According to Diseases of Poultry, transient paralysis syndrome in one form of Mareks chickens show signs of imbalance and paralysis of the neck or limbs for only 1-2 days, followed by a complete recovery. Then a few weeks later, they can die from Mareks lymphoma tumors. Here is the book online with excerpts to read:Is it fairly common for a bird to recover from paralysis? My PR could not use her legs at all but is now walking, jumping, running, etc and appears to be fine other than the tumor that is now growing on her face (I can try and get a pic of that this afternoon). Most of the stories I've read on here, the paralysis seems to be more long-lasting than hers. So perhaps hers was something else, although the tumor makes me think otherwise.
https://books.google.com/books?id=MVAbAAAAQBAJ&q=mareks+disease#v=snippet&q=mareks disease&f=false