Cerejo A, Silva P A, Dias C, Vaz R
Department of Neurosurgery, Hospital S. João, Porto, Portugal.
Surg Neurol Int. 2011 Mar 23;2:37. doi: 10.4103/2152-7806.78250.
The management of incidental unruptured aneurysms remains a matter of controversy; middle-sized or large anterior circulation incidental aneurysms, in young or middle age patients, should be considered for treatment. Surgical clipping is an accepted treatment for middle cerebral artery unruptured aneurysms. Ischemic events can occur even in cases of incidental aneurysm surgery. Since regional cerebral blood flow can be compromised due to temporary arterial clipping or to incorrect placement of defi nitive clip, we performed intra-operative monitoring of brain tissue oxygen concentration (PtiO(2)), to detect changes in brain oxygenation due to reduced blood fl ow, eventually leading to ischemia, during surgery of middle cerebral artery incidental aneurysms.
PtiO(2) monitoring was performed during surgery of eight patients harboring incidental MCA aneurysms, using a polarographic microcatheter (Licox, GMS - Kiel, Germany), placed in the temporal lobe on the side of the lesion, from dural opening to dural closure.
Basal values varied between 2.3 and 27.3 mmHg; these values are lower than those previously described in the literature as "normal" for uninjured brain or in cases of subarachnoid hemorrhage. In all patients, a significant decrease in PtiO2 was found in every period of temporary clipping of MCA. Post-operative infarction in the territory of middle cerebral artery occurred in one patient and, in that case, there was a persistent minimum value of 0.6 mmHg, without recovery after the placement of the definitive clip. In another patient, an incorrect placement of the definitive clip could be predicted by a decrease in PtiO(2) value.
PtiO(2) monitoring during aneurysm surgery shows brain tissue perfusion in real time and there is a correlation between any episode of reduced blood flow to the affected vascular territory during surgery and a decrease of PtiO2 values. Unexpected low basal values were obtained in "uninjured" brain, with no influence from subarachnoid hemorrhage. The values of risk for brain infarction during temporary arterial occlusion still need further studies, but an incomplete recovery or a persistent fall in PtiO(2) values after definitive clipping should be considered as an indication for verification of the position of the clip.
偶然发现的未破裂动脉瘤的治疗仍存在争议；对于年轻或中年患者的中型或大型前循环偶然动脉瘤，应考虑进行治疗。手术夹闭是大脑中动脉未破裂动脉瘤公认的治疗方法。即使在偶然动脉瘤手术中也可能发生缺血事件。由于临时动脉夹闭或永久性夹放置不当可能会损害局部脑血流量，因此我们在大脑中动脉偶然动脉瘤手术期间对脑组织氧浓度（PtiO₂）进行术中监测，以检测因血流减少最终导致缺血引起的脑氧合变化。
使用极谱微导管（Licox，德国基尔GMS公司），在8例患有大脑中动脉偶然动脉瘤的患者手术期间进行PtiO₂监测，将其置于病变侧颞叶，从硬膜切开至硬膜缝合。
基础值在2.3至27.3 mmHg之间变化；这些值低于先前文献中描述的未受伤大脑或蛛网膜下腔出血病例的“正常”值。在所有患者中，大脑中动脉临时夹闭的每个阶段均发现PtiO₂显著降低。1例患者发生大脑中动脉区域术后梗死，在该病例中，持续最低值为0.6 mmHg，放置永久性夹后未恢复。在另一例患者中，PtiO₂值降低可预测永久性夹放置不当。
动脉瘤手术期间的PtiO₂监测可实时显示脑组织灌注情况，手术期间流向受影响血管区域的任何血流减少事件与PtiO₂值降低之间存在相关性。在“未受伤”的大脑中获得了意外的低基础值，不受蛛网膜下腔出血的影响。临时动脉闭塞期间脑梗死的风险值仍需进一步研究，但永久性夹闭后PtiO₂值未完全恢复或持续下降应被视为检查夹子位置的指征。
