can hydrocephalus become nph?

my son was diagnosed with a posteria fossa arachnoid cyst & hydrocephalus as a baby a VP shunt is in situ in the 4th ventricle and has undergone many shunt revisions within the first 5 years of his life.
now a teenager he has had made fantastic progress and had no shunt problems for around ten years until recently.
he has intermittant symptoms headaches nausea disturbed vision falling etc. scans showed that his shunt had broken however there was no evidence of pressure, his neurologist is making frequent neuro obs at least once a week for the next couple of months before making a decision on whether or not to replace the broken shunt with a new one.
I am baffled that my son has clear symptoms of hydrocephalus yet no pressure on his brain - is there a possibility that the arachnoid cyst is no longer obstructing and he now has NPH? Is this possible?

[selmaS]

Hi...I pray all is figured out for ur DS and he is soon on the road to recovery....may I ask was he ever checked for chiari or a syrinx?

"selma"