Smaller cerebral aneurysms producing more extensive subarachnoid hemorrhage following rupture: a radiological investigation and discussion of theoretical determinants

The influence of aneurysm morphology on the volume of hemorrhage after rupture

OBJECTIVE

Factors determining the risk of rupture of intracranial aneurysms have been extensively studied; however, little attention is paid to variables influencing the volume of bleeding after rupture. In this study the authors aimed to evaluate the impact of aneurysm morphological variables on the amount of hemorrhage.

METHODS

This was a retrospective cohort analysis of a prospectively collected data set of 116 patients presenting at a single center with subarachnoid hemorrhage due to aneurysmal rupture. A volumetric assessment of the total hemorrhage volume was performed from the initial noncontrast CT. Aneurysms were segmented and reproduced from the initial CT angiography study, and morphology indexes were calculated with a computer-assisted approach. Clinical and demographic characteristics of the patients were included in the study. Factors influencing the volume of hemorrhage were explored with univariate correlations, multiple linear regression analysis, and graphical probabilistic modeling.

RESULTS

The univariate analysis demonstrated that several of the morphological variables but only the patient's age from the clinical-demographic variables correlated (p < 0.05) with the volume of bleeding. Nine morphological variables correlated positively (absolute height, perpendicular height, maximum width, sac surface area, sac volume, size ratio, bottleneck factor, neck-to-vessel ratio, and width-to-vessel ratio) and two correlated negatively (parent vessel average diameter and the aneurysm angle). After multivariate analysis, only the aneurysm size ratio (p < 0.001) and the patient's age (p = 0.023) remained statistically significant. The graphical probabilistic model confirmed the size ratio and the patient's age as the variables most related to the total hemorrhage volume.

CONCLUSIONS

A greater aneurysm size ratio and an older patient age are likely to entail a greater volume of bleeding after subarachnoid hemorrhage.

Risk Factors for Higher Volume of Hemorrhage in Ruptured Anterior Circulation Intracranial Aneurysms

Purpose: To explore the influencing factors of volume hemorrhage in ruptured anterior circulation aneurysms, so as to identify the characteristics of anterior circulation aneurysms with high volume of hemorrhage, and to provide advice for clinical diagnosis and treatment for those aneurysms. Methods: We retrospectively reviewed 437 cases of ruptured anterior intracranial aneurysms in our center between the years 2012 and 2017. According to the inclusion criteria, a total of 100 qualified patients were screened out. We collected demographic characteristics, environmental exposure, and admission status of enrolled patients. In addition, morphological parameters and location of aneurysms were also included. The semiautomatic threshold method was used to measure the volume of hemorrhage. According to the results, the patients were divided into the group with high blood volume and low blood volume. Univariate and multivariate logistic regression analyses were used to discover the related factors affecting the bleeding volume. Results: In univariable analysis, pulse pressure (P = 0.014) showed a significant difference at the P < 0.05 test level. In terms of aneurysm morphology, the irregular shape (P < 0.001), calcification (P = 0.001), and flow angle (P = 0.006) showed significant statistical differences between the two groups at the P < 0.01 level (P < 0.01). Multivariate logistic regression analysis showed that irregular shape (OR = 5.370 P = 0.002 < 0.05), large flow angle (OR = 1.033 P = 0.016 < 0.05), and calcification (OR = 5.460 P = 0.003 < 0.05) were risk factors for volume of hemorrhage in ruptured anterior circulation aneurysms. The influence of hypertension history was at critical state (OR = 2.877 P = 0.051 > 005). Conclusions: According to our analysis results, intracranial anterior circulation aneurysms with irregular shapes, calcifications, and large flow angle are more dangerous. Aneurysms with these characteristics often have a large amount of hemorrhage, requiring timely treatment in clinical practice.

Size of ruptured intracranial aneurysms: a systematic review and meta-analysis

BACKGROUND

There is wide variation in the reported size of ruptured intracranial aneurysms and methods of size estimation. There is widespread belief that small aneurysms < 7 mm do not rupture. Therefore, we performed a systematic review and meta-analysis of the literature to determine the size of ruptured aneurysms according to aneurysm locations and methods of size estimation.

METHODS

We searched PubMed, Cochrane, CINAHL, and EMBASE databases using a combination of Medical Subject Headings (MeSH) terms. We included articles that reported mean aneurysm size in consecutive series of ruptured intracranial. We excluded studies limited to a specific aneurysm location or type. The random-effects model was used to calculate overall mean size and location-specific mean size. We performed meta-regression to explain observed heterogeneity and variation in reported size.

RESULTS

The systematic review included 36 studies and 12,609 ruptured intracranial aneurysms. Overall mean aneurysm size was 7.0 mm (95% confidence interval [CI 6.2-7.4]). Pooled mean size varied with location. Overall mean size of 2145 ruptured anterior circulation aneurysms was 6.0 mm (95% CI 5.6-6.4, residual I² = 86%). Overall mean size of 743 ruptured posterior circulation aneurysms was 6.2 mm (95% CI 5.3-7.0, residual I² = 93%). Meta-regression identified aneurysm location and definition of size (i.e., maximum dimension vs. aneurysm height) as significant determinants of aneurysm size reported in the studies.

CONCLUSIONS

The mean size of ruptured aneurysms in most studies was approximately 7 mm. The general wisdom that aneurysms of this size do not rupture is incorrect. Location and size definition were significant determinants of aneurysm size.

Magnesium and Hemorrhage Volume in Patients With Aneurysmal Subarachnoid Hemorrhage

OBJECTIVES

We tested the hypothesis that admission serum magnesium levels are associated with extent of hemorrhage in patients with aneurysmal subarachnoid hemorrhage.

DESIGN

Single-center prospective observational study.

SETTING

Tertiary hospital neurologic ICU.

PATIENTS

Patients with aneurysmal subarachnoid hemorrhage.

INTERVENTIONS

Clinically indicated CT scans and serum laboratory studies.

MEASUREMENTS AND MAIN RESULTS

Demographic, clinical, laboratory, and radiographic data were analyzed. Extent of initial hemorrhage was graded semi-quantitatively on admission CT scans using the modified Fisher scale (grades: 0, no radiographic hemorrhage; 1, thin [< 1 mm in depth] subarachnoid hemorrhage; 2, thin subarachnoid hemorrhage with intraventricular hemorrhage; 3, thick [≥ 1 mm] subarachnoid hemorrhage; 4, thick subarachnoid hemorrhage with intraventricular hemorrhage). We used both ordinal (modified Fisher scale) and dichotomized (thick vs thin subarachnoid hemorrhage) univariate and adjusted logistic regression models to assess associations between serum magnesium and radiographic subarachnoid hemorrhage severity. Data from 354 patients (mean age 55 ± 14 yr, 28.5% male, median admission Glasgow Coma Scale 14 [10-15]) were analyzed. Mean magnesium was lower in patients with thick versus thin subarachnoid hemorrhage (1.92 vs 1.99 mg/dL; p = 0.022). A monotonic trend across categories of modified Fisher scale was found using analysis of variance and Spearman rank correlation (p = 0.015 and p = 0.008, respectively). In adjusted ordinal and binary regression models, lower magnesium levels were associated with higher modified Fisher scale (odds ratio 0.33 per 1 mg/dL increase; 95% CI, 0.14-0.77; p = 0.011) and with thick subarachnoid hemorrhage (odds ratio 0.29 per 1 mg/dL increase; 95% CI, 0.10-0.78; p = 0.015).

