Fig. 3.  Signal intensity changes in the major arteries after stellate ganglion block (SGB). The percentage change of the signal intensity of the major cerebral arteries before and after SGB treatment. The error bars represent SEM. The values are also presented in table 2. *P < 0.001; **P < 0.001; ***P = 0.002; ****P = 0.002. Contra = contralateral; ECA = external carotid artery; ICA = internal carotid artery; Ipsi = ipsilateral; VA = vertebral artery.