Early Phase Functional Recovery after Spinal Intramedullary Tumor Resection Could Predict Ambulatory Capacity at 1 Year after Surgery

This is a single-center retrospective cohort study with a university hospital setting. This study aims to evaluate the short-term course of physical function and walking ability after intramedullary spinal cord tumor (ISCT) resection and predict walking independence 1 year after surgery. Although several reports have shown the postoperative functional prognosis of spinal intramedullary tumors with long-term follow-up, no reports have identified the predictors associated with the functional outcome at an early stage. A total of 79 individuals who underwent ISCT resection at our institute between 2014 and 2019 were enrolled in the study, whose preoperative walking state was independent ambulator regardless of cane support with the Functional Independence Measure Locomotor Scale (FIM-L) score of ≥6. The FIM-L, the American Spinal Injury Association (ASIA) motor and sensory scores in the lower extremities, and the Walking Index for Spinal Cord Injury II (WISCI II) were assessed for walking independence, lower-limb function, and walking ability, respectively. These evaluations were performed at 4 time points: preoperatively, 1 week (1W), 2 weeks (2W), and 1 year after surgery. In the early phase after surgery, 71% and 43% of the participants were nonindependent ambulators at 1W and 2W, respectively. Histopathology indicated that patients with solid tumors (ependymoma, astrocytoma, or lipoma) showed significantly lower indices at 1W and 2W than those with vascular tumors (hemangioblastoma or cavernous hemangioma). Regarding tumor location, thoracic cases exhibited poorer lower-limb function at 1W and 2W and poorer walking ability at 2W than cervical cases. According to the receiver operating characteristic (ROC) analysis, 2 WISCI II points at 2W had the highest sensitivity (100%) and specificity (92.2%) in predicting the level of walking independence at 1 year postoperatively (the area under the ROC curve was 0.99 (95% confidence interval, 0.93-1.00). The higher the lower-limb function scores in the early phase, the better the improvement in walking ability is predicted 1 year after ISCT resection.