Background and purpose: Although cerebral hyperperfusion after carotid endarterectomy (CEA) often impairs cognitive function, MRI does not always demonstrate structural brain damage associated with postoperative cognitive impairment. The purpose of the present study was to determine whether postoperative cortical neural loss, which can be detected by (123)I-iomazenil single-photon emission CT, is associated with cerebral hyperperfusion after CEA and whether it correlates with postoperative cognitive impairment.
Methods: In 60 patients undergoing CEA for ipsilateral internal carotid artery stenosis (>70%), cerebral blood flow was measured using N-isopropyl-p-[(123)I]-iodoamphetamine single-photon emission CT before and immediately after CEA and on the third postoperative day. The distribution of benzodiazepine receptor binding potential in the cerebral cortex was assessed using (123)I-iomazenil single-photon emission CT before and 1 month after surgery and was analyzed using 3-dimensional stereotactic surface projection. Neuropsychological testing was also performed preoperatively and at the first postoperative month.
Results: Post-CEA hyperperfusion and postoperative cognitive impairment were observed in 9 patients (15%) and 8 patients (13%), respectively. Post-CEA hyperperfusion was significantly associated with postoperative hemispheric reduction of benzodiazepine receptor binding potential (95% CIs, 2.765 to 148.804; P=0.0031). Post-CEA hyperperfusion (95% CIs, 1.183 to 229.447; P=0.0370) and postoperative hemispheric reduction of benzodiazepine receptor binding potential (95% CIs, 1.003 to 77.381; P=0.0496) were also significantly associated with postoperative cognitive impairment.
Conclusions: Cerebral hyperperfusion after CEA results in postoperative cortical neural loss that correlates with postoperative cognitive impairment.