44-year-old lived normal life with brain mostly replaced by fluid sac

The Whippet is a newsletter from McKinley Valentine of Melbourne, Australia. Each issue is a collection of marvelous miscellany. The most recent issue has a section about people who found out they have large portions of their brains missing despite living normal lives.

One example:

A 44-year-old man seeks treatment for weakness in his left leg. When the doctors hear he had hydrocephalus as a kid (water on the brain), they do an MRI just in case it's relevant. They discover that a fluid-filled sac has filled most of his skull, "leaving little more than a thin sheet of actual brain tissue".

The photo of the guy's brain is astounding.

Previously:
Split brain explainer video: You Are Two
The neuroscience of creativity (and yes, right brain/left brain is mostly bullshit)