05), more than 100 emboli per case (p < 0.04), and palpable aortic plaque (p < 0.02). Group B patients had a significant decline in the neurobehavioral event rate (group A, 69%, 140/203; versus group B, 60%, 115/192; p < 0.05) of postoperative neurobehavioral deficits at 1 week and at 1 month (group A, 29%, 52/180; versus group B, 18%, 35/198; p < 0.01). The stroke rate was less than 2% in both groups (p = not significant). Modifications of surgical technique used in group B patients included increased use of single cross-clamp technique, increased venting of the left ventricle, and application of transesophageal and epiaortic ultrasound scanning to locate and avoid trauma to aortic atherosclerotic plaques.

CONCLUSIONS

Neurobehavioral changes after coronary artery bypass grafting are common and associated with cerebral microembolization. Surgical technical maneuvers designed to reduce emboli production may improve neurobehavioral outcome.

Genetics of intracranial aneurysms

The etiology and pathogenesis of intracranial aneurysms are clearly multifactorial, with genetic factors playing an increasingly recognized role. Intracranial aneurysms have been associated with numerous heritable connective tissue disorders, which account for at least 5% of cases. Of these disorders, the most important are Ehlers-Danlos syndrome Type IV, Marfan's syndrome, neurofibromatosis Type 1, and autosomal dominant polycystic kidney disease; the association with intracranial aneurysms, however, has been firmly established only for polycystic kidney disease. Familial intracranial aneurysms are not rare but account for 7 to 20% of patients with aneurysmal subarachnoid hemorrhage and are generally not associated with any of the known heritable connective tissue disorders. First-degree relatives of patients with aneurysmal subarachnoid hemorrhage are at an approximately fourfold increased risk of suffering ruptured intracranial aneurysms, compared to the general population. Various possible modes of inheritance have been identified in families with intracranial aneurysms, suggesting genetic heterogeneity. Although the benefits have never been quantified, screening for asymptomatic intracranial aneurysms should be considered in families with two or more affected members. The yield of such a screening program may approximate 10%. Although it is unlikely that there is a single gene with major effect, much effort is currently being directed at locating intracranial aneurysm genes.

Brain attack. Introduction

In today's medical community, the term "brain attack" is used in two ways. It is used as a synonym for stroke, and also as a reference to an educational and logistic campaign aimed at earlier recognition and treatment of stroke. This article presents an introduction to both uses of the phrase "brain attack," and focuses on the need for a brain attack campaign.

Unruptured intracranial vertebral artery dissection. Clinical course and serial radiographic imagings

BACKGROUND AND PURPOSE

Intracranial vertebral artery dissection is an increasingly recognized cause of stroke. However, little is known about its natural history and clinical manifestations, and appropriate management protocol has not yet been established. This study was performed to clarify its clinical course and determine the best management protocol.

METHODS

This study is a retrospective clinical and radiographic review of 11 patients with 13 lesions who presented between 1990 and 1996. Patients with a history of trauma and those who presented with subarachnoid hemorrhage were excluded. The 11 patients comprised seven men and four women, who ranged in age from 34 to 71 years, with a mean age of 47 years. Ten patients presented with ischemic symptoms.

RESULTS

Although recurrent ischemic attacks were observed in two patients, most (90%) subsequently made a good recovery and returned to their previous lifestyle. Five arteries showed the typical "string sign" or "pearl and string sign" on initial angiography. They changed in the follow-up examinations, which demonstrated either resolution of the stenosis or progression to complete occlusion. In contrast, the angiographic signs of complete occlusion (three arteries) or aneurysmal dilatation without luminal stenosis (four arteries) remained unchanged during the observation period of 5 months to 2.5 years. MRI was a sensitive tool for diagnosing intracranial vertebral artery dissection; intramural thrombus and intimal flap were the two major findings. MR angiography was also useful for demonstrating abnormalities of the arterial signal column such as pseudolumen or aneurysmal dilatation.

CONCLUSIONS

The natural history of unruptured intracranial vertebral artery dissection seems relatively benign, with a high probability (62%) of spontaneous angiographic cure. Some persistent aneurysmal dilatation may be amenable to intravascular coil embolization.

[Management of delayed ischemic neurological deficit in subarachnoid hemorrhage before aneurysmal surgery]

The incidence of rerupture during the period of delayed ischemic neurological deficit (DIND) was studied in patients with aneurysmal subarachnoid hemorrhage (SAH) before surgical aneurysmal obliteration, and optimal management of DIND for preventing rerupture is discussed. At Tokai University Hospital, 511 patients with SAH were admitted during the 5-year period from 1988 to 1992. Of these, 247 had not undergone obliteration of the aneurysm neck within 3 days after SAH. In this group, 31% (77 patients) developed DIND. Of these 77 patients, 40 were managed with induced hypertension and/or hypervolemic therapy for DIND (25 with both (group 1), 15 with normotensive hypervolemic therapy (group 2)), and 37 did not receive either kind of therapy (group 3). The incidences of rerupture were as follows: all SAH patients: 11.5%; group 1: 48%; group 2: 7%; group 3: 11%. The incidence of rerupture in group 1 was significantly higher than that in the other groups. On the other hand, the favorable outcome rate (excellent and good) was as follows: group 1: 40%; group 2: 73%; group 3: 22%. This rate was significantly higher in patients who received normotensive hypervolemic therapy, than in other groups. This study suggests that, to avoid rerupture and unfavorable outcome, normotensive hypervolemic therapy is the optimal management approach in patients with DIND after SAH who have not undergone obliteration of the aneurysmal neck.