oo, "waterhead babies" brings up some scary results. The real name of the disease is Hydrocephalus. We need the new system:
http://www.smbs.buffalo.edu/pth600/IMC-Path/images/Year2/Hydrocephalus-Clinical.jpg
Oh my!! That is horrible... I never heard of that before...
I don't know if it's actually a disease, it may be just a condition due to trauma, or birth defect. I don't know how else to describe it, though. Maybe "condition" is the right word.