CONCLUSIONS

These data support the hypothesis that magnesium influences hemorrhage severity in patients with aneurysmal subarachnoid hemorrhage, potentially through a hemostatic mechanism.

Endovascular Treatment of Small Ruptured Intracranial Aneurysms (<5 mm) : Long-term Clinical and Angiographic Outcomes and Related Predictors

Purpose

To investigate the long-term clinical and angiographic outcomes and their related predictors in endovascular treatment (EVT) of small (<5 mm) ruptured intracranial aneurysms (SRA).

Methods

The study retrospectively reviewed patients with SRAs who underwent EVT between September 2011 and December 2016 in two Chinese stroke centers. Medical charts and telephone call follow-up were used to identify the overall unfavorable clinical outcomes (OUCO, modified Rankin score ≤2) and any recanalization or retreatment. The independent predictors of OUCO and recanalization were studied using univariate and multivariate analyses. Multivariate Cox proportional hazards models were used to identify the predictors of retreatment.

Results

In this study 272 SRAs were included with a median follow-up period of 5.0 years (interquartile range 3.5–6.5 years) and 231 patients with over 1171 aneurysm-years were contacted. Among these, OUCO, recanalization, and retreatment occurred in 20 (7.4%), 24 (12.8%), and 11 (7.1%) patients, respectively. Aneurysms accompanied by parent vessel stenosis (AAPVS), high Hunt-Hess grade, high Fisher grade, and intraoperative thrombogenesis in the parent artery (ITPA) were the independent predictors of OUCO. A wide neck was found to be a predictor of recanalization. The 11 retreatments included 1 case of surgical clipping, 6 cases of coiling, and 4 cases of stent-assisted coiling. A wide neck and AAPVS were the related predictors.

Conclusion

The present study demonstrated relatively favorable clinical and angiographic outcomes in EVT of SRAs in long-term follow-up of up to 5 years. THE AAPVS, as a morphological indicator of the parent artery for both OUCO and retreatment, needs further validation.

Small Aneurysms Should Be Clipped?

Background:

Cerebral aneurysm prevalence may vary from 0.4% to 10%. The decision to treat or not incidental aneurysms remains controversial, especially when the lesions are small (<5 mm). Many recent publications are demonstrating that these lesions often bleed.

Methods:

We reviewed admitted patients with angiographic studies submitted to intracranial aneurysm surgical treatment from April 2012 to July 2013 in the Neurosurgery Department of São Paulo Medical School University (15 months), to define the rate and risk of bleeding. In addition, we proceeded literature review with collected 357 papers (past 5 years) which were selected 50 that were focused on our research. Clinical patients’ status at the time of discharge was evaluated with the modified Rankin scale.

Results:

A series of 118 cases of surgically clipped aneurysms was analyzed: 73.7% woman; Ruptured (61 cases, 51%); middle cerebral artery (51 cases, 43%) was the more common aneurysm. Small size (<5 mm) was 25 cases (21%); that 2 died (16%), 3 (25%) with severe disability,restricted to bed and dependent on nursing care; blood pressure was the main risk factors (56%); and an aneurysm <2 mm (100%) was ruptured.

Conclusion:

The number of small aneurysms in our series was significant (25 cases, 21%), and its rate of bleeding was high (25 cases, 48%), resulting in death and disability in a significant number of cases. Our tendency is for surgical treatment when it is associated with risk factors.

Small ruptured intracranial aneurysms: the risk of massive bleeding and rebleeding

OBJECTIVE

The risk of hemorrhagic events in small ruptured aneurysms remains unclear. Due to less arterial wall, small ruptured aneurysms may be correlated with massive bleeding and rebleeding. Therefore, it may contribute to treatment to evaluate the amount of bleeding and the risk of rebleeding in small ruptured aneurysms.

METHODS

A retrospective cohort study of all consecutive patients with intracranial aneurysms admitted to our hospital from February 2013 to December 2017 was carried out. Ruptured aneurysms were divided into small ruptured aneurysm (0-5 mm) group and large ruptured aneurysm (5 mm) group for analysis. The difference of bleeding volume, rebleeding and clinical outcome were analyzed between the two groups.

RESULTS

A total of 738 patients with aneurysmal subarachnoid hemorrhage (SAH) were included in this study and small ruptured aneurysms accounted for 49.2% of all ruptured aneurysms. Univariate analysis showed that the amount of bleeding (14.5 ± 7.1 vs. 14.4 ± 7.3; P = 0.867), rebleeding (8.3% vs. 10.9%; P = 0.261) and poor outcome (29.6% vs. 23.1%; P = 0.055) were similar between the two groups. Multivariable analysis showed that hypertension was obviously associated with the amount of bleeding (adjusted odds ratio (aOR), 3.25 [1.81-4.69]; P < 0.001) and rebleeding (aOR, 3.31 [1.10-9.99]; P = 0.034) in small ruptured aneurysms, and its effect on rebleeding of small ruptured aneurysms is greater than that of large ruptured aneurysms.

CONCLUSIONS

The risk of hemorrhagic events in small ruptured aneurysms is similar to that in large ruptured aneurysms, especially those patients with small ruptured aneurysms that complicated with hypertension are at an increased risk of massive SAH and rebleeding.

Endovascular Management of Microcerebral Aneurysms with Diameter Smaller than 3 mm: Is It Feasible and Safe?

BACKGROUND

The neurosurgical management of microcerebral aneurysms with diameter smaller than 3 mm remains a great challenge as many complications can occur.

AIM

Our target was to assess the efficacy and usefulness of endovascular treatment of these lesions.

METHODS

We did a prospective and retrospective gathering of the results of endovascular treatments for a group of 16 patients with 16 microcerebral aneurysms. Four patients were treated by direct coil embolization, and 12 patients were managed by remodeling techniques.

RESULTS

Coil embolization was technically accessible in all cases. Initial complete occlusion is achieved in 12 patients. We did not face major technical complications such as aneurysmal rupture or coil migration during the endovascular management in 15 patients. Only in 1 case the second and last coil (2⁄1 mm) migrated distally and could not be retrieved. In this case clinical evidence of neurologic deterioration and weakness in left lower limb due to right anterior cerebral artery territory stroke was evidenced in the follow-up computed tomography scan. Follow-up clinical and radiological studies were available for 9 of 12 surviving patients and showed complete occlusion in 7 cases, and in 1 case aneurysm tiny recanalization was demonstrated after 1 year, which was retreated with complete occlusion, and in another case tiny aneurysm recanalization at the neck appeared after 2 years, which was left under observation.

CONCLUSIONS

Endovascular treatment is a beneficial and effective therapeutic alternative to microsurgery for microaneurysms. The long-term assessment of endovascular management for these lesions was not included in that study.

Consecutive Endovascular Treatment of 20 Ruptured Very Small (<3 mm) Anterior Communicating Artery Aneurysms

BACKGROUND

Small aneurysms located at the anterior communicating artery carry significant procedural challenges due to a complex anatomy. Recent advances in endovascular technologies have expanded the use of coil embolization for small aneurysm treatment. However, limited reports describe their safety and efficacy profiles in very small anterior communicating artery aneurysms.

