J Neurosurg 115:18–23, 2011 18 J Neurosurg / Volume 115 / July 2011 V enous sacrifce in neurosurgery can lead to dev- astating consequences. 19 The attention that the neurosurgical community has paid to this issue has been minimal, and nothing new has been added to the literature that might allow the surgeon to predict the consequences of venous sacrifce for a specifc patient. The general trend in recent years has been for neurosur- geons to avoid the question of “sacrifce” whenever and wherever possible. Interestingly enough, venous sacrifce may actually prove to be desirable under certain circum- stances: 1) as a way of increasing the exposure of a tar- geted pathological site; or 2) as a means of allowing for a more radical tumor resection. Nevertheless, the results of intended or unintended venous sacrifce are unpre- dictable, particularly because we lack an intraoperative method that would provide reliable data to determine the presence of venous collateral circulation. 2,30 Recently, microscope-integrated near-infrared ICG videoangiogra- phy has been employed during vascular neurosurgery as a means of visualizing the arterial fow during aneurysm clipping, bypasses, and treatment of vascular malforma- tions. 3,4,8,9,13,16,21,22 There is, however, a paucity of data that have shed any light on the dynamics of venous ICG videoangiography. 6,7,10,14 The purpose of this paper is to evaluate whether venous ICG videoangiography has any potential to be able to predict the presence of a safe col- lateral circulation for veins that are at risk for intended or unintended damage. Methods In a 3-year period (between December 2006 and December 2009), 221 patients underwent ICG videoan- giography during standard craniotomies for treatment of tumors and/or vascular malformations at our institution. All of these procedures followed the standard protocol that has been described elsewhere. 20–22 Written informed consent was obtained from all patients. In all cases, ICG was administered intravenously by an anesthesiologist (25 mg in 5 ml of saline). After a few seconds, vessel fuo- rescence appeared under the microscope (Pentero, Carl Zeiss Co.) and was cleared within 10–15 minutes, which Venous sacrifce in neurosurgery: new insights from venous indocyanine green videoangiography Clinical article *P aolo Ferroli, M.D., Francesco acerbi, M.D., Ph.D., Giovanni TrinGali, M.D., erMinia albanese, M.D., MorGan broGGi, M.D., anGelo Franzini, M.D., anD Giovanni broGGi, M.D. Department of Neurosurgery, Fondazione IRCCS Istituto Neurologico Besta, Milan, Italy, Object. The purpose of this paper is to evaluate whether venous indocyanine green (ICG) videoangiography has any potential for predicting the presence of a safe collateral circulation for veins that are at risk for intentional or unintentional damage during surgery. Methods. The authors performed venous ICG videoangiography during 153 consecutive neurosurgical proce- dures. On those occasions in which a venous sacrifce occurred during surgery, whether that sacrifce was preplanned (intended) or unintended, venous ICG videoangiography was repeated so as to allow us to study the effect of venous sacrifce. A specifc test to predict the presence of venous collateral circulation was also applied in 8 of these cases. Results. Venous ICG videoangiography allowed for an intraoperative real-time fow assessment of the exposed veins with excellent image quality and resolution in all cases. The veins observed in this study were found to be ex- tremely different with respect to fow dynamics and could be divided in 3 groups: 1) arterialized veins; 2) fast-drain- ing veins with uniform flling and clear fow direction; and 3) slow-draining veins with nonuniform flling. Temporary clipping was found to be a simple and reversible way to test for the presence of potential anastomotic circulation. Conclusions. Venous ICG videoangiography is able to reveal substantial variability in the venous fow dynam- ics. “Slow veins,” when they are tributaries of bridging veins, might hide a potential for anastomotic circulation that deserve further investigation. (DOI: 10.3171/2011.3.JNS10620) Key WorDs • cerebral veins • cerebrovascular neurosurgery • indocyanine green angiography • surgical technique Abbreviations used in this paper: ICG = indocyanine green; ROI = region of interest. * Drs. Ferroli and Acerbi contributed equally to this work.