2023 Volume 72 Issue 1 Pages 55-60
One of the complications of carotid endarterectomy (CEA) is cerebral ischemia caused by the clumping of the internal carotid artery. The incidence of cerebral ischemia depends more on the blood supply from other arteries than on the operated internal carotid artery. We investigated the relationship between the structure of the Willis artery circle on magnetic resonance angiography (MRA) images and the attenuation of the amplitudes of somatosensory (SEP)- and motor (MEP)-evoked potentials during the clumping of the internal carotid artery. The subjects were 205 patients who underwent SEP and MEP intraoperative monitoring during CEA. They were classified into four groups according to the MRA pattern of the anterior part of the Willis artery circle, i.e., the cerebral artery origin (A1) and the anterior communicating artery (A-com). During the clumping of the internal carotid artery, the SEP and MEP amplitudes decreased by 50% or more,in comparison with those before clumping. The incidence of SEP/MEP reduction of more than 50% was 6.1% in the group with bilateral A1 and A-com on MRA, 21.1% in the group with no A1 on the operated side, 50.0% in the group with no A1 on the non-operated side, and 100% in the group with no A-com. The presence or absence of blood supply from the non-operated to the operated side was one of the factors related to cerebral ischemia during the clumping of the internal carotid artery. The absence of A1 or A-com on MRA on the non-operated side indicates a high risk of cerebral ischemia during the clumping of the internal carotid artery in CEA.
