In what types of patients has cryotherapy been shown to reduce spasticity?   Cryotherapy has been shown to reduce spasticity in hemiplegic patients and patients with multiple sclerosis.  Remember, patients with multiple sclerosis tend to have worse function when they over heat.   Referenced from Braddom's Physical Medicine and Rehabilitation

What is the theory of how heat therapy works?   The heat causes vasodilation leading to increased blood flow to the area and delivery of  nutrients.  In addition, this vasodilation causes venous structures to increase their ability to remove byproducts and waste from the area.   Referenced from Braddom Physical Medicine and Rehabilitation