Hi,
What constitutes "acute onset" or "overnight onset" occasionally gets brought up on these forums.
We know not ALL pandas kids have an overnight onset (or the onset is mistaken for the "terrible twos" etc). Per Dr. Latimer (IOCDF conf 2012): "Acute onset kids are easiest ones to diagnose."
And parents have wondered what constitutes "acute onset"? Does it truly have to be "overnight"? or can it be something that evolves over weeks/months?
Here is an interesting case study(1998, Swedo) on young girl with PANDAS. Her "overnight onset" actually evolved over a course of 2 mo. (started with hypersensitivity to clothing)....evolved to tics a few weeks later, then obsessions/compulsions a few days after that.
http://journals.psychiatryonline.org/article.aspx?Volume=155&page=1592&journalID=13
So, it seems that "evolving over 2 mo." would still be considered "acute onset"...