RESUMEN
INTRODUCTION: Intraoperative neuromonitoring in aneurysm surgery can be very useful to determine inadequate positions of the vascular clip that cause partial or complete compromise of the cerebral sanguineous flow in the vascular territories irrigated by the arteries related to aneurysm. The direct visualization of these arteries after the application of the surgical clip can be insufficient in detecting this potentially detrimental situation. Knowing this circumstance on the onset would allow the neurosurgeon to correct it and to avoid, therefore, cerebral ischemic tissue hypoxia. We show the utility of the intraoperative monitoring of the oxygen tissue pressure (PtiO2) and the somatosensorial evoked potential (SSEP) for the detection of these situations with the example of a clinical case. CLINICAL CASE: We present the case of a 62 year-old woman, that presented with subarachnoid hemorrhage of aneurysmal origin. The cerebral arteriography demonstrated the existence of an aneurysm of the posterior communicating artery that was treated initially by endovascular procedure with partial exclusion of the aneurysm. For this reason it was decided to complete the treatment with a programmed surgery. The patient was put on an intraoperative monitoring system with a PtiO2 sensor located in the risk area and with SSEP. After positioning the surgical clip the partial oxygen pressure decreased rapidly, as well as the amplitude of the cortical potential of the left posterior tibial nerve. The knowledge of this situation allowed the detection of a trapped posterior communicating artery. After correcting this situation by replacing the surgical clip, both variables recovered to their basal values. CONCLUSIONS: The intraoperative PtiO2 monitoring, combined with neurophysiologic monitoring during aneurysm surgery offers a fast and trustworthy form of early detection of ischemic phenomena caused by bad positioning of the surgical clip.