Aneurysm Prevalence and Quality of Life During Screening in Relatives of Patients With Unruptured Intracranial Aneurysms: A Prospective Study

BACKGROUND AND OBJECTIVES

Screening for unruptured intracranial aneurysms (UIAs) is effective for first-degree relatives (FDRs) of patients with aneurysmal subarachnoid hemorrhage (aSAH). Whether screening is also effective for FDRs of patients with UIA is unknown. We determined the yield of screening in such FDRs, assessed rupture risk and treatment decisions of aneurysms that were found, identified potential high-risk subgroups, and studied the effects of screening on quality of life (QoL).

METHODS

In this prospective cohort study, we included FDRs, aged 20-70 years, of patients with UIA without a family history of aSAH who visited the Neurology outpatient clinic in 1 of 3 participating tertiary referral centers in the Netherlands. FDRs were screened for UIA with magnetic resonance angiography between 2017 and 2021. We determined UIA prevalence and developed a prediction model for UIA risk at screening using multivariable logistic regression. QoL was evaluated with questionnaires 6 times during the first year after screening and assessed with a linear mixed-effects model.

RESULTS

We detected 24 UIAs in 23 of 461 screened FDRs, resulting in a 5.0% prevalence (95% CI 3.2-7.4). The median aneurysm size was 3 mm (interquartile range [IQR] 2-4 mm), and the median 5-year rupture risk assessed with the PHASES score was 0.7% (IQR 0.4%-0.9%). All UIAs received follow-up imaging, and none were treated preventively. After a median follow-up of 24 months (IQR 13-38 months), no UIA had changed. Predicted UIA risk at screening ranged between 2.3% and 14.7% with the highest risk in FDRs who smoke and have excessive alcohol consumption (c-statistic: 0.76; 95% CI 0.65-0.88). At all survey moments, health-related QoL and emotional functioning were comparable with those in a reference group from the general population. One FDR with a positive screening result expressed regret about screening.

DISCUSSION

Based on the current data, we do not advise screening FDRs of patients with UIA because all identified UIAs had a low rupture risk. We observed no negative effect of screening on QoL. A longer follow-up should determine the risk of aneurysm growth requiring preventive treatment.

Clinical Response following Hypertension-Induction for clinical Delayed Cerebral Ischemia following Subarachnoid Haemorrhage - a retrospective multicentre cohort study

BACKGROUND

Hypertension-induction is often used for treating delayed cerebral ischemia (DCI) following aneurysmal subarachnoid haemorrhage (aSAH), however, high-quality studies on its efficacy are lacking. We studied immediate and 3-/6-month clinical efficacy of hypertension-induction in aSAH patients with clinical DCI.

METHODS

A retrospective, multicentre, comparative, observational cohort study in aSAH patients with clinical deterioration due to DCI, admitted to three tertiary referral hospitals in the Netherlands from 2015-2019. Two hospitals used a strategy of hypertension-induction (HTI group) and one hospital had no such strategy (control group). We calculated adjusted relative risks (aRR) using Poisson regression analyses for the two primary (clinical improvement of DCI-symptoms at day 1 and 5 after DCI-onset) and secondary outcomes (DCI-related cerebral infarction, in-hospital mortality and poor clinical outcome (modified Rankin Scale 4-6) assessed at 3 or 6 months), using the intention-to-treat principle. We also performed as-treated and per-protocol analyses.

RESULTS

The aRR for clinical improvement on day 1 after DCI in the HTI group was 1.63, 95% C.I. 1.17-2.27 and at day 5 after DCI 1.04, 95% C.I. 0.84 to 1.29. Secondary outcomes were comparable between the groups. The as-treated and per-protocol analyses yielded similar results.

CONCLUSIONS

No clinical benefit of hypertension-induction is observed five days after DCI due to spontaneous reversal of DCI-symptoms in patients treated without hypertension-induction. 3-/6-Month clinical outcome was similar between both groups. Therefore, these data suggest that one may consider to not apply hypertension-induction in aSAH patients with clinical DCI.

Lumbar puncture for treating acute hydrocephalus after aneurysmal subarachnoid haemorrhage

BACKGROUND

External ventricular drainage (EVD) for acute hydrocephalus after aneurysmal subarachnoid haemorrhage (aSAH) carries a risk of complications. We studied the proportion of patients in whom EVD can be avoided by treating acute hydrocephalus with ≥1 lumbar punctures (LP).

METHODS

From a prospectively collected database, we retrieved data on all aSAH patients admitted between 2007 and 2017 who developed acute hydrocephalus (i.e. neurological deterioration and ventricular enlargement <72 h after aSAH). Our regime is to consider LP as initial treatment. We calculated the proportions of patients (with corresponding 95% confidence interval (CI)) who improved after the initial LP and the extent of clinical improvement, the proportions of patients who were treated with only ≥1 LP(s), and those of patients needing continuous external ventricular or external lumbar drainage, or permanent ventriculoperitoneal or lumboperitoneal drainage.

RESULTS

Of 1391 consecutive aSAH patients, 473 (34%) had acute hydrocephalus, of whom 388 (82%) were treated. Of the 86 patients with LP as initial treatment, 70 (81% [95% CI 72-88]) showed initial improvement (with increase in median Glasgow Coma Score from 10 (IQR 7-12) to 12 (IQR 9-14) after initial LP), 39 (45% [95% CI 35-56]) improved with LP only, 41 (48% [95% CI 37-58]) needed continuous drainage and six (7% [95% CI 3-14]) needed permanent drainage.

CONCLUSION

Around half the patients treated with LP for deterioration from acute hydrocephalus after aSAH does not require continuous extraventicular or extralumbar drainage.

Tranexamic Acid After Aneurysmal Subarachnoid Hemorrhage: Post Hoc Analysis of the ULTRA Trial

BACKGROUND AND OBJECTIVES

The ULTRA trial showed that ultra-early and short-term tranexamic acid treatment after subarachnoid hemorrhage did not improve clinical outcome at 6 months. An expected proportion of the included patients experienced nonaneurysmal subarachnoid hemorrhage. In this post hoc study, we will investigate whether ultra-early and short-term tranexamic acid treatment in patients with aneurysmal subarachnoid hemorrhage improves clinical outcome at 6 months.

METHODS

The ULTRA trial is a multicenter, prospective, randomized, controlled, open-label trial with blinded outcome assessment, conducted between July 24, 2013, and January 20, 2020. After confirmation of subarachnoid hemorrhage on noncontrast CT, patients were allocated to either ultra-early and short-term tranexamic acid treatment with usual care or usual care only. In this post hoc analysis, we included all ULTRA participants with a confirmed aneurysm on CT angiography and/or digital subtraction angiography. The primary endpoint was clinical outcome at 6 months, assessed by the modified Rankin scale (mRS), dichotomized into good (0-3) and poor (4-6) outcomes.

RESULTS

Of the 813 ULTRA trial patients who experienced an aneurysmal subarachnoid hemorrhage, 409 (50%) were assigned to the tranexamic acid group and 404 (50%) to the control group. In the intention-to-treat analysis, 233 of 405 (58%) patients in the tranexamic acid group and 238 of 399 (60%) patients in the control group had a good clinical outcome (adjusted odds ratio [aOR] 0.92; 95% CI 0.69-1.24). None of the secondary outcomes showed significant differences between the treatment groups: excellent clinical outcome (mRS 0-2) (aOR 0.76; 95% CI 0.57-1.03), all-cause mortality at 30 days (aOR 0.91; 95% CI 0.65-1.28), and all-cause mortality at 6 months (aOR 1.10; 95% CI 0.80-1.52).

DISCUSSION

Ultra-early and short-term tranexamic acid treatment did not improve clinical outcomes at 6 months in patients with aneurysmal subarachnoid hemorrhage and therefore cannot be recommended.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov (NCT02684812; submission date February 18, 2016, first patient enrollment on July 24, 2013).

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that tranexamic acid does not improve outcomes in patients presenting with aneurysmal subarachnoid hemorrhage.

Development of the SAFETEA Scores for Predicting Risks of Complications of Preventive Endovascular or Microneurosurgical Intracranial Aneurysm Occlusion

BACKGROUND AND OBJECTIVES

Preventive unruptured intracranial aneurysm (UIA) occlusion can reduce the risk of subarachnoid hemorrhage, but both endovascular and microneurosurgical treatment carry a risk of serious complications. To improve individualized management decisions, we developed risk scores for complications of endovascular and microneurosurgical treatment based on easily retrievable patient, aneurysm, and treatment characteristics.

METHODS

For this multicenter cohort study, we combined individual patient data from patients with UIA aged 18 years or older undergoing preventive endovascular treatment (standard, balloon-assisted or stent-assisted coiling, Woven EndoBridge-device, or flow-diverting stent) or microneurosurgical clipping at one of the 10 participating centers from 3 continents between 2000 and 2018. The primary outcome was death from any cause or clinical deterioration from neurologic complications ≤30 days. We selected predictors based on previous knowledge about relevant risk factors and predictor performance and studied the association between predictors and complications with logistic regression. We assessed model performance with calibration plots and concordance (c) statistics.

