After my dad had surgery to correct increasing fluid build up behind scar tissue from a World War II brain injury, he came out of the surgery totally demented. Whether the dementia came from a combination of his age and the scar tissue, anesthetic or something else, we didn't know. All we knew was that he came out of surgery with a voice in his head and very little ability to discern the difference between what was a happening in this head and the reality of this world. That he was irreversibly altered was obvious.
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