OBJECTIVE

We sought to review and report the immediate and long-term clinical as well as radiographic outcomes of consecutive patients with ruptured very small anterior communicating artery aneurysms treated with current endovascular coil embolization techniques.

METHODS

A prospectively maintained single-institution neuroendovascular database was accessed to identify consecutive cases of very small (<3 mm) ruptured anterior communicating artery aneurysms treated endovascularly between 2006 and 2013.

RESULTS

A total of 20 patients with ruptured very small (<3 mm) anterior communicating artery aneurysms were consecutively treated with coil embolization. The average maximum diameter was 2.66 ± 0.41 mm. Complete aneurysm occlusion was achieved for 17 (85%) aneurysms and near-complete aneurysm occlusion for 3 (15%) aneurysms. Intraoperative perforation was seen in 2 (10%) patients without any clinical worsening or need for an external ventricular drain. A thromboembolic event occurred in 1 (5 %) patient without clinical worsening or radiologic infarct. Median clinical follow-up was 12 (±14.1) months and median imaging follow-up was 12 (±18.4) months.

CONCLUSION

This report describes the largest series of consecutive endovascular treatments of ruptured very small anterior communicating artery aneurysms. These findings suggest that coil embolization of very small aneurysms in this location can be performed with acceptable rates of complications and recanalization.

Neuroimaging characteristics of ruptured aneurysm as predictors of outcome after aneurysmal subarachnoid hemorrhage: pooled analyses of the SAHIT cohort

OBJECT Neuroimaging characteristics of ruptured aneurysms are important to guide treatment selection, and they have been studied for their value as outcome predictors following aneurysmal subarachnoid hemorrhage (SAH). Despite multiple studies, the prognostic value of aneurysm diameter, location, and extravasated SAH clot on computed tomography scan remains debatable. The authors aimed to more precisely ascertain the relation of these factors to outcome. METHODS The data sets of studies included in the Subarachnoid Hemorrhage International Trialists (SAHIT) repository were analyzed including data on ruptured aneurysm location and diameter (7 studies, n = 9125) and on subarachnoid clot graded on the Fisher scale (8 studies; n = 9452) for the relation to outcome on the Glasgow Outcome Scale (GOS) at 3 months. Prognostic strength was quantified by fitting proportional odds logistic regression models. Univariable odds ratios (ORs) were pooled across studies using random effects models. Multivariable analyses were adjusted for fixed effect of study, age, neurological status on admission, other neuroimaging factors, and treatment modality. The neuroimaging predictors were assessed for their added incremental predictive value measured as partial R(2). RESULTS Spline plots indicated outcomes were worse at extremes of aneurysm size, i.e., less than 4 or greater than 9 mm. In between, aneurysm size had no effect on outcome (OR 1.03, 95% CI 0.98-1.09 for 9 mm vs 4 mm, i.e., 75th vs 25th percentile), except in those who were treated conservatively (OR 1.17, 95% CI 1.02-1.35). Compared with anterior cerebral artery aneurysms, posterior circulation aneurysms tended to result in slightly poorer outcome in patients who underwent endovascular coil embolization (OR 1.13, 95% CI 0.82-1.57) or surgical clipping (OR 1.32, 95% CI 1.10-1.57); the relation was statistically significant only in the latter. Fisher CT subarachnoid clot burden was related to outcome in a gradient manner. Each of the studied predictors accounted for less than 1% of the explained variance in outcome. CONCLUSIONS This study, which is based on the largest cohort of patients so far analyzed, has more precisely determined the prognostic value of the studied neuroimaging factors. Treatment choice has strong influence on the prognostic effect of aneurysm size and location. These findings should guide the development of reliable prognostic models and inform the design and analysis of future prospective studies, including clinical trials.

Risk Factors for Cerebral Vasospasm Following Aneurysmal Subarachnoid Hemorrhage: A Review of the Literature

OBJECTIVE

To examine the literature on risk factors for cerebral vasospasm (CV), one of the most serious complications following aneurysmal subarachnoid hemorrhage (SAH), with special reference to the definition of CV.

METHODS

Using standard search engines, including PubMed, the medical literature on risk factors for CV after SAH was reviewed, and the best definition representative of CV was searched.

RESULTS

Severe SAH evident on computed tomography scan was the only consistent risk factor for CV after SAH. Effects of risk factors on CV, including age, clinical grade, rebleeding, intraventricular or intracerebral hemorrhage on computed tomography scan, acute hydrocephalus, aneurysm site and size, leukocytosis, interleukin-6 level, and cardiac abnormalities, appeared to be associated with the severity of SAH rather than each having a direct effect. Cigarette smoking, hypertension, and left ventricular hypertrophy on electrocardiogram were associated with CV without any relationship to SAH severity. With regard to parameters representative of CV, the grade of angiographic vasospasm (i.e., the degree of arterial narrowing evident on angiography) was the most adequate. Nevertheless, few reports on the risk factors associated with angiographic vasospasm grade have been reported to date.

CONCLUSIONS

Severe SAH evident on computed tomography scan appears to be a definite risk factor for CV after SAH, followed by cigarette smoking, hypertension, and left ventricular hypertrophy on electrocardiogram. To understand the pathogenesis of CV, further studies on the relationships between risk factors, especially factors not related to the severity of SAH, and angiographic vasospasm grade are necessary.

Perioperative variables contributing to the rupture of intracranial aneurysm: an update

Background. Perioperative aneurysm rupture (PAR) is one of the most dreaded complications of intracranial aneurysms, and approximately 80% of nontraumatic SAHs are related to such PAR aneurysms. The literature is currently scant and even controversial regarding the issues of various contributory factors on different phases of perioperative period. Thus this paper highlights the current understanding of various risk factors, variables, and outcomes in relation to PAR and try to summarize the current knowledge. Method. We have performed a PubMed search (1 January 1991–31 December 2012) using search terms including “cerebral aneurysm,” “intracranial aneurysm,” and “intraoperative/perioperative rupture.” Results. Various risk factors are summarized in relation to different phases of perioperative period and their relationship with outcome is also highlighted. There exist many well-known preoperative variables which are responsible for the highest percentage of PAR. The role of other variables in the intraoperative/postoperative period is not well known; however, these factors may have important contributory roles in aneurysm rupture. Preoperative variables mainly include natural course (age, gender, and familial history) as well as the pathophysiological factors (size, type, location, comorbidities, and procedure). Previously ruptured aneurysm is associated with rupture in all the phases of perioperative period. On the other hand intraoperative/postoperative variables usually depend upon anesthesia and surgery related factors. Intraoperative rupture during predissection phase is associated with poor outcome while intraoperative rupture at any step during embolization procedure imposes poor outcome. Conclusion. We have tried to create such an initial categorization but know that we cannot scale according to its clinical importance. Thorough understanding of various risk factors and other variables associated with PAR will assist in better clinical management as well as patient care in this group and will give insight into the development and prevention of such a catastrophic complication in these patients.

Subarachnoid haemorrhage WFNS grade V: is maximal treatment worthwhile?

