BACKGROUND: Many reports suggest that cervical sympathectomy improves cerebral blood flow. But the basal & medial areas of brain are innervated bilaterally, so unilateral sympathectomy may not improve the outcome of infarction of those areas effectively. Actually it was reported that only bilateral, not unilateral cervical sympathectomy increased the blood flow of thalamus which known to be innervated bilaterally, and also reported that unilateral sympathectomy did not reduce the infarct size of caudate nucleus. So we studied the effect of bilateral superior cervical sympathectomy on focal cerebral infarction. METHODS: Twenty rabbits were divided into two groups. In the sham-operated control group (n=10), focal infarction was achieved by administering an autologous blood clot into the internal carotid artery after exposure of bilateral superior cervical sympathetic ganglia. In the sympathectomy group (n=10), bilateral superior cervical sympathetic ganglia were excised following embolization. Seven hours after embolization, brains were sliced into 2 mm coronal sections, stained with 2,3,5-triphenyltetrazolium chloride, and infarct sizes were determined via image analysis. RESULTS: There were no differences in the physiologic variables between two groups. The percentage of infarct size was significantly greater in the control group as compared to the sympathectomy group in both cortex (23+/-8% vs 12+/-5%, respectively; P<0.05) and subcortical area (35+/-8% vs 17+/-8%, respectively; P<0.05). CONCLUSIONS: These results suggest that bilateral superior cervical sympathectomy may reduce the infarct size of subcortical area as well as of cerebral cortex measured at 7 hours following induction of focal cerebral infarction.