PURPOSE: To assess the feasibility of Shear Wave Elastography (SWE) for quantifying upper limb spasticity in people after brain injury. METHODS: This observational study included 52 patients with upper limb spasticity after brain injury. Participants underwent a two-week rehabilitation treatment. The modified Ashworth scale (MAS), upper extremity section of the Fugl-Meyer motor scale (FMMS-UE), Barthel index (BI) and SWE were assessed before and after a two-week rehabilitation. The shear modulus was used to evaluate the stiffness of the biceps brachii at the transverse and longitudinal plane of 0°and 90°elbow flexion. RESULTS: In our study, paretic side shear modulus values were significantly larger than non-paretic sides (all p-values <
0.05), with significant reductions only on the paretic side (all p-values <
0.001) after 2-week rehabilitation treatment. At baseline, MAS and shear modulus had a significant positive correlation. After rehabilitation, only the longitudinal plane shear modulus showed a correlation with MAS. No significant correlations were found between shear modulus and FMMS-UE or BI scores, except for a negative correlation between shear modulus and BI at 0° transverse plane flexion. CONCLUSIONS: Our findings indicate that SWE effectively quantifies upper limb spasticity and can assess the impact of rehabilitation treatment.