Longitudinal motor recovery trajectories in brainstem glioma associated with preoperative DTI-based corticospinal tract involvement patterns.

PURPOSE: Despite the high risk of postoperative motor dysfunction from corticospinal tract (CST) involvement, no preoperative system integrates CST-tumor interactions to stratify the prognosis in brainstem gliomas (BSGs).

METHODS

We enrolled 180 BSG patients who underwent craniotomy between 2020 and 2023. Preoperative DTI tractography classified CST-tumor relationships as displacement, infiltration, and traverse types. Clinical, pathological, and follow-up data (KPS, mRS, MRC, OS) were systematically collected at predefined intervals. Longitudinal outcomes were analyzed using linear mixed-effects models; survival was assessed by Kaplan-Meier.

RESULTS

The cohort comprised 51 displacement (28.3%), 83 infiltration (46.1%), and 46 traverse (25.6%) cases, with excellent inter-rater reliability (κ = 0.93). Tumor biology, CST fractional anisotropy (FA), and preoperative functional status demonstrated clear gradients across subtypes. The traverse type was predominantly high-grade (97.8%), exhibited the lowest FA (0.424 ± 0.055), and had the poorest preoperative KPS/mRS (all P < 0.001). Conversely, the displacement type was mostly low-grade (74.5%), showed the highest FA (0.45 ± 0.038), and had superior functional status; infiltration was intermediate. FA correlated positively with preoperative muscle strength (ρ = 0.238, P = 0.001). Longitudinal trajectories differed significantly (P_FDR < 0.05): displacement patients recovered rapidly, traverse patients showed minimal recovery with late decline, and infiltration was intermediate. Median OS was not reached for displacement, versus 15.3 months for infiltration and 12.0 months for traverse; all pairwise comparisons were significant.

CONCLUSION

This DTI-based CST-tumor classification system effectively stratifies BSG patients preoperatively and is associated with distinct recovery trajectories, providing a hypothesis-generating framework for surgical planning.