Longitudinal analysis of the recovery of trunk control and upper extremity following stroke: An individual growth curve approach.

Background and Purpose: Trunk control is thought to contribute to upper extremity function. It is unclear whether recovery of trunk control has an impact on the recovery of the upper extremity in people with stroke. This longitudinal study monitored the recovery of trunk control and upper extremity in the first 6 months following stroke. Methods: Forty-five participants with stroke were assessed monthly for 6 months following stroke. Trunk control was assessed using the Trunk Impairment Scale (TIS); upper extremity impairment and function were assessed with the Fugl-Meyer (FMA) and Streamlined Wolf Motor Function Test (SWMFT) respectively. The SWMFT included the performance time (SWMFT-Time) and functional ability scale (SWMFT-FAS). The individual growth curve modeling was used to analyze the longitudinal data. Results: The recovery curve of TIS, FMA, SWMFT-Time and SWMFT-FAS followed a quadratic trend, with the rate of recovery decreasing from the first to sixth month. As TIS score improved over time, FMA, SWMFT-Time and SWMFT-FAS improved in parallel with the TIS score. TIS at each time point was found to be a significant predictor of FMA, SWMFT-Time and SWMFT-FAS at 6 months post stroke. Conclusion: Our work has provided, for the first time, substantial evidence that the pattern of recovery of trunk control is similar to that of the recovery of upper extremity following stroke. In addition, this study provides evidence on which to design a prospective study to evaluate whether improvement in trunk control early post-stroke results in better long-term upper extremity function.