Principles & Practice of Pain Medicine > Part VI. Pain Therapies > B. Injections and Neurolytic Therapies for Pain > Chapter 69. Sympathetic Blocks Samuel C. Sayson, Somayaji Ramamurthy

Celiac Plexus and Splanchnic Nerve Blocks

"The celiac plexus is a dense matrix of diffuse nerve fibers and ganglia located around the abdominal aorta and periaortic space at the level of the T12 and L1 vertebrae. The most distinct feature of the celiac plexus are the paired semilunar ("celiac") ganglia that lie immediately superior to the pancreas in the midline and are flanked in close approximation by the adrenals. These "paired" ganglia can actually vary in number and size.¹⁸ The aorta is surrounded by the plexus, which makes this large vascular structure an important landmark in performing the block. In fact, transgression of the aorta has been used in identifying needle placement.¹⁹ In addition to the celiac ganglia, the components of the celiac plexus include the greater, lesser, and least (also called lowest) splanchnic nerves; there are also contributions from the aorticorenal ganglia and aortic and superior hypogastic plexus. It is important to realize that the celiac plexus is not a distinct entity but a diffuse network that varies in size, network, and position. The most consistent landmark is the celiac artery because these elements intertwine around the base of this artery.Posterolateral techniques allow access to both the splanchnic nerves and the celiac plexus. The posterolateral approach is one originally defined by Kappis and refined by Moore.²⁷ Frequently used variations of the posterolateral approach include the transcrural approach, the transaortic approach, and the retrocrural or deep splanchnic approach...."