Lacunar Infarcts: Etiology, Diagnosis, and Management

Introduction to Lacunar Infarcts

Lacunar infarcts are subcortical strokes measuring <1.5 cm in diameter caused primarily by small vessel disease affecting penetrating arteries deep in the brain or brain stem, rather than by atherosclerosis that affects other stroke subtypes 1
Patients typically present with one of the classical lacunar syndromes, including pure motor hemiparesis 1

Diagnosis requires neuroimaging (CT or MRI) showing a small (<1.5 cm) subcortical infarct 1
The term "lacunar infarct" should be reserved for cystic lesions smaller than 1 cm located in the basal ganglia, brain stem, or deep white matter 2
Potential sources of cardioembolism and ipsilateral large-artery stenosis should be excluded to confirm the diagnosis 1

Standard acute stroke management protocols apply 1
Among stroke subtypes, patients with small-artery occlusion have the highest survival rate (85% at 2 years) 1

Lacunar infarcts are subcortical strokes measuring <1.5 cm in diameter on CT or MRI without evidence of a concomitant cortical infarct, primarily caused by small vessel disease affecting penetrating arteries deep in the brain or brain stem 3

Among stroke subtypes, patients with small-artery occlusion have the highest survival rate (85% at 2 years) compared to other stroke subtypes 3
In the Oxfordshire Community Stroke Study, only 2 of 133 lacunar stroke patients died of cardiac causes within 30 days after stroke, compared with 6 of 209 patients with partial or total anterior circulation infarcts 4

The American Heart Association recommends excluding ipsilateral large-artery stenosis (>50% stenosis of relevant vessels) to classify infarcts as lacunar 5, 6
The American Stroke Association suggests confirming small vessel disease pattern rather than atherosclerotic or embolic mechanisms, and the presence of hypertension and absence of signs of small vessel disease decreases the likelihood of true lacunar infarcts 7

The American Heart Association states that short-term prognosis is favorable with the highest survival rate among stroke subtypes (85% at 2 years) and lowest 90-day mortality (3.3%) 5, 6
The American Stroke Association indicates that long-term prognosis is concerning, with increased risk of death, stroke recurrence, and development of dementia 5, 6

The American Stroke Association recommends aggressive blood pressure control as hypertension is the primary modifiable risk factor 8
The American Heart Association suggests statin therapy provides benefit across all ischemic stroke subtypes, including small-vessel disease (HR 0.85, 95% CI 0.64-1.12 in SPARCL trial) 9, 10
The American College of Cardiology indicates that the annual risk of MI and vascular death approaches 2% even after lacunar infarcts, though lower than other stroke subtypes 8, 11
The American Heart Association recommends cardiac evaluation may still be warranted despite the small-vessel etiology, as 23% of patients with penetrating artery disease had abnormal cardiac stress tests in one study 5, 6

The thalamus is a deep brain territory supplied by penetrating arterioles that are particularly vulnerable to hypertensive small vessel disease, with the underlying pathology being arteriolosclerosis (lipohyalinosis), characterized by concentric hyalinized vascular wall thickening of penetrating arterioles in deep territories, according to the American Heart Association 12

Diabetes mellitus is present in 44.4% of cases, and is a key risk factor for arteriolosclerosis, as stated by the American Diabetes Association 13
Age is also a risk factor for arteriolosclerosis, with the American Heart Association noting its significance in the development of small vessel disease 12

Lacunar infarcts are cystic lesions < 1 cm located in the basal ganglia, brainstem, or deep white‑matter regions (excluding the cerebral cortex) in patients with incidentally identified small vascular brain lesions. 14

All patients with incidentally discovered small vascular brain lesions should receive a transthoracic echocardiogram (TTE) to screen for structural heart disease and reduced left‑ventricular ejection fraction. 15

TEE is recommended for patients younger than 55 years who have cryptogenic small vascular brain lesions after completion of the initial work‑up. 15
TEE should be performed when the preceding TTE reveals abnormalities that require further characterization, such as valvular disease, atrial septal abnormalities, or suspicion of left‑atrial appendage thrombus. 15
TEE is indicated when the clinical history suggests a cardioembolic source (e.g., palpitations or known valvular disease) in the context of incidentally found small vascular brain lesions. 15

The defining characteristic of lacunar syndromes is the lack of cortical signs; patients do not exhibit aphasia (language dysfunction) despite acute stroke symptoms. 16

Vascular cognitive impairment develops in roughly 20 % of individuals after a first lacunar stroke and in more than one‑third of those who experience recurrent lacunar events. 16
White‑matter hyperintensities are present in almost all older adults who have hypertension and lacunar disease, although the severity of these imaging findings varies widely. 17
Silent lacunar infarcts are identified in 10 %–30 % of patients with lacunar pathology and contribute to progressive cognitive decline even though they produce no obvious acute neurological deficits. 17