Brain Artery Widening — Not Blockages — May Be the True Cause of Lacunar Strokes

Scientists Uncover a New Explanation for a Common Type of Stroke

Researchers may have finally cracked one of neurology's persistent mysteries — what actually triggers lacunar strokes, a form of stroke that strikes approximately 35,000 people in the UK every single year. The findings not only reshape our understanding of this condition but could also explain a longstanding puzzle: why widely used stroke medications so often fail these patients.

What Are Lacunar Strokes?

Lacunar strokes represent roughly one quarter of all strokes recorded across the United Kingdom. For years, medical professionals believed these events were triggered by fatty deposits clogging the brain's arteries — the same general mechanism behind many other stroke types. This assumption helped guide treatment decisions, including the use of aspirin and other anticoagulant medications.

However, a newly published study is challenging that foundational belief in a significant way.

The New Finding: Widening Arteries, Not Blocked Ones

Rather than arterial blockage, the research points to the enlargement and widening of blood vessels within the brain as the driving force behind lacunar strokes. The study, conducted by academics at the University of Edinburgh in collaboration with the UK Dementia Research Institute, examined 229 patients who had suffered either a lacunar stroke or a mild non-lacunar stroke.

The data revealed a striking pattern: patients with widening arteries were more than four times as likely to experience a lacunar stroke compared to those without this vascular characteristic. In contrast, the narrowing of large arteries — a hallmark of other stroke types — was notably absent in lacunar cases.

Why This Explains Treatment Failures

This discovery carries profound implications for how lacunar strokes are managed clinically. Anti-platelet drugs such as aspirin are a cornerstone of ischaemic stroke prevention, yet they have consistently shown limited effectiveness against lacunar strokes. The new research offers a compelling reason why.

Professor Joanna Wardlaw, a specialist in applied neuroimaging at the University of Edinburgh and group leader at the UK Dementia Research Institute, emphasized the importance of this distinction.

"This study provides strong evidence that lacunar stroke is not caused by fatty blockage of larger arteries, but by disease of the small vessels within the brain itself," she said. "Recognising this distinction is crucial, because it explains why conventional treatments like anti-platelet drugs are not as effective for this type of stroke and highlights the urgent need to develop new therapies that target the underlying microvascular damage."

A Call for Greater Investment in Stroke Research

The findings have been welcomed by patient advocacy organizations, who see them as a springboard for much-needed progress in stroke care. Maeva May, Director of Policy at the Stroke Association, praised the research for demonstrating how scientific inquiry can directly improve patient outcomes.

"There is still so much we don't know about stroke despite it being the leading cause of complex adult disability and the fourth leading cause of death in the UK," May noted. She stressed the importance of translating such discoveries into real-world treatments for the 240 stroke survivors who leave hospital every day across the country.

May also highlighted a critical funding gap, pointing out that stroke research receives less than 1% of total UK research funding — a figure she described as wholly inadequate given the condition's devastating impact. She called for stroke research to be elevated as a national priority, with clear pipelines connecting laboratory breakthroughs to frontline patient care.

What Comes Next?

While this study marks a significant step forward, researchers acknowledge that more work is needed to develop targeted therapies that address microvascular damage specifically. The hope is that by understanding the true biological mechanism behind lacunar strokes, scientists can design treatments that are far more effective than the current standard of care.

For the tens of thousands of people affected by lacunar strokes in the UK each year, that prospect represents a genuinely meaningful reason for optimism.