Abstract:Objective The aim of this study was to explore reliable features that can be used to differentiate the stump of occluded middle cerebral artery (MCA) branch from real MCA branch aneurysms, and to propose same warning notes. Method This study reported 3 patients with MCA branch occlusion mimicking an bifurcation aneurysm. Then, we reviewed the literature and described the characteristics of all pooled MCA branch occlusion patients. The pooled MCA branch occlusion patients were compared with real small MCA aneurysms (≤5 mm) diagnosed at the same period of that 3 cases reported in this study. The clinical and radiological information, including branch number of MCA, aneurysm appearance (conic, columnar and saccular), height of the aneurysm (Ha), width of the aneurysm (Wa), width of the aneurysm neck (Wn), width of the largest branch of MAC at the same level of protruding lesion (Wb), moyamoya vessels, ratio of aneurysm parameters (Ha/Wa>1, Wa/Wn≤1 and Wa/Wb≤1) were retrieved and compared. Results According to the t test and Fisher test, conic shape (P=0.015), saccular shape (P=0.011) Wa/Wn≤1 (P=0.011), Wa/Wb≤1 (P=0.022), were significantly associated with artery occlusion. However, the results of multivariate analysis showed that only conic shape (P=0.046) and Wa/Wb≤1 (P=0.031) were the independent features related with MCA major branch occlusion. Conclusions In diagnosing protruding vascular lesions at the MCA bifurcation, the possibility of a vascular stump should be considered when the lesion is conic shape and with a diameter smaller than the largest opening branch at the same level. High resolution magnetic resonance imaging may be needed for differential diagnosis.