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

Background: Acute cerebral microinfarct (A-CMI) is presumed to be of ischemic origin and can be detected as small diffusion-weighted imaging (DWI) lesions in any parenchymal region of the brain (diameter<5 mm). Since the recent small subcortical infarcts (RSSI) not having a lower size cutoff according to their definition, whether the lesion with size compatible with A-CMI in subcortical area (As-CMI) has distinct clinical and imaging features are largely unknown. Methods: : Patients were selected with a magnetic resonance DWI-confirmed RSSI between January 2010 and November 2020 in a consecutive cohort. We measured axial infarct diameter and classified patients into two groups: As-CMI group (diameter<5mm) versus Larger RSSI group (diameter 5-20mm). 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: : A total of 23 (3.9%) were As-CMI in 584 patients with RSSI. 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 a lower percentage of dysarthria in As-CMI group ( p =0.008). In multivariate analysis, patients with As-CMI were independently associated with lacunes (presence of lacunes and multiple lacunes) (adjusted odds ratio [aOR] 2.88; 95% confidence interval [CI] 1.21-6.84 and 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 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.