I found only a slightly increased difficulty in reaching the very highest notes (F5, G5, A5) - which I could hit reasonably easily before but find harder now, but have been able to get after practice. However, my mixed voice seems to have improved with the surgery, so I can hit G4 up to C5 in an almost chest voice-like mix which I wasn't able to do before, although it may just have been due to me doing more singing at the time (although I wasn't training on using mixed voice at that time).