Background and Objectives It is our hypothesis that stellate ganglion block increases regional blood flow on the blocked side, but does not change cardiac output, suggesting that the corresponding regional blood flow on the contralateral side may decrease, which would be disadvantageous for patients with bilateral sympatheticallymaintained pain. The aim of this study is to examine the effect of stellate ganglion block on facial skin blood flow.

Methods Skin blood flow on the right and left forehead was measured by a laser blood flowmeter before stellate ganglion block and 15 minutes after the block. The block was performed for 8 outpatients with acute or chronic pain in the head or neck using a 24-gauge needle, 5 mL of 1% mepivacaine, and a paratracheal approach at the C6 transverse process. Time control without the block was obtained with 9 healthy volunteers.

Results All the patients developed the Horner's syndrome on the blocked side, but not on the contralateral side. The facial skin blood flow increased from 7.5 ± 1.1 mL/min/100 g to 14.5 ± 1.4 mL/min/100 g on the blocked side (P < .01) and from 8.8 ± 1.2 mL/min/100 g to 12.8 ± 1.7 mL/min/100 g on the contralateral side (P < .05). The healthy volunteers without the block showed no significant change (from 10.1 ± 0.8 mL/min/100 g to 10.3 ± 0.7 mL/min/100 g).

Conclusions Our study suggests that stellate ganglion block may increase the contralateral regional skin blood flow.