I was involved in an accident where i was knocked unconscious and as a matter of routine the er had a catscan done. It showed a larger than normal “empty” space in my head that they thought mightve been fluid buildup from a concussion. I was talking clearly despite the apparent pressure on my brain so they sent me to a neurologist at a larger facility who ran a series of mris that showed a lack of a corpus callosum as the cause of extra space.