Tract-based lesion mapping of quiet-standing postural control phenotypes in patients with subacute stroke

Standing balance impairment after stroke is clinically important; however, patients with similar bedside balance scores may rely on different postural control strategies. We examined whether quiet-standing center-of-pressure (CoP) measurements can identify postural control phenotypes in subacute stroke and whether these phenotypes are associated with tract-level lesion patterns. Within 2 months of stroke onset, 75 patients underwent 30-s eyes-open posturography and magnetic resonance imaging (diffusion weighted imaging or fluid-attenuated inversion recovery) upon admission. Multivariate analysis of 52 CoP variables identified four clinically interpretable postural control components, and clustering of these components revealed three phenotypes: a high-frequency sway profile, a relatively low-frequency and spatially constrained profile, and a profile characterized by large medio-lateral (ML) sway. Clinical balance, trunk, motor, sensory, and walking scores did not differ across phenotypes, indicating that these groups were not captured by standard bedside scales. Tract-based lesion mapping using Lesion Quantification Toolkit-derived percentage damage values showed that the phenotype with larger ML sway had greater damage in an ascending sensory tract component mainly involving the Medial lemniscus and Spinothalamic tract. These findings suggest that posturography-based phenotyping can reveal clinically hidden heterogeneity in post-stroke standing balance and may help identify tract-level anatomical substrates relevant to targeted assessment and rehabilitation.