livingwithdisability:

Resource pdf. Downloadable guide to help parents of children with severe intellectual and/or communication difficulties understand how pain may affect their child. 

It does so by explaining possible causes of pain in children with intellectual disability, presenting information about how pain may be shown by children who cannot tell us they are in pain and discussing the effects of untreated pain.

http://w3.cerebra.org.uk/help-and-information/guides-for-parents/pain-in-children-with-severe-intellectual-disability-a-guide-for-parents/