BACKGROUND

Aneurysmal subarachnoid haemorrhage (SAH) WFNS grade V is commonly known to be associated with high mortality and a very poor prognosis for survivors. Therefore, maximal invasive therapy is frequently delayed until any spontaneous improvement with or without an external ventricular drainage occurs. The aim of the study was to verify possible predictive factors and the probability of a favourable outcome in maximally treated patients.

METHODS

One hundred and thirty-eight consecutive patients with WFNS grade V SAH were admitted between 03/2006 and 12/2010. Thirty-five patients died before aggressive therapy could proceed. One hundred and three patients received maximal treatment and were retrospectively evaluated. The outcome was assessed at discharge and in the follow-up with the Glasgow Outcome Scale. Univariate and multivariate linear regression models were performed to find predictors for an unfavourable outcome.

RESULTS

Despite treatment, early mortality was 30 % (n = 31). At discharge, the rate of both vegetative and severely disabled patients was 27 % (n = 28). Favourable outcome at discharge was observed in 16 % (n = 16) of cases, whereas in the follow-up it rose to 26 % (n = 27). Multivariate full model regression identified intraventricular haematoma (IVH) and increasing age as independently predictive for poor outcome.

CONCLUSIONS

Despite treatment, initial mortality and severe disability remain high. Nevertheless, a favourable outcome was achieved in 26 % of aggressively treated patients, rendering the withdrawal of maximal therapy for WFNS grade V SAH patients unacceptable today. In cases of old patients with IVH, the indication for aggressive therapy should be put in place more carefully due to a very poor prognosis.

The relationship between subarachnoid hemorrhage volume and development of cerebral vasospasm

Objective

The objective of this study is to verify the relationship between subarachnoid hemorrhage (SAH) volume (not Fisher grade) and development of cerebral vasospasm prospectively.

Methods

Patients who visited our hospital with a diffuse or localized thick subarachnoid blood clot seen on computed tomography (CT), taken within 48 hours after SAH and the aneurysm was confirmed by CT Angiogram (CTA) from March 2010 to July 2011 were enrolled in this study. CTA was checked at least twice after admission. Angiographic vasospasm (AVS) on CTA was defined as irregularity or narrowing of intracranial vessels on follow up CTA compared with initial CTA. Total intracranial hemorrhage (ICH) volume (subdural, SAH, intracerebral and intraventricular) was calculated and SAH volume (all supratentorial and infratentorial cisterns) was also calculated using the MIPAV software package.

Results

A total of 55 patients were included in our study. Thirty six patients did not show AVS on CTA or clinical deterioration (non vasospasm group: NVS). AVS without ischemic neurologic symptoms was observed in four patients and development of symptomatic vasospasm (SVS), defined as AVS with ischemic symptoms, was observed in 15 patients. SAH volume in SVS patients was statistically larger than that in NVS patients (p < 0.05). Total ICH volume in SVS patients was larger than that in NVS patients. However, the difference was not statistically significant.

Conclusion

Results of this study indicate an association of development of vasospasm with the SAH volume, not intracranial hemorrhage.

Sensitivity of flow simulations in a cerebral aneurysm

The flow in a cerebral aneurysm on the Anterior Communicating Artery is simulated based on patient medical imaging. The sensitivity of the flow pattern is assessed with respect to variation of outflow split and geometric parameters. A comparison is made between the results from unsteady pulsatile computations and steady-state computations. The results show that for this case there is no significant sensitivity to pulsatile flow-rate variations. Steady-state and pulsatile simulations both predict a strong sensitivity to outflow split and geometric smoothing. It is therefore proposed to analyse the stability of aneurysmal flow with an extensive sensitivity study based on steady-state computations and use this sensitivity for rupture prediction.

Dissecting aneurysm of the anterior temporal artery: case report

A 65-year-old woman presented a rare dissecting aneurysm of the anterior temporal artery (ATA) manifesting as headache. Computed tomography and magnetic resonance imaging revealed a mixed-density mass in the horizontal segment of the middle cerebral artery. Emergent angiography demonstrated aneurysmal dilatation and a thrombosed mass in the sylvian fissure. Infectious aneurysm was excluded. She underwent emergent surgery to reduce the risk of repeated infarction and hemorrhage. The distal side of the ATA manifested occlusive changes suggestive of arterial dissection. The proximal side of the ATA was ligated and the lesion was excised. Histological examination confirmed that the aneurysmal dilatation was attributable to arterial dissection due to disruption of the internal elastic lamina. Distal dissecting aneurysms may occur in the absence of infectious disease. We recommend that ruptured distal dissecting aneurysms be treated surgically in the acute stage immediately after detection.

Predictors of postoperative mortality in ruptured aneurysms of internal carotid artery

BACKGROUND AND PURPOSE

An analysis of predictors of mortality in patients with ruptured intracranial aneurysm is an important aspect in the assessment of outcome. The aim of the study was to analyse factors determining mortality risk after the surgical treatment of ruptured internal carotid artery (ICA) aneurysm.

MATERIAL AND METHODS

This study comprised 242 patients operated on between 1997 and 2006 in the Neurosurgery Department of the Medical University Hospital in Gdansk, Poland. Multivariate logistic regression, ROC curves (for model assessment as a mortality classifier) and population attributable risk for contribution of individual factor mortality explanation were used to assess factors related to in-hospital mortality.

RESULTS

14.9% of patients died postoperatively. In univariate analysis, increased risk of death was related to the Glasgow Coma Scale score, WFNS score, Hunt-Hess and Fisher grade, preoperative neurological deficit, delayed cerebral ischaemia (DCI), trapping and bypass operative method. Multivariate analysis revealed two independent predictors of in-hospital mortality: DCI and Hunt-Hess grade. 91% of mortality risk was attributed to grade 4 or 5 in Hunt-Hess scale and DCI. The dominant predictor of survival was the Hunt-Hess scale. Increase by one grade in the Hunt-Hess scale resulted in two-fold increase of in-hospital mortality risk.

CONCLUSIONS

Postoperative mortality after ICA aneurysm rupture is determined by clinical status at admission and the occurrence of DCI.

Automatic aneurysm neck detection using surface Voronoi diagrams

A new automatic approach for saccular intracranial aneurysm isolation is proposed in this work. Due to the inter- and intra-observer variability in manual delineation of the aneurysm neck, a definition based on a minimum cost path around the aneurysm sac is proposed that copes with this variability and is able to make consistent measurements along different data sets, as well as to automate and speedup the analysis of cerebral aneurysms. The method is based on the computation of a minimal path along a scalar field obtained on the vessel surface, to find the aneurysm neck in a robust and fast manner. The computation of the scalar field on the surface is obtained using a fast marching approach with a speed function based on the exponential of the distance from the centerline bifurcation between the aneurysm dome and the parent vessels. In order to assure a correct topology of the aneurysm sac, the neck computation is constrained to a region defined by a surface Voronoi diagram obtained from the branches of the vessel centerline. We validate this method comparing our results in 26 real cases with manual aneurysm isolation obtained using a cut-plane, and also with results obtained using manual delineations from three different observers by comparing typical morphological measures.

