SSDI in never "permanent". SS determines the likelihood of a person's condition improving and then send either a short or long form Continuing Disability Review. Usually they just send the short form. If the answers meet their satisfaction, then benefits continue and your doctors are never contacted.

If you are required to go through the long form CDR, it seems reasonable that complications from your original disease have made it difficult for you to consider returning to work--that's not uncommon.

I'm not sure if you've read this guide: http://nymakesworkpay.org/docs/Guide_CDR.pdf
but the advice does apply nationally. Read it carefully and ask any questions if you don't understand.

If there is a CHANCE you might be able to return to work, you can do so and still collect benefits during a Trial Work Period (which is 9 months) and if you're unable to manage, you still will collect SSDI. You MUST notify SS if you work any hours. You can work pt and make up to the SGA level which is $1070 per month for 2014, while still collecting SSDI. If you make near the max, expect that they will do a very thorough review to determine if you can make more than the SGA (Significant Gainful Activity) level and if so, they'll terminate your benefits.