Introduction: Internal carotid artery (ICA) occlusion can be found in up to 15% of patients with transient ischemic attacks and strokes. Common causes include cardiac sources, like Atrial Fibrillation (AF) or large vessel atherosclerosis. Spontaneous recanalization of an occluded ICA has been infrequently described, and most commonly occurs within a short period after the diagnosis of the presumed acute occlusion. The underlying disease will direct treatment plans of such patients. We aim to study spontaneous recanalization rates, and the clinical and sonographic features that may affect their recanalization rates.
Hypothesis: Acute carotid occlusion by embolic thrombus is more likely to recanalize than that due to underlying ruptured plaque.
Methods: A 5.5-year retrospective review of Singapore General Hospital Neurovascular Laboratory database from 2010, identifying all patients with acute symptomatic Extracranial Carotid Occlusion. The clinical and sonographic features were also collected.
Results: We identified 178 (2.5%) patients with symptomatic ICA occlusion out of 7229 patients (mean age 64 years, 69% males, 74% Chinese). 88% of them had hyperlipidemia, 74% hypertension, 45% diabetes mellitus, 39% smokers, 28% ischemic heart disease, 16% previous stroke, 15% AF and 7% prior neck irradiation. Most (97%) had unilateral carotid occlusions. Underlying calcified plaques were found in 37% of patients while 63% had homogenous, echoic to anechoic lesions (of which 25% were also mobile). Sixteen of 81(20%) patients had recanalized on repeat scan (median time to scan: 95 days): Of the 16 patients, 1 had underlying calcified plaque which recanalized to severe stenosis. The other 15 patients had homogenous, echoic-hypoechoic lesions that recanalized to extensive, severe stenosis in 6 and focal, severe stenosis in 3.
Conclusions: Symptomatic carotid occlusion is not common in our patients. However, about 20% showed evidence of recanalization and more than half to severe stenosis. Such patients may benefit from carotid revascularization. This highlights the importance of repeating carotid studies in Acute Carotid Occlusion. Further prospective studies may provide insights into the recanalization mechanisms of an occluded carotid artery.