And how exactly did Pitou do that? She's a soldier, not a neurologist or a neurosurgeon. She probably read some book again and did some hasty operation, not really knowing what needs to be done. I'm sure she did plenty of damage to Palm's brain, though, which again adds to the long list of reasons why Pitou needs to die when this arc is finishing. Or at least have her own brain so damaged she can't tell the left from right.
I didn't find Killua's breakdown too badly animated or feeling artificial because of that. But it slightly annoys me how he's looking less and less like a tough assassin. Right now Gon's the one looking far more merciless and asskicking than Killua.