Clinical features and imaging markers of small vessel disease in symptomatic acute subcortical cerebral microinfarcts

BACKGROUND: As currently defined, recent small subcortical infarcts (RSSI) do not have a lower size boundary, and the smallest diffusion-weighted imaging (DWI) infarcts, which we term acute subcortical cerebral microinfarcts (As-CMI) with lesion diameter less than 5 mm, might have clinical implications distinct from RSSI. We aimed to investigate the distinct characteristics of As-CMI as compared to the larger size of RSSI regarding vascular risk factors, clinical manifestation, radiological markers of SVD distribution, and outcomes. METHODS: In a consecutive cohort, patients were selected with a magnetic resonance DWI-confirmed RSSI between January 2010 and November 2020. We measured axial infarct diameter and classified patients into two groups: The As-CMI group (diameter < 5 mm) versus the Larger RSSI group (diameter 5-20 mm). Clinical variables, including vascular risk factors, clinical symptoms/signs, lesion locations, and radiological markers of cerebral small vessel disease (SVD) on MRI were analyzed between the two groups. Patients were followed up for 12 months and functional outcomes were measured by the modified ranking scale (mRS). RESULTS: In a total of 584 patients with RSSI, 23 (3.9%) were defined as As-CMI. The most common neurological deficits with As-CMI were hemiparalysis (n = 20), followed by central facial/lingual palsy (n = 10) and hemidysesthesia (n = 10). Most As-CMIs were located in the basal ganglia (n = 11), followed by the thalamus (n = 5) and centrum semiovale (n = 4). No different regional distributions and symptoms/signs frequencies were found between the two groups except for a lower percentage of dysarthria in the As-CMI group (p = 0.008). In a multivariate analysis, patients with As-CMI were independently associated with the presence of lacunes (adjusted odds ratio [aOR] 2.88; 95% confidence interval [CI] 1.21–6.84), multiple lacunes (aOR 3.5, CI 1.29–9.48) and higher total SVD burden (aOR 1.68, CI 1.11–2.53). Patients with As-CMI did not show a better functional outcome after 12 months of follow-up. CONCLUSIONS: Patients with As-CMI had a non-specific clinical profile but a higher burden of SVD, indicating As-CMI might be s sign of more severe small vascular injury. Whether its vascular features are associated with worse cognitive outcomes requires further investigation.