Factors Influencing Upper-limb Spasticity in Post-stroke Patients during Convalescent Rehabilitation: A Single-center Retrospective Study.

Objectives: This study characterized the joint-specific time course of upper-limb spasticity to identify predictors of subsequent spasticity progression in post-stroke patients undergoing inpatient rehabilitation in a convalescent (Kaifukuki) rehabilitation ward (KRW). Methods: This single-center retrospective cohort study included 76 post-stroke patients with upper-limb paresis admitted to a KRW between January and December 2020. Spasticity of the elbow, wrist, and finger flexors was assessed monthly using the Modified Ashworth Scale (MAS) at 1-4 months after admission. Upper-limb motor function and neurological findings, including tendon reflexes, were evaluated at admission. Motor recovery was classified using the Brunnstrom recovery stage (BRS). Multivariate logistic regression analysis was used to identify factors associated with increased finger flexor spasticity (MAS ≥1+) at discharge. Results: Upper-limb spasticity increased 2 months after admission, with earlier increases observed in distal joints when compared with proximal joints. By discharge, approximately one-third of patients demonstrated increased spasticity. At 3 months after admission, increased spasticity was most frequent in patients with BRS3 (upper limb, 59%; hand/fingers, 84%). Multivariate analysis revealed that lower Fugl-Meyer Assessment scores of the upper extremity and greater tendon reflex hyperreflexia at admission were independently associated with increased finger flexor spasticity at discharge. Conclusions: Upper-limb spasticity tended to increase earlier in distal joints, particularly in the wrist and finger flexors, than in the proximal joint during subacute inpatient rehabilitation. Severe upper-limb paresis and tendon reflex hyperreflexia at admission may be risk factors for worsening finger spasticity.