Neuroimaging Evaluation of Non-Aneurismatic "Top of the Basilar" Syndrome

Purpose: We aim to evaluate the clinical and imaging features of "Top of the basilar" syndrome (TOB-S). Method: We retrospectively evaluated the clinical and imaging features of thirty consecutive TOB-S patients. We analyzed the ischemic parenchymal lesions and vascular disturbances with anatomic correlation by using magnetic resonance imaging (MRI), diffusion-weighted MRI (DWI), computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA). Results: Thirty patients (14 males and 16 females) with a mean age of 61 years (range: 32-78 years) were diagnosed as TOB-S based on the neuroimaging and clinical findings. Large artery atherosclerosis (LAA) was the common etiology (63.3%), including the subgroups of in situ steno/occlusive, artery to artery embolus (AA), arterial branch (AB) occlusion, and AA+AB combination. The other etiologies were cardioembolism (CE) (16.6%), arterial dissection (AD) (10.0%), vasculitis (6.6%), and undetermined (3.3%). The patients represented 'superficial', 'deep' and 'superficial plus deep' infarcts with segmental, territorial or scattered patterns. The most clinical manifestations were motor deficits, alteration of consciousness, visual/oculomotor disturbance, cerebellar dysfunction, behavioral disorder and speech disorder. Conclusion: The accurate evaluation of imaging findings in TOB-S is essential for diagnosis and appropriate management. Familiarity with the vascular anatomy, supplying territories, and infarction patterns of the ischemic lesions is crucial.