Deepak Gulati, MD
I would like to start by sharing a case recently presented to our hospital. A young woman presented with small midbrain stroke and is found to have eccentric subocclusive clot in top of basilar artery with dolichoectasia of the long segment involving from left V4 segment to bilateral posterior cerebral arteries and fusiform aneurysm of basilar artery. Unfortunately, she developed diffuse subarachnoid hemorrhage on day 3 of hospital course involving basal cisterns, leading ultimately to withdrawal of care by family. This case raised curiosity and frustration at the same time due to the lack of information on the natural course, prognosis, prevention and treatment of dolichoectasia. Hence, I chose to write this blog on this article with a focus on dolichoectasia.
Intracranial arterial dolichoectasia (IADE) is an arteriopathy characterized by abnormal elongation, tortuosity, and dilation of the cerebral arteries. IADE is present in about 12% of patients with stroke and affects the basilar artery in 80% of cases. IADE has various clinical presentations, ranging from asymptomatic to symptomatic with cranial nerve or brainstem compression, brain infarction, or intracranial haemorrhage. IADE has received little attention compared with other large vessel arteriopathies, such as intracranial atherosclerosis (ICAS). ICAS involves lipid infiltration and an inflammatory process of the arterial wall intima, whereas IADE involves rarefaction of the elastic tissue of the tunica media and fragmentation of the internal elastic lamina. This study aimed to investigate the risk factors of IADE and ICAS and explore the association of these two with different neuroimaging phenotypes of cerebral small vessel disease (CSVD), i.e. multilacunes, leukoaraiosis and état criblé.
This study is a cross-sectional analysis of an ongoing community-based cohort study in China. This study performed the final analysis on 1237 inhabitants aged 35 and above who underwent MRI brain. Diameters of basilar artery and bilateral ICA and basilar artery dolichoectasia were assessed on time-of-flight MRA (TOF-MRA) to evaluate IADE.
The prevalence of IADE is found to be lower in this study as compared to prior stroke studies and could be due to the absence of standard definition and higher prevalence of IADE in patients with stroke. 3.6% of participants had BADE, and 5.9% had BA or ICA dilation. The prevalence of ICAS in at least one artery was 15.7%. Participants with arterial dilation or BADE were older, while participants with ICAS, on average, had heavier burden of vascular risk factors. Overall, ICAS and IADE are found to have different vascular risk factor profiles in this study and also correlated with different neuroimaging markers of cerebral small vessel disease. ICAS was associated with lacunes, severe WMH (white matter hyperintensity) and brain atrophy, whereas IADE was mainly associated with PVS (perivascular space) dilation and, to a lesser extent, with lacunes and microbleeds.
There are several limitations of this study, including the cross-sectional analysis design, inability of MRA to delineate arterial wall, the selected population with higher prevalence of ICAS, and no information on the Circle of Willis. Further studies with uniform definition based on non-invasive and cost-effective diagnostic tests and involving different populations are needed to elucidate the clinical significance of this vasculopathy. There also appears to be a need for a randomized control trial to address the management issues in patients with IADE.