What Are Lacunar Infarcts in CADASIL? Symptoms Explained

When you read an MRI report that mentions lacunar infarcts, it is completely normal to feel alarmed and wonder, “Did I have a stroke without even knowing it?” The short answer is that a lacunar infarct is a tiny area of stroke damage deep within the brain ^[1]. In CADASIL, these small strokes often occur “silently” or “covertly,” meaning they happen without the dramatic, immediate symptoms many people associate with a stroke ^[2][3]. However, the accumulation of these tiny injuries over time, along with other small-vessel damage, can contribute substantially to gradual changes like brain fog and slowed processing ^[4][5].

What exactly is a Lacunar Infarct?

In CADASIL, a genetic mutation causes abnormal proteins to build up in the walls of the small blood vessels deep inside the brain ^[6]. This buildup thickens and stiffens the vessels.

When one of these tiny penetrating vessels becomes completely blocked, a small area of surrounding brain tissue loses its blood supply and dies. This tiny area of damage is a lacunar infarct (or a “lacune”) ^[6][1]. Because they occur in the subcortical areas (the deep structures) of the brain, they differ from strokes that affect the cortex (the outer surface of the brain) ^[7]. While a lacunar stroke is small, it can still cause lasting issues and should never be dismissed as harmless ^[6].

Seeing “lacunar infarcts” on an MRI confirms there has been prior damage to your small blood vessels, but the phrase alone does not mean you are having a new stroke right now ^[8][9]. Radiologists look at specific MRI sequences (like diffusion-weighted imaging) and compare the scan to older ones to determine if a lacune is “acute” (recent) or “chronic” (old).

The Reality of “Silent” Strokes

Many people with CADASIL discover chronic lacunar infarcts on a routine MRI without having any memory of a stroke event ^[5].

An infarct may go unrecognized for a few reasons. It might be very small, it might occur in an area of the brain that produces less obvious physical deficits, or it might cause subtle symptoms that you simply did not realize were a stroke ^[2][3].

However, they are not always completely silent. Sometimes they cause acute symptoms that can be either temporary (often called a transient ischemic attack, or TIA) or persistent. These symptoms can include:

• Sudden weakness or numbness in an arm, leg, or one side of the face
• A facial droop
• Slurred speech (dysarthria) or trouble understanding language
• Sudden severe imbalance, confusion, or vision changes ^[2][3]

Emergency Warning: If you experience any of these sudden symptoms, call your local emergency number (like 911) immediately—do not drive yourself. Note the time the symptoms started. Even if the symptoms resolve quickly, you still need urgent medical evaluation. Do not assume it is “just CADASIL” or a migraine aura.

The Connection to “Brain Fog” and Cognition

While a single covert lacunar infarct might not cause a noticeable immediate problem, the accumulation of these tiny injuries takes a toll on the brain’s networks ^[8].

In CADASIL, cognitive changes are driven by the overall burden of small-vessel damage, which includes not just lacunes, but also white matter changes and microbleeds ^[8][10]. This combined damage can contribute substantially to:

• Slower processing speed: Taking longer to think through problems or respond ^[10].
• Executive dysfunction: Struggling to multitask, plan, or stay organized ^[4].
• Fatigue: Feeling mentally exhausted after tasks.

These subtle changes can sometimes begin before a patient has ever experienced a recognized stroke ^[4][5]. However, it is important to know that not every instance of “brain fog” means you have had a new stroke. Fatigue, sleep problems, depression, anxiety, and medication side effects can all cause similar symptoms and are highly treatable. Neuropsychological testing—a detailed evaluation of your memory and thinking—can help map out exactly what is causing your cognitive symptoms ^[4].

What This Means for Your Care

You cannot undo the chronic lacunar infarcts that have already happened, but you can work with your neurologist to protect your vascular health.

In CADASIL, the brain’s blood vessels have poor hemodynamic reserve, meaning they struggle to adapt to sudden changes in blood flow ^[6][11]. Because of this, factors that drop blood pressure too low—such as severe dehydration, significant bleeding, or anemia—can potentially trigger an ischemic event ^[6][11].

However, management must be highly individualized. You should not independently change your blood pressure medications or fluid intake. Work with your neurologist to set safe, personalized targets for your blood pressure (ensuring it is neither too high nor too low) and to manage other vascular risk factors safely ^[6].