Treating patients with head and neck tumor occasionally requires permanent occlusion of the internal carotid artery (ICA). To assess whether a patient will tolerate this occlusion, we studied stump pressure, EEG and angiogram under direct clipping of the common carotid artery during surgery for severely invasive hypopharyngeal carcinoma. In other cases, we tried balloon test occlusion and measured cerebral blood flow (CBF) with positron emission tomography (PET) using C15O2. This direct clipping test can be performed with the usual surgical instruments and provides significant information on carotid ligation. However, we recognized that the information was not sufficient for a clear assessment even if the stump pressure and EEG were within the normal range. Balloon occlusion test and PET were performed in two cases. The first case showed temporary hemiplegia after a slight decrease in stump pressure, while the second case did not show any change despite a severe decrease in stump pressure. The second case showed an increase of CBF on PET. Stump pressure does not necessarily reflect changes in CBF, and PET should be used for more reliable assessment.
