The hypogastric sympathetic plexus is situated at the inferior end of the sympathetic chain and is located just anterior and slightly lateral to the L5-S1 intervertebral disc space (Figure 12.5). It is in close proximity to the iliac artery and vein.
Indications for hypogastric plexus blockade include the following:
Upper pelvic malignant pain Endometriosis to the upper pelvis
Figure 12.5. The hypogastric sympathetic plexus and the impar ganglion. Variability in location occurs, and the intended block is anterior to the L5-S1 disc and anterior to the sacrococcygeal junction, respectively.
The technique for hypogastric plexus blockade involves placement of needles from posterior to anterior by means of fluoroscopic or CT guidance.2,6 The needles pass in an anterior fashion and slightly superior to inferior over the iliac crest in a lateral to medial angulation. The needle tips will lie just anterior to the L5-S1 disc space. Aspiration followed by injection 3 to 5 mL of radiographic contrast material ensures that the needle tips are not in a vascular structure (Figure 12.6).
Figure 12.6. (A) Hypogastric plexus blockade in a prone patient. In this posteroanterior view, the needle is directed fluoroscopically from a starting point slightly superior to the iliac crest and lateral to the spine in an inferior-medial direction (arrow). The tip of the needle is situated anterior to L5-S1. Radiographic contrast material (arrowheads) should spread along the prespinus area but should not be in vessels or the bowel. (B) The lateral view confirms the trajectory of the needle (arrows). The needle tip lies immediately anterior to the L5-S1 disc. Radiographic contrast material (arrowheads) spreads along the anterior aspect of the L5-S1 disc without evidence of spread into the bowel or adjacent vessels.
Following confirmation of optimal needle tip location, treatment can be with either 10 to 15 mL of bupivacaine 0.25% for temporary relief. For permanent neurolysis, 10 mL of absolute alcohol (or 6% phenol) is injected (with the patient under general anesthesia).
Complications result from intravascular injection of alcohol or phenol or injury to the bowel from injection of these substances.
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