Intracranial Vascular Calcification is Protective from Vasospasm after Aneurysmal Subarachnoid Hemorrhage

Intracranial artery calcification as an independent predictor of ischemic stroke: a systematic review and a meta-analysis

BACKGROUND AND PURPOSE

The association between intracranial artery calcification (IAC) and the risk of ischemic stroke occurrence or poor prognosis had not yet been fully understood. In this study, we conducted a meta-analysis of existing studies aimed to assess whether IAC can be used to predict future ischemic stroke and post-stroke mortality.

METHODS

Medline, Cochrane, Web of Science and Google Scholar databases were searched up to June 30, 2022. Studies were included if they reported risk ratio (RR) or odds ratios (OR) and corresponding 95% confidence intervals (CI) of stroke concerning the presence of IAC. Random or fixed effects model meta-analyses were performed. Meta-analysis was conducted by using Stata version 16.0.

RESULTS

Twelve studies involving 9346 participants were included. Compared with those without IAC, patients with IAC had a higher risk of stroke occurrence (adjusted OR 1.62, 95% CI 1.18-2.23, P = 0.001) and stroke recurrence (adjusted OR 1.77, 95% CI 1.25-2.51, P = 0.003). However, we did not find a significant correlation between IAC and post-stroke mortality (pooled OR 1.12, 95% CI 0.80-1.56, P = 0.504).

CONCLUSIONS

Our meta-analysis demonstrated that the presence of IAC was identified as an independent risk factor for ischemic stroke occurrence and recurrence but is not a predictor of post-stroke mortality.

Subarachnoid Hemorrhage from Ruptured Internal Carotid Artery Aneurysm: Association with Arterial Tortuosity

OBJECTIVE

Many researchers have found a correlation between tortuous arteries and development of aneurysms in cerebral arteries. We decided to determine whether tortuosity of the internal carotid artery can be related to its aneurysm rupture.

METHODS

We retrospectively analyzed the internal carotid artery anatomy of 149 patients with internal carotid artery aneurysms. For each patient, we calculated relative length (RL), sum of angle metrics (SOAM), triangular index (TI), product of angle distance (PAD), and inflection count metrics (ICM).

RESULTS

A total of 33 patients (22.15%) had subarachnoid hemorrhage. These patients had significantly lower SOAM (0.31 ± 0.17 vs. 0.42 ± 0.21; P < 0.01), TI (0.27 ± 0.09 vs. 0.31 ± 0.11; P = 0.03) and ICM (0.25 ± 0.11 vs. 0.31 ± 0.17; P = 0.04). In multivariate logistic regression analysis, higher SOAM (odds ratio, 0.780; 95% confidence interval, 0.619-0.961; P = 0.025) remained independently associated with lower risk of internal carotid artery aneurysm rupture. In addition, we found significant positive correlation of aneurysm dome size with SOAM (R = 0.224; P = 0.013) and PAD (0.269; P < 0.01). Our study also showed that age (R = 0.252; P = 0.036), Glasgow Coma Scale score (R = -0.706; P < 0.01), and TI (R = -0.249; P = 0.042) were independently correlated with modified Rankin Scale score on discharge.

CONCLUSIONS

Lower tortuosity might be a protective factor against internal carotid artery aneurysm rupture and poor outcome after subarachnoid hemorrhage. Higher tortuosity is correlated with internal carotid artery aneurysm growth.

Intracranial Arterial Calcifications: Potential Biomarkers of Stroke Risk and Outcome

Intracranial artery calcifications (IAC), a common and easily identifiable finding on computed tomorgraphy angiography (CTA), has gained recognition as a possible risk factor for ischemic stroke. While atherosclerosis of intracranial arteries is believed to be a mechanism that commonly contributes to ischemic stroke, and coronary artery calcification is well-established as a predictor of both myocardial infarction (MI) and ischemic stroke risk, IAC is not currently used as a prognostic tool for stroke risk or recurrence. This review examines the pathophysiology and prevalence of IAC, and current evidence suggesting that IAC may be a useful tool for prediction of stroke incidence, recurrence, and response to acute ischemic stroke therapy.

Histology-Verified Intracranial Artery Calcification and Its Clinical Relevance With Cerebrovascular Disease

Intracranial artery calcification (IAC) was regarded as a proxy for intracranial atherosclerosis (ICAS). IAC could be easily detected on routine computer tomography (CT), which was neglected by clinicians in the previous years. The evolution of advanced imaging technologies, especially vessel wall scanning using high resolution-magnetic resonance imaging (HR-MRI), has aroused the interest of researchers to further explore the characteristics and clinical impacts of IAC. Recent histological evidence acquired from the human cerebral artery specimens demonstrated that IAC could mainly involve two layers: the intima and the media. Accumulating evidence from histological and clinical imaging studies verified that intimal calcification is more associated with ICAS, while medial calcification, especially the internal elastic lamina, contributes to arterial stiffness rather than ICAS. Considering the highly improved abilities of novel imaging technologies in differentiating intimal and medial calcification within the large intracranial arteries, this review aimed to describe the histological and imaging features of two types of IAC, as well as the risk factors, the hemodynamic influences, and other clinical impacts of IAC occurring in intimal or media layers.

Impact of aneurysm morphology on aneurysmal subarachnoid hemorrhage severity, cerebral infarction and functional outcome

OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with high morbidity. The objective was to evaluate, whether specific morphological aneurysm characteristics could serve as predictive values for aSAH severity, disease-related complications and clinical outcome.

METHODS

A total of 453 aSAH patients (mean age: 54.9 ± 13.8 years, mean aneurysm size: 7.5 ± 3.6 mm) treated at a single center were retrospectively included. A morphometric analysis was performed based on angiographic image sets, determining aneurysm location, aneurysm size, neck width, aneurysm size ratios, aneurysm morphology and vessel size. The following outcome measures were defined: World Federation of Neurosurgical Societies (WFNS) grade 4 and 5, Fisher grade 4, vasospasm, cerebral infarction and unfavorable functional outcome.

RESULTS

Regarding morphology parameters, aneurysm neck width was an independent predictor for Fisher 4 hemorrhage (OR: 1.1, 95%CI: 1.0-1.3, p = 0.048), while dome width (OR: 0.92, 95%CI: 0.86-0.97, p = 0.005) and internal carotid artery location (OR: 2.1, 95%CI: 1.1-4.2, p = 0.028) predicted vasospasm. None of the analyzed morphological characteristics prognosticated functional outcome. Patient age (OR: 0.95, 95%CI: 0.93-0.96, p < 0.001), WFNS score (OR: 4.8, 95%CI: 2.9-8.0, p < 0.001), Fisher score (OR: 2.3, 95%CI: 1.4-3.7, p < 0.001) and cerebral infarction (OR: 4.5, 95%CI: 2.7-7.8, p < 0.001) were independently associated with unfavorable outcome.

CONCLUSIONS

The findings indicate a correlation between aneurysm morphology, Fisher grade and vasospasm. Further studies will be required to reveal an independent association of aneurysm morphology with cerebral infarction and functional outcome.

Computed tomography angiography findings predictive of post-intervention vasospasm in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

To evaluate the association of CT/CT angiography (CTA) findings and clinical characteristics with subsequent vasospasm in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS-

Consecutive presentation CTA head exams in patients with aSAH between January 2005 and June 2015 were retrospectively evaluated for intracranial arterial calcification, undulation and non-calcified stenosis. Additional variables including modified Fisher Scale (mFS), Glasgow Coma Scale (GCS) and neurological exam status were reviewed. Associations of CTA findings with the incidence of angiographic vasospasm were assessed with multivariate logistic regression models using the least absolute shrinkage and selection operator machine-learning algorithm. Model performance was summarized using c-index with bootstrap optimism-adjustment.

RESULTS

Intracranial arterial calcification, seen in 51.7% of 195 total patients, was protective against vasospasm (OR-0.6; 95% CI-0.52-0.67; p = 0.009), while arterial undulation (24%) was associated with subsequent vasospasm (OR-2.6; 95% CI-1.3-5.1; p = 0.007). Non-calcified intracranial arterial stenosis (5%) was associated with subsequent vasospasm, (OR-4.7; 95% CI-1.0-22.8; p = 0.054). Least absolute shrinkage and selection operator selected all three CTA findings as predictors in a multivariate model for vasospasm in addition to clinical factors, which demonstrated superior predictive performance (c-index-0.74; 95% CI-0.69-0.82) compared to a model based on mFS and clinical factors only (c-index-0.66; 95% CI-0.57-0.75; p = 0.010 for the difference).

CONCLUSION

Presentation CTA findings combined with clinical factors may better predict the development of vasospasm in patients with aSAH compared to current prognostic models alone.

ADVANCES IN KNOWLEDGE

The combination of initial CT/CTA and clinical findings better predict development of vasospasm after aSAH. This can lead to better markers for use in future clinical trials to develop vasospasm preventative treatments and potentially provide better targets for early aggressive treatment.

Intracranial Arterial Calcification: Prevalence, Risk Factors, and Consequences: JACC Review Topic of the Week

Intracranial large and small arterial calcifications are a common incidental finding on computed tomography imaging in the general population. Here we provide an overview of the published reports on prevalence of intracranial arterial calcifications on computed tomography imaging and histopathology in relation to risk factors and clinical outcomes. We performed a systematic search in Medline, with a search filter using synonyms for computed tomography scanning, (histo)pathology, different intracranial arterial beds, and calcification. We found that intracranial calcifications are a frequent finding in all arterial beds with the highest prevalence in the intracranial internal carotid artery. In general, prevalence increases with age. Longitudinal studies on calcification progression and intervention studies are warranted to investigate the possible causal role of calcification on clinical outcomes. This might open up new therapeutic directions in stroke and dementia prevention and the maintenance of the healthy brain.

Effect of Inflow Arterial Calcification on Arteriovenous Fistula Maturation

BACKGROUND

The aim of this study is to investigate the effect of preexisting calcification in the inflow artery on maturation and flow volume of an arteriovenous fistula (AVF).

METHODS

Patients who underwent AVF creation for hemodialysis were prospectively recruited between March and November 2017. On preoperative duplex ultrasound, calcification in the arterial media within 5 cm of the planned anastomosis area was assessed. Clinical maturation was defined as the successful use of the fistula for ≥75% of the dialysis sessions during a month within 6 months after surgery. Radiological maturation was defined as a venous diameter of ≥0.4 cm and a flow volume of ≥500 mL/min. Flow volumes of the inflow artery and the cephalic vein were measured at 6 and 12 weeks after AVF creation.

RESULTS

Eighteen patients with calcification and 29 patients without calcification were enrolled in this study. There was no significant difference in the clinical and radiological maturation between the groups. The flow volume of the inflow artery, measured at 6 weeks postoperatively, was significantly higher in the noncalcification group than in the calcification group (P = 0.042). The flow volume of the inflow artery in the noncalcification group was increased at 12 weeks postoperatively (P = 0.091). Flow volume of the vein was higher in the noncalcification group than in the calcification group, although it did not reach statistical significance.

CONCLUSIONS

In conclusions, preexisting arterial calcification did not adversely affect the AVF maturation. However, arterial calcification correlated with the flow volume of the inflow artery of AVF.

Thick Clot in the Inferior Limiting Sulcus on Computed Tomography Image as an Indicator of Sylvian Subpial Hematoma in Patients with Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

Sylvian subpial hematoma (SSH) is occasionally observed in aneurysm subarachnoid hemorrhage (aSAH) when accompanied with the thick clot in the inferior limiting sulcus (ILS). We aimed to determine whether the thickness of the clot in the ILS (TCILS) was an indicator of SSH.

METHODS

Data from 150 consecutive patients with aSAH were retrospectively analyzed. The relationship between TCILS on axial computed tomography (CT) image and intraoperatively confirmed SSH was reviewed. In patients without SSH, the average of the clot thickness in the bilateral ILS was used. The primary outcome was SSH.

RESULTS

The median TCILS of the SSH group (n = 18, 12%) was larger than that of the non-SSH group (n = 132, 88%) (21 vs. 2.1 mm, respectively; P < 0.001). The intraclass correlation coefficients for clot thickness in the right and left ILS between 2 observers were 0.97 (P < 0.001) and 0.85 (P < 0.001). The TCILS threshold of ≥6.0 mm was associated with SSH, with a sensitivity of 89% and specificity of 99%. The unadjusted and adjusted odds ratios of the SSH of clot thickness in the affected ILS ≥6 mm relative to clot thickness in the affected ILS <6 mm were 263 (95% confidence interval [CI], 46-5063) and 137 (95% CI, 19-3029), respectively.

CONCLUSIONS

The clot thickness in the ILS on CT image was easily measured and could be a marker of SSH. SSH assessment could be useful in helping us predict the clinical course in patients with aSAH.

Effects of Clot Removal by Meticulous Irrigation and Continuous Low-Dose Intravenous Nicardipine on Symptomatic Cerebral Vasospasm in Patients with Aneurysmal Subarachnoid Hemorrhage Treated by Clipping

BACKGROUND

Symptomatic cerebral vasospasm (SCV) is the second most common of morbidity and mortality in aneurysmal subarachnoid hemorrhage (aSAH) after rebleeding. Blood breakdown products are one of the leading causes of vasospasm. We hypothesized that meticulous subarachnoid clot removal in addition to continuous low-dose intravenous nicardipine (CLIN) could reduce the incidence of SCV.

METHODS

SCV was defined as new focal neurologic signs, consciousness deterioration, or both when the cause was believed to be ischemia attributable to vasospasm after other possible causes of worsening were excluded. Initial brain damage was defined as continued consciousness disturbance after clipping without acute hydrocephalus, ischemic lesions, or focal sign before clipping. Poor outcome was defined as a Glasgow Outcome Scale score of 3-5 at 30 days. We compared the variables for 460 aSAH patients with and without SCV, and with and without poor outcome by multivariate analysis.

RESULTS

All patients underwent clipping with meticulous irrigation for clot removal, and SCV was observed in 56 patients (12%). SCV was observed in 2 patients (2.9%) among 70 patients treated with CLIN. There was a higher proportion of patients who were older than 65 years (P = 0.032) and female (P = 0.038), and a lower proportion of patients with CLIN (P = 0.026) among patients with SCV. The outcomes for 109 patients (27%) were poor; age greater than 65 years (P < 0.0001) and initial brain damage (P = 0.008) were related to the poor outcomes.

CONCLUSIONS

The present study showed that meticulous irrigation for clot removal and CLIN might reduce the incidence of SCV in patients with aSAH.