Acute Ischemic Stroke Caused by Internal Carotid Artery Occlusion: Impact of Occlusion Type on the Prognosis

We aimed to compare clinical outcomes of acute ischemic stroke (AIS) due to internal carotid artery (ICA) occlusion following mechanical thrombectomy (MT), focusing on occlusion types. We retrospectively reviewed 67 AIS patients who had an ICA occlusion on computed tomography angiography and underwent MT in a single tertiary center. ICA occlusion types were categorized as (1) true cervical ICA (cICA) occlusion (true occlusion), (2) pseudo-occlusion of the cICA (pseudo-occlusion), and (3) distal ICA (dICA) occlusion. We compared the clinical characteristics and their outcomes according to the ICA occlusion type. Fourteen patients were diagnosed with true occlusion, 32 with pseudo-occlusion, and 21 with dICA occlusion. The main etiologies were atherothrombotic in true occlusion (64.3%) and cardioembolic in pseudo-occlusion (81.3%) and dICA occlusion (71.4%) (P < 0.001). Pseudo-occlusion showed lower rates of successful reperfusion (37.5%, P = 0.009, 78.6% in true occlusion and 71.4% in dICA occlusion) and poor functional outcome at 3 months (18.8%, P = 0.037, 50% in true occlusion and 47.6% in dICA occlusion) with statistical significance. The infarction volume (169.4 ± 154.4 mL, P = 0.004, 29.2 ± 52.7 mL in true occlusion and 105.8 ± 13.4 mL in dICA occlusion) was significantly higher in pseudo-occlusion. On multivariate logistic analysis, pseudo-occlusion (odds ratio [OR]: 4.84, 95% confidence interval [CI] 1.02–22.87, P = 0.023) was an independent risk factor for poor reperfusion, which was significantly associated with a poor functional prognosis (OR: 22.04, 95% CI 1.99–243.83, P = 0.012). Patients with pseudo-occlusion showed poorer clinical outcomes compared with other ICA occlusion types, possibly due to a poor reperfusion rate after MT.