Ultrasound-guided lumbar sympathetic block is useful in the diagnosis and treatment of a variety of painful conditions including reflex sympathetic dystrophy of the pelvis and lower extremity, causalgia involving the lower extremity, acute herpes zoster in the distribution of the lumbosacral dermatomes, hyperhidrosis, phantom limb pain, peripheral neuropathies, sympathetically mediated pain of malignant origin, and ureteral calculi (Fig. 114.1). Ultrasound-guided lumbar sympathetic block is useful in the diagnosis and treatment of a number of diseases that have in common their ability to cause acute vascular insufficiency. These diseases include acute frostbite, acute angina, ergotism, obliterative vascular disease, Raynaud disease, scleroderma, vasospastic disorders, posttraumatic vascular insufficiency, and embolic phenomenon (Table 114.1). Ultrasound-