I have repeatedly read that there is evidence that the Egyptians were capable of and actively performing brain surgery as early as the Old Kingdom. According to an AP press releases by the Director of Antiquities for Giza, Zahi Hawass, in the late 1990s a skeleton has been excavated in the worker's tombs at the Great Pyramid of a man that apparently has had a brain tumor removed and lived on for 14 years afterwards.

This claim has been further spread for example by the (rather pop-history oriented) Campbell:

"The Egyptians knew how to heal broken bones, prevent wounds from becoming infected, and even perform brain surgery; evidence reveals that one worker survived fourteen years after having a brain tumor surgically removed."

(Campbell, Kenneth C.: "Western Civilization: A Global and Comparative Approach: to 1715 (Volume 1)", p. 20)

This is however not a very well sourced claim and all seems to boil down to the ominous press release and has not been independently confirmed (AFAIK) since then. So take it with a large pinch of salt for now.

hi! if you don't get answers here, you might try x-posting to /r/AskScience (Medicine category)