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Sacral Sympathetic Chain

truncus sympathicus — pars sacralis

The sacral sympathetic chain lies on the anterior surface of the sacrum medial to the sacral foramina, continuing from the lumbar sympathetic chain and terminating at the ganglion impar (ganglion of Walther) at the tip of the coccyx where the two sides converge. The sacral sympathetic ganglia (S2-S5) provide sympathetic innervation to the pelvic viscera via the hypogastric nerves, contribute to the pelvic plexus, and supply cutaneous sympathetics to the perineum and lower limb via the sacral spinal nerves.

Region: Pelvis & Hip

Clinical Relevance

Clinical Notes

The sacral sympathetic chain and ganglion impar are relevant in interventional pain management for pelvic and perineal pain syndromes, coccydynia, and sympathetically maintained pain of the perineum. Ganglion impar block (injection of local anaesthetic at the sacrococcygeal junction targeting the fused terminal sympathetic ganglion) is used for intractable coccygeal and perineal pain from malignancy, radiation proctitis, and chronic proctalgia. Pelvic hyperhidrosis involving the perineum and lower buttocks is treated by sacral sympathectomy targeting these ganglia.

Pathology

Common Injuries & Conditions

Ganglion Impar Block for Intractable Perineal Pain

Fluoroscopy-guided needle placement at the sacrococcygeal disc or ligament targets the ganglion impar — the terminal fusion of the sacral sympathetic chains — with local anaesthetic and steroid injection providing relief for intractable coccydynia and perineal pain from malignancy or radiation injury.