Cortical blood flow recorded during early or delayed surgery for ruptured intracranial aneurysms.

Forty-three patients were operated on for ruptured intracranial aneurysms during a 12-month-period. Intraoperative evaluation of cortical blood flow by means of a thermal diffusion probe was performed in 23 out of the 41 patients who were operated on for aneurysms of the anterior circulation. The autoregulation index was determined at the time of raising the systemic blood pressure after clipping of the aneurysm(s). No statistically significant difference was found between the averages of the autoregulation indexes calculated in the subgroups of patients submitted respectively to early or delayed surgery. There was no correlation of both cortical blood flow and autoregulation with either age of the patients, or preoperative neurological grade. On the contrary, the autoregulation index showed a statistically significant correlation with outcome.