Lacunar Infarcts: Definition, Characteristics, and Clinical Implications
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. 1, 2, 3
Definition and Pathophysiology
- Lacunar infarcts result from occlusion of a single penetrating artery and account for approximately 25% of all ischemic strokes 4
- Unlike other stroke subtypes, lacunar infarcts are generally not caused by atherosclerosis but rather by a distinct arteriopathy of small vessels 3
- 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
- These infarcts represent a manifestation of cerebral small vessel disease affecting penetrating arteries deep in the brain 3
Clinical Presentation
- Patients typically present with one of the classical lacunar syndromes: 2, 3
- Pure motor hemiparesis
- Pure sensory syndrome
- Sensorimotor stroke
- Ataxic hemiparesis
- Dysarthria-clumsy hand syndrome
- Less frequently, patients may present with atypical lacunar syndromes 4
Diagnosis
- Diagnosis requires neuroimaging (CT or MRI) showing a small (<1.5 cm) subcortical infarct 2, 3
- Potential sources of cardioembolism and ipsilateral large-artery stenosis should be excluded to confirm the diagnosis 2, 3
- Modern imaging techniques have improved the ability to differentiate lacunar infarcts from other stroke subtypes 5
Risk Factors
- Hypertension is the strongest risk factor for lacunar infarcts with an odds ratio of 8.9 6
- Diabetes mellitus is another major risk factor (odds ratio 2.3) 4, 6
- Current smoking significantly increases risk (odds ratio 6.6) 6
- Regular physical exercise may be protective against lacunar infarcts (odds ratio 0.3) 6
Prognosis
- Lacunar infarcts show a paradoxical clinical course: 4
- Favorable short-term prognosis with low early mortality and reduced functional disability
- Increased risk of death, stroke recurrence, and dementia in the mid- and long-term
- Among stroke subtypes, patients with small-artery occlusion have the highest survival rate (85% at 2 years) compared to other stroke subtypes 1, 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 1
- Despite their initially favorable appearance, lacunar infarcts should be regarded as potentially severe conditions rather than benign disorders 4, 7
Management
- Standard acute stroke management protocols apply to lacunar infarcts 2
- Response to intravenous thrombolysis appears similar to other subtypes of ischemic strokes 7
- Secondary prevention is critical and includes: 4, 7
- Antiplatelet drugs
- Careful blood pressure control
- Statin therapy
- Modification of lifestyle risk factors
Clinical Pitfalls and Considerations
- Asymptomatic progression of small-vessel disease is a typical feature of lacunar infarcts 4
- Silent small vessel disease in the brain at the time of an index stroke has significant prognostic implications 7
- Up to one-third of apparent lacunar infarcts may have causes other than penetrating small vessel disease 7
- The presence of "silent" lacunar infarcts increases the risk of cognitive decline and dementia 8