The Science of Pain--a podcast from Scientic America, with a transcript at the link.

The beginning of the podcast talks about empathy with pain, and I cannot imagine how disturbing it must have been to participate in the study that he ran.

After that he talks about pain as a disease, and the nature of chronic pain. Apparently it might not just be the drugs that make us stupid, but neural changes in response to pain that just don't get undone. They're still researching if they are permanent.