RESULTS

Of the 1,282 included patients, 94 (7.3%) had neurologic symptoms that resolved <30 days, 140 (10.9%) had persisting neurologic symptoms, and 6 died (0.5%). At 30 days, 52 patients (4.1%) were dead or dependent. Predictors of procedural complications were size of aneurysm, aneurysm location, familial subarachnoid hemorrhage, earlier atherosclerotic disease, treatment volume, endovascular modality (for endovascular treatment) or extra aneurysm configuration factors (for microneurosurgical treatment, branching artery from aneurysm neck or unfavorable dome-to-neck ratio), and age (acronym: SAFETEA). For endovascular treatment (n = 752), the c-statistic was 0.72 (95% CI 0.67-0.77) and the absolute complication risk ranged from 3.2% (95% CI 1.6%-14.9%; ≤1 point) to 33.1% (95% CI 25.4%-41.5%; ≥6 points). For microneurosurgical treatment (n = 530), the c-statistic was 0.72 (95% CI 0.67-0.77) and the complication risk ranged from 4.9% (95% CI 1.5%-14.9%; ≤1 point) to 49.9% (95% CI 39.4%-60.6%; ≥6 points).

DISCUSSION

The SAFETEA risk scores for endovascular and microneurosurgical treatment are based on 7 easily retrievable risk factors to predict the absolute risk of procedural complications in patients with UIAs. The scores need external validation before the predicted risks can be properly used to support decision-making in clinical practice.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that SAFETEA scores predict the risk of procedural complications after endovascular and microneurosurgical treatment of unruptured intracranial aneurysms.

Quality of Life Outcomes Over Time in Patients With Unruptured Intracranial Aneurysms With and Without Preventive Occlusion: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

In counseling patients with an unruptured intracranial aneurysm (UIA), quality of life (QoL) outcomes are important for informed decision making. We evaluated QoL outcomes in patients with and without preventive aneurysm occlusion at multiple time points during the first year after UIA diagnosis and studied predictors of QoL outcomes.

METHODS

We performed a prospective cohort study in patients aged ≥18 years with a newly diagnosed UIA in 2 tertiary referral centers in the Netherlands between 2017 and 2019. Patients were sent QoL questionnaires at 7 (aneurysm occlusion) or 5 (no occlusion) moments during the first year after diagnosis. We collected baseline data on patient and aneurysm characteristics, passive coping style (Utrecht Coping List), occlusion modality, and neurologic complications. We assessed health-related QoL (HRQoL) with the EuroQol 5 dimensions (EQ-5D), emotional functioning with the Hospital Anxiety and Depression Scale (HADS), and restrictions in daily activities with the Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-P). We used a linear mixed-effects model to assess the course of QoL over time and to explore predictors of QoL outcomes.

RESULTS

Of 153 eligible patients, 99 (65%) participated, of whom 30/99 (30%) underwent preventive occlusion. Patients undergoing occlusion reported higher baseline levels of passive coping, anxiety and depression, and restrictions than patients without occlusion. During recovery after occlusion, patients reported more restrictions compared with baseline (adjusted USER-P decrease 1 month post occlusion: -12.8 [95% CI -23.8 to -1.9]). HRQoL and emotional functioning gradually improved after occlusion (EQ-5D increase at 1 year: 8.6 [95% CI 0.1-17.0] and HADS decrease at 1 year: -5.4 [95% CI -9.4 to -1.5]). In patients without occlusion, the largest HRQoL improvement occurred directly after visiting the outpatient aneurysm clinic (EQ-5D increase: 9.2 [95% CI 5.5-12.8]). At 1 year, QoL outcomes were comparable in patients with and without occlusion. Factors associated with worse QoL outcomes were a passive coping style in all patients, complications in patients with occlusion, and higher rupture risks in patients without occlusion.

DISCUSSION

After UIA diagnosis, QoL improves gradually after preventive occlusion and directly after counseling at the outpatient clinic in patients without occlusion, resulting in comparable 1-year QoL outcomes. A passive coping style is an important predictor of poor QoL outcomes in all patients with UIA.

Does the Internal Carotid Artery Attenuate Blood-Flow Pulsatility in Small Vessel Disease? A 7 T 4D-Flow MRI Study

Background

Increased cerebral blood‐flow pulsatility is associated with cerebral small vessel disease (cSVD). Reduced pulsatility attenuation over the internal carotid artery (ICA) could be a contributing factor to the development of cSVD and could be associated with intracranial ICA calcification (iICAC).

Purpose

To compare pulsatility, pulsatility attenuation, and distensibility along the ICA between patients with cSVD and controls and to assess the association between iICAC and pulsatility and distensibility.

Study Type

Retrospective, explorative cross‐sectional study.

Subjects

A total of 17 patients with cSVD, manifested as lacunar infarcts or deep intracerebral hemorrhage, and 17 age‐ and sex‐matched controls.

Field Strength/Sequence

Three‐dimensional (3D) T1‐weighted gradient echo imaging and 4D phase‐contrast (PC) MRI with a 3D time‐resolved velocity encoded gradient echo sequence at 7 T.

Assessment

Blood‐flow velocity pulsatility index (vPI) and arterial distensibility were calculated for seven ICA segments (C1–C7). iICAC presence and volume were determined from available brain CT scans (acquired as part of standard clinical care) in patients with cSVD.

Statistical Tests

Independent t‐tests and linear mixed models. The threshold for statistically significance was P < 0.05 (two tailed).

Results

The cSVD group showed significantly higher ICA vPI and significantly lower distensibility compared to controls. Controls showed significant attenuation of vPI over the carotid siphon (−4.9% ± 3.6%). In contrast, patients with cSVD showed no attenuation, but a significant increase of vPI (+6.5% ± 3.1%). iICAC presence and volume correlated positively with vPI (r = 0.578) in patients with cSVD and negatively with distensibility (r = −0.386).

Conclusion

Decreased distensibility and reduced pulsatility attenuation are associated with increased iICAC and may contribute to cSVD. Confirmation in a larger prospective study is required.

Evidence Level

2

Technical Efficacy

Stage 2

Trigger Factors for Spontaneous Intracerebral Hemorrhage: A Case-Crossover Study

BACKGROUND AND PURPOSE

Whether certain activities can trigger spontaneous intracerebral hemorrhage (ICH) remains unknown. Insights into factors that trigger vessel rupture resulting in ICH improves knowledge on the pathophysiology of ICH. We assessed potential trigger factors and their risk for ICH onset.

METHODS

We included consecutive patients diagnosed with ICH between July 1, 2013, and December 31, 2019. We interviewed patients on their exposure to 12 potential trigger factors (eg, Valsalva maneuvers) in the (hazard) period soon before onset of ICH and their normal exposure to these trigger factors in the year before the ICH. We used the case-crossover design to calculate relative risks (RR) for potential trigger factors.

RESULTS

We interviewed 149 patients (mean age 64, 66% male) with ICH. Sixty-seven (45%) had a lobar hemorrhage, 60 (40%) had a deep hemorrhage, 19 (13%) had a cerebellar hemorrhage, and 3 (2%) had an intraventricular hemorrhage. For ICH in general, there was an increased risk within an hour after caffeine consumption (RR=2.5 [95% CI=1.8-3.6]), within an hour after coffee consumption alone (RR=4.8 [95% CI=3.3-6.9]), within an hour after lifting >25 kg (RR=6.6 [95% CI=2.2-19.9]), within an hour after minor head trauma (RR=10.1 [95% CI=1.7-60.2]), within an hour after sexual activity (RR=30.4 [95% CI=16.8-55.0]), within an hour after straining for defecation (RR=37.6 [95% CI=22.4-63.4]), and within an hour after vigorous exercise (RR=21.8 [95% CI=12.6-37.8]). Within 24 hours after flu-like disease or fever, the risk for ICH was also increased (RR=50.7 [95% CI=27.1-95.1]). Within an hour after Valsalva maneuvers, the RR for deep ICH was 3.5 (95% CI=1.7-6.9) and for lobar ICH the RR was 2.0 (95% CI=0.9-4.2).

CONCLUSIONS

We identified one infection and several blood pressure related trigger factors for ICH onset, providing new insights into the pathophysiology of vessel rupture resulting in ICH.

Pulsatility Attenuation along the Carotid Siphon in Pseudoxanthoma Elasticum

We compared velocity pulsatility, distensibility, and pulsatility attenuation along the intracranial ICA and MCA between 50 patients with pseudoxanthoma elasticum and 40 controls. Patients with pseudoxanthoma elasticum had higher pulsatility and lower distensibility at all measured locations, except for a similar distensibility at C4. The pulsatility attenuation over the siphon was similar between patients with pseudoxanthoma elasticum and controls. This finding suggests that other disease mechanisms are the main contributors to increased intracranial pulsatility in pseudoxanthoma elasticum.

Role of Rare Genetic Variants Found in Families With Intracranial Aneurysms in the General Dutch and UK Population

[Figure: see text].

Management decisions on unruptured intracranial aneurysms before and after implementation of the PHASES score

BACKGROUND

In management decisions on saccular unruptured intracranial aneurysms (UIAs) the risk of rupture is an important factor. The PHASES score, introduced in 2014, provides absolute 5-year risks of rupture based on six easily retrievable patient and aneurysm characteristics. We assessed whether management decisions on UIAs changed after implementation of the PHASES score.

PATIENT AND METHODS

We included all patients with UIAs who were referred to two Dutch tertiary referral centers for aneurysm care in the Netherlands (University Medical Center Utrecht (UMCU) and Leiden University Medical Center (LUMC)) between 2011 and 2017. Analyses were done on an aneurysm level. We calculated the overall proportion of UIAs with a decision to treat before and after PHASES implementation and studied the influence of age and center on post-implementation management changes.

