Can someone sue for not receiving medical treatment while incarcerated?

Question Details:

My boyfriend was incarcerated from 05/08 until 11/09. During his incarceration he began having problems walking and stumbling. He saw the prison PA who scheduled him for tests including an MRI. He was transferred soon after that to another prison and saw the PA at that facility who told him there was nothing wrong with him and that it was all in his head; that was in 02/09. Since he has been home we have had an MRI done and he has been diagnosed with MS. He has significant permanent damage because he was basically denied medical treatment while in prison. Can he sue? Important Notice