To date, clinical tests are unable to differentiate between the cause of muscle stiffness, although a manual instrumented spasticity assessment for the lower limb that utilizes surface electromyogram has recently been proposed. This study intends to use shear wave elastography to assess individual muscle stiffness parameters and the individual response to botulinum toxin injection in the elbow and wrist flexors. Collection of baseline spasticity parameters could then be used to predict the effect of botulinum toxin type A and ultimately serve as a basis for development of a treatment model for muscle spasticity in patients with spastic cerebral palsy.

Inclusion Criteria:

• Patients with unilateral spastic cerebral palsy with presence of dynamic muscle spasticity in the elbow and/or wrist flexors, who will be able to provide consent.
• Consent may be obtained from a parent or legal guardian, as applicable.

Exclusion Criteria:

• Prior surgical procedure in the affected upper extremity
• Unrelated orthopedic injury to the affected upper extremity
• Current oral or intrathecal antispasticity therapy
• Prior Botulinum toxin type A injection in preceding 6 months

Patients with unilateral spastic CP with presence of dynamic muscle spasticity in the elbow and/or wrist flexors, who will be able to provide consent. Consent may be obtained from a parent or legal guardian, as applicable.