Leslie, Your son sounds so much like ours! I was able to put it all together (as you read in the book) by studying his head circumference growth as compared to his body’s growth. My son’s symptoms, like your son’s, included behavioral problems and occurred at about 18 months of age (when the sutures of the skull normally close). Like your son, our son’s growth also stopped. It was scary as heck, as I’m sure you can relate! There are articles about how external communicating hydrocephalus can affect behavior. With his history of large head circumferences, is that enough for your doctor to perform an MRI? Likely not, but honestly, it is enough for me! 😉 Because so many of us do not have papilledema which most doctors think is necessary for high ICP, without papilledema, it is a tough sell. With our son, we trialed Diamox before his MRI (because my response was so dramatic and he was SO miserable). Then we sort of backed up and did an MRI. I wonder if your son is old enough to respond to your questions about the symptoms of high ICP? That may help… Keep up the quest, Leslie, because relieving that pressure, if it is high, is life-changing. It is just so hard to figure out if his pressure is still high… I understand that. Big hug,