Multimodal Assessment for Balloon Test Occlusion of the Internal Carotid Artery

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Objective: Permanent therapeutic occlusion of the carotid artery is one of the treatment options for patients with a large/giant internal carotid artery aneurysm or tumor involving the neck or skull base. Balloon test occlusion (BTO) is performed to predict the tolerance of parent artery occlusion (PAO). The authors combined various modalities to improve the sensitivity of BTO. The purpose of this study is to present the efficacy of the multimodal BTO.Methods: Between January 2008 and September 2014, a total of 50 patients (internal carotid aneurysms: 39, neck or skull base tumor: 8, others: 3; mean 58.4 years, range 7–81 years; 10 men and 40 women) underwent multimodal BTO. Tolerance of PAO was evaluated by the algorithm with various assessment modalities including neurological symptoms with/without induced hypotension, findings of angiogram (collateral flow, venous phase laterality), perfusion CT, and stump pressure. Clinical data of patients with BTO were analyzed retrospectively. Procedures were performed in the angio/CT combination suite. BTO was performed in the usual fashion and when the patient passed the immediate test occlusion, perfusion CT was performed. Subsequently, the angiogram under balloon inflation followed. If the patient did not show neurological symptoms for 20 min, hypotension was induced by intravenous injection of the vasodilator. Neurological symptoms were then checked for more than 30 min.Results: By multimodal assessment of BTO, 33 patients were considered tolerable, six were partially tolerable, and 11 were intolerable. Thirteen of 33 patients with predictive tolerance underwent PAO without bypass, and all but one showed no hemodynamic ischemia postoperatively. Three of six patients with predictive partial tolerance were treated by PAO with extracranial-intracranial bypass, and they experienced no hemodynamic ischemia. In contrast, one with predictive partial tolerance treated by PAO without bypass developed ischemic events as feared.Conclusions: The multimodal BTO is helpful to evaluate the tolerance of PAO and is a reliable predictor of postoperative ischemic events. It reduces risks and increases treatment safety for permanent therapeutic occlusion of the carotid artery.