[Thermographic assessments of the sympathetic blockade by stellate ganglion block (2)--Comparison and analysis of thermographic patterns between C7-SGB and C6-SGB in 20 healthy volunteers].

We studied effects of two methods of stellate ganglion block (SGB) by evaluating the extent and strength of sympathetic blockade using infrared thermography, and classifying thermographic hot areas in the ipsilateral hand after SGB. Twenty healthy volunteers (18 females, 2 males, age 29.7 +/- 7.7 years) were subjects for this study. C7 and C6-SGBs were performed on each subject using 5 ml of 1% plain mepivacaine at the anterior face of 7th cervical transverse process in C7-SGB or at the top of the anterior tubercle of 6th cervical transverse process in C6-SGB. Thermography was performed before and 30 minutes after SGB. On the thenar and the hypothenar as well as the second, and the fourth finger tips, changes of skin temperature in the C7-SGB group were significantly larger than those in the C6-SGB group (P less than 0.05). There were no significant differences on the forehead or the cheek between the two groups. Thermographic hot areas on the ipsilateral hand after SGB were classified into three patterns as follows; whole hot area, partial hot area and absent hot area. Frequency of whole hot area pattern in the C7-SGB group (65%) was significantly higher than the one (30%) in the C6-SGB group (P less than 0.05). Frequency of absent hot area pattern in the C7-SGB group (5%) was significantly lower than the one (35%) in the C6-SGB group (P less than 0.05). All subjects showed Horner's sign. No severe side-effect occurred in either group, but complaints of dysphagia appeared significantly more frequently in the C6-SGB group than in C7-SGB (P less than 0.05). In conclusion, C7-SGB was considered to be superior to C6-SGB in strength and certainty of the lower cervical and upper thoracic sympathetic blockade, with less of side-effects.