Prevalence of Upper Extremity Distal Predominant Weakness Pattern in Chronic Stroke

Background: Hemiparesis after subcortical stroke is classically described as distal upper-extremity (UE) predominant, but prevalence data in chronic stroke is limited. Objective: Determine the prevalence of distal predominant UE weakness in exclusively subcortical chronic stroke versus other stroke distributions, characterize cohort differences, and describe UE weakness patterns in chronic stroke overall. Methods: Outpatient records were retrospectively reviewed to identify chronic stroke subjects. Lesion locations were classified from radiographic reports as exclusively subcortical or not (using a whole brain and supratentorial definition). UE weakness was categorized as distal predominant or not. Prevalence was compared with $\chi$-squared testing and odds ratios (OR). Results: 250 subjects were included (mean 861 days post-stroke). Using the whole-brain definition, distal predominant weakness occurred in 30.6% of exclusively subcortical versus 17.4% of non-exclusively subcortical strokes (OR 2.09, 95% CI 1.15-3.81; p=0.014). Using the supratentorial definition, distal predominant weakness occurred in 27.9% versus 17.9%, respectively (OR 2.16, 95% CI 1.17-3.96; p=0.012). Across all chronic strokes, 60% had no UE weakness; distal predominant weakness was the most common weakness pattern (23%), followed by uniform UE weakness (12%); proximal predominant weakness was rare (3%). Conclusions: Distal predominant UE weakness is more prevalent in chronic exclusively subcortical stroke than in non-subcortical stroke. These prevalence estimates may help predict long-term outcomes based on lesion location, support rehabilitation planning, and aid clinical lesion localization and research prioritization.