My nephew is actually diagnosed with hydrocephalus. Thank God, we detected it earlier.
Some info about this, which taken from this link http://kidshealth.org/parent/medical/brain/hydrocephalus.html
Currently he is undergoing the 'shunt' treatment (I believe it is the right term).
Hydrocephalus is a brain condition that gets its name from the Greek word for water (meaning "hydro") and head (meaning "cephalus"). It occurs when cerebral spinal fluid (CSF) — the clear, water-like fluid that surrounds and cushions the brain and spinal cord — is unable to drain from the brain. It then pools, causing a backup of fluid in the skull.
Sometimes referred to as "water on the brain," hydrocephalus can cause babies' and young children's heads to swell to accommodate the excess fluid. Older kids, whose skull bones have matured and fused together, experience painful headaches due to increased pressure in the head.
If left untreated, hydrocephalus can lead to brain damage, a loss in mental and physical abilities, and even death. With early diagnosis and timely treatment, however, most children recover successfully.