Stroke is a leading cause of death and long-term disability worldwide, yet medical science is still uncovering fundamental truths about how different types of stroke actually occur. A significant new study published in the journal Circulation is challenging decades of assumptions about the most common subtype of ischemic stroke — and the implications for prevention and treatment are substantial.
What Is a Lacunar Stroke?
Approximately 87% of all strokes are ischemic, meaning they result from reduced or blocked blood flow to the brain rather than bleeding. Of these, roughly 25% are classified as lacunar strokes — small strokes that occur deep within the brain’s white matter, affecting structures such as the thalamus, basal ganglia, and brainstem.
The term “lacunar” comes from the Latin word for “lake,” referring to the tiny fluid-filled cavities these strokes can leave behind in brain tissue. Unlike larger strokes that affect broad regions of the brain, lacunar strokes are typically smaller in scope, but they can still cause significant motor, sensory, and cognitive impairment — and they tend to recur.
Lacunar strokes are strongly linked to cerebral small vessel disease (cSVD), a condition involving progressive damage to the tiny blood vessels supplying the brain’s deep structures. cSVD is also associated with cognitive decline, white matter changes, depression, and an increased risk of dementia over time.
The Old Assumption: Blocked Arteries
For years, lacunar strokes were assumed to follow the same basic mechanism as larger ischemic strokes: a small artery in the brain narrows or becomes blocked, cutting off blood supply to a small area of tissue. This assumption shaped treatment protocols — the standard approach involves antiplatelet medications (such as aspirin or clopidogrel), blood pressure-lowering drugs, and cholesterol-reducing statins, all of which are designed to address arterial narrowing and clot formation.
But a growing body of evidence has suggested this model may be incomplete — or even incorrect for this particular stroke type.
What the New Research Found
A study led by Professor Joanna Wardlaw, CBE, Professor of Applied Neuroimaging at the University of Edinburgh, enrolled 229 stroke patients between 2018 and 2021 — 131 with lacunar strokes and 98 with mild non-lacunar ischemic strokes. Participants underwent clinical assessments and MRI brain scans at enrollment and again one year later.
The findings, published in Circulation, were striking: narrowing of large arteries was not associated with lacunar stroke or cSVD. Instead, researchers found a pattern pointing in the opposite direction — widening and elongation of the brain’s small arteries.
Patients with these widened, tortuous small brain arteries were four times more likely to have experienced a lacunar stroke than those without these changes. These arterial changes were also strongly linked to nearly every marker of cerebral small vessel disease measured in the study.
Perhaps most concerning: despite receiving standard preventive treatments, more than 25% of patients experienced silent strokes — small strokes that occur without obvious symptoms — within one year of follow-up. This suggests that current first-line therapies may not be adequately addressing the underlying mechanism driving disease progression.
Why This Distinction Matters
If lacunar strokes are driven by arterial widening and small vessel dysfunction — rather than blockages — then treatments designed primarily to prevent clotting or reduce arterial narrowing may be attacking the wrong target. This doesn’t mean current medications are useless, but research suggests they may be insufficient to halt the progression of cerebral small vessel disease on their own.
The mechanisms behind arterial widening in the brain are not yet fully understood, but researchers believe they may involve inflammation, disruption of the blood-brain barrier, and impaired vascular regulation — processes quite distinct from the atherosclerosis that drives most large-vessel strokes.
“Understanding the true mechanism behind lacunar strokes is critical to developing treatments that actually work for this patient group,” the Edinburgh research team noted in their analysis.
New Treatments Under Investigation: The LACI-3 Trial
Building on these mechanistic insights, researchers are now conducting the LACI-3 trial, which is testing two medications — cilostazol and isosorbide mononitrate — that may work through vascular pathways beyond simple clot prevention. The trial is recruiting approximately 1,300 patients across 38 centers in the United Kingdom.
Cilostazol is a phosphodiesterase inhibitor that improves blood flow and has anti-inflammatory properties. Isosorbide mononitrate is a nitric oxide donor that helps relax and dilate blood vessels. Both are thought to address aspects of vascular dysfunction that standard antiplatelet therapy does not target. Results from LACI-3 could significantly reshape stroke prevention guidelines for patients with small vessel disease.
Risk Factors for Cerebral Small Vessel Disease
While this research is reshaping scientific understanding, the known risk factors for cSVD and lacunar stroke remain consistent with those for cardiovascular disease broadly. Research suggests these factors play an important role:
- Hypertension: High blood pressure is among the strongest modifiable risk factors for small vessel disease. Studies indicate controlling blood pressure significantly reduces cSVD progression.
- Diabetes: Elevated blood glucose levels are associated with microvascular damage throughout the body, including the brain.
- Smoking: Tobacco use accelerates vascular injury and inflammation.
- Sedentary lifestyle: Regular physical activity is associated with better cerebrovascular health and reduced stroke risk.
- Diet quality: Evidence from observational studies links adherence to a Mediterranean-style diet — rich in vegetables, whole grains, fish, and olive oil — with reduced markers of cerebrovascular disease.
The Broader Picture: Silent Strokes and Cognitive Decline
One of the most sobering findings in the Edinburgh study was the high rate of silent strokes occurring even in patients already on treatment. Silent strokes do not cause obvious stroke symptoms, but over time, cumulative damage from multiple silent lacunar strokes is thought to contribute significantly to vascular dementia and cognitive impairment in older adults.
Experts recommend that individuals with known risk factors — particularly hypertension or diabetes — discuss comprehensive brain imaging with their healthcare provider, especially if they notice subtle changes in memory, walking, or mood. Early identification of white matter changes on MRI may help guide more aggressive risk factor management.
What This Means for Patients and Clinicians
The University of Edinburgh study underscores the importance of distinguishing between stroke subtypes rather than treating all ischemic strokes with a one-size-fits-all approach. For patients who have experienced a lacunar stroke, consulting with a specialist familiar with cerebral small vessel disease — and discussing participation in clinical trials such as LACI-3 — may be worth exploring.
For the general public, the core message remains: managing blood pressure, maintaining a healthy weight, staying physically active, and not smoking are among the most evidence-backed strategies for protecting brain vascular health. These lifestyle factors appear relevant regardless of the precise mechanism underlying any individual’s stroke risk.
As researchers continue to map the biology of small vessel disease, treatments tailored to its unique mechanisms may eventually offer patients with lacunar stroke a more targeted — and more effective — path to prevention.
Disclosure: This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before making changes to your health regimen.