The lumbar sympathetic trunk is the continuation of the thoracic sympathetic chain as it passes posterior to the medial arcuate ligament into the retroperitoneum. It descends along the anterolateral surface of the lumbar vertebral bodies medial to the psoas major, typically bearing four ganglia at each lumbar level. It gives grey rami communicantes to each lumbar spinal nerve and lumbar splanchnic nerves to the abdominal and pelvic autonomic plexuses.
Lumbar sympathectomy, performed chemically by alcohol injection or surgically by ganglia excision, is used for chronic lower limb ischaemia when revascularisation is not possible, complex regional pain syndrome (CRPS) of the lower limb, hyperhidrosis of the feet, and Raynaud phenomenon. The right lumbar sympathetic trunk lies behind the inferior vena cava; the left lies adjacent to the aorta. Percutaneous neurolysis is performed under CT guidance at L2-L3 level. Genitofemoral neuralgia from injury to the genitofemoral nerve crossing the psoas is a complication of lumbar sympathectomy.
Chemical or surgical lumbar sympathectomy blocks sympathetic vasoconstriction and reduces pain in complex regional pain syndrome of the lower limb, providing temporary or lasting relief particularly when sympathetically maintained pain is confirmed by diagnostic sympathetic block with a positive response.
The genitofemoral nerve crosses the psoas at the level of the lumbar sympathetic ganglia and is vulnerable during lumbar sympathectomy, causing groin, scrotal, and medial thigh pain as a recognised complication managed with neuropathic pain medications or further nerve block.
