Celiac plexus lies anterior to the aorta at the level of the first lumbar vertebra, between the origin of celiac and superior mesenteric arteries The adre nal glands lie lateral to the plexus and stomach and pancreas lie anteriorly. The connections include Preganglionic sympathetic fibres from splanchnic nerves, Preganglionic parasympathetic from vagus, Sensory fibres from phrenic and vagus, Afferent fibres concerned with nociception
The three pairs of splanchnic nerves descending to the celiac plexus are
1) Greater splanchnic nerves from T5-T9
2) Lesser splanchnic nerves from T10 and T11 segments
3) Least splanchnic from T12
The three pairs of ganglia in the plexus are
1)Celiac ganglia
2)Superior mesenteric ganglia
3)Aorticorenal ganglia
The nociceptive afferent fibres travel from viscera along with the sympathetic fibres, through the ganglia, splanchnic nerve, sympathetic chain, white rami communicans and then synapse in the dorsal root ganglia.The proximal axon of these bodies synapse in the dorsal horn of the spinal cord
The blockade of the celiac pleexus causes blockade of pain transmission from the visceral structures including Pancreas, Liver, Gall bladder, Omentum, Mesentery, Alimentary tract, and complete blockade of the Sympathetic fibres causing increased Parasympathetic activity manifested as increased intestinal motility and relaxed sphincters. The sympathetic blockade to the splanchnic vessels cause vasodialatation and hypotension
Agents used for blockade are 0.5% bupivacaine with adrenaline1:200000 around 30ml, 15 ml on either side with or without steroids(dexamethasone) for chronic pain. Neurolytic blockade is indicated in abdominal malignancies where alcohol 50-100% or 10% phenol is used. The pain on injection of alcohol can be minimised with combination of bupivacaine 1:1 ratio
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