Differentiating Acute from Chronic Carotid Occlusion in Ischemic Stroke within 8 Hours of Onset: Relevance for Mechanical Thrombectomy (P05.240)

Abstract

Objective: To differentiate the above in view of possibility of mechanical thrombectomy for acute carotid occlusion. Background Mechanical thrombectomy (MT) is approved for large vessel occlusion within 8 hours of ischemic stroke onset. On magnetic resonance angiography (MRA) or CT angiography (CTA) absent internal carotid artery (ICA) is either due to acute occlusion by thrombus or chronic carotid occlusion. It is important to differentiate them as the former can be treated with MT. Design/Methods: All patients presenting within 8 hours of stroke onset between Jan 2009 to April 2011 were included in this retrospective study. Cases were obtained from the Department9s Acute Stroke Registry. Clinical presentation, neuroimaging (MRI/CT brain/angiography) and carotid ultrasound were reviewed. Results: Of 273 patients who met inclusion criteria, 8 presented with acute and 5 with chronic occlusion. Patients with chronic occlusion did not have hemodynamic compromise such as volume loss/hypotension pre-stroke. History and neurological examination could not discriminate acute from chronic occlusion. All patients had cortical signs and contralateral extremity weakness. Neuroimaging findings: (i) Pattern of infarcts: acute occlusion – hemispheric (7 patients) and watershed (1 patient). Chronic occlusion – watershed in all cases. (ii) Presence of middle cerebral artery (MCA) collaterals: acute occlusion: all had absent ICA and MCA, except for one patient with absent ICA and present MCA collaterals. Chronic occlusion: all had absent ICA and 3 had MCA collaterals whereas 2 did not. (iii) Hyperdense MCA sign was seen in only 2 patients with acute occlusion and not in chronic occlusion. (iv) Carotid ultrasound showed recent thrombus in acute occlusion. In chronic occlusion it revealed a high resistance pattern or occluded ICA. Conclusions: Neuroimaging (infarct pattern, MCA collaterals, and hyperdense MCA sign) and carotid ultrasound differentiates acute from chronic occlusion and is helpful in selecting patients for MT. History and clinical examination were not useful distinguishing features. Disclosure: Dr. Wijesoma has nothing to disclose. Dr. Chua has nothing to disclose. Dr. Sitoh has nothing to disclose.