Using thermal diffusion flowmetry in the assesment of regional cerebral blood flow in cerebral aneurysm microsurgery

Introduction. The thermal diffusion flowmetry (TDF) is a technique that allows the measurement of the regional cerebral blood flow (rCBF) through an implanted microprobe in a cerebral region of interest. The monitoring is continuous, real-time and quantitative (ml/100g/min). The purpose of our clinical work has been to show the technical details and preliminary results by using this monitoring technique during the microsurgical management of cerebral aneurysms and along the postoperative period. The aim of the monitoring of the rCBF is to identify and evaluate ischemic events related with the temporary artery clipping or malposition of the final clip. Clinical materials. A total of five patients have been monitored (4 woman and one man with an average age of 50.8 years). Two patients harboured one aneurysm in the middle cerebral artery, other two patients had two aneurysms each one on the internal carotid artery in the exit of the posterior communicating and anterior choroidal artery and the fifth harboured a paraclinoid internal carotid artery aneurysm. All patients were operated on using standard microsurgical techniques through a pterional approach. Surgery was done under neurophysiological monitoring and direct microdoppler fluometry assesment. Just before craniotomy the TDF microprobe was inserted 2,5 cm deep into the white matter through a small burr-hole placed on the coronal line and 2 cm away the midline to measure in the anterior cereral artery vascular sector and 6cm away of the midline to measure in the middle cerebral artery territory. Patients were under continuous monitoring during surgery and along the postoperative period in the recovery unit. A total of 14 temporary artery clippings (between 2-4) with an average total clipping time of 7.2 minutes (ranging 1.6 to 16) and 16 definitive clip replacements (ranging 2 to 8) were done at surgery. Patient with paraclinoid aneurysm was operated on using the retrograde aspiration technique and the internal carotid artery was kept closed 45 mimutes. keeping Some illustrative cases and demonstrative records are presented. Conclusions. The use of TDF allows a quantitative real-time measurement of the rCBF in the areas of interest monitored during the microsurgical management of the cerebral aneurysms which leads to detect ischemic events helpping to avoid ischemic sequelae. The detection of ischemic events in real time would make possible the use of therapeutic measures ealier and more efficienty.