RESULTS

We included 623 patients with 803 UIAs. The proportion of UIAs with a decision to treat was 123/360 (34.2%) before and 117/443 (26.4%) after PHASES implementation (absolute risk difference: -7.8%; 95% CI: -14.1 to -1.4). The decision to treat was made at a higher median PHASES score after implementation (7 points (IQR 5;10) pre- versus 8 points (IQR 5;10) post-implementation; p = 0.14). The reduced proportion with a treatment decision after implementation was most pronounced in patients <50 years (-22.3%; 95% CI: -39.2 to -3.4) and was restricted to treatment decisions made at the UMCU (-10.6%; 95% CI: -18.5 to -2.5).

DISCUSSION AND CONCLUSIONS

Management of UIAs changed following implementation of the PHASES score, but the impact of PHASES implementation on treatment decisions differed across age subgroups and centers.

Ultra-early tranexamic acid after subarachnoid haemorrhage (ULTRA): a randomised controlled trial

BACKGROUND

In patients with aneurysmal subarachnoid haemorrhage, short-term antifibrinolytic therapy with tranexamic acid has been shown to reduce the risk of rebleeding. However, whether this treatment improves clinical outcome is unclear. We investigated whether ultra-early, short-term treatment with tranexamic acid improves clinical outcome at 6 months.

METHODS

In this multicentre prospective, randomised, controlled, open-label trial with masked outcome assessment, adult patients with spontaneous CT-proven subarachnoid haemorrhage in eight treatment centres and 16 referring hospitals in the Netherlands were randomly assigned to treatment with tranexamic acid in addition to care as usual (tranexamic acid group) or care as usual only (control group). Tranexamic acid was started immediately after diagnosis in the presenting hospital (1 g bolus, followed by continuous infusion of 1 g every 8 h, terminated immediately before aneurysm treatment, or 24 h after start of the medication, whichever came first). The primary endpoint was clinical outcome at 6 months, assessed by the modified Rankin Scale, dichotomised into a good (0-3) or poor (4-6) clinical outcome. Both primary and safety analyses were according to intention to treat. This trial is registered at ClinicalTrials.gov, NCT02684812.

FINDINGS

Between July 24, 2013, and July 29, 2019, we enrolled 955 patients; 480 patients were randomly assigned to tranexamic acid and 475 patients to the control group. In the intention-to-treat analysis, good clinical outcome was observed in 287 (60%) of 475 patients in the tranexamic acid group, and 300 (64%) of 470 patients in the control group (treatment centre adjusted odds ratio 0·86, 95% CI 0·66-1·12). Rebleeding after randomisation and before aneurysm treatment occurred in 49 (10%) patients in the tranexamic acid and in 66 (14%) patients in the control group (odds ratio 0·71, 95% CI 0·48-1·04). Other serious adverse events were comparable between groups.

INTERPRETATION

In patients with CT-proven subarachnoid haemorrhage, presumably caused by a ruptured aneurysm, ultra-early, short-term tranexamic acid treatment did not improve clinical outcome at 6 months, as measured by the modified Rankin Scale.

FUNDING

Fonds NutsOhra.

Velocity Pulsatility and Arterial Distensibility Along the Internal Carotid Artery

Background Attenuation of velocity pulsatility along the internal carotid artery (ICA) is deemed necessary to protect the microvasculature of the brain. The role of the carotid siphon within the whole ICA trajectory in pulsatility attenuation is still poorly understood. This study aims to assess arterial variances in velocity pulsatility and distensibility over the whole ICA trajectory, including effects of age and sex. Methods and Results We assessed arterial velocity pulsatility and distensibility using flow-sensitized 2-dimensional phase-contrast 3.0 Tesla magnetic resonance imaging in 118 healthy participants. Velocity pulsatility index (vPI=(V_max-V_min)/V_mean) and arterial distensibility defined as area pulsatility index (A_max-A_min)/A_mean) were calculated at C1, C3, and C7 segments of the ICA. vPI increased between C1 and C3 (0.85±0.13 versus 0.93±0.13, P<0.001 for averaged right+left ICA) and decreased between C3 and C7 (0.93±0.13 versus 0.84±0.13, P<0.001) with overall no effect (C1-C7). Conversely, the area pulsatility index decreased between C1 and C3 (0.18±0.06 versus 0.14±0.04, P<0.001) and increased between C3 and C7 (0.14±0.04 versus 0.31±0.09, P<0.001). vPI in men is higher than in women and increases with age (P<0.015). vPI over the carotid siphon declined with age but remained stable over the whole ICA trajectory. Conclusions Along the whole ICA trajectory, vPI increased from extracranial C1 up to the carotid siphon C3 with overall no effect on vPI between extracranial C1 and intracranial C7 segments. This suggests that the bony carotid canal locally limits the arterial distensibility of the ICA, increasing the vPI at C3 which is consequently decreased again over the carotid siphon. In addition, vPI in men is higher and increases with age.

Location-specific risk factors for intracerebral hemorrhage: Systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of studies reporting on risk factors according to location of the intracerebral hemorrhage.

METHODS

We searched PubMed and Embase for cohort and case-control studies reporting ≥100 patients with spontaneous intracerebral hemorrhage that specified the location of the hematoma and reported associations with risk factors published until June 27, 2019. Two authors independently extracted data on risk factors. Estimates were pooled with the generic variance-based random-effects method.

RESULTS

After screening 10,013 articles, we included 42 studies totaling 26,174 patients with intracerebral hemorrhage (9,141 lobar and 17,033 nonlobar). Risk factors for nonlobar intracerebral hemorrhage were hypertension (risk ratio [RR] 4.25, 95% confidence interval [CI] 3.05-5.91, I ² = 92%), diabetes mellitus (RR 1.35, 95% CI 1.11-1.64, I ² = 37%), male sex (RR 1.63, 95% CI 1.25-2.14, I ² = 61%), alcohol overuse (RR 1.48, 95% CI 1.21-1.81, I ² = 19%), underweight (RR 2.12, 95% CI 1.12-4.01, I ² = 31%), and being a Black (RR 2.83, 95% CI 1.02-7.84, I ² = 96%) or Hispanic (RR 2.95, 95% CI 1.69-5.14, I ² = 71%) participant compared with being a White participant. Hypertension, but not any of the other risk factors, was also a risk factor for lobar intracerebral hemorrhage (RR 1.83, 95% CI 1.39-2.42, I ² = 76%). Smoking, hypercholesterolemia, and obesity were associated with neither nonlobar nor lobar intracerebral hemorrhage.

CONCLUSIONS

Hypertension is a risk factor for both nonlobar and lobar intracerebral hemorrhage, although with double the effect for nonlobar intracerebral hemorrhage. Diabetes mellitus, male sex, alcohol overuse, underweight, and being a Black or Hispanic person are risk factors for nonlobar intracerebral hemorrhage only. Hence, the term hypertensive intracerebral hemorrhage for nonlobar intracerebral hemorrhage is not appropriate.

Prediction of Outcome Using Quantified Blood Volume in Aneurysmal SAH

BACKGROUND AND PURPOSE

In patients with SAH, the amount of blood is strongly associated with clinical outcome. However, it is commonly estimated with a coarse grading scale, potentially limiting its predictive value. Therefore, we aimed to develop and externally validate prediction models for clinical outcome, including quantified blood volumes, as candidate predictors.

MATERIALS AND METHODS

Clinical and radiologic candidate predictors were included in a logistic regression model. Unfavorable outcome was defined as a modified Rankin Scale score of 4-6. An automatic hemorrhage-quantification algorithm calculated the total blood volume. Blood was manually classified as cisternal, intraventricular, or intraparenchymal. The model was selected with bootstrapped backward selection and validated with the R ², C-statistic, and calibration plots. If total blood volume remained in the final model, its performance was compared with models including location-specific blood volumes or the modified Fisher scale.

RESULTS

The total blood volume, neurologic condition, age, aneurysm size, and history of cardiovascular disease remained in the final models after selection. The externally validated predictive accuracy and discriminative power were high (R ² = 56% ± 1.8%; mean C-statistic = 0.89 ± 0.01). The location-specific volume models showed a similar performance (R ² = 56% ± 1%, P = .8; mean C-statistic = 0.89 ± 0.00, P = .4). The modified Fisher models were significantly less accurate (R ² = 45% ± 3%, P < .001; mean C-statistic = 0.85 ± 0.01, P = .03).

CONCLUSIONS

The total blood volume-based prediction model for clinical outcome in patients with SAH showed a high predictive accuracy, higher than a prediction model including the commonly used modified Fisher scale.

Update of the ULtra-early TRranexamic Acid after Subarachnoid Hemorrhage (ULTRA) trial: statistical analysis plan

BACKGROUND

Recurrent bleeding from an intracranial aneurysm after subarachnoid hemorrhage (SAH) is associated with unfavorable outcome. Recurrent bleeding before aneurysm occlusion can be performed occurs in up to one in five patients and most often happens within the first 6 h after the primary hemorrhage. Reducing the rate of recurrent bleeding could be a major factor in improving clinical outcome after SAH. Tranexamic acid (TXA) reduces the risk of recurrent bleeding but has thus far not been shown to improve functional outcome, probably because of a higher risk of delayed cerebral ischemia (DCI). To reduce the risk of ultraearly recurrent bleeding, TXA should be administered as soon as possible after diagnosis and before transportation to a tertiary care center. If TXA is administered for a short duration (i.e., < 24 h), it may not increase the risk of DCI. The aim of this paper is to present in detail the statistical analysis plan (SAP) of the ULTRA trial (ULtra-early TRranexamic Acid after Subarachnoid Hemorrhage), which is currently enrolling patients and investigating whether ultraearly and short-term TXA treatment in patients with aneurysmal SAH improves clinical outcome at 6 months.

