Hua Tuo
Hua Tuo is later summoned by Cao Cao to cure a chronic excruciating pain in his head, which turns out to be due to a brain tumour. Hua Tuo tells Cao Cao that in order to remove the tumor, it would be necessary to open up the brain by cutting open the head, getting the tumor out, and sewing it back, with Cao Cao completely anesthesized in the process. However, Cao Cao suspects that Hua Tuo is planning to murder him so he has Hua Tuo arrested and imprisoned. (Cao Cao's suspicions are in part due to a previous attempt by Ji Ping, an imperial physician, to force him to consume poisoned medicine.)