Clinical and magnetic resonance imaging features in acute ischemic stroke with early wallerian degeneration: a case-control study

Background: In advanced stages, Wallerian degeneration (WD) after cerebral infarction appears as an abnormality in the descending corticospinal tract on T2-weighted images. However, early WD in this region is detectable via diffusion-weighted imaging (DWI) within the first 14 days. We aimed to investigate the clinical and imaging characteristics of early WD using patient data. Methods: We retrospectively reviewed clinical characteristics and magnetic resonance imaging (MRI) features of 105 acute stroke cases. Early WD factors, including the time from symptom onset to MRI scan, Brunnstrom stage at admission and discharge, risk factors for ischemic stroke, classification per the Stop Stroke Study Trial of Org 10,172 in Acute Stroke Treatment classification, infarct location, responsible artery, and MRI slice number for small-artery disease, were evaluated. Data were analysed using Wilcoxon and chi-squared or Fisher’s exact tests. Additionally, changes in MRI signals were evaluated in specific early WD cases. Results: Early WD was identified in 22 (21%) patients, and 15 cases involved small-artery disease. The infarctions were located in the paraventricular corona radiata. Patients with early WD had significantly lower Brunnstrom stage scores at admission (p < 0.001) and discharge (p = 0.0012) than those without early WD. For small-artery disease, early WD cases showed a significantly higher MRI slice number than those without early WD (p < 0.001), with the lenticulostriate artery (LSA) identified as the responsible artery (p = 0.033). In the chronic phase, high DWI signals indicating early WD disappeared in all seven patients. Nine patients with early WD exhibited concurrent high signals on DWI and fluid-attenuated inversion recovery (FLAIR) in the descending corticospinal tract. Persistent high FLAIR signals detected in two patients with early WD with follow-up indicated irreversible changes. Conclusions: The degree of pyramidal tract damage and severity of paralysis are reliable indicators of early WD. Early WD may also occur in small-artery disease, with the main responsible artery being the LSA. DWI and FLAIR imaging can reflect the progression from early WD to chronic WD. © The Author(s) 2025.