acephalia (noun) acephalic (adjective)
The absence of a head or the absence of a brain
"Comparative anatomy, and acephalic monstrosities among the mammalia and man, furnish incontrovertible proofs of the brain not being the origin of the nervous system at large."
--Johann Gaspar Spurzheim, The Anatomy of the Brain (1826)
Yoko Ono once said, "Consider if it is such a catastrophe to live without your head." She added that it might make it easier to move around, since one's body would be so much lighter. Zen humor aside, I can't imagine what it would be like to live in a state of acephalia. I often live in my head -- the curse or blessing of the introvert, depending on how you look at it. I do have a rich interior life that would be hard to give up.
I wouldn't mind getting rid of the nattering jukebox of stuck records that is sometimes set to forte in my head, though.
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TWITO, page 10