Why is Aetna requesting an IME? How should I handle it?

AETNA approved my LTD Claim in 04/2013. I have had five lumbar fusions surgeries without much let up in the pain. In 11/2013, I was diagnosed with CRPS. There was never an issue with my claim until my case was assigned a new Claim Manager. She said the she had my file reviewed and was going to send me to an IME. I am confused because there were no additional medical records requested since the last review in 04/2014. I called the IME to confirm my appointment and they told me that AETNA has not provided them with any of my records, so I need to bring them all. My Orthopedic Surgeon has indicated a need for more surgery but is concerned about causing further issues with my CRPS. I undergo monthly peripheral nerve blocks in order to control my CRPS, and it is slowly getting better. I do want to return to work and my Doctors and I have talked about possibly working from home a couple of hours per day to see how it goes. However, they do not want to proceed in this direction until the CRPS is better controlled and I have the needed surgery. How can I prepare for this IME? Should I talked to the Doctor doing the IME about my desire to return to work and the conditions?