This is no joke. My dad's best friend had a brain tumor removed and woke up having forgotten how to play the guitar, which he had been playing since he was 13. He had to relearn. In all other respects, he was fine, though.
People have to remain conscious during brain surgery in order to ensure unexpected things don't happen. Unlike most other organs of the body you can be causing absurd amounts of damage to the brain and not even know it.
This is pretty much the only way we know to make sure that everything is okay. We have to ask the patient.
fuckin surgeons are so cocky they think they are God of the medical field lets have this guy play a saxophone because we went through 12 years of training and could do brain surgery with our eyes closed literally--we have it under control.