The present report is of two patients who, immediately after internal carotid endarterectomy, presented with unexplained hemiplegia, despite normal findings on repeated MRI scans, which secondarily evolved into homolateral subacute corticobasal syndrome (CBS), with asymmetrical hemispheric hypometabolism and evidence of dopaminergic denervation. This prompted us to propose an hypothesis of transient cerebral hypoxia arising during the surgical clamping period that might have provoked a prolonged or permanent functional lesion of the left hemisphere and basal ganglia, with no visible infarction on MRI but only synaptic rearrangement of the neural networks, thereby revealing or exacerbating a potentially preexisting silent impairment.