Upper extremity spasticity means that the muscles in your arm are too tight, often due to conditions like a stroke or spinal injury. This study checks how well a device called the iovera° system works to help with this problem. The iovera° system uses a special needle to target nerves in your shoulder and elbow. Before using it, doctors will numb the area with a local anesthetic called lidocaine. Randomized means participants will be randomly chosen to either use the iovera° system or a pretend version called a sham treatment. Double-blind means neither you nor the person giving the treatment knows which one you get. The study will last about 13 weeks, with check-ups at 3, 7, and 13 weeks after treatment to see how well it works and if it's safe.

• The study lasts 13 weeks with three follow-up visits.
• Participants receive either real or sham treatment.
• The procedure uses local anesthetic and targets specific nerves.