Abstract WP270: Etiopathologies of Symptomatic and Asymptomatic Intracranial Large Arterial Disease: the Results of HR-MRI and Genetic Studies

Introduction: Intracranial large arterial disease (ILAD) is common, especially in Asians. We compared clinical, genetic, and imaging features between symptomatic and asymptomatic ILAD. Methods: We conducted a prospective study of patients with acute symptomatic ILAD and subjects with asymptomatic ILAD diagnosed during medical checkups. Patients who had steno-occlusive lesions on the middle cerebral artery and/or distal internal carotid artery underwent high-resolution MRI (HR-MRI) and RNF213 (p.Arg4810Lys variant) gene studies. We excluded patients who had proximal embolic sources in ipsilateral carotid and heart. A presumptive etiology of ILAD was made based on HR-MRI and RNF213 gene studies. Patients were classified into intracranial atherosclerosis (ICAS) when relevant plaques existed on HR-MRI; moyamoya disease (MMD) when patients had RNF213 variant and HR-MRI showed no plaque but characteristic features of MMD (negative remodeling and basal collaterals); and intracranial arterial dissection (ICAD) when pathognomic features (intimal flap/double lumen or mural hematoma) exist on HR-MRI. Results: Among 224 patients analyzed, 124 were symptomatic and 100 were asymptomatic. ICAS-type was more common in symptomatic ILAD than in asymptomatic ILAD (61.4% vs. 45.0%, p=0.009). The RNF213 variant was observed in one third of ICAS-type ILAD (37.0% in asymptomatic and 38.6% in symptomatic). Similarly, the proportion of MMD-type was similar between asymptomatic (33, 21.3%) and symptomatic (32, 19.0%) ILAD. Multivariate testing showed that symptomatic ILAD was associated with the presence of intracranial plaque on HR-MRI, regardless of the presence of the RNF213 variant, site of ILAD, and number of tandem stenosis. Conclusions: While various etiopathologies can cause ILAD, ICAS is an important pathology of symptomatic ILAD and should be target for medical management.