Objective To investigate the effect of postoperative pain on plasma cortisol and preoperative scalp nerve block on reducing postoperative stress after clipping of intracranial aneurysm. Methods Forty-six ASA I-Ⅱ patients aged 19-65 yr undergoing clipping of cerebral aneurysms were recruited and randomly divided into a preoperative scalp nerve block group(group N) and a control group(group M) with 23 in each group. The patients in the group N received scalp nerve block with 0.5% Ropivacaine after induction w...