Is it possible that there is no visible head enlargement for a child with hydrocephalus?

Depends: The term hydrocephalus is generally used to describe any condition producing an excess of fluid within the brain. The more common form is due to a blockage of the spinal fluid plumbing system with a buildup of pressure that can expand the infant skull. Another cause is the loss of brain substance due to injury (stroke, infection) & fluid fills is the empty space under little or no pressure.