Isolated middle cerebral artery disease: clinical and neuroradiological features depending on the pathogenesis

Background: Isolated atherosclerotic middle cerebral artery (MCA) disease is often difficult to differentiate from cardioembolic disease if intracranial atherosclerosis coexists with cardiac disease. Objectives: To evaluate whether clinical and neuroradiological features of isolated MCA disease differ according to the underlying aetiology. Methods: Isolated MCA disease was defined as a unilateral angiographically occlusive lesion of the MCA on the symptomatic side without lesions of other intracranial or extracranial vessels. Patients with isolated MCA disease were divided into atherosclerotic and potentially cardioembolic, and the clinical, laboratory, and neuroradiological data analysed. Results: Among the 850 consecutive patients with acute ischaemic stroke or transient ischaemic attack, 107 (12.6%) met the criteria for isolated MCA disease (76 with atherosclerotic disease and 31 with a potential source of cardiac embolism). Total anterior circulation infarcts were more common and baseline NIHSS score was higher in potentially embolic occlusions than in atherosclerotic disease (each p<0.001). While cortical infarcts and territorial infarcts were more common in the potential embolism group (p = 0.028 and p<0.001, respectively), subcortical border zone infarcts were more common in the atherosclerotic group (p<0.001). Multiple regression analysis showed that border zone infarcts and mild stroke were independently associated with atherosclerotic MCA disease, while territorial and cortical infarcts were associated with potential cardiac embolic disease. Conclusions: Clinical and neuroradiological characteristics can differentiate isolated atherosclerotic MCA disease from MCA disease associated with potential sources of cardiac embolism, and may reflect the differences in underlying pathogenesis.