The role of oculopneumoplethysmography in detecting acute carotid artery thrombosis in patients with neurologic deficits after carotid endarterectomy

Abstract

Background: This study analyzes the role of oculopneumoplethysmography (OPG/Gee) in detecting acute carotid thrombosis (CAT) after carotid endarterectomy (CEA) in a timely fashion for immediate exploration, and minimizing unnecessary surgery. Patients and methods: Fifty-three patients with neurologic deficits that were noticed after CEA in the operating or recovery room had immediate OPG/Gee. Patients with a positive OPG underwent immediate exploration. Patients with a negative OPG had a duplex ultrasound (DU), and if positive for ≥50% stenosis, the patient underwent exploration. If the DU was negative, the patient underwent cerebral computed tomography scanning and angiography. Results: Thirty-one of 53 (58%) had a positive OPG, 30 (97%) of whom had CAT on exploration. Twenty-two of 53 (42%) with a negative OPG had a DU, 4 of whom had ≥50% stenosis (1 thrombosis) that was confirmed by exploration. The remaining 18 patients had a negative DU that was confirmed by angiography. OPG had an overall accuracy of 96% in detecting acute CAT, with a sensitivity of 97%, specificity of 95%, positive predictive value (PPV) of 97%, and a negative predictive value (NPV) of 95%. Combined OPG and selective DU had an overall accuracy of 98% in detecting surgically correctable lesions, with 100% sensitivity, 95% specificity 97% PPV, and 100% NPV. Mandatory exploration in all 53 patients would have resulted in 19 (36%) unnecessary surgeries versus 1 of 53 (2%) if exploration had been done based on OPG with selective DU ( P <0.05). Even if exploration was done based only on the OPG, 30 of 34 surgical lesions would have been explored within a few minutes; only 4 would have been delayed until a DU was performed. Conclusions: OPG/Gee is very sensitive and timely in detecting acute CAT, and carotid exploration in these patients can improve the results of CEA. It also minimizes unnecessary explorations. Patients with a negative OPG should undergo DU, and if positive, they should undergo exploration.