What are lacunar infarcts?

Lacunar Infarcts: Small Vessel Occlusions with Important Clinical Implications

Lacunar infarcts are small subcortical infarcts measuring less than 1.5 cm in diameter on CT or MRI, resulting from occlusion of a single penetrating artery and representing approximately 25% of all ischemic strokes. 1

Definition and Pathophysiology

Lacunar infarcts are characterized by:

• Small subcortical lesions measuring <1.5 cm in diameter on neuroimaging
• Caused by occlusion of a single penetrating artery supplying deep brain structures
• Most commonly affecting the basal ganglia, internal capsule, thalamus, corona radiata, and brainstem
• Primarily associated with cerebral small vessel disease 1, 2

The pathophysiological mechanisms include:

• Lipohyalinosis (degeneration of small vessel walls)
• Microatheroma formation at the origin of penetrating arteries
• Less commonly, embolic occlusion from cardiac or large artery sources 3

Risk Factors

The primary risk factors for lacunar infarcts are:

• Hypertension (most significant risk factor)
• Diabetes mellitus
• Advanced age
• Smoking
• Hyperlipidemia 2, 4

Clinical Presentation

Lacunar infarcts typically present with one of the classic "lacunar syndromes":

1. Pure motor hemiparesis (weakness affecting face, arm, and leg on one side)
2. Pure sensory syndrome (numbness/paresthesia on one side)
3. Sensorimotor stroke (combined motor and sensory deficits)
4. Ataxic hemiparesis (weakness with ipsilateral incoordination)
5. Dysarthria-clumsy hand syndrome 2, 5

Unlike cortical strokes, lacunar infarcts typically do not cause:

• Aphasia
• Neglect
• Visual field defects
• Other higher cortical dysfunctions

Diagnosis

Diagnosis of lacunar infarcts requires:

• Clinical presentation with a typical lacunar syndrome
• Neuroimaging (CT or MRI) showing a small (<1.5 cm) subcortical infarct or normal findings
• Exclusion of other potential causes of symptoms 1

MRI is more sensitive than CT for detecting small infarcts, particularly in the brainstem and posterior fossa.

Prognosis and Long-term Outcomes

Lacunar infarcts have a paradoxical clinical course:

• Short-term prognosis: Generally favorable with low early mortality and better functional outcomes at hospital discharge compared to other stroke subtypes 1
• Long-term prognosis: Less favorable with:
  • Risk of recurrent stroke similar to other ischemic stroke subtypes
  • Increased risk of cognitive decline and dementia
  • Increased long-term mortality, primarily from cardiovascular causes 4, 6

According to population studies, patients with small-artery occlusion have the highest survival rate (85% at 2 years) compared to other stroke subtypes, with cardioembolic stroke having the lowest survival rate (55%) 1.

Management and Secondary Prevention

Management of lacunar infarcts includes:

1. Acute treatment:

   • Intravenous thrombolysis if presenting within the treatment window
   • Response to thrombolysis appears similar to other ischemic stroke subtypes 4

2. Secondary prevention:

   • Antiplatelet therapy (first-line treatment)
   • Aggressive blood pressure control
   • Statin therapy
   • Diabetes management
   • Lifestyle modifications (smoking cessation, diet, exercise) 2, 4

Clinical Implications

Despite their small size, lacunar infarcts should not be considered benign:

• They represent manifestations of a progressive small vessel disease
• Silent progression of small vessel disease is common
• Cumulative burden of small vessel disease increases risk of cognitive impairment
• Patients require rigorous management and long-term follow-up 2, 7

Common Pitfalls in Management

1. Underestimating the long-term risks associated with lacunar infarcts
2. Inadequate blood pressure control after lacunar stroke
3. Failing to screen for and manage other vascular risk factors
4. Not recognizing the increased risk of cognitive decline and dementia
5. Overlooking the need for long-term follow-up and monitoring

Lacunar infarcts should be regarded as a potentially serious condition requiring comprehensive evaluation and aggressive management of vascular risk factors to prevent recurrent stroke, cognitive decline, and premature death.