Wiktionary
n. 1 Surgery on any part of the nervous system, especially the brain; neurosurgery. 2 (context uncountable idiomatic English) Something that is overly complex, detailed or confusing.
WordNet
n. any surgical procedure involving the brain
Usage examples of "brain surgery".
These rooms were fitted out with the special needs of brain surgery in mind.
The pituitary adjustments so that her body would not outgrow the final capsule and the delicate brain surgery that made Helva the ship had been, as always, expensive.
At least for the brain surgery I'd been knocked out, but for everything else, I was fully awake, and there were bruises and scabs and needle marks all over me, in the backs of my hands, my arms, my groin.
But on the other hand, it wasn't entirely appropriate to be jovial on the eve of brain surgery.
A trio of lights surrounded the upper part of her head, like some brain surgery contraption in a science-fiction movie.