Fig. 4.  Signal intensity changes in the branches of the major arteries before and after stellate ganglion block (SGB). The percentage changes of the signal intensity of the branches of the external carotid artery (ECA), internal carotid artery (ICA), and vertebral artery (VA) are shown in A , B , and C , respectively. The values are also presented in table 2. (A ) *P < 0.001; **P < 0.001. (B ) *P = 0.008; **P = 0.014. (C ) *P = 0.046; **P = 0.005. BA = basilar artery; Contra = contralateral; Ipsi = ipsilateral; MCA = middle cerebral artery; OA = ophthalmic artery; OPA = occipital artery; PCA = posterior cerebral artery; STA = superficial temporal artery.