A portable biomedical device for post-stroke spasticity assessment: preliminary validation study

Purpose This preliminary validation study investigated the feasibility of a portable biomedical device equipped with force and motion sensors for objectively quantifying resistance to passive movement in individuals with chronic post-stroke hemiparesis. The study examined associations between device-derived measurements and clinical spasticity scores obtained using the Modified Ashworth Scale (MAS). Methods Twenty-one individuals with chronic post-stroke hemiparesis were evaluated. MAS grading and device-based measurements were performed simultaneously during the same passive stretch to ensure comparable biomechanical conditions. Synchronized resistance-force and angular-displacement data were recorded during assessments of the shoulder adductors, elbow flexors, and wrist flexors. Associations between device measurements and MAS scores were analyzed using Spearman's rank correlation. Results Strong positive correlations were observed between device-derived resistance measurements and MAS scores for the shoulder adductors (ρ = 0.79, p < 0.001) and elbow flexors (ρ = 0.80, p < 0.001). A moderate correlation was found for the wrist flexors (ρ = 0.47, p = 0.003). Conclusion The findings provide preliminary evidence of concurrent associations between quantitative resistance measurements and MAS scores, supporting the device's feasibility as an adjunct tool for objective biomechanical assessment of post-stroke spasticity. However, larger studies incorporating independent blinded examiners, repeated measurements, and formal reliability analyses are necessary to establish its measurement properties and clinical applicability.