Fig. 2. Vascular changes induced by stellate ganglion block (SGB). (A ) Vascular imaging of the external carotid artery (ECA) group, the ECA and superficial temporal artery (STA), of two representative subjects before and after right SGB treatment. (B ) Images of the basilar artery (BA), vertebral artery (VA), and their branches before and after SGB. ICA = internal carotid artery.