Augmentative and alternative communication (AAC) has been used by patients with acquired expressive communication disorders as an alternative to natural speech. The use of symbols to express pain, which is intangible, is challenging because designing a series of comprehensible symbols to represent personal experiences such as pain is not…

Background: Prader-Willi Syndrome (PWS) is a rare genetically determined neurodevelopmental disorder with a complex phenotype that changes with age. The rarity of the syndrome and the need to control for different variables such as genetic sub-type, age and gender limits clinical studies of sufficient size in any one country. A clinical research…