Neck clipping of paraclinoid small aneurysms

Paraclinoid small aneurysms with a diameter less than 5 mm may be difficult to handle intraoperatively. We have encountered 9 such aneurysms among 375 cases. The most frequent location was the ophthalmic segment (n = 6) followed by the anterior wall (n = 3) of the internal carotid artery (ICA). The endovascular procedure was not suitable for this particular lesion because of the difficulty in deploying the coil across such small aneurysms. One patient with an ophthalmic segment aneurysm underwent endovascular treatment first; however, the procedure was aborted because of mechanical vasospasm. Finally the patient underwent craniotomy, and the aneurysm was successfully clipped. Two patients with anterior wall aneurysms presented with subarachnoid hemorrhage, and the blood blister-like aneurysms were clipped without sacrifice of the ICA. Five patients with unruptured aneurysms of the ophthalmic segment and one such case of the anterior wall of ICA were all clipped uneventfully. The operative procedure for these small aneurysms is deemed straightforward: (1) high attention should be paid to avoid premature rupture; (2) both the internal carotid artery and optic nerve are mobilized and the anterior clinoid process and falciform ligament are removed, then the aneurysmal neck is created; (3) the neck of the aneurysm is created by pushing the wall of the ICA slightly away during clip application; this is called the "nip on method." Although neck clipping of small aneurysms can be difficult, no efforts should be spared to accomplish direct neck clipping.

Prevalence of unruptured intracranial aneurysm on MR angiography

Objective

To evaluate the prevalence of incidentally found unruptured intracranial aneurysms (UIAs) on the brain MR angiography (MRA) from a community-based general hospital.

Materials and Methods

This was a prospectively collected retrospective study, carried out from January 2004 to December 2004. The subjects included 3049 persons from a community-based hospital in whom MRA was performed according to a standardized protocol in an outpatient setting. Age- and sex-specific prevalence of UIAs was calculated. The results by MRA were compared with intra-arterial digital subtraction angiography (DSA) findings.

Results

Unruptured intracranial aneurysms were found in 137 (5%) of the 3049 patients (M:F = 43:94; mean age, 60.2 years). The prevalence of UIAs was 5% (n = 94) in women and 4% (n = 43) in men, respectively (p = 0.2046) and showed no age-related increase. The most common site of aneurysm was at the distal internal carotid artery (n = 64, 39%), followed by the middle cerebral artery (n = 40, 24%). In total, 99% of aneurysms measured less than 12 mm, and 93% of aneurysms measured less than 7 mm. Direct comparisons between MRA and DSA were available in 70 patients with 83 UIAs; the results revealed two false positive and two false negative results.

Conclusion

This community-hospital based study suggested a higher prevalence of UIAs observed by MRA than previously reported. These findings should be anticipated in the design and use of neuroimaging in clinical practice.

Tiny intracranial aneurysms: endovascular treatment by coil embolisation or sole stent deployment

PURPOSE

Tiny intracranial aneurysms pose a significant therapeutic challenge for interventional neuroradiologists. The authors report their preliminary results of endovascular treatment of these aneurysms.

METHODS

Between January 2002 and December 2009, 52 tiny intracranial aneurysms (defined as ≤ 3 mm in maximum diameter) in 46 patients (22 men; mean age, 57.9 years) were treated by endosaccular coil embolisation or sole stent deployment in the parent artery. Of 52 aneurysms, 29 had ruptured and 23 remained unruptured. The initial angiographic results, procedural complications, and clinical outcomes were assessed at discharge. Imaging follow-up was performed with cerebral angiography.

RESULTS

One aneurysm coiling procedure failed because of unsuccessful micro-catheterization. Forty-three aneurysms were successfully coil embolized, of which complete occlusion was obtained in 14, subtotal occlusion in 18 and incomplete occlusion in 11. The other 8 aneurysms were treated by sole stent deployment in the parent artery. Procedural complications (2 intraprocedural ruptures and 3 thromboembolic events) occurred in 5 (9.6%) of 52 aneurysms, resulting in permanent morbidity in only 1 (2.2%, 1/46) patient. No rebleeding occurred during clinical follow-up (mean duration, 46.7 months). Of the 16 coiled aneurysms that receiving repetitive angiography, 6 initially completely and 3 subtotally occluded aneurysms remained unchanged, 4 initially subtotally and 3 incompletely occluded aneurysms progressed to total occlusion. Five sole stent deployed aneurysms received angiographic follow-up (mean duration, 10.0 months), of which 3 remained unchanged, 1 became smaller and 1 progressed to total occlusion.

CONCLUSION

Endovascular treatment of tiny intracranial aneurysms is technical feasible and relatively safe. Coil embolisation seems to be effective in preventing early recanalisation, whereas sole stenting technique needs further investigation to determine its effectiveness.

Intraventricular hemorrhage volume predicts poor outcomes but not delayed ischemic neurological deficits among patients with ruptured cerebral aneurysms

BACKGROUND

Intraventricular hemorrhage (IVH) predicts worse outcomes following aneurysmal subarachnoid hemorrhage (SAH). One potential mechanism is that IVH predisposes to the development of delayed ischemic neurological deficits (DINDs). No previous studies have evaluated the association between IVH volume (in milliliters) and subsequent development of DINDs or poor outcomes.

OBJECTIVE

To assess the association between the volume of IVH and the subsequent development of DINDs, delayed cerebral infarction, death, and poor neurological outcomes, specifically among patients with concomitant SAH and IVH.

METHODS

We performed a cohort study involving 152 consecutive patients with concomitant SAH and IVH. To determine volume of IVH, we used the IVH Score, shown to correlate well with computerized volumetric assessment. To determine the relative quantity of subarachnoid blood, we applied the SAH Sum Score. Multivariate logistic regression was used to adjust for potential confounders.

RESULTS

There was no significant association between IVH volume and the development of DINDs or delayed infarction. In contrast, patients with poor neurological outcomes had significantly larger baseline IVH volume (mean, 11.8 mL vs 3.8 mL, P = .001). In the multivariate analysis, IVH volume was an independent predictor of poor outcomes (OR per mL: 1.11 [1.04-1.18]). Patients in the highest quartile for IVH volume were far more likely to progress to poor outcome compared with those in the lowest quartile (OR 4.09 [1.32-12.65]). Interobserver agreement in the determination of IVH Score was moderate to good.

CONCLUSIONS

IVH volume is an independent predictor of poor neurological outcomes, even after adjusting for the amount of subarachnoid blood. The pathophysiology of this association does not appear to involve an increased risk of DINDs or delayed infarction. Measures aimed at accelerating IVH clearance, such as intraventricular thrombolysis, merit further evaluation.

Small Unruptured Intracranial Aneurysm Verification Study

Background and Purpose— The natural history and optimal management of incidentally found small unruptured aneurysms <5 mm in size remain unclear. A prospective study was conducted to determine the optimal management for incidentally found small unruptured aneurysms.

Methods— From September 2000 to January, 2004, 540 aneurysms (446 patients) were registered. Four hundred forty-eight unruptured aneurysms <5 mm in size (374 patients) have been followed up for a mean of 41.0 months (1306.5 person-years) to date. We calculated the average annual rupture rate of small unruptured aneurysms and also investigated risk factors that contribute to rupture and enlargement of these aneurysms.

