Utility of Ultrasound Elastography to Evaluate Poststroke Spasticity and Therapeutic Efficacy: A Narrative Review

Poststroke spasticity (PSS) is a common complication that affects function and daily self-care. Conservative PSS treatments include traditional rehabilitation, botulinum toxin injection, and extracorporeal shock wave therapy. Currently, the Modified Ashworth Scale and Modified Tardieu Scale are widely used tools to clinically evaluate spasticity, but the best tool for PSS assessment remained controversial. Ultrasound elastography (UE), including shear wave and strain image as the emerging method to evaluate soft tissue elasticity, became popular in clinical applications. Spastic biceps and gastrocnemius muscles were reported to be significantly stiffer compared to nonparetic muscles or healthy control using shear wave or strain elastography. More studies investigated the utility, reliability, and validity of UE in patients with PSS, but the contemporary consensus for the utility of UE in the measurement and therapeutic follow-up of PSS remained lacking. Therefore, this narrative review aimed to appraise the literature on the shear wave and strain elastography on PSS and summarize the roles of UE in assessing the therapeutic efficacy of different PSS interventions.