Silent brain infarct after carotid artery surgery: incidence and prevention.

To determine the prevalence and mechanisms of postoperative silent brain infarct, brain CT was routinely performed before and after carotid endarterectomy during the same period of hospitalization. Between June 1991 and May 1993, 69 patients who underwent 74 carotid endarterectomies (five two-staged bilateral procedures) were enrolled in the study. Ipsilateral brain infarct was observed on the preoperative CT scans in 25 cases. Of these 25 infarcts, three occurred in 20 patients (15%), without symptoms, 13 in 41 patients (32%) with transient ischemic attacks (TIAs), and 9 in 13 patients (70%) with cerebrovascular accident. After surgery, two patients (2.7% of procedures) had monoparesia of an upper limb with no corresponding abnormality seen on CT scans, and two (2.7%) had TIAs, associated with CT evidence of a new lesion in one patient. Five silent brain infarcts (6.8%) were detected, including four in the hemisphere contralateral to the restored carotid artery. These study results indicate there is no correlation between the occurrence of postoperative silent brain infarct and the presence of ulcerated stenosis of the carotid artery documented by Doppler ultrasound examination. Silent infarct was not observed in any of the 24 patients (32%) in whom a shunt had been used during the procedure. After a review of the literature, we propose wider use of intraoperative shunts to prevent postoperative silent brain infarct.