Results— The average annual risks of rupture associated with small unruptured aneurysms were 0.54% overall, 0.34% for single aneurysms, and 0.95% for multiple aneurysms. Patient <50 years of age ( P =0.046; hazard ratio, 5.23; 95% CI, 1.03 to 26.52), aneurysm diameter of ≥4.0 mm ( P =0.023; hazard ratio, 5.86; 95% CI, 1.27 to 26.95), hypertension ( P =0.023; hazard ratio, 7.93; 95% CI, 1.33 to 47.42), and aneurysm multiplicity ( P =0.0048; hazard ratio, 4.87; 95% CI, 1.62 to 14.65) were found to be significant predictive factors for rupture of small aneurysms.

Conclusions— The annual rupture rate associated with small unruptured aneurysms is quite low. Careful attention should be paid to the treatment indications for single-type unruptured aneurysms <5 mm. If the patient is <50 years of age, has hypertension, and multiple aneurysms with diameters of ≥4 mm, treatment should be considered to prevent future aneurysmal rupture.

Endovascular treatment of very small intracranial aneurysms

Object

Endovascular treatment of very small aneurysms poses a significant technical challenge for endovascular therapists. The authors review their experience with a series of patients who had intracranial aneurysms smaller than 3 mm in diameter.

Methods

Between 1995 and 2006, 97 very small aneurysms (defined for purposes of this study as < 3 mm in diameter) were diagnosed in 94 patients who were subsequently referred for endovascular treatment. All patients presented after subarachnoid hemorrhage, which was attributed to the very small aneurysms in 85 patients. The authors reviewed the endovascular treatment, the clinical and angiographic results of the embolization, and the complications.

Results

Five (5.2%) of the 97 endovascular procedures failed, and these patients underwent craniotomy and clip ligation. Of the 92 aneurysms successfully treated by coil embolization, 64 (69.6%) were completely occluded and 28 (30.4%) showed minor residual filling or neck remnants on the immediate postembolization angiogram. Complications occurred in 7 (7.2%) of 97 procedures during the treatment (3 thromboembolic events [3.1%] and 4 intraprocedural ruptures [4.1%]). Seventy-six patients were followed up angiographically; 4 (5.3%) of these 76 showed angiographic evidence of recanalization that required retreatment. The clinical outcomes for the 76 patients were also graded using the Glasgow Outcome Scale. In 61 (80.3%) cases the outcomes were graded 4 or 5, whereas in 15 (19.7%) they were graded 3. Seven patients (7.4%) died (GOS Grade 1), 2 due to procedure-related complications (intraoperative rupture) and 5 due to complications related to the presenting subarachnoid hemorrhage.

Conclusions

Endosaccular coil embolization of very small aneurysms is associated with relatively high rates of intraprocedural rupture, especially intraoperative rupture. With the advent of more sophisticated endovascular materials (microcatheters and microguidewires, soft and ultrasoft coils, and stents) endovascular procedures have become feasible and can lead to a good angiographic outcome.

The effectiveness and feasibility of endovascular coil embolization for very small cerebral aneurysms: mid- and long-term follow-up

BACKGROUND

Endovascular embolization for very small cerebral aneurysms (VSCAs) is still controversial. We report our experience with endovascular coil embolization for these lesions and assess the feasibility and effectiveness.

METHODS

We conducted a review of our experience with endovascular treatment of a series of 19 patients with 20 VSCAs, located at the supraclinoid segment of the internal cranial artery (ICA) in seven, the cavernous ICA segment in three, the anterior communicating artery in five, vertebral artery-posterior inferior cerebellar artery in two, bifurcation of the middle cerebral artery in one, the pericallosal artery in one, and the P2 segment in one. The World Federation of Neurosurgical Societies classification before treatment was grade I in 14 patients and grade II in five patients. The strategy of endovascular treatment included coil occlusion, balloon-assisted coiling, and stent-assisted coiling. Occlusion rate was divided into (1) total/near total, occlusion rate 95-100%; (2) subtotal, occlusion rate 80-95%; and (3) partial, occlusion rate<80%. Clinical outcome of patients with ruptured aneurysm was ascertained according to the Glasgow Outcomes Scale.

RESULTS

All patients were successfully treated with coil embolization; immediate angiography determined occlusion of the aneurysm, including total occlusion in five, subtotal occlusion in nine, and partial occlusion in six. During 1-2 years of follow-up, all aneurysms were confirmed as complete occlusion by control angiography. No recurrence or coil compaction occurred. No rehemorrhage or ischemic stroke occurred.

CONCLUSION

Endovascular coil embolization for VSCAs is effective and feasible. Initial subtotal or partial aneurysm occlusion might progress to total occlusion.

Endovascular Treatment for Very Small Supraclinoid Aneurysms with Stent-Assisted Coiling. Long-Term Follow-up in Six Cases

SUMMARY

The endovascular treatment of very small aneurysms (lesions less than 3 mm in maximum diameter) with wide necks remains a challenge for saccular embolization. We retrospectively analyzed our data using Neuroform stent-assisted coiling for very small supraclinoid aneurysms with wide neck to evaluate the feasibility and efficacy of endovascular treatment of these lesions. We conducted a review of our experience and results of endovascular treatments in six patients with seven very small aneurysms. All aneurysms were located at the side wall of the supraclinoid segment of the ICA. They were ruptured in two patients and unruptured in four. The technique of stent-assisted coiling was used in all cases with coiling before stenting and additional coils after deployment of the stent in the same session. All patients were successfully embolized with stent-assisted coiling. The coils were introduced into the lumen for subtotal occlusion in five aneurysms and for partial occlusion in two. During one to two years follow-up angiography, all aneurysms were completely occluded and no recurrence occurred. No complications were observed. Endovascular stent-assisted coil embolization of supraclinoid very small aneurysms with wide necks is effective and feasible. Subtotal aneurysm occlusion might progress to total occlusion.

Endovascular therapy of distal anterior cerebral artery aneurysms-an effective treatment option

BACKGROUND

Surgical treatment of APAs is associated with relatively high morbidity and mortality. The aim of this study was to illustrate the technical achievements of endovascular procedures in the distal anterior cerebral artery area, technical difficulties and how they can be overcome, and the outcome of endovascular treatment of APAs.

METHODS

Between 1997 and 2006, of 49 patients with APAs at our institution, 29 were treated endovascularly (4.1% of all endovascularly treated aneurysms; F:M = 3.8; mean age, 52.8 +/- 11.5 years), and 12 were treated surgically. Twenty-one (72.4%) of the endovascularly treated patients had a subarachnoid hemorrhage. The mean observation period was 25 +/- 22.8 months.

RESULTS

In 27 (93.1%) cases, complete occlusion of the aneurysm was achieved. The intervention led to 5 (17.2%) cases of minor complications with no neurologic deficits: 2 thromboembolisms, 1 local thrombus, 1 occlusion, and 1 recurrent hemorrhage. Mortality related to the intervention was 3.4%. There was no morbidity associated with the elective procedures. The dome-to-neck ratio is the main predictor of reperfusion. The most important factor impairing the outcome in terms of the GOS status is the presence of an intraparenchymal hematoma, followed by thrombembolic complications.

CONCLUSION

Endovascular treatment of APAs is feasible, safe, and effective. Mortality and morbidity are comparable with surgical therapy. An intraparenchymal hematoma has a severe negative influence on the patient's condition after rehabilitation. In these cases, surgical intervention should be considered. In case of incomplete occlusion of the aneurysm, prompt reintervention is required.

