Validity of venous phase delay assessment in balloon occlusion test of internal carotid artery

The aim of the present study was to investigate the utility of venous phase delay assessment to evaluate the balloon occlusion test (BOT) of the internal carotid artery (ICA). A total of 38 patients who received BOT of the ICA were included in this retrospective study. Clinical examination and venous phase assessment were performed in all patients to evaluate their suitability for the evaluation of the BOT of the ICA. The venous phase delay assessment compared the venous phase of supratentorial and infratentorial structures between hemispheres. Venous phase delay was defined as the time lag for opacification of the first cortical vein between the occluded hemisphere and the hemisphere examined. The results of the clinical examination and the venous phase delay assessment were compared. In most patients negative on clinical examination, the venous phase delay was no more than 2 sec, while for most patients positive on clinical examination, the delay was >2 sec. All patients with a venous phase delay of >4 sec had a positive clinical result. The present results indicated that venous phase delay assessment is a reliable method for evaluating BOT of the ICA, and in those with a delay of <2 sec, parent vessel occlusion of the ICA, which may be used as a pre-operative procedure prior to tumor resection for patients suffering from neck or skull-base tumors, was considered safe.