Measurement of Cortical Microcirculation During Intracranial Aneurysm Surgery by Combined Laser-Doppler Flowmetry and Photospectrometry

BACKGROUND: Accidental vessel occlusion is one major risk of intracranial aneurysm surgery potentially causing cerebral ischemia. The intraoperative assessment of cerebral ischemia remains a technological challenge. OBJECTIVE: As a novel approach, cortical tissue integrity was monitored using simultaneous measurements of regional capillary-venous cerebral blood flow (rvCBF), oxygen saturation (Srvo(2)), and hemoglobin amount (rvHb) during aneurysm surgery. METHODS: Fifteen patients scheduled for aneurysm surgery of the anterior and posterior circulation were included. A fiber optic probe was placed on the cortex associated with the distal branch of the aneurysmatic vessel. Blinded measurements by combined laser-Doppler flowmetry (rvCBF) and photospectrometry (Srvo(2), rvHb) were performed before and after surgical clipping or trapping of the aneurysm. Data were correlated with postoperative imaging and neurological outcome. RESULTS: Cortical measurements could be successfully performed in all patients. Significant increase (>25% change from baseline) or decrease (<25% change from baseline) of rvCBF, Srvo(2), and rvHb was detectable in 33 to 46% of patients after surgical intervention. Severe decrease (>50% change from baseline) of all parameters or solitary of rvCBF was correlated to reduced cerebral perfusion and neurological deficits in 2 patients. CONCLUSION: Combined laser-Doppler flowmetry and photospectrometry provides real-time information on cortical microcirculation. Intraoperative alterations of parameters (rvCBF, Srvo(2), rvHb) might reflect changes of cerebral tissue integrity during intracranial aneurysm surgery.