Endovascular treatment of very small intracranial aneurysms

BACKGROUND

The treatment of very small cerebral aneurysms with maximal diameter less than 3 mm remains a challenge for endovascular and surgical treatment. Endovascular treatment of these lesions may be difficult and associated with high risk of complications because of their small size. Our purpose was to assess the feasibility and results of endovascular treatment of these lesions.

METHODS

We conducted a retrospective review of our experience and results of endovascular treatments for a series of 11 consecutive patients with 11 very small aneurysms. Of 11 aneurysms, 10 were acutely ruptured, and 1 was unruptured with a previous subarachnoid hemorrhage from another aneurysm. Aneurysms were located at the internal carotid artery (n = 4), the anterior communicating artery (n = 6), and the vertebral artery (n = 1). Seven patients were treated with coil embolization, and remodeling technique was used in 1 case. Three cases underwent intravascular stent implantation. Coil packing was done after in 2 of 3 aneurysms, and stent implantation alone was used in the remaining aneurysm.

RESULTS

Coil embolization and stent deployment were carried out without difficulty in all cases. Coil packing was not available after stent implantation in 1 case for unsuccessful navigation of microcatheter into the aneurysm sac. Immediate angiography demonstrated complete occlusion in 10 cases and nearly complete occlusion in 1 case with stent implantation alone. No stent thrombosis and aneurysmal rupture was encountered during treatment. With the exception of 1 patient (Hunt and Hess grade 4) who died of pneumonia 4 weeks after treatment, no clinical evidence of neurologic deterioration and hemorrhagic complication was seen during the follow-up period in the remaining 10 patients. Follow-up angiography for 3 to 12 months (mean, 5.3 months) was available in 6 (60%) of 10 surviving patients, and no aneurysm recanalization was found.

CONCLUSIONS

Endovascular treatment may be a feasible and effective therapeutic alternative for very small aneurysms. The long-term efficacy and durability of endovascular treatment for these lesions remains to be determined in a large series.

Relation among aneurysm size, amount of subarachnoid blood, and clinical outcome

Object

The authors of recent reports have suggested that smaller aneurysms are associated with more extensive sub-arachnoid hemorrhage (SAH), which could potentially presage poor outcome in patients harboring these lesions. The authors reviewed their clinical experience to determine if this theory has a basis in truth.

Methods

The authors undertook a retrospective review of a consecutive series of patients with aneurysmal SAH. Computed tomography scans and angiograms were studied to establish SAH scores and aneurysm size.

Results

One hundred thirty-three patients were treated during a 2-year period (January 2003–December 2004). There were 101 female and 32 male patients whose mean age was 56.7 years. The location distribution of aneurysms that bled was as follows: anterior communicating artery (56 cases), posterior communicating artery (34 cases), middle cerebral artery (21 cases), posterior circulation (16 cases), and paraclinoid region (six cases). The mean aneurysm size was 6.2 mm (range 2–26 mm). The mean SAH score was 18.3 (not normally distributed, p < 0.01, D'Agostino–Pearson test). One hundred three patients underwent surgical exploration and placement of an aneurysm clip, 21 underwent deployment of a coil, and two underwent both therapies; seven patients died prior to intervention.

No correlation was found between aneurysm size and SAH score (rS = −0.023, p = 0.8) or between small aneurysm size and poor Glasgow Outcome Scale score (p = 0.13). In fact, the trend was the opposite. The SAH score did, however, correspond strongly with the admission Hunt and Hess grade (p < 0.0001), indicating the strong correlation between grade and volume of intracranial blood. Outcome was best explained in the multivariate analysis by the following factors: admission Hunt and Hess grade, age, and clinical vasospasm (p < 0.0001) with the proportion of cases correctly classified as 79.7%.

Conclusions

Evaluation of the results in the present clinical series suggests that there is no relation between aneurysm size and volume of subarachnoid blood. The volume of cisternal blood correlates with Hunt and Hess grade but is not an independent determinant of outcome. Outcome is related to the following triad of well-established clinical factors: Hunt and Hess grade, age, and clinical vasospasm.

Characteristics and management of ruptured distal middle cerebral artery aneurysms

OBJECTIVE

Distal middle cerebral artery (dMCA) aneurysms are very rare with a reported frequency of 2-6%. Typically, patients with ruptured distal MCA aneurysms have poor clinical outcomes because often there is both a subarachnoid haemorrhage (SAH) and an intracerebral haematoma (ICH). The goals of this study were to identify the characteristics of the distal MCA aneurysms and evaluate the optimal treatment for a good outcome.

METHODS

The clinical, neuroradiological and operative records of 8 patients with a ruptured distal MCA aneurysm who underwent surgical management were reviewed retrospectively. The outcomes were presented according to the Glasgow Outcome Scale (GOS).

RESULTS

The clinical characteristics of the patients with ruptured dMCA aneurysms included the following: (1) a fusiform appearance in five out of eight (63%) patients. (2) Mean aneurysm size of 9.4 mm (range 2-35 mm). (3) The location being M2 (insular segment) in three, M2-3 junction in three, and M3 (opercular segment) in two patients. (4) Brain CT images revealed both SAH and an ICH in six of eight (75%) patients with the mean size of the ICH being 10 cc (range 5-25 cc). (5) Re-bleeding occurred in four out of eight (50%) of patients. All patients underwent early surgical treatment and the procedures used for surgical repair were, clipping in five patients, trapping in two, and trapping with end-to-end bypass surgery in one patient. Clinical outcomes were poor in two patients (death) due to severe brain swelling.

CONCLUSIONS

In this study, dMCA aneurysms had a fusiform shape and a high re-bleeding rate; if ruptured, there was generally ICH and SAH. A good clinical outcome was associated with adequate control of brain swelling and early surgery to prevent re-bleeding.

Subarachnoid clot volume correlates with age, neurological grade, and blood pressure

OBJECTIVE

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is associated with the volume and location of subarachnoid blood clots. Factors that influence the volume of SAH have seldom been studied.

METHODS

Two independent sets of data were analyzed. Data from 3028 patients with SAH enrolled in four clinical trials of the drug tirilazad were analyzed in addition to data from 74 patients with SAH who underwent digital volumetric analysis of admission computed tomographic scans to determine the subarachnoid clot volume. In the smaller sample of 74 patients, aneurysm width, length, neck size, aspect ratio, and volume were measured on diagnostic cerebral angiograms. Statistical inference bearing on the question of what factors are associated with clot volume was derived by univariate methods, including analysis of variance, chi and t tests, and polytomous logistic regression.

RESULTS

Of 22 clinical parameters examined by univariate analysis of the tirilazad dataset, age, World Federation of Neurological Surgeons (WFNS) clinical grade, time from SAH to admission, history of hypertension or diabetes mellitus, aneurysm location, and admission diastolic and systolic blood pressure were correlated with the subarachnoid clot volume (P < 0.05). Polytomous logistic regression found that only age, WFNS grade, time to admission, admission systolic blood pressure, and history of hypertension were higher in patients with larger subarachnoid clots (P < 0.05). Analysis of 74 patients with quantitative subarachnoid clot volumes also found that age and WFNS grade were higher in patients with larger subarachnoid clots (P < 0.05). No aneurysm location or measurement of aneurysm size showed a statistically significant relationship to clot volume in either dataset.

