This question already has an answer here:
In 2268, Spock's brain has been stolen by hostile aliens and later re-transplanted by Dr. Leonard McCoy. But 10 years earlier, Spock talks to his self from 2387 about future things and how to tackle them. In these discussions, did Spock learn about his brain being at risk or did he not?
At least, one would expect the older Spock would warn his younger alter ego to avoid removal of his brain, since Dr. Leonard McCoy ran into severe complications while finishing the surgery, so probably the whole procedure caused secondary damages to his nervous system.
Still, to my knowledge there are no historical records about such a dialog, so did Spock in fact conceal this information to his younger ego and, if so, why?