[Block of the superior cervical ganglion of the Truncus sympathicus. Why it often is not possible!]

For the transoral block of the superior cervical ganglion (SCG) of the sympathetic trunk we investigated the dissemination of three of three different volumes. The aim was to find an ideal volume and reasons for a failure of the technique.

40 preserved heads were investigated. 35 were injected with the contrast agent Jopamiro. 1 ml was applied on the left side of 30 heads, 2 ml on all right sides. 5 heads were injected with 5 ml into the parapharyngeal space (PPS) on the right and into the prevertebral space (PVS) on the left side. All heads were investigated by CT-Scans and 3D reconstruction. 5 cadavers were injected with 5 ml blue coloured water for dissection.

1 or 2 ml showed very similar dissemination. To reach the PPS, the needle had to be pushed laterally or, if the direction was changed more medially, the needle had to be pulled back. Feeling two resistances, the PVS was reached instead of the SCG. 5 ml spread to other regions of the head.

1 ml seems to be sufficient to block the SCG. The guidelines have to be strictly followed to avoid failure of the block. 5 ml disseminate to unexpected and undesirable regions.