The purpose of this study is to assess the outcomes of an anesthetic technique which is not
synthetic opioid based, on postoperative pain modulation and development of post craniotomy
headache against a cohort of patients where an opioid based standard anesthetic technique was
used for craniotomy. The hypothesis that is tested is that the use of agents other than
synthetic short acting opioids will reduce the amount of postoperative pain and the incidence
of headache after surgery.