METHODS/DESIGN

The ULTRA trial is a multicenter, prospective, randomized, open, blinded endpoint, parallel-group trial currently ongoing at 8 tertiary care centers and 16 of their referral centers in the Netherlands. Participants are randomized to standard care or to receive TXA at a loading dose of 1 g, immediately followed by 1 g every 8 h for a maximum of 24 h, in addition to standard care, as soon as SAH is diagnosed. In the TXA group, TXA administration is stopped immediately prior to treatment (coil or clip) of the causative aneurysm. Primary outcome is the modified Rankin Scale (mRS) score at 6 months after SAH, dichotomized into good (mRS 0-3) and poor (mRS 4-6) outcomes, assessed blind to treatment allocation. Secondary outcomes include case fatalities at 30 days and at 6 months and causes of poor clinical outcome. Safety outcomes are recurrent bleeding, DCI, hydrocephalus, per-procedural complications, and other complications such as infections occurring during hospitalization. Data analyses will be according to this prespecified SAP.

TRIAL REGISTRATION

Netherlands Trial Register, NTR3272. Registered on 25 January 2012. ClinicalTrials.gov, NCT02684812. Registered on 17 February 2016.

Co-prevalence of extracranial carotid aneurysms differs between European intracranial aneurysm cohorts

Background and purpose

Previously, we showed that co-prevalence of extracranial carotid artery aneurysms (ECAAs) in patients with intracranial aneurysms (IAs) was 2% in a Dutch cohort. In order to obtain more precise estimates and discover potential predictors of ECAA co-prevalence in the European population, we retrospectively compared differences and similarities of our Dutch cohort with a Finnish cohort using protocolled imaging of the cerebrovascular tree.

Methods

IA patients within the prospective database of the Kuopio University Hospital were eligible for this study (n = 1,118). Image analysis and hospital chart review were conducted.

Results

In total, 458 patients with complete carotid imaging conform protocol were analyzed. Twenty-four ECAAs in 21 patients were identified (4.6%, 95% CI 2.9–6.9), a higher co-prevalence than in the Dutch cohort (1.9%; 95% CI 1.0–3.3), prevalence odds ratio (POR) 2.45 (95% CI 1.19–5.03). In the Finnish cohort, 25% of all ECAAs were located around the carotid bifurcation, others in the internal carotid artery distally from the bifurcation. Independent predictors for ECAA co-prevalence were origin of country (POR 2.41, 95% CI 1.15–5.06) and male gender (POR 2.25, 95% CI 1.09–4.64).

Conclusion

The co-prevalence of ECAA in IA patients was twice as high in the Finnish compared to the Dutch IA cohort, with origin of country and male gender as independent predictors. Twenty-five percent of ECAAs would be missed, if the carotid bifurcation was not imaged. Therefore, we propose to always include imaging of the carotid bifurcation as the gold standard technique to identify ECAA in IA patients.

Concordance in Aneurysm Size at Time of Rupture in Familial Intracranial Aneurysms

Background and Purpose- Intracranial aneurysm (IA) size and location are important determinants of aneurysm rupture risk. In familial IAs there is concordance of location; however, if such concordance exists for size is unknown. We analyzed the concordance of aneurysm size at time of rupture in familial IAs. Methods- In pairs of affected relatives with aneurysmal subarachnoid hemorrhage, the ratio between the largest and the smallest aneurysm size at time of rupture was calculated. We also compared the proportion of families in which both IAs ruptured at a size < or ≥7 mm with the proportion of families in which one IA ruptured at <7 mm and another ≥7 mm. We calculated the repeatability with corresponding 95% CI for aneurysm size at time of rupture. Results- About 130 patients from 64 families were included. Of the 68 affected pairs 18 (26%) had a ratio ≤1.2, 38 (57%) had a ratio >1.2, and 12 (17%) had a ratio ≥3. We found no difference between the proportion of families (n=31; 49%) who both had IA at time of rupture <7 mm (n=20; 31%) or both ≥7 mm (n=11; 18%) and the proportion of those families with one patient with an IA <7 mm and another with an IA ≥7 mm (n=33; 51%; P=0.86). Overall, the repeatability in aneurysm size at rupture within familial IAs was 0.10 (95% CI, 0-0.35). Conclusions- There is no good concordance in aneurysm size at rupture within familial IAs. These data suggest that size of a ruptured IA in a family member should not significantly impact on the management of a familial unruptured IA in a relative.

External Validation of the ELAPSS Score for Prediction of Unruptured Intracranial Aneurysm Growth Risk

Background and Purpose

Prediction of intracranial aneurysm growth risk can assist physicians in planning of follow-up imaging of conservatively managed unruptured intracranial aneurysms. We therefore aimed to externally validate the ELAPSS (Earlier subarachnoid hemorrhage, aneurysm Location, Age, Population, aneurysm Size and Shape) score for prediction of the risk of unruptured intracranial aneurysm growth.

Methods

From 11 international cohorts of patients ≥18 years with ≥1 unruptured intracranial aneurysm and ≥6 months of radiological follow-up, we collected data on the predictors of the ELAPSS score, and calculated 3- and 5-year absolute growth risks according to the score. Model performance was assessed in terms of calibration (predicted versus observed risk) and discrimination (c-statistic).

Results

We included 1,072 patients with a total of 1,452 aneurysms. During 4,268 aneurysm-years of follow-up, 199 (14%) aneurysms enlarged. Calibration was comparable to that of the development cohort with the overall observed risks within the range of the expected risks. The c-statistic was 0.69 (95% confidence interval [CI], 0.64 to 0.73) at 3 years, compared to 0.72 (95% CI, 0.68 to 0.76) in the development cohort. At 5 years, the c-statistic was 0.68 (95% CI, 0.64 to 0.72), compared to 0.72 (95% CI, 0.68 to 0.75) in the development cohort.

Conclusions

The ELAPSS score showed accurate calibration for 3- and 5-year risks of aneurysm growth and modest discrimination in our external validation cohort. This indicates that the score is externally valid and could assist patients and physicians in predicting growth of unruptured intracranial aneurysms and plan follow-up imaging accordingly.

Assessment of the Most Optimal Control Tissue for Intracranial Aneurysm Gene Expression Studies

Background and Purpose- Finding adequate control tissue for intracranial aneurysm (IA) pathophysiological studies, including gene expression studies, can be challenging. We compared gene expression profiles of superficial temporal, cortical, and circle of Willis (CoW) arteries and IA in search of the most optimal control tissue for future experiments. Methods- We compared RNA-sequencing data of IA samples and of superficial temporal, cortical, and CoW artery samples using Pearson correlation, Euclidean distance, and principal component analysis. We used the Mann-Whitney U test for comparison of Pearson correlation coefficients and Euclidean distances, to assess which control tissue is most similar to IA in terms of gene expression. Other unrelated tissues were used as negative controls. Results- The cortical and the CoW arteries were more similar to IA in terms of gene expression than the superficial temporal artery. This was based on Pearson correlation (+0.023 [90% CI, 0.017/0.029; P=1.9E-09] for the cortical artery and +0.034 [90% CI, 0.028/0.040; P=6.0E-15] for the CoW artery compared with the superficial temporal artery), Euclidean distance (-25.71 [90% CI, -31.54/-20.02; P=1.9E-11] for the cortical artery and -38.09 [90% CI, -44.08/-32.19; P<2.2E-16] for the CoW artery compared with the superficial temporal artery) and principal component analysis. In all analyses, the unrelated tissues formed separate groups compared with IA and the 3 control arteries. Conclusions- The cortical arteries and the CoW arteries are better controls for gene expression studies on IA than the superficial temporal artery. This probably relates to differences in anatomy of these tissues, such as the presence of an external elastic lamina in the extracranial vasculature and absence in the intracranial vasculature, because IAs, cortical arteries, and CoW arteries are all intracranial while the superficial temporal artery is extracranial. Since CoW arteries can only be obtained postmortem, cortical arteries are preferred over CoW arteries.

Histological Differences of the Vascular Wall Between Sites With High and Low Prevalence of Intracranial Aneurysm

Intracranial aneurysms (IAs) develop more often on bifurcations compared with the rest of the circle of Willis (CoW). We investigated histological differences between 2 high IA prevalence sites (anterior communicating artery [AcomA] and basilar tip) and 2 corresponding low IA prevalence sites (anterior cerebral artery [ACA] and basilar artery [BA]) using histological sections of 10 CoWs without IAs. Medial defect density in the AcomA was 0.24 medial defects/mm compared with 0.02 for the A1 part and 0.03 for the A2 part of the ACA. In the basilar tip we found 0.15 medial defects/mm compared with 0.14 in the BA. Vascular smooth muscle cells (VSMCs) were more often disorganized in both high-prevalence sites (AcomA: 10/10, basilar tip: 5/10) compared with low-prevalence sites (both ACA and BA: 1/10). Intima thickening was more severe in the high-prevalence sites. Vascular wall thickness was not significantly different between high- and low-prevalence sites, but had a larger variance in high- compared with low-prevalence sites (AcomA vs ACA: p = 6.8E-12, basilar tip vs BA: p = 0.02). Disorganized VSMCs at high-prevalence sites likely result in a higher susceptibility to hemodynamic stress, leading to more vascular remodeling (such as intima thickening), which could increase the likelihood of IA formation.

