Seven-day Accelerometer-derived Wrist Activity after Acute Stroke Stratified by Hemiparesis Severity: A Prospective Observational Pilot Study.

Objectives: This hypothesis-driven prospective pilot study characterized 7-day trajectories of bilateral wrist activity after acute stroke by baseline Fugl-Meyer Assessment-Upper Extremity (FMA-UE) severity. We hypothesized that mild impairment would be associated with greater paretic-side activity and more symmetric activity, whereas bilateral balance would change little despite clinical improvement. Methods: Patients who began rehabilitation within 3 days after stroke wore bilateral wrist accelerometers for 7 days. Exploratory strata were mild (FMA-UE >45) and severe (≤45), based on an inflection point of 45.3 reported for subacute stroke. Daily vector magnitude (VM) and magnitude ratio [MR = log Results: Of 32 enrolled patients, 24 completed monitoring (mild impairment, n = 16; severe impairment, n = 8). At day 1, the severe group had lower paretic VM [β = -468,257 counts/day; 95% confidence interval (CI) -826,564 to -109,949; P = 0.010] and MR (β = -0.348; 95% CI -0.515 to -0.181; P <0.001) than the mild group. In the mild reference group, day coefficients were positive for non-paretic VM (β = 46,589; P <0.001) and paretic VM (β = 34,801; P = 0.002). Group-by-day interactions were nonsignificant, and MR showed no significant day effect. FMA-UE and Action Research Arm Test scores increased in both groups. Conclusions: Wrist activity and bilateral balance differed by baseline severity. MR showed no significant temporal change despite improved clinical motor scores. Bilateral wrist accelerometry may complement clinical assessment but reflects overall wrist acceleration rather than purposeful upper-limb use.