Association of Corticospinal Tract Asymmetry With Ambulatory Ability After Intracerebral Hemorrhage

Background: Ambulatory ability after intracerebral hemorrhage (ICH) is important to patients. We tested whether asymmetry between ipsi- and contra-lesional corticospinal tracts (CSTs) assessed by diffusion tensor imaging (DTI) is associated with post-ICH ambulation. Methods: Patients with spontaneous supratentorial ICH were recruited from 8 US sites between 2017 and 2024. For each patient, fractional anisotropy (FA) asymmetry index (AI) was computed for the whole CST and on a subset of fibers restricted to the cerebral peduncle (CP). Clinical and radiographic features were collected. The primary outcome was Barthel Index Mobility Score (BIMS) at 3 months (dichotomized outcome [DO]: BIMS 15 = good [independent ambulation]; BIMS < 15 = poor [non-independent ambulation]; ordinal outcome [OO]: BIMS 0, 5, 10, 15). Two imputation-based multiple logistic regression analyses accounted for whether ICH prevented tracking of CSTs. Odds ratios (ORs) were reported for a change of 0.1 and 95% confidence intervals (CIs). Results: At 3 months, 124 patients were eligible for inclusion. In addition to known clinical variables, CST and CP FA AI were associated with poor BIMS (OR 2.97, CI 1.12–7.90, p = 0.029; OR 3.80, CI 1.63–8.84, p = 0.002). In Model 1, unresolved FA (FA zero) was not correlated with lower BIMS (DO: OR 3.25, CI 0.62–17.07, p = 0.163; ordinal outcomes: OR 2.02, CI 0.48–8.55, p = 0.341). In Model 2, the combination of CST FA AI and FA zero correlated with lower BIMS (DO: joint p-value =0.041; OO: p = 0.030). CP FA asymmetry was associated with lower BIMS (DO: OR 3.96, CI 1.25–12.55, p = 0.019; OO: OR 3.39, CI 1.24–9.27, p = 0.017). Conclusion: DTI-assessed CST integrity may be an additional tool physicians can utilize to guide post-ICH ambulatory expectations.