| Title: | Prediction of Cerebral Ischemia in Neurovascular Surgery |
| Authors: | Mateo Calderon-Arnulphi, MD; Gatto Rodolfo, MD; Ali Alaraj, MD; Hrachya Nersesyan, MD; William Mantulin, MD; Antonios Michalos, MD; Enrico Gratton , PhD; Fady T. Charbel, MD |
| Abstract: | Monitoring of brain tissue oxygenation during neurovascular surgery could be of great value to neurosurgeons. It provides real time feedback that may detect acute ischemic injury. This information is not available with current intraoperative techniques. Frequency domain near infrared spectroscopy (FD-NIRS) allows quantitative continuous, real time, non-invasive measurements of tissue Oxy- (HbO2), Deoxy- (HHb), total (tHb) hemoglobin concentrations and brain tissue oxygen saturation (SO2). FD-NIRS has two major advantages: It provides quantitative values and is independent from oxygenation of the scalp tissue.
We have monitored 22 neurovascular procedures using FD-NIRS including: 11 neurovascular bypasses, 3 carotid endarterectomies, 2 aneurysm clipping, 1 AVM resection and 5 balloon occlusion tests. FD-NIRS sensors were applied bilaterally on the scalp of patients on the affected and the contralateral side. Variations of the measurement reflected tissue perfusion. One patient bleed during surgery, had brain edema and died two weeks after surgery (Figure 1); another patient had an occipital stroke immediately after surgery. Because the degree of ischemic insult to the brain depends on the amount and duration of decreased HbO2 concentration, we developed an index to quantify and predict the severity of ischemic insults. We plotted the index of 44 events (drops of HbO2 concentration) as a function of time (Figure 2). We were able to separate events that did not cause any brain damage from events that have caused brain injury with a 100% specificity and sensitivity. Quantifying a drop in HbO2 concentration over a measured time course during surgery provided information for constructing the cerebral oxygenation perfusion index to distinguish safe events from unsafe conditions. FD-NIRS provides quantitative, non-invasive, continuous real time information about the brain oxygenation and hemodynamics directly related to vascular events. Integrating this new index score with continuous intraoperative oxygenation monitoring may help to prevent serious ischemic injury. |
| Corresponding Author: | Mateo Calderon-Arnulphi, MD |
| Format: | Oral Poster (View) |
| Meeting: | CNS 2005 Boston, Massassuchets |