Preoperative evaluation of patients with extracranial carotid disease. Plethysmographic criteria for the use of a shunt, and for avoidance of surgery.

Eighty five angiographically studied patients (mean age 52) with carotid artery disease were preoperatively evaluated for the type and adequacy of their collateral circulation by the use of supraorbital photo-electric plethysmography (SPP). According to certain criteria we identified the candidates for surgery with or without shunt or for conservative treatment. Sixty patients presented evidence of extracranial collateral mainly from the ipsilateral superficial temporal artery (49 of 60), 11 patients revealed evidence of intracranial collateral mainly from the contralateral internal carotid artery (9 of 11), while in the rest, 14 patients, the source of the collateral circulation was undeterminable. Furthermore, an adequate circle of Willis was found in 67 patients and an inadequate one in the rest 7 (4 of 60, and 3 of 14). The majority of the surgically treated patients (74 of 81) were subjected to surgery without shunt (91%) while only 7 necessitated the use of a shunt (9%). No neurological complication was encountered and the single death (1.3%) was not directly related to the surgery itself. According to the present study, the careful preoperative determination of the collateral circulation, with the simple technique of SPP and the identification of patients at high risk under certain criteria could help the surgeon to decide about the advisability of a shunt or not and about the avoidance of surgery as well. This technique may be valuable where other more sophisticated forms of monitoring, such as EEG, evoked potentials or blood flow, are not readily available.