EEG monitoring during angiographic balloon test carotid occlusion: experience in sixteen cases.

Ipsilateral hemispheric ischaemia related to permanent or temporary arterial occlusion at the time of operation is a potential risk of surgery upon some aneurysms or tumours which involve the internal carotid artery. Presurgical evaluation of the risks of temporary or permanent internal carotid artery occlusion may help predict patients in these circumstances at risk of stroke. Balloon test occlusion studies involve the elective preoperative occlusion of the internal carotid artery by a deflatable balloon inserted into the cerebral circulation under angiographic control. We have performed 16 balloon test occlusion studies; 2 subjects developed clinical and electroencephalographic changes when the carotid artery was temporarily occluded, and these changes reverted to normal when the balloon was deflated. The results of the test occlusion studies helped in planning the surgical management of all the subjects involved.