Sorry, this might be long, but....
At 4 mos. I switched pediatricians and the dr. asked me if my son had always had a big head (which he had). It was in the 95th percentile and he mentioned hydrocephalus to me, but said we'd just watch for any dramatic changes and not to worry about it. I tried not to and was reassured at all subsequent visits when it stayed in that range. I was also reassured by the fact that my DS reached all developmental milestones even before he was supposed to.
Cut to 18 mos. old, my DS had a seizure lasting over an hour. They found nothing and ruled it febrile, but we met with a ped. neurologist and had an MRI and EEG to rule anything else out, since it lasted so long. We just had our appt on Monday and she said EEG was good, the brain looked well formed, no problems and that he had a thin layer of fluid called benign hydrocephalus which was not causing pressure on the brain and said that would not have caused a seizure. She said that's why his head was bigger and that between 18 and 24 months, their head circumference will plateau, so his head shouldn't be much bigger (he's now 20 mos w/ a head circumference of 20 in.).
I was surprised to even hear hydro and wasn't really prepared w/ questions, but I thought benign means good, right? Well, of course I had to google it and found all sorts of things that it does. Now I'm wondering if his head is going to stop growing and plateau in the next few months, will the fluid start putting pressure on his brain? Will he start having problems or can their bodies start absorbing it better as they get older? Once you have hydrocephalus, do you always?
I'm trying to reassure myself w/ the fact that the ped. neur. made it seem like my DS's case was not a big deal at all and I don't think she would have sugarcoated it and even now, he's ahead of the game developmentally, but I'm a mother who can't help but worry!