Comparison of different injectate volumes for stellate ganglion block: an anatomic and radiologic study.

Background: Volumes from 5 to 20 mL of local anesthetic are used for stellate ganglion block. The variation of practice gave us the impetus to investigate the distribution of 3 different volumes of solution. We documented the regions reached by each volume to assess the possibility to reduce the injectate to 5 mL.

Materials And Method: A total of 42 cadavers (84 halves), fixed by Thiel's method and on which pulse simulation was performed, were investigated. Of these 84 halves, 28 were injected with 5 mL of contrast (group A), 28 halves with 10 mL (group B), and 28 halves with 20 mL (group C), according to the tissue-displacement method. Immediately after injection, the cadavers were investigated by use of CT scans with a possible 3-dimensional reconstruction. In addition, 4 halves of group A and group B were dissected, and the contrast distribution was determined by photography.

Results: Group A showed a constant dissemination from C4 to Th2-Th3, without spreading to ventral or lateral regions. In group B, a persistent spread from C4 to Th3 was documented. Ventral and lateral regions were also reached in one third of the specimens. Group C showed a constant dissemination from C3 to Th4-Th5, with additional spread to ventral, lateral, and posterior regions of the neck similar to that in group B.

Conclusion: The use of 5 mL results in an almost ideal vertical distribution in most of the cadavers, whereas high volumes--20 mL more so than 10 mL--are at risk of spreading extensively in both the vertical direction and also uncontrollably to other regions of the neck.