The condition appears to be distinct entity from intracranial atherosclerotic stenosis, with implications for practice.
Intracranial arterial dolichoectasia (IADE) is a distinct entity, with a different risk factor profile and imaging phenotype from intracranial atherosclerotic stenosis (ICAS), according to an imaging study published online March 26, 2018, ahead of print in Stroke.
Yi-Cheng Zhu, MD, PhD (Peking Union Medical College Hospital, Beijing, China), a senior author of the study, explained to Neurovascular Exchange that intracranial arterial dolichoectasia “is associated with poor outcomes, such as increased risk of vascular morbidity and mortality.”
As such, “identifying risk factors for IADE can recognize high-risk patient,” he said via email, noting that the pathophysiologic mechanisms underlying the condition are still unclear. “Previously studies revealed conflicting results about the risk factors for IADE,” indicated Zhu. “Some studies suggested that atherosclerosis is an underlying etiology of dolichoectasia, whereas others did not find this association.”
The investigators assessed the presence of IADE based on basilar artery dolichoectasia (ie, diameter, height of bifurcation, and laterality of basilar artery) as well as dilation of the basilar artery and internal carotid artery (intracranial volume-adjusted diameter ≥ 2 SD) in 1,237 patients aged 57.2 ± 9.4 years who underwent MRI and MR angiography.
IAS, meanwhile, was defined as any degree of stenosis in at least 1 intracranial artery. The neuroimaging markers of cerebral small vessel disease, including lacunes, white matter hyperintensities, microbleeds, dilated perivascular spaces, and brain atrophy, were also evaluated.
Overall, 45/1,237 patients (3.6%) were found to have basilar arterial dolichoectasia, 67/1,142 (5.9%) had intracranial arterial dilation, and 194/1,237 (15.7%) had intracranial atherosclerotic stenosis. Older age, higher systolic blood pressure, diabetes mellitus, higher LDL cholesterol, and lower HDL cholesterol were all associated with the presence of intracranial atherosclerotic stenosis (P < 0.001). Of these factors, only older age was associated with intracranial arterial dolichoectasia.
Intracranial atherosclerotic stenosis was also associated with lacunes (OR 2.91; 95% CI 1.96-4.34), as well as increased white matter hyperintensities volume and brain atrophy (all P < 0.001).
Basilar arterial dolichoectasia was mainly associated with dilated perivascular spaces in the basal ganglia and, to a lesser extent, with lacunes and microbleeds.
Imaging Predictors of Basilar Arterial Dolichoectasia
|
|
OR (95% CI) |
P Value |
|
Dilated Perivascular Spaces in Basal Ganglia |
2.20 (1.20-4.02 |
0.01 |
|
Lacunes |
2.06 (1.01-4.24) |
0.05 |
|
Cerebral Microbleeds |
2.02 (0.96-4.27) |
0.07 |
The findings reveal that intracranial arterial dolichoectasia and intracranial atherosclerotic stenosis have different risk factor profiles, Zhu said, as well as different imaging phenotypes of cerebral small vessel disease.
“ICAS and IADE are related to different downstream arteriolar lesions,” he noted. “ICAS is associated with ischemic cerebral small vessel disease (lacunes, white matter hyperintensities, and brain atrophy), whereas IADE is mainly associated with dilated perivascular spaces. In clinical practice, patients with different intracranial large-vessel lesions may have different [outcomes].”
The next steps are to develop a standard definition of intracranial arterial dolichoectasia as well as a method of assessing it objectively, Zhu concluded.
Source:
Zhai FF, Yan S, Li ML, et al. Intracranial arterial dolichoectasia and stenosis: risk factors and relation to cerebral small vessel disease. Stroke. 2018;Epub ahead of print.
Disclosures:
Zhu reports no relevant conflicts of interest.