Peripheral Modulation of Muscle Stiffness and Spasticity

Inclusion Criteria: * Ischemic or hemorrhagic stroke 4-180 months prior * Moderately-severe muscle stiffness * Lack of full passive and active range of motion in at least 2/4 areas (shoulder, elbow, forearm, wrist) in the hemiparetic upper limb; * Willingness to have MRI, complete all clinical assessments, and comply with study protocols; * Ability to give informed consent and HIPPA certifications; and Exclusion Criteria: * treatment of spasticity with Botulinum toxin or intrathecal baclofen within the past six months, phenol injections within the past 12 months, or ongoing adjustment of anti-spastic medications; * other neurologic condition that may affect motor response (e.g., Parkinson's disease, amyotrophic lateral sclerosis (ALS), MS); * clinically significant cognitive dysfunction with score \<19 on Folstein's Mini Mental Status Examination or depression with score \>10 on the Patient Health Questionnaire-9 (PHQ-9); * pregnancy; * known hypersensitivity to hyaluronidase; * claustrophobia; * standard contraindications for MRI * Any condition that will preclude the patient from completing the protocol as determined by the PI