A man with an unusually tiny brain manages to live an entirely normal life despite his condition, which was caused by a fluid build-up in his skull.

The black area above actually shows the space in his head…the white is brain.
The images on the right are images of a normal brain.
Scans of the 44-year-old man’s brain showed that a huge fluid-filled chamber called a ventricle took up most of the room in his skull, leaving little more than a thin sheet of actual brain tissue
However the man is a happily married man with 2 children and works as a civil servant.
Intelligence tests showed the man had an IQ of 75, below the average score of 100 but not considered mentally retarded or disabled.
You obviously don’t need a huge amount of intelligence to work as a civil servant!