Clinical implications of topographic anatomy on the ganglion impar.

THE blockade of the ganglion impar, a single ganglion converged by the caudal ends of the two sympathetic trunks, has been described to relieve the intractable perineal pain of sympathetic origin in patients with rectal, anal, colon, bladder, or cervical cancer. The success rate of this method depends on the anatomical variability of the location of the ganglion, but its location has been variably reported from the anterior to the sacrococcygeal joint or the coccyx, to the tip of the coccyx. Accordingly, this study was performed to identify the location of the ganglion impar and to determine its shape and size and its topographic relation with the branch of the sacral nerve, in the hope that this might facilitate a more successful blockade of the ganglion.