Clinical and magnetic resonance imaging characteristics of cerebral watershed infarction

Abstract

Background: Watershed infarction is a distinct subtype of ischemic stroke occurring in the border zones between the terminal vascular territories of major cerebral arteries. Aim: To investigate the clinical and magnetic resonance imaging (MRI) features of watershed infarction. Materials and Methods: This hospital-based prospective cohort study included 200 patients with acute ischemic stroke admitted to the Stroke Unit of the Third State Central Hospital between July 2025 and July 2026. Patients were classified into WI (n=53) and non-watershed infarction (NWI, n=147) groups based on diffusion-weighted imaging (DWI) and cerebral arterial territories. WI was further classified into cortical, internal, and combined subtypes, and their anatomical and morphological features were evaluated on DWI. Stroke etiology was classified using the TOAST criteria and neurological severity using the National Institutes of Health Stroke Scale (NIHSS). Statistical analyses were performed using Stata 14.2 (p<0.05). Results: Of 200 patients, 53 (26.5%) had WI and 147 (73.5%) had NWI. Mean NIHSS scores were lower in the WI than NWI group at admission (4.75±3.32 vs 9.71±5.08) and discharge (2.53±2.73 vs 6.90±4.93; both p<0.001). Among patients with WI, 40 (75.5%) had cortical, 7 (13.2%) internal, and 6 (11.3%) combined WI. Mean NIHSS scores for cortical, internal, and combined WI were 3.30±1.92, 10.14±2.34, and 8.17±2.79 at admission and 1.33±1.14, 7.43±2.57, and 4.83±2.79 at discharge, respectively (both p<0.001). On DWI, the MCA–PCA watershed territory was the most frequent location of cortical WI (47.5%), and 77.5% had a wedge-shaped component. Confluent distribution was observed in 57.1% of internal WI, while cigar-shaped morphology was present in 61.5% of cases with an internal watershed component. Etiology differed among WI subtypes (p=0.030), with all internal WI cases attributed to large-artery atherosclerosis. Conclusion: Watershed infarction subtypes differed in clinical severity and etiological distribution, while MRI demonstrated distinct anatomical, distributional, and morphological characteristics of cortical and internal watershed infarctions.