Cerebral Microbleeds and Dilative Remodeling of the Basilar Artery: A Magnetic Resonance Imaging Study

Vertebrobasilar dolichoectasia in patients with cerebrovascular ischemic stroke: does it have a role in cerebral microbleeds?

Background

Vertebrobasilar dolichoectasia (VBD) may account for cerebral microbleeds (CMBs) in ischemic cerebrovascular stroke.

Objectives

To examine whether VBD is associated with the involvement of CMBs in any region and, if so, whether it is associated with CMBs among ischemic stroke patients located in posterior circulation territory. For patients with VBD, we also studied ischemic stroke subtypes, and checked whether dolichoectasia was linked to vascular risk factors.

Methods

Two hundred ischemic stroke patients in whom detailed clinical data and brain MRI sequences were obtained, and stroke subtyping with TOAST classification (Trial of ORG 10172 in Acute Stroke Treatment) was performed.

Results

The mean age of patients was (65.22 ± 12.88), male patients were more frequent (67.5%); dyslipidemia was the most frequent risk factor (55%). Cardio-embolic stroke subtype was the most frequent (37%) and (71.5%) of patients had no history of previous use of antithrombotic drugs. Ectasia was found in 28 (14%), dolichosis was found in 50 (25%) and vertebrobasilar dolichoectasia was found in 19 (9.5%) of patients. Cerebral microbleeds were detected in 114 (57%) patients. Mild degree CMBs was the most prevalent among patients 69 (61%) and were located predominantly in both anterior and posterior territories 41 (36%). CMBs were significantly more frequent in hypertensive and older patients.

Conclusions

In patients with VBD, severe degree CMBs were more common and were located as a vascular territory supplied by vessels originating from dolichoectatic parent vessels in the posterior region.

A 9-Year Longitudinal Study of Basilar Artery Diameter

Background Dilatation of the basilar artery ( BA ) has been recognized as a predictor of cardiovascular events ( CVE s). However, it is unclear if the longitudinal change in BA diameter (Δ BA ) is associated with CVE s. Methods and Results In a cohort of Japanese participants with vascular risk factors in an observational study, we evaluated the relationship of Δ BA to CVE s and the time course of the BA diameter. The short axis of the BA diameter was measured at the midpons level in T2-weighted images. Brain magnetic resonance imaging measurements included cerebral small-vessel disease, lacunars, and white matter hyperintensities. First, 493 patients were analyzed by the time-dependent Cox proportional hazards model to evaluate the association between Δ BA and CVE s, with adjustment for age, sex, vascular risk factors, and magnetic resonance imaging parameters. Second, we assessed the longitudinal Δ BA in 164 patients who underwent long-term follow-up magnetic resonance imaging, by linear regression analysis. In the mean follow-up of 8.7 years, 105 patients developed CVE s. A smaller Δ BA was independently associated with the high incidence of CVE s (hazard ratio, 0.36; 95% CI, 0.16-0.78; P=0.010; n=493). After a mean interval of 9.4 years, the average Δ BA was 0.41±0.46 mm (excluding patients with fetal-type circle of Willis). Progression of BA dilatation was associated with men but inversely associated with initial BA diameter and fetal-type circle of Willis (n=164). Conclusions BA diameter increased over time (excluding the patients with fetal-type circle of Willis), whereas Δ BA was inversely associated with the incidence of CVE s.

Association between Intracranial Arterial Dolichoectasia and Cerebral Small Vessel Disease and Its Underlying Mechanisms

Intracranial arterial dolichoectasia (IADE), also known as dilatative arteriopathy of the brain vessels, refers to an increase in the length and diameter of at least one intracranial artery, and accounts for approximately 12% of all patients with stroke. However, the association of IADE with stroke is usually unclear. Cerebral small vessel disease (CSVD) is characterized by pathological changes in the small vessels. Clinically, patients with CSVD can be asymptomatic or present with stroke or cognitive decline. In the past 20 years, a series of studies have strongly promoted an understanding of the association between IADE and CSVD from clinical and pathological perspectives. It has been proposed that IADE and CSVD may be attributed to abnormal vascular remodeling driven by an abnormal matrix metalloproteinase/tissue inhibitor of metalloproteinase pathway. Also, IAD-Erelated hemodynamic changes may result in initiation or progression of CSVD. Additionally, genetic factors are implicated in the pathogenesis of IADE and CSVD. Patients with Fabry’s disease and late-onset Pompe’s disease are prone to developing concomitant IADE and CSVD, and patients with collagen IV alpha 1 or 2 gene (COL4A1/COL4A2) and forkhead box C1 (FOXC1) variants present with IADE and CSVD. Race, strain, familial status, and vascular risk factors may be involved in the pathogenesis of IADE and CSVD. As well, experiments in mice have pointed to genetic strain as a predisposing factor for IADE and CSVD. However, there have been few direct genetic studies aimed towards determining the association between IADE and CSVD. In the future, more clinical and basic research studies are needed to elucidate the causal relationship between IADE and CSVD and the related molecular and genetic mechanisms.

Anatomical distribution of cerebral microbleeds and intracerebral hemorrhage in vertebrobasilar dolichoectasia

OBJECTIVES

Vertebrobasilar dolichoectasia (VBD) is a dilatative arteriopathy associated with intracerebral hemorrhage. In the present study, we sought to evaluate the frequency and anatomical distribution of cerebral microbleeds (cMBs) and intracerebral hemorrhage (ICH) in VBD.

METHODS

From a MRI database 94 VBD patients were identified and analyzed with special emphasis on cMBs and ICH on T2*-weighted gradient echo images (GRE) in relation to the established diagnostic MRI criteria of VBD (diameter, height, and lateral position). cMBs/ICH location was categorized into anterior/posterior circulation. Clinical information like demographic details, clinical symptoms, and comorbidities were abstracted from the case records. An extensive modelling approach using generalized linear mixed-effects models was used.

RESULTS

Overall, 79 (84.0%) patients (mean age 72.1±10.0 years, 74.7% male) with a standard stroke MRI protocol including T2*-weighted images were included in the analysis. cMBs were observed in 38/79 (48.1%) patients, ranging from 1 to 84 cMBs per patient. In the posterior circulation cMBs were observed more frequently (34/38 (89.5%)) in comparison to the anterior circulation (24/38 (63.2%)). cMBs were observed in the thalamus in 20/38 (52.6%), hippocampus in 1/38 (2.6%), occipital lobe in 18/38 (47.4%), pons in 6/38 (15.8%), medulla oblongata in 2/38 (5.2%), and cerebellum in 14/38 (36.8%) patients. ICH was observed in only 6/79 (7.6%) patients. There were significantly more cMBs in the posterior- (NCMBs-PC = 1.717, 95%CI: 1.336-2.208, p = 0.0315) than in the anterior circulation. Logistic regression model showed a significant positive effect of clinical symptoms such as ischemic, TIA and hemorrhagic stroke on the presence of cMBs (OR = 3.34, 95%CI [2.0-5.57], p = 0.0184; ndf = 78, AIC = 107.51). General linear model showed that clinical symptoms have a highly significant effect on the number of cMBs (N = 2.78, 95%CI [2.51-3.07], p<2*10-16; ndf = 78, AIC = 1218).

CONCLUSION

cMBs and ICH may be observed in the anterior and posterior circulation in VBD but they occur more frequently in the posterior circulation. Most common anatomical locations of cMBs in VBD were the thalamus, occipital lobe and cerebellum. This posterior dominance of cMBs and ICH in VBD might reflect a specific underlying vascular pathology.

Dolichoectasia and Small Vessel Disease in Young Patients With Transient Ischemic Attack and Stroke

BACKGROUND AND PURPOSE

We evaluated whether basilar dolichoectasia is associated with markers of cerebral small vessel disease in younger transient ischemic attack and ischemic stroke patients.

METHODS

We used data from the SIFAP1 study (Stroke in Young Fabry Patients), a large prospective, hospital-based, screening study for Fabry disease in young (<55 years) transient ischemic attack/stroke patients in whom detailed clinical data and brain MRI were obtained, and stroke subtyping with TOAST classification (Trial of ORG 10172 in Acute Stroke Treatment) was performed.

RESULTS

Dolichoectasia was found in 508 of 3850 (13.2%) of patients. Dolichoectasia was associated with older age (odds ratio per decade, 1.26; 95% confidence interval, 1.09-1.44), male sex (odds ratio, 1.96; 95% confidence interval, 1.59-2.42), and hypertension (odds ratio, 1.39; 95% confidence interval, 1.13-1.70). Dolichoectasia was more common in patients with small infarctions (33.9% versus 29.8% for acute lesions, P=0.065; 29.1% versus 16.5% for old lesions, P<0.001), infarct location in the brain stem (12.4% versus 6.9%, P<0.001), and in white matter (27.8% versus 21.1%, P=0.001). Microbleeds (16.3% versus 4.7%, P=0.001), higher grades of white matter hyperintensities (P<0.001), and small vessel disease subtype (18.1% versus 12.4%, overall P for differences in TOAST (P=0.018) were more often present in patients with dolichoectasia.

CONCLUSIONS

Dolichoectasia is associated with imaging markers of small vessel disease and brain stem localization of acute and old infarcts in younger patients with transient ischemic attack and ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00414583.

Deep white matter hyperintensities, decreased serum low-density lipoprotein, and dilative large arteriopathy

Deep white matter hyperintensities (DWMHs) seen on magnetic resonance imaging (MRI) are thought to reflect small-vessel diseases (SVDs) and may have a background that differs from that of stenotic large-vessel diseases. We assessed risk factors for DWMHs and investigated the association between DWMHs and dilative changes in the basilar artery (BA) on MRI in nonstroke patients. We reviewed clinical information and MRI findings for 149 outpatients aged 46-90 years, excluding those with a previous symptomatic cerebrovascular event. DWMHs were graded 0-3, and the maximal BA diameter and area were measured from the flow void on axial T2-weighted MRI to assess dilatation. We divided the patients into groups with and without DWMH grade 2 or 3, and compared clinical information and BA parameters in these groups. The two groups demonstrated significant differences in age, serum low-density lipoprotein (LDL) level, estimated glomerular filtration rate (eGFR), and BA parameters. An adjusted logistic regression analysis including BA diameter found that age (odds ratio [OR], 1.974 per 10 years; 95% confidence interval [CI], 1.030-1.112; P = .0006), LDL (OR, 0.811 per 10 mg/dL; 95% CI, 0.964-0.965; P = .0085), eGFR (OR, 0.835 per 10 mL/min/1.73 m(2); 95% CI, 0.967-0.998; P = .0229), and BA diameter (OR, 2.515 per 1 mm; 95% CI, 1.191-4.098; P = .0119) were independently associated with the presence of DWMHs. An analysis including the BA area yielded similar results. DWMHs are manifestations of SVDs and show a strong association with lower serum LDL level, lower eGFR, and BA dilatation.