Infarct Laterality Patterns in Relation to A1 Segment Hypoplasia/Aplasia According to Etiological Subtype

Area of Science:

• Neurology
• Vascular Neurology
• Neuroimaging

Background:

• The Circle of Willis (CoW) is crucial for collateral cerebral circulation.
• Anatomical variations, specifically A1 segment hypoplasia or aplasia, can impact cerebral hemodynamics.
• The role of these variations in cerebral infarction distribution is debated.

Purpose of the Study:

• To investigate the association between A1 segment hypoplasia/aplasia and infarct laterality.
• To analyze this association across different etiological stroke subtypes: lacunar, cardioembolic stroke (CES), and embolic stroke of undetermined source (ESUS).

Main Methods:

• Retrospective analysis of 198 patients with unilateral anterior circulation infarction.
• Assessment of the Circle of Willis using magnetic resonance angiography (MRA).
• Definition of A1 hypoplasia (<1 mm diameter) and aplasia (non-visualization); identification of minor (affected) and dominant (contralateral) sides.

Main Results:

• 30% of patients exhibited A1 hypoplasia or aplasia, with similar prevalence across lacunar, ESUS, and CES subtypes.
• Infarcts occurred on the A1 dominant side in 53% (lacunar), 55% (ESUS), and 75% (CES) of cases.
• The observed differences in infarct laterality did not reach statistical significance (p=0.43), likely due to limited sample size.

Conclusions:

• Prevalence of A1 segment hypoplasia/aplasia was consistent across studied stroke types.
• No statistically significant association was found between A1 variations and infarct laterality.
• Findings are inconclusive due to sample size limitations, suggesting the need for further hypothesis-generating research.