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.