Anterior Choroidal Artery Territory Infarction: Lesions Confined to versus beyond the Internal Capsule

<b><i>Background:</i></b> Studies investigating the clinical features and stroke mechanisms of anterior choroidal artery (AchA) infarction have reported inconsistent results. This may be partly due to different degrees of inclusion of patients with isolated posterior limb of the internal capsule (PLIC) lesions, which may be supplied by lenticulostriate arteries rather than AchA. The purpose of this study was to investigate clinical features and stroke mechanisms of AchA infarction, with particular attention to the above problem. <b><i>Methods:</i></b> We evaluated patients with AchA infarction assessed with diffusion-weighted imaging and magnetic resonance angiography, who were admitted to the Asan Medical Center from July 2001 to April 2011. Probable AchA (pAchA) infarction was diagnosed when the lesions were confined to the lower part of the PLIC, while definite AchA (dAchA) infarction was diagnosed when the lateral geniculate body, the uncus, or the cerebral peduncle were concomitantly involved. We assessed imaging findings, stroke mechanisms, and clinical features, and investigated the differences between patients with dAchA infarction and those with pAchA infarction. <b><i>Results:</i></b> We identified 127 patients with AchA infarction: 34 with dAchA infarctions, 90 with pAchA infarctions, and 3 without PLIC lesions. The most important stroke mechanism was small artery disease (SAD), followed by large artery disease (LAD). In patients with LAD, distal internal carotid artery (ICA) disease was a relatively important cause of stroke. The dAchA group, as compared with the pAchA group, was more frequently related to cardioembolism (12 vs. 2%, p = 0.03), distal ICA steno-occlusion (35 vs. 2%, p = 0.001), severe neurologic deficits (higher National Institute of Health Stroke Scale scores and more severe limb weakness), and less often associated with SAD (56 vs. 78%, p = 0.02). <b><i>Conclusion:</i></b> In general, SAD was the most important stroke mechanism for AchA infarction followed by LAD. However, dAchA infarction and pAchA infarction differ in that the former was more often associated with cardioembolism, distal ICA steno-occlusion, a worse clinical status and less often associated with SAD than the latter. The different proportion of patients with pure PLIC lesions included in previous studies may have led to inconsistent and confusing results, which should be considered to gain a proper understanding of AchA infarction.