Balloon Test Occlusion of Internal Carotid Artery in Recurrent Nasopharyngeal Carcinoma Before Endoscopic Nasopharyngectomy: A Single Center Experience

ObjectivesEndoscopic nasopharyngectomy (ENPG) is a promising way in treating recurrent nasopharyngeal carcinoma (rNPC), but sometimes may require therapeutic internal carotid artery (ICA) occlusion beforehand. Balloon test occlusion (BTO) is performed to evaluate cerebral ischemic tolerance for ICA sacrifice. However, absence of neurological deficits during BTO does not preclude occur of delayed cerebral ischemia after permanent ICA occlusion. In this study, we evaluate the utility of near-infrared spectroscopy (NIRS) regional cerebral oxygen saturation (rSO2) monitoring during ICA BTO to quantify cerebral ischemic tolerance and to identify the valid cut-off values for safe carotid artery occlusion. This study also aims to find out angiographic findings of cerebral collateral circulation to predict ICA BTO results simultaneously.Material and Methods87 BTO of ICA were performed from November 2018 to November 2020 at authors’ institution. 79 angiographies of collateral flow were performed in time during BTO and classified into several Subgroups and Types according to their anatomic and collateral flow configurations. 62 of 87 cases accepted monitoring of cerebral rSO2. Categorical variables were compared by using Fisher exact tests and Mann–Whitney U tests. Receiver operating characteristic curve analysis was used to determine the most suitable cut-off value.ResultsThe most suitable cut-off △rSO2 value for detecting BTO-positive group obtained through ROC curve analysis was 5% (sensitivity: 100%, specificity: 86%). NIRS rSO2 monitoring wasn’t able to detect BTO false‐negative results (p = 0.310). The anterior Circle was functionally much more important than the posterior Circle among the primary collateral pathways. The presence of secondary collateral pathways was considered as a sign of deteriorated cerebral hemodynamic condition during ICA BTO. In Types 5 and 6, reverse blood flow to the ICA during BTO protected patients from delayed cerebral ischemia after therapeutic ICA occlusion (p = 0.0357). In Subgroup IV, absence of the posterior Circle was significantly associated with BTO-positive results (p = 0.0426).ConclusionAngiography of cerebral collateral circulation during ICA BTO is significantly correlated with ICA BTO results. Angiographic ICA BTO can be performed in conjunction with NIRS cerebral oximeter for its advantage of being noninvasive, real-time, cost-effective, simple for operation and most importantly for its correct prediction of most rSO2 outcomes of ICA sacrifice. However, in order to ensure a safe carotid artery occlusion, more quantitative adjunctive blood flow measurements are recommended when angiography of cerebral collateral circulation doesn’t fully support rSO2 outcome among clinically ICA BTO-negative cases.

Hunterian Ligation With Distal Revascularization for Management of a Previously Coiled Giant Internal Cerebral Artery Aneurysm: 2-Dimensional Operative Video

Unclippable giant aneurysms pose a significant microsurgical challenge. Options for management are highly dependent on the aneurysm characteristics and cerebrovascular anatomy. Hunterian (proximal) ligation with either high-flow or low-flow distal revascularization is an option for the treatment of aneurysms of the internal carotid artery (ICA). This patient had a multiply recurrent supraclinoid ICA aneurysm following endovascular treatment and progressive ipsilateral homonymous hemianopsia. In preparation for the clip occlusion of the proximal ICA, the patient underwent a balloon test occlusion of the ICA, which had a negative result, indicative of tolerance. A pterional craniotomy was used to perform a low-flow bypass, superficial temporal artery to M2, and clip occlusion of the proximal ICA. The patient tolerated the procedure well with some pressure-dependent contralateral symptoms, which resolved. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Ocular Ischemic Syndrome: The Red Eye Revisited

Ocular ischemic syndrome (OIS) is a vision-threatening condition due to inadequate arterial supply to the orbital contents. OIS is commonly described secondary to severe carotid artery stenosis and most often observed by ophthalmologists. However, OIS may rarely also result in an interventional radiology setup during balloon test occlusion (BTO) of the internal carotid artery. BTO is a procedure to assess for the adequacy of the circle of Willis to compensate for a permanent parent arterial sacrifice by temporarily occluding the flow in the internal carotid artery using a balloon. Here, we present a case of OIS in a patient who underwent BOT as a part of presurgical evaluation for the excision of carotid body tumor.