Topographic Evaluation of Acute Isolated Unilateral Thalamic Infarctions on Diffusion-weighted Imaging

Abstract

The thalamus plays a major role in regulating arousal, consciousness, and activity. Distinct vascular distribution of the thalamus causes different syndromic presentations of thalamic nuclei infarctions. During the evaluation of acute thalamic infarction, it is important to determine the thalamic vascular zone that is affected. This study aimed to assess the topography of acute isolated unilateral thalamic infarction on diffusionweighted imaging, and to investigate the distribution of classic and variant type thalamic infarctions. Methods: The imaging database of the 336 consecutive patients with acute thalamic infarction admitted to the radiology department between January 2015 and February 2020 were retrospectively reviewed. Specifically, patients with acute isolated unilateral thalamic infarction were included. The most affected thalamic territory, variant/classical territory rates, and the comparison of age and gender were evaluated. Results: A total of 141 patients (classic territory group: 104, variant territory group: 37) were reviewed. The ratio of affected classic territory to variant territory was 2.8. Affected classic territories were inferolateral (n=68), anterior (n=25), paramedian (n=11), and posterior (n=0). Affected variant territories were posterolateral (n=18), central (n=13), and anteromedian (n=6). Comparing the patients in both groups, age, sex, and side were similar, p=0.435, p=0.71, and p=0.85, respectively. Relevant arteries did not have stenosis in 96.2% of patients, and no significant difference was observed between both groups, p=0.631. Conclusion: In isolated acute unilateral thalamic ischemia, the ratio of the affected variant to the classic territory was approximately 1/3. Therefore, during the radiologic evaluation of acute thalamic ischemia, a variant thalamic territory should be considered in the presence of infarction that does not fit the classic territory, in order to avoid clinical-radiological discrepancies.