CONCLUSION

SAH volume is correlated with clinical characteristics, including age, history of hypertension, admission systolic blood pressure, and WFNS grade. Anatomic aneurysm characteristics such as size and location do not reliably predict clot volume.

Genetics Of Intracranial Aneurysms

Despite advances in the treatment of intracranial aneurysms (IA) in recent years, the overall outcome of patients with aneurysmal subarachnoid hemorrhage has shown only modest improvement. Given this poor prognosis, diagnosis of IA before rupture is of paramount importance. Currently, there are no reliable methods other than screening imaging studies of high-risk individuals to diagnose asymptomatic patients. Multiple levels of evidence suggest that environmental factors acting in concert with genetic susceptibilities lead to the formation, growth, and rupture of aneurysms in these patients. Epidemiological studies have already identified aneurysm-specific risk factors such as size and location, as well as patient-specific risk factors, such as age, sex, and presence of medical comorbidities, such as hypertension. In addition, exposure to certain environmental factors such as smoking have been shown to be important in the formation of IA. Furthermore, substantial evidence proves that certain loci contribute genetically to IA pathogenesis. Genome-wide linkage studies using relative pairs or rare families that are affected with the Mendelian forms of IA have already shown genetic heterogeneity of IA, suggesting that multiple genes, alone or in combination, are important in the disease pathophysiology. The linkage results, along with association studies, will ultimately lead to the identification of IA susceptibility genes. Identification of the genes important in IA pathogenesis will not only provide novel insights into the primary determinants of IA, but will also result in new opportunities for early diagnosis in the preclinical setting. Ultimately, novel therapeutic strategies based on biology will be developed, which will target these newly elucidated genetic susceptibilities.

Modern cross-sectional imaging in the diagnosis and follow-up of intracranial aneurysms

Digital subtraction angiography (DSA) is still considered the gold standard for most applications in neurovascular imaging. However, with the ongoing development of cross-sectional imaging modalities DSA is increasingly being replaced by less invasive methods. This contribution describes the diagnostic value and the increasing potential of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) in the diagnosis and follow-up of intracranial aneurysms. The main role of CTA is in the diagnosis and therapy planning of ruptured aneurysms; in contrast, MRA plays an increasingly important role in the screening for asymptomatic aneurysms (especially in cases of familial subarachnoid hemorrhage) and in the follow-up after endovascular therapy with coils and/or intracranial stents. Technical issues concerning examination technique are covered here as well as an approach to advanced postprocessing of the image data. Furthermore, a brief outlook on the impact of new developments (MRA with parallel imaging and at 3.0 T) is given.

A proposed parent vessel geometry-based categorization of saccular intracranial aneurysms: computational flow dynamics analysis of the risk factors for lesion rupture

OBJECT

The authors created a simple, broadly applicable classification of saccular intracranial aneurysms into three categories: sidewall (SW), sidewall with branching vessel (SWBV), and endwall (EW) according to the angiographically documented patterns of their parent arteries. Using computational flow dynamics analysis (CFDA) of simple models representing the three aneurysm categories, the authors analyzed geometry-related risk factors such as neck width, parent artery curvature, and angulation of the branching vessels.

METHODS

The authors performed CFDAs of 68 aneurysmal geometric formations documented on angiograms that had been obtained in patients with 45 ruptured and 23 unruptured lesions. In successfully studied CFDA cases, the wall shear stress, blood velocity, and pressure maps were examined and correlated with aneurysm rupture points. Statistical analysis of the cases involving aneurysm rupture revealed a statistically significant correlation between aneurysm depth and both neck size (p < 0.0001) and caliber of draining arteries (p < 0.0001). Wider-necked aneurysms or those with wider-caliber draining vessels were found to be high-flow lesions that tended to rupture at larger sizes. Smaller-necked aneurysms or those with smaller-caliber draining vessels were found to be low-flow lesions that tended to rupture at smaller sizes. The incidence of ruptured aneurysms with an aspect ratio (depth/neck) exceeding 1.6 was 100% in the SW and SWBV categories, whereas the incidence was only 28.75% for the EW aneurysms.

CONCLUSIONS

The application of standardized categories enables the comparison of results for various aneurysms' geometric formations, thus assisting in their management. The proposed classification system may provide a promising means of understanding the natural history of saccular intracranial aneurysms.

A 70-year-old woman with poor grade subarachnoid hemorrhage complicated by carotid stenosis, cerebral vasospasm, and cerebral rebleed

INTRODUCTION

Subarachnoid hemorrhage is one of the most common entities encountered in neurocritical care units. Knowledge of disease sequelae and their management is paramount for all neurointensivists.

MATERIALS AND METHODS

This study relates the case of a 70-year-old woman with poor grade subarachnoid hemorrhage who underwent endovascular detachable coil embolization of a right internal carotid artery aneurysm. Her hospital course was subsequently complicated by symptomatic carotid stenosis and cerebral vasospasm requiring intervention.

DISCUSSION

The discussants present their views regarding five main questions pertaining to management of the patient regarding the choice of endovascular versus surgical aneurysm occlusion, stent-supported angioplasty in a patient with a recent subarachnoid hemorrhage, and treatment options for vasospasm.

Endovascular coiling of multiple (more than four) intracranial aneurysms. Case report

SUMMARY

The incidence of multiple intracranial aneurysms has been reported from 5% to 35%. But over four multiple aneurysms are extremely rare. Sometimes it is very difficult to draw a clear line between ruptured ones and unruptured others especially in multiple aneurysm cases with even distribution of subarachnoid haemorrhage on basal cistern. We present two cases of multiple aneurysms, more than four, which were successfully treated by endovascular coiling at the same time. Our experience suggests an endovascular procedure would be the gold standard of treatment for ruptured multiple intracranial aneurysms.

Outcome after subarachnoid hemorrhage from a very small aneurysm: a case-control series

Object. A case-control analysis of patients with SAH was performed to compare risk factors and outcomes at 6 months posthemorrhage in patients with a very small aneurysm compared with those with a larger aneurysm.

Methods. All patients with SAH who were treated between January 1998 and December 1999 were studied. A very small aneurysm was defined as “equal to or less than 5 mm in diameter.” Clinical data and treatment summaries were maintained in an electronic database. The Glasgow Outcome Scale (GOS) score was determined by an independent registrar.

One hundred twenty-seven patients were treated. A very small aneurysm was the cause of SAH in 42 patients (33%), whereas 85 (67%) had aneurysms larger than 5 mm (mean diameter 11 mm). There were no differences in demographic variables or medical comorbidities between the two groups. Thick SAH (Fisher Grade 3 or 4) was more common in patients with a very small aneurysm than in those with a larger aneurysm (p = 0.028). One hundred eight patients underwent microsurgery (85%), 15 underwent coil embolization (12%), and four (3%) required both procedures. Vasospasm occurred in nine patients (21%) with very small aneurysms compared with 14 (16%) with larger aneurysms (p = 0.62). Shunt-dependent hydrocephalus occurred in nine patients (21%) with very small aneurysms and in 19 (22%) with larger aneurysms (p = 1). The mean GOS score for both groups was 4 (moderately disabled) at 6 months.

Conclusions. Small aneurysms produce thick SAH more often than larger aneurysms. There is no difference in outcome after SAH between patients with a very small aneurysm and those with a larger aneurysm.