Existence and Significance of Internal Border Zone Infarcts with Accessory Lesions Located in the Anteromedial Temporal Lobe

Objectives: To examine the existence and significance of internal border zone (IBZ) infarcts with accessory lesions in the anteromedial temporal lobe (ATL). Materials and methods: IBZ infarcts located at the corona radiata were selected based on diffusion-weighted imaging of 2535 consecutive patients with ischemic stroke and the presence of lesions in the ATL was identified. The Mann-Whitney U test, Student t-test, Pearson x(2) test, or Fisher exact test was used to analyze differences between the IBZ infarct groups with and without accessory lesions in the ATL. Results: Thirty-six of 2535 patients (1.4%) had IBZ infarcts. The IBZ group with accessory lesions in the ATL (17 cases, 47.2%) showed a higher portion of occluded middle cerebral arteries than the IBZ group without accessory lesions in the ATL (p = 0.02). The initial National Institutes of Health Stroke Scale score (odds ratio, 2.03; 95% confidence interval, 1.04-3.99; = 0.039) and progression after admission (odds ratio, 25.43; 95% confidence interval, 2.47-261.99; p = 0.007) were independently associated with poor prognosis in patients with IBZ infarcts. There were no differences in the progression rate and clinical outcomes, regardless of the presence of lesions in the ATL. Conclusions: Our study suggests the existence of a distinct type of IBZ infarct characterized by accessory lesions in the ATL, which is associated with different arterial features but has a similar clinical course to IBZ infarcts without accessory lesions in the ATL.