Gadolinium Enhancement of the Aneurysm Wall in Unruptured Intracranial Aneurysms Is Associated with an Increased Risk of Aneurysm Instability: A Follow-Up Study

BACKGROUND AND PURPOSE

Previous studies have suggested that gadolinium enhancement of the wall of unruptured intracranial aneurysms on MR imaging may reflect aneurysm wall instability. However, all previous studies were cross-sectional. In this longitudinal study, we investigated whether aneurysm wall enhancement is associated with an increased risk of aneurysm instability.

MATERIALS AND METHODS

We included all patients 18 years of age or older with ≥1 unruptured aneurysm from the University Medical Center Utrecht, the Netherlands, who were included in 2 previous studies with either 3T or 7T aneurysm wall MR imaging and for whom it was decided not to treat the aneurysm but to monitor it with follow-up imaging. We investigated the risk of growth or rupture during follow-up of aneurysms with and without gadolinium enhancement of the aneurysm wall at baseline and calculated the risk difference between the 2 groups with corresponding 95% confidence intervals.

RESULTS

We included 57 patients with 65 unruptured intracranial aneurysms. After a median follow-up of 27 months (interquartile range, 20-31 months), growth (n = 2) or rupture (n = 2) was observed in 4 of 19 aneurysms (21%; 95% CI, 6%-54%) with wall enhancement and in zero of 46 aneurysms (0%; 95% CI, 0%-8%) without enhancement (risk difference, 21%; 95% CI, 3%-39%).

CONCLUSIONS

Gadolinium enhancement of the aneurysm wall on MR imaging is associated with an increased risk of aneurysm instability. The absence of wall enhancement makes it unlikely that the aneurysm will grow or rupture in the short term. Larger studies are needed to investigate whether aneurysm wall enhancement is an independent predictor of aneurysm instability.

The relationship between ischaemic brain lesions and cognitive outcome after aneurysmal subarachnoid haemorrhage

Background

Cerebral ischaemia is thought to be an important determinant of cognitive outcome after aneurysmal subarachnoid haemorrhage (aSAH), but the exact relationship is unclear. We studied the effect of ischaemic brain lesions during clinical course on cognitive outcome 2 months after aSAH.

Methods

We studied 74 consecutive patients admitted to the University Medical Center Utrecht who had MRI post-coiling (3–21 days post-aSAH) and neuropsychological examination at 2 months. An ischaemic lesion was defined as hyperintensity on T2-FLAIR and DWI images. We measured both cognitive complaints (subjective) and cognitive functioning (objective). The relationship between ischaemic brain lesions and cognitive outcome was analysed by logistic regression analyses.

Results

In 40 of 74 patients (54%), 152 ischaemic lesions were found. The median number of lesions per patient was 2 (1–37) and the median total lesion volume was 0.2 (0–17.4) mL. No difference was found between the group with and the group without ischaemic lesions with respect to the frequency of cognitive complaints. In the group with ischaemic lesions, significantly more patients (55%) showed poor cognitive functioning compared to the group without ischaemic lesions (26%) (OR 3.4, 95% CI 1.3–9.1). We found no relationship between the number and volume of the ischaemic lesions and cognitive functioning.

Conclusions

Ischaemic brain lesions detected on MRI during clinical course after aSAH is a marker for poor cognitive functioning 2 months after aSAH, irrespective of the number or volume of the ischaemic lesions. Network or connectivity studies are needed to better understand the relationship between location of the ischaemic brain lesions and cognitive functioning.

Chromatin Conformation Links Putative Enhancers in Intracranial Aneurysm-Associated Regions to Potential Candidate Genes

Background

We previously showed that intracranial aneurysm (IA)–associated single‐nucleotide polymorphisms are enriched in promoters and putative enhancers identified in the human circle of Willis, on which IAs develop, suggesting a role for promoters and enhancers in IAs. We further investigated the role of putative enhancers in the pathogenesis of IA by identifying their potential target genes and validating their regulatory activity.

Methods and Results

Using our previously published circle of Willis chromatin immunoprecipitation and sequencing data, we selected 34 putative enhancers in IA‐associated regions from genome‐wide association studies. We then used a chromatin conformation capture technique to prioritize target genes and found that 15 putative enhancers interact with the promoters of 6 target genes: SOX17,CDKN2B,MTAP,CNNM2,RPEL1, and GATA6. Subsequently, we assessed the activity of these putative enhancers in vivo in zebrafish embryos and confirmed activity for 8 putative enhancers. Last, we found that all 6 target genes are expressed in the circle of Willis, on the basis of RNA sequencing data and in situ hybridization. Furthermore, in situ hybridization showed that these genes are expressed in multiple cell types in the circle of Willis.

Conclusions

In 4 of 6 IA‐associated genome‐wide association study regions, we identified 8 putative enhancers that are active in vivo and interact with 6 nearby genes, suggesting that these genes are regulated by the identified putative enhancers. These genes, SOX17,CDKN2B,MTAP,CNNM2,RPEL1, and GATA6, are therefore potential candidate genes involved in IA pathogenesis and should be studied using animal models in the future.

Stress in Patients With (Un)ruptured Intracranial Aneurysms vs Population-Based Controls

BACKGROUND

Stress is associated with increased risk of stroke and might predispose to presence and rupture of intracranial aneurysms.

OBJECTIVE

To study the association of recent and lifelong stress with unruptured intracranial aneurysm (UIA) and aneurysmal subarachnoid hemorrhage (ASAH).

METHODS

In 227 UIA patients (mean age 61 ± 11 yr), 490 ASAH patients (59 ± 11 yr), and 775 controls (51 ± 15 yr) who were randomly retrieved from the general population, we assessed occurrence of major life events and perceived stress during the preceding 12 mo and the entire life. With multivariable logistic regression analysis, we calculated odds ratios (ORs) with 95% confidence intervals (95% CIs) for 4 categories of life events (financial-related, work-related, children-related, and death of family members) and for periods of perceived stress at home and at work (never vs sometimes, often, or always). We adjusted for sex, age, alcohol consumption, smoking, and hypertension.

RESULTS

The 4 categories of life events and perceived stress at work had ORs ranging from 0.4 to 1.7, of which financial stress for UIA was statistically significant (95% CI: 1.1-2.5). ORs for chronic perceived stress at home in the previous year were 4.3 (95% CI: 1.8-10.3) for UIA and 2.5 (1.2-5.5) for ASAH, and for lifelong exposure 5.7 (2.2-14.5) for UIA and 3.0 (1.3-7.0) for ASAH.

CONCLUSION

For some components of stress, there may be a relation with UIA and ASAH. The mechanisms underlying this relation should be unraveled; strategies to improve coping with stress may reduce the risk of rupture in patients with unruptured aneurysms.

Effect of magnesium on cognition after aneurysmal subarachnoid haemorrhage in a randomized trial

Background and purpose

In randomized trials magnesium supplementation did not improve clinical outcome after aneurysmal subarachnoid haemorrhage (aSAH) on handicap scales. After aSAH, many patients have cognitive problems that may not translate into handicap. The effect of magnesium on cognitive outcome after aSAH was studied.

Methods

In total, 209 patients who had been included in the Magnesium for Aneurysmal Subarachnoid Haemorrhage (MASH‐2) trial in the University Medical Centre of Utrecht were studied. Patients had been randomized to 64 mmol magnesium sulfate daily or placebo during hospitalization. Three months after aSAH patients underwent a neuropsychological examination (NPE) consisting of six neuropsychological tests or a brief cognitive assessment. Poisson and linear regression analyses were used to analyse the effect of magnesium on cognition.

Results

In the magnesium group 53 (49.5%) of the 107 patients and in the placebo group 51 (50.0%) of the 102 patients scored lower than the median cognitive score [relative risk 0.99, 95% confidence interval (CI) 0.76–1.30]. Linear regression analyses showed no significant relationship between intervention and cognition (B = 0.05, 95% CI −0.15 to 0.33).

Conclusions

Treatment with magnesium has no effect on cognitive outcome after aSAH.

Fourth European stroke science workshop

Lake Eibsee, Garmisch-Partenkirchen, 16 to 18 November, 2017: The European Stroke Organisation convened >120 stroke experts from 21 countries to discuss latest results and hot topics in clinical, translational and basic stroke research. Since its inception in 2011, the European Stroke Science Workshop has become a cornerstone of European Stroke Organisation's academic activities and a major highlight for researchers in the field. Participants include stroke researchers at all career stages and with different backgrounds, who convene for plenary lectures and discussions. The workshop was organised in seven scientific sessions focusing on the following topics: (1) acute stroke treatment and endovascular therapy; (2) small vessel disease; (3) opportunities for stroke research in the omics era; (4) vascular cognitive impairment; (5) intracerebral and subarachnoid haemorrhage; (6) alternative treatment concepts and (7) neural circuits, recovery and rehabilitation. All sessions started with a keynote lecture providing an overview on current developments, followed by focused talks on a timely topic with the most recent findings, including unpublished data. In the following, we summarise the key contents of the meeting. The program is provided in the online only Data Supplement. The workshop started with a key note lecture on how to improve the efficiency of clinical trial endpoints in stroke, which was delivered by Craig Anderson (Sydney, Australia) and set the scene for the following discussions.

Predicting the presence of macrovascular causes in non-traumatic intracerebral haemorrhage: the DIAGRAM prediction score

OBJECTIVE

A substantial part of non-traumatic intracerebral haemorrhages (ICH) arises from a macrovascular cause, but there is little guidance on selection of patients for additional diagnostic work-up. We aimed to develop and externally validate a model for predicting the probability of a macrovascular cause in patients with non-traumatic ICH.

METHODS

The DIagnostic AngioGRAphy to find vascular Malformations (DIAGRAM) study (n=298; 69 macrovascular cause; 23%) is a prospective, multicentre study assessing yield and accuracy of CT angiography (CTA), MRI/ magnetic resonance angiography (MRA) and intra-arterial catheter angiography in diagnosing macrovascular causes in patients with non-traumatic ICH. We considered prespecified patient and ICH characteristics in multivariable logistic regression analyses as predictors for a macrovascular cause. We combined independent predictors in a model, which we validated in an external cohort of 173 patients with ICH (78 macrovascular cause, 45%).

RESULTS

Independent predictors were younger age, lobar or posterior fossa (vs deep) location of ICH, and absence of small vessel disease (SVD). A model that combined these predictors showed good performance in the development data (c-statistic 0.83; 95% CI 0.78 to 0.88) and moderate performance in external validation (c-statistic 0.66; 95% CI 0.58 to 0.74). When CTA results were added, the c-statistic was excellent (0.91; 95% CI 0.88 to 0.94) and good after external validation (0.88; 95% CI 0.83 to 0.94). Predicted probabilities varied from 1% in patients aged 51-70 years with deep ICH and SVD, to more than 50% in patients aged 18-50 years with lobar or posterior fossa ICH without SVD.

CONCLUSION

The DIAGRAM scores help to predict the probability of a macrovascular cause in patients with non-traumatic ICH based on age, ICH location, SVD and CTA.

Association of Quantified Location-Specific Blood Volumes with Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Delayed cerebral ischemia is a severe complication of aneurysmal SAH and is associated with a high case morbidity and fatality. The total blood volume and the presence of intraventricular blood on CT after aneurysmal SAH are associated with delayed cerebral ischemia. Whether quantified location-specific (cisternal, intraventricular, parenchymal, and subdural) blood volumes are associated with delayed cerebral ischemia has been infrequently researched. This study aimed to associate quantified location-specific blood volumes with delayed cerebral ischemia.

MATERIALS AND METHODS

Clinical and radiologic data were collected retrospectively from consecutive patients with aneurysmal SAH with available CT scans within 24 hours after ictus admitted to 2 academic centers between January 2009 and December 2011. Total blood volume was quantified using an automatic hemorrhage-segmentation algorithm. Segmented blood was manually classified as cisternal, intraventricular, intraparenchymal, or subdural. Adjusted ORs with 95% confidence intervals for delayed cerebral ischemia per milliliter of location-specific blood were calculated using multivariable logistic regression analysis.

RESULTS

We included 282 patients. Per milliliter increase in blood volume, the adjusted OR for delayed cerebral ischemia was 1.02 (95% CI, 1.01-1.04) for cisternal, 1.02 (95% CI, 1.00-1.04) for intraventricular, 0.99 (95% CI, 0.97-1.02) for intraparenchymal, and 0.96 (95% CI, 0.86-1.07) for subdural blood.

CONCLUSIONS

Our findings suggest that in patients with aneurysmal subarachnoid hemorrhage, the cisternal blood volume has a stronger relation with delayed cerebral ischemia than the blood volumes at other locations in the brain.

Quantification of Intracranial Aneurysm Volume Pulsation with 7T MRI

BACKGROUND AND PURPOSE

Aneurysm volume pulsation is a potential predictor of intracranial aneurysm rupture. We evaluated whether 7T MR imaging can quantify aneurysm volume pulsation.

MATERIALS AND METHODS

In Stage I of the study, 10 unruptured aneurysms in 9 patients were studied using a high-resolution (0.6-mm, isotropic) 3D gradient-echo sequence with cardiac gating. Semiautomatic segmentation was used to measure aneurysm volume (in cubic millimeters) per cardiac phase. Aneurysm pulsation was defined as the relative increase in volume between the phase with the smallest volume and the phase with the largest volume. The accuracy and precision of the measured volume pulsations were addressed by digital phantom simulations and a repeat image analysis. In Stage II, the imaging protocol was optimized and 9 patients with 9 aneurysms were studied with and without administration of a contrast agent.

RESULTS

The mean aneurysm pulsation in Stage I was 8% ± 7% (range, 2%-27%), with a mean volume change of 15 ± 14 mm³ (range, 3-51 mm³). The mean difference in volume change for the repeat image analysis was 2 ± 6 mm³. The artifactual volume pulsations measured with the digital phantom simulations were of the same magnitude as the volume pulsations observed in the patient data, even after protocol optimization in Stage II.

CONCLUSIONS

Volume pulsation quantification with the current imaging protocol on 7T MR imaging is not accurate due to multiple imaging artifacts. Future studies should always include aneurysm-specific accuracy analysis.

Heritability of circle of Willis variations in families with intracranial aneurysms

Background

Intracranial aneurysms more often occur in the same arterial territory within families. Several aneurysm locations are associated with specific circle of Willis variations. We investigated whether the same circle of Willis variations are more likely to occur in first-degree relatives than in unrelated individuals.

Methods

We assessed four circle of Willis variations (classical, A1-asymmetry, incomplete posterior communicating artery and fetal circulation) in two independent groups of families with familial aneurysms and ≥2 first-degree relatives with circle of Willis imaging on MRA/CTA. In each (index) family we determined the proportion of first-degree relatives with the same circle of Willis variation as the proband and compared it to the proportion of first-degree relatives of a randomly selected unrelated (comparison) family who had the same circle of Willis variation as the index family’s proband. Concordance in index families and comparison families was compared with a conditional logistic events/trials model. The analysis was simulated 1001 times; we report the median concordances, odds ratios (ORs), and 95% confidence intervals (95%CI). The groups were analysed separately and together by meta-analysis.

Results

We found a higher overall concordance in circle of Willis configuration in index families than in comparison families (meta-analysis, 244 families: OR 2.2, 95%CI 1.6–3.0) mostly attributable to a higher concordance in incomplete posterior communicating artery (meta-analysis: OR 2.8, 95%CI 1.8–4.3). No association was found for the other three circle of Willis variations.

Conclusions

In two independent groups of families with familial aneurysms, the incomplete PcomA variation occurred more often within than between families suggesting heritability of this circle of Willis variation. Further studies should investigate genetic variants associated with circle of Willis formation.

Migraine prevalence in patients with unruptured intracranial aneurysms: A case-control study

OBJECTIVES

Migraine is a suggested risk factor for aneurysmal subarachnoid hemorrhage (aSAH). An increased risk of aSAH in migraineurs may be explained by an increased prevalence of unruptured intracranial aneurysms (UIA). We performed a case-control study to compare lifetime migraine prevalence in patients with UIA, patients with a history of transient ischemic attact (TIA) or ischemic stroke and controls without a history of aSAH, TIA or ischemic stroke.

MATERIALS AND METHODS

Patients with UIA were recruited from two university hospitals. Data on patients with TIA/stroke were retrieved from a previous study. Partners of patients with UIA or TIA/stroke were included as controls. Migraine history was assessed via a telephone interview based on the International Classification of Headache Disorders, second edition criteria. We calculated odds ratios (OR) for migraine with univariable and multivariable logistic regression analyses, adjusted for age, sex, hypertension and smoking.

RESULTS

We included 172 patients with UIA, 221 patients with TIA or stroke, and 164 controls. In UIA patients, migraine prevalence was 24.4% compared with 14.6% in controls (UIA vs. controls; OR 1.9; 95% confidence interval [CI] 1.1-3.5) and 22.2% in TIA/stroke patients (UIA vs. TIA/stroke; OR 1.1; 95% CI 0.7-1.8). After adjustments, the OR for migraine in UIA patients versus controls were 1.7 (95% CI 1.0-3.1) and 0.9 (95% CI 0.5-1.0) versus TIA/stroke. Results were comparable for migraine with and without aura.

CONCLUSIONS

Migraine prevalence is possibly increased in patients with UIA compared with controls and comparable with the prevalence in patients with TIA or stroke. Further studies are needed to confirm our findings and to investigate the underlying pathophysiology.

A strategy to expeditious invasive treatment improves clinical outcome in comatose patients with aneurysmal subarachnoid haemorrhage

BACKGROUND

In patients with poor clinical condition after aneurysmal subarachnoid haemorrhage (aSAH), treatment is often deferred until patients show signs of improvement. Early external ventricular drainage and aneurysm occlusion may improve prognosis also in poor grade patients. The clinical outcome of an expeditious approach was compared with that of a conservative approach.

METHODS

In all, 285 consecutive World Federation of Neurological Surgeons (WFNS) grade V aSAH patients admitted to three university hospitals between January 2000 and June 2007 were included. Two hospitals followed an expeditious approach, one a more conservative approach. Groups were compared with respect to demographic and clinical characteristics and outcome. Univariable and multivariable analyses were performed to determine the associations with good outcome (Glasgow Outcome Scale scores 4-5), using logistic regression models.

RESULTS

Good outcome was seen more often in expeditiously treated patients [22% vs. 11%; odds ratio (OR) 2.24, 95% confidence interval (CI) 1.17-4.27]. Expeditiously treated patients more often underwent aneurysm occlusion than conservatively treated patients (64% vs. 27%; OR 4.86, 95% CI 2.93-8.05) and placement of an external ventricular catheter (82% vs. 31%; OR 10.05, CI 5.72-10.66). There was no significant difference in rebleeding between patient groups. Occlusion of the aneurysm was the only variable that remained significant in the multivariable model with an OR of 43.73 (95% CI 10.34-184.97).

CONCLUSIONS

An expeditious invasive treatment strategy in WFNS grade V aSAH patients can lead to a better outcome. Hesitance in the early stages seems a self-fulfilling prophecy for a poor outcome.

Shared Genetic Risk Factors of Intracranial, Abdominal, and Thoracic Aneurysms

Background

Intracranial aneurysms (IAs), abdominal aortic aneurysms (AAAs), and thoracic aortic aneurysms (TAAs) all have a familial predisposition. Given that aneurysm types are known to co‐occur, we hypothesized that there may be shared genetic risk factors for IAs, AAAs, and TAAs.

Methods and Results

We performed a mega‐analysis of 1000 Genomes Project‐imputed genome‐wide association study (GWAS) data of 4 previously published aneurysm cohorts: 2 IA cohorts (in total 1516 cases, 4305 controls), 1 AAA cohort (818 cases, 3004 controls), and 1 TAA cohort (760 cases, 2212 controls), and observed associations of 4 known IA, AAA, and/or TAA risk loci (9p21, 18q11, 15q21, and 2q33) with consistent effect directions in all 4 cohorts. We calculated polygenic scores based on IA‐, AAA‐, and TAA‐associated SNPs and tested these scores for association to case‐control status in the other aneurysm cohorts; this revealed no shared polygenic effects. Similarly, linkage disequilibrium–score regression analyses did not show significant correlations between any pair of aneurysm subtypes. Last, we evaluated the evidence for 14 previously published aneurysm risk single‐nucleotide polymorphisms through collaboration in extended aneurysm cohorts, with a total of 6548 cases and 16 843 controls (IA) and 4391 cases and 37 904 controls (AAA), and found nominally significant associations for IA risk locus 18q11 near RBBP8 to AAA (odds ratio [OR]=1.11; P=4.1×10⁻⁵) and for TAA risk locus 15q21 near FBN1 to AAA (OR=1.07; P=1.1×10⁻³).

Conclusions

Although there was no evidence for polygenic overlap between IAs, AAAs, and TAAs, we found nominally significant effects of two established risk loci for IAs and TAAs in AAAs. These two loci will require further replication.

Thinner Regions of Intracranial Aneurysm Wall Correlate with Regions of Higher Wall Shear Stress: A 7T MRI Study

BACKGROUND AND PURPOSE

Both hemodynamics and aneurysm wall thickness are important parameters in aneurysm pathophysiology. Our aim was to develop a method for semi-quantitative wall thickness assessment on in vivo 7T MR images of intracranial aneurysms for studying the relation between apparent aneurysm wall thickness and wall shear stress.

MATERIALS AND METHODS

Wall thickness was analyzed in 11 unruptured aneurysms in 9 patients who underwent 7T MR imaging with a TSE-based vessel wall sequence (0.8-mm isotropic resolution). A custom analysis program determined the in vivo aneurysm wall intensities, which were normalized to the signal of nearby brain tissue and were used as measures of apparent wall thickness. Spatial wall thickness variation was determined as the interquartile range in apparent wall thickness (the middle 50% of the apparent wall thickness range). Wall shear stress was determined by using phase-contrast MR imaging (0.5-mm isotropic resolution). We performed visual and statistical comparisons (Pearson correlation) to study the relation between wall thickness and wall shear stress.

RESULTS

3D colored apparent wall thickness maps of the aneurysms showed spatial apparent wall thickness variation, which ranged from 0.07 to 0.53, with a mean variation of 0.22 (a variation of 1.0 roughly means a wall thickness variation of 1 voxel [0.8 mm]). In all aneurysms, apparent wall thickness was inversely related to wall shear stress (mean correlation coefficient, -0.35; P < .05).

CONCLUSIONS

A method was developed to measure the wall thickness semi-quantitatively, by using 7T MR imaging. An inverse correlation between wall shear stress and apparent wall thickness was determined. In future studies, this noninvasive method can be used to assess spatial wall thickness variation in relation to pathophysiologic processes such as aneurysm growth and rupture.

Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study

STUDY QUESTION

What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage?

METHODS

This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MRA was performed four to eight weeks later. DSA was performed when the CT angiography or MRI/MRA results were inconclusive or negative. The main outcome was a macrovascular cause, including arteriovenous malformation, aneurysm, dural arteriovenous fistula, and cavernoma. Three blinded neuroradiologists independently evaluated the images for macrovascular causes of haemorrhage. The reference standard was the best available evidence from all findings during one year's follow-up.

STUDY ANSWER AND LIMITATIONS

A macrovascular cause was identified in 69 patients (23%). 291 patients (98%) underwent CT angiography; 214 with a negative result underwent additional MRI/MRA and 97 with a negative result for both CT angiography and MRI/MRA underwent DSA. Early CT angiography detected 51 macrovascular causes (yield 17%, 95% confidence interval 13% to 22%). CT angiography with MRI/MRA identified two additional macrovascular causes (18%, 14% to 23%) and these modalities combined with DSA another 15 (23%, 18% to 28%). This last extensive strategy failed to detect a cavernoma, which was identified on MRI during follow-up (reference strategy). The positive predictive value of CT angiography was 72% (60% to 82%), of additional MRI/MRA was 35% (14% to 62%), and of additional DSA was 100% (75% to 100%). None of the patients experienced complications with CT angiography or MRI/MRA; 0.6% of patients who underwent DSA experienced permanent sequelae. Not all patients with negative CT angiography and MRI/MRA results underwent DSA. Although the previous probability of finding a macrovascular cause was lower in patients who did not undergo DSA, some small arteriovenous malformations or dural arteriovenous fistulas may have been missed.

WHAT THIS STUDY ADDS

CT angiography is an appropriate initial investigation to detect macrovascular causes of non-traumatic intracerebral haemorrhage, but accuracy is modest. Additional MRI/MRA may find cavernomas or alternative diagnoses, but DSA is needed to diagnose macrovascular causes undetected by CT angiography or MRI/MRA.

FUNDING, COMPETING INTERESTS, DATA SHARING

Dutch Heart Foundation and The Netherlands Organisation for Health Research and Development, ZonMw. The authors have no competing interests. Direct requests for additional data to the corresponding author.

Early Magnesium Treatment After Aneurysmal Subarachnoid Hemorrhage: Individual Patient Data Meta-Analysis

BACKGROUND AND PURPOSE

Delayed cerebral ischemia (DCI) is an important cause of poor outcome after aneurysmal subarachnoid hemorrhage (SAH). Trials of magnesium treatment starting <4 days after symptom onset found no effect on poor outcome or DCI in SAH. Earlier installment of treatment might be more effective, but individual trials had not enough power for such a subanalysis. We performed an individual patient data meta-analysis to study whether magnesium is effective when given within different time frames within 24 hours after the SAH.

METHODS

Patients were divided into categories according to the delay between symptom onset and start of the study medication: <6, 6 to 12, 12 to 24, and >24 hours. We calculated adjusted risk ratios with corresponding 95% confidence intervals for magnesium versus placebo treatment for poor outcome and DCI.

RESULTS

We included 5 trials totaling 1981 patients; 83 patients started treatment<6 hours. For poor outcome, the adjusted risk ratios of magnesium treatment for start <6 hours were 1.44 (95% confidence interval, 0.83-2.51); for 6 to 12 hours 1.03 (0.65-1.63), for 12 to 24 hours 0.84 (0.65-1.09), and for >24 hours 1.06 (0.87-1.31), and for DCI, <6 hours 1.76 (0.68-4.58), for 6 to 12 hours 2.09 (0.99-4.39), for 12 to 24 hours 0.80 (0.56-1.16), and for >24 hours 1.08 (0.88-1.32).

CONCLUSIONS

This meta-analysis suggests no beneficial effect of magnesium treatment on poor outcome or DCI when started early after SAH onset. Although the number of patients was small and a beneficial effect cannot be definitively excluded, we found no justification for a new trial with early magnesium treatment after SAH.

Hemodynamic Differences in Intracranial Aneurysms before and after Rupture

BACKGROUND AND PURPOSE

Rupture risk of intracranial aneurysms may depend on hemodynamic characteristics. This has been assessed by comparing hemodynamic data of ruptured and unruptured aneurysms. However, aneurysm geometry may change before, during, or just after rupture; this difference causes potential changes in hemodynamics. We assessed changes in hemodynamics in a series of intracranial aneurysms, by using 3D imaging before and after rupture.

MATERIALS AND METHODS

For 9 aneurysms in 9 patients, we used MRA, CTA, and 3D rotational angiography before and after rupture to generate geometric models of the aneurysm and perianeurysmal vasculature. Intra-aneurysmal hemodynamics were simulated by using computational fluid dynamics. Two neuroradiologists qualitatively assessed flow complexity, flow stability, inflow concentration, and flow impingement in consensus, by using flow-velocity streamlines and wall shear stress distributions.

RESULTS

Hemodynamics changed in 6 of the 9 aneurysms. The median time between imaging before and after rupture was 678 days (range, 14-1461 days) in these 6 cases, compared with 151 days (range, 34-183 days) in the 3 cases with unaltered hemodynamics. Changes were observed for flow complexity (n = 3), flow stability (n = 3), inflow concentration (n = 2), and region of flow impingement (n = 3). These changes were in all instances associated with aneurysm displacement due to rupture-related hematomas, growth, or newly formed lobulations.

CONCLUSIONS

Hemodynamic characteristics of intracranial aneurysms can be altered by geometric changes before, during, or just after rupture. Associations of hemodynamic characteristics with aneurysm rupture obtained from case-control studies comparing ruptured with unruptured aneurysms should therefore be interpreted with caution.

Additional Value of Intra-Aneurysmal Hemodynamics in Discriminating Ruptured versus Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Hemodynamics are thought to play an important role in the rupture of intracranial aneurysms. We tested whether hemodynamics, determined from computational fluid dynamics models, have additional value in discriminating ruptured and unruptured aneurysms. Such discriminative power could provide better prediction models for rupture.

MATERIALS AND METHODS

A cross-sectional study was performed on patients eligible for endovascular treatment, including 55 ruptured and 62 unruptured aneurysms. Association with rupture status was tested for location, aneurysm type, and 4 geometric and 10 hemodynamic parameters. Patient-specific spatiotemporal velocities measured with phase-contrast MR imaging were used as inflow conditions for computational fluid dynamics. To assess the additional value of hemodynamic parameters, we performed 1 univariate and 2 multivariate analyses: 1 traditional model including only location and geometry and 1 advanced model that included patient-specific hemodynamic parameters.

RESULTS

In the univariate analysis, high-risk locations (anterior cerebral arteries, posterior communicating artery, and posterior circulation), daughter sacs, unstable inflow jets, impingements at the aneurysm body, and unstable complex flow patterns were significantly present more often in ruptured aneurysms. In both multivariate analyses, only the high-risk location (OR, 3.92; 95% CI, 1.77-8.68) and the presence of daughter sacs (OR, 2.79; 95% CI, 1.25-6.25) remained as significant independent determinants.

CONCLUSIONS

In this study population of patients eligible for endovascular treatment, we found no independent additional value of aneurysmal hemodynamics in discriminating rupture status, despite high univariate associations. Only traditional parameters (high-risk location and the presence of daughter sacs) were independently associated with ruptured aneurysms.

Management of extracranial carotid artery aneurysm

INTRODUCTION

Aneurysms of the extracranial carotid artery (ECAA) are rare. Several treatments have been developed over the last 20 years, yet the preferred method to treat ECAA remains unknown. This paper is a review of all available literature on the risk of complications and long-term outcome after conservative or invasive treatment of patients with ECAA.

METHODS

Reports on ECAA treatment until July 2014 were searched in PubMed and Embase using the key words aneurysm, carotid, extracranial, and therapy.

RESULTS

A total of 281 articles were identified. Selected articles were case reports (n = 179) or case series (n = 102). Papers with fewer than 10 patients were excluded, resulting in the final selection of 39 articles covering a total of 1,239 patients. Treatment consisted of either conservative treatment in 11% of the cases or invasive treatment in 89% of the cases. Invasive treatment comprised surgery in 94%, endovascular approach in 5%, and a hybrid approach in 1% of the patients. The most common complication described after invasive therapy was cranial nerve damage, which occurred in 11.8% of patients after surgery. The 30 day mortality rate and stroke rate in conservatively treated patients was 4.67% and 6.67%, after surgery 1.91% and 5.16%. Information on confounders in the present study was incomplete. Therefore, adjustments to correct for confounding by indication could not be done.

CONCLUSIONS

This review summarizes the largest available series in the literature on ECAA management. The number of ECAAs reported in current literature is scarce. The early and long-term outcome of invasive treatment in ECAA is favorable; however, cranial nerve damage after surgery occurs frequently. Unfortunately, due to limitations in reporting of results and confounding by indication in the available literature, it was not possible to determine the optimal treatment strategy. There is a need for a multicenter international registry to reveal the optimal treatment for ECAA.

Evaluation of genetic risk loci for intracranial aneurysms in sporadic arteriovenous malformations of the brain

BACKGROUND

In genome-wide association studies (GWAS) five putative risk loci are associated with intracranial aneurysm. As brain arteriovenous malformations (AVM) and intracranial aneurysms are both intracranial vascular diseases and AVMs often have associated aneurysms, we investigated whether these loci are also associated with sporadic brain AVM.

METHODS

We included 506 patients (168 Dutch, 338 American) and 1548 controls, all Caucasians. Controls had been recruited as part of previous GWAS. Dutch patients were genotyped by KASPar assay and US patients by Affymetrix SNP 6.0 array. Associations in each cohort were tested by univariable logistic regression modelling, with subgroup analysis in 205 American cases with aneurysm data. Meta-analysis was performed by a Mantel-Haenszel fixed-effect method.

RESULTS

In the Dutch cohort none of the single nucleotide polymorphisms (SNPs) were associated with AVMs. In the American cohort, genotyped SNPs near SOX-17 (OR 0.74; 95% CI 0.56-0.98), RBBP8 (OR 0.76; 95% CI 0.62-0.94) and an imputed SNP near CDKN2B-AS1 (OR 0.79; 95% CI 0.64-0.98) were significantly associated with AVM. The association with SNPs near SOX-17 and CDKN2B-AS1 but not RBBP8 were strongest in patients with AVM with associated aneurysms. In the meta-analysis we found no significant associations between allele frequencies and AVM occurrence, but rs9298506, near SOX-17 approached statistical significance (OR 0.77; 95% CI 0.57-1.03, p=0.08).

CONCLUSIONS

Our meta-analysis of two Caucasian cohorts did not show an association between five aneurysm-associated loci and sporadic brain AVM. Possible involvement of SOX-17 and RBBP8, genes involved in cell cycle progression, deserves further investigation.

Yield of spinal imaging in nonaneurysmal, nonperimesencephalic subarachnoid hemorrhage

OBJECTIVE

We studied the yield of MRI of the spinal neuraxis in patients with nonperimesencephalic subarachnoid hemorrhage (NPSAH).

METHODS

In a prospective, multicenter study, we performed T1-weighted and T2-weighted MRI of the spinal axis in a consecutive series of patients with a spontaneous NPSAH without intracranial vascular pathology on intracranial vascular imaging.

RESULTS

A spinal origin of the hemorrhage was found in 3 of 75 patients (4%; 95% confidence interval 0-8.4). The lesions were 1 lumbar ependymoma and 2 cervical cavernous malformations. All 3 patients presented without focal neurologic deficits and 2 had a CT-negative subarachnoid hemorrhage but positive lumbar puncture. Patients with a spinal origin were younger than patients without a spinal origin (38 vs 56 years; p < 0.05), which was the only significant difference between groups.

CONCLUSIONS

The yield and clinical relevance of MRI of the spinal axis in patients who present with NPSAH is low. We do not recommend routine MRI of the spinal axis in this patient population, but it might be justified in a subgroup of patients.

Rupture-associated changes of cerebral aneurysm geometry: high-resolution 3D imaging before and after rupture

BACKGROUND AND PURPOSE

Comparisons of geometric data of ruptured and unruptured aneurysms may yield risk factors for rupture. Data on changes of geometric measures associated with rupture are, however, sparse, because patients with ruptured aneurysms rarely have undergone previous imaging of the intracranial vasculature. We had the opportunity to assess 3D geometric differences of aneurysms before and after rupture. The purpose of this study was to evaluate possible differences between prerupture and postrupture imaging of a ruptured intracranial aneurysm.

MATERIALS AND METHODS

Using high-quality 3D image data, we generated 3D geometric models before and after rupture and compared these for changes in aneurysm volume and displacement. A neuroradiologist qualitatively assessed aneurysm shape change, the presence of perianeurysmal hematoma, and subsequent mass effect exerted on aneurysm and parent vessels.

RESULTS

Aneurysm volume was larger in the postrupture imaging in 7 of 9 aneurysms, with a median increase of 38% and an average increase of 137%. Three aneurysms had new lobulations on postrupture imaging; 2 other aneurysms were displaced up to 5 mm and had changed in geometry due to perianeurysmal hematoma.

CONCLUSIONS

Geometric comparisons of aneurysms before and after rupture show a large volume increase, origination of lobulations, and displacement due to perianeurysmal hematoma. Geometric and hemodynamic comparison of series of unruptured and ruptured aneurysms in the search for rupture-risk-related factors should be interpreted with caution.

Genetic risk load according to the site of intracranial aneurysms

OBJECTIVE

We investigated whether risk alleles of single nucleotide polymorphisms associated with intracranial aneurysm (IA) are enriched in patients with familial IA, IA located at the middle cerebral artery (MCA), or IA rupture at a younger age.

METHODS

In this case-only study, we calculated genetic risk scores (GRS) for 973 Dutch and 718 Finnish patients with IA by summing effect size-weighted risk allele counts of 7 single nucleotide polymorphisms associated with IAs previously identified through genome-wide association studies. We tested the GRS for association with presence of familial IA or IA at the MCA using logistic regression, and with age at time of IA rupture using linear regression. We also calculated odds ratios with 95% confidence intervals for the proportion of patients with each characteristic in the highest compared with the lowest GRS tertile.

RESULTS

GRS were higher in IA at the MCA in the Dutch (p = 2.5 × 10(-4)), Finnish (p = 0.039), and combined cohort (p = 4.9 × 10(-5)). GRS were not associated with familial IA in the Dutch (p = 0.34), Finnish (p = 0.45), and combined cohort (p = 0.98), or with age at time of IA rupture in the Dutch (p = 0.28), Finnish (p = 0.86), and combined cohort (p = 0.45). In the combined cohort, odds ratios were 0.89 (0.67-1.20) for familial IA, 1.03 (0.79-1.34) for lower age, and 1.54 (1.20-1.98) for MCA aneurysms.

CONCLUSIONS

Our findings suggest that genetic risk factors have a larger role in the development of IA at the MCA than at other sites, and that genetic heterogeneity should be considered in future genetic studies.