billn, Dr. K used to say (and may still say, as my information is a couple of years old) that if the IVIG worked, some observable improvement was expected within the first 3 months. The improvement could take two forms: (A) the beginning of a gradual improvement in symptoms, or ( an almost sudden cessation of symptoms. In the case of (A), the time to full or nearly full recovery was not well-defined. I appreciate your suggestion regarding there being a mechanism similar to fever rather than lesions. The basal ganglia apparently increases in volume with PANDAS. I've seen literature describing the antibodies as "attacking" the basal ganglia and some that say the anitbodies "interfere." Someone may have a good resource, but I haven't read anything that specified exactly what the interaction of the antibodies was.
With Sydenham's chorea, there may be some damage to brain tissue that occurs, and it may linger after the antibodies have passed. But anecdotally, that doesn't seem like that's necessarily the same case for PANDAS. There are instances where a high dose steroid burst greatly alleviated symptoms in a very short (e.g., 48 hour) period, even after years of PANDAS. That doesn't suggest lesions, or at least, suggests they aren't main cause of symptoms.
