Intraoperative monitoring of intraarterial paraganglioma embolization by indocyaningreen fluorescence angiography

Preoperative arterial embolization (AE) of paraganglioma (PG) is widely used to diminish intraoperative blood loss. Thereby conditions for a resection of the tumor shall be improved and risks for facial, vagal or hypoglossus nerve injuries are reduced. The vascularization of jugular and tympanic PGs is particularly complex due to collaterals with the vertebral and internal carotid arteries. Thus AE is often not complete and intraoperative blood loss may still be considerable. The postinterventional perfusion is of interest for the surgeon. We evaluated the arterial perfusion after AE using indocyaningreen (ICG) angiography. Six patients with PG, two carotid PGs, two jugular PGs, one vagal PG and one tympanic PG underwent surgery 1 day after AE. After tumor was exposed, ICG was intravenously applied followed by fluorescence angiography. Residual perfusion was assessed on the video clip and the perfusion index was automatically calculated by the IC-CALC software. This index was compared with the radiologist’s assessment of arteriographic control after AE. Two of the six patients showed only marginal residual perfusion. These were patients with carotid PGs. The patient with the vagal PG showed 20%, the patients with jugular PGs 80 and 60% and the patient with the tympanic PG had 70% residual blood flow. The preoperative AE is rarely complete in PGs of the petrous bone. Intraoperative fluorescence angiography is a reliable procedure to evaluate the efficiency of preoperative embolization and can help the surgeon to estimate intraoperative bleeding favouring risks.