Lacunar Stroke May Not Be About Blocked Arteries
A new Circulation study suggests small vessel stroke may be linked more to abnormal artery widening than large artery plaque blockage.
A new study challenges the usual mental model of lacunar stroke. Researchers found that lacunar stroke and cerebral small vessel disease were not strongly linked to large artery narrowing from plaque.
Instead, they were strongly associated with abnormal widening, lengthening, and twisting of the basilar artery, a condition called dolichoectasia. This does not prove causation, but it may help explain why standard secondary stroke prevention does not always prevent recurrent lacunar stroke or cognitive decline in these patients.
Study Details
Lacunar stroke is a common type of ischemic stroke involving small, deep areas of the brain. It accounts for about 20% to 30% of ischemic strokes, and it is closely linked with cerebral small vessel disease. Traditionally, many clinicians have thought about ischemic stroke through the lens of blockage: plaque, narrowing, clotting, and downstream loss of blood flow.
This study asks whether that model fully explains lacunar stroke. The answer appears to be no. The researchers found little evidence that large artery stenosis was driving lacunar stroke. Instead, the stronger signal came from basilar artery dolichoectasia, meaning the artery was widened, elongated, or twisted.
The study was published online in Circulation on May 6, 2026.
Methodology
Researchers studied 229 patients with recent lacunar or mild nonlacunar ischemic stroke from the prospective Mild Stroke Study 3 cohort. Participants had clinical testing, cognitive assessment, and MRI imaging at baseline and during one year of follow-up.
About 57% of participants had lacunar stroke. About 21% had large artery stenosis, while 16% had basilar artery dolichoectasia. The team then examined whether artery narrowing or artery widening was more strongly linked with lacunar stroke, small vessel disease markers, new infarcts, and white matter injury progression.
The researchers also performed a systematic review and meta-analysis of 27 studies including more than 9500 patients with lacunar stroke, which supported the main finding that large artery stenosis showed little evidence of a causal relationship with lacunar infarction, while artery widening was more consistently linked with small vessel disease features.
Key Findings
Large artery stenosis was associated with lower odds of lacunar stroke compared with nonlacunar stroke, with an odds ratio of 0.49.
Large artery stenosis was not associated with cerebral small vessel disease markers or new infarcts in this analysis.
Basilar artery dolichoectasia was strongly associated with lacunar stroke, with an odds ratio of 4.67.
Basilar artery dolichoectasia was also linked with higher small vessel disease burden, new infarcts, and greater progression of white matter hyperintensities over one year.
The findings support the idea that lacunar stroke may often reflect intrinsic small vessel pathology rather than the same plaque-driven mechanism seen in many larger artery strokes.
Implications for Practice
For patients, the key message is not to stop current stroke prevention treatment. Blood pressure control, smoking cessation, diabetes management, cholesterol management, physical activity, and adherence to prescribed medications still matter. High blood pressure remains one of the most important treatable stroke risk factors.
But this research suggests that lacunar stroke may need a more specific treatment strategy. If the underlying disease process is more about small vessel dysfunction and abnormal vessel structure than large artery plaque blockage, then simply applying the same treatment logic used for other ischemic strokes may not be enough.
For clinicians, the study reinforces the need to distinguish lacunar stroke from other ischemic stroke subtypes. It also supports more interest in mechanism-specific trials. One example mentioned by the researchers is LACunar Intervention Trial-3, a phase 3 study testing isosorbide mononitrate and/or cilostazol in lacunar stroke patients in the UK.
A careful note: this is still association, not proof of causation. Doctor who were not part of the study, cautioned that artery widening may be a risk marker rather than a direct cause of lacunar infarcts. More work is needed to understand the mechanism.