The effects of stellate ganglion block on the electroencephalogram in rats.

Purpose: It is reported that the sympathetic nervous system may play an important role in the arousal response. The present study evaluated the effect of stellate ganglion block (SGB) on electroencephalogram (EEG) activity in rats.
Materials and Methods: Adult male Sprague-Dawley rats were divided into two groups: SGB (n = 10) or intramuscular (IM, n = 10) injection was performed with 0.2 ml 0.25 % bupivacaine. The spectral edge frequency 95 % (SEF 95 %), median frequency (MF), beta to theta ratio (BTR), and beta to delta ratio (BDR) were estimated 30 min before bupivacaine injection and 15, 20, 25, 30, 45, 55, and 100 min after SGB or IM injection.
Results: Ipsilateral ptosis occurred in all the rats that underwent SGB but did not occur in the IM group. Significant decrease of the 95 % SEF value, MF, BTR, and BDR was observed from 15 to 45 min after SGB compared with those of the IM group, respectively (p < 0.05).
Conclusions: SGB with 0.2 ml 0.25 % bupivacaine significantly decreased EEG activities in rats. These results suggest that SGB can induce a sedative effect in rats. Further studies are required to investigate the behavioral tests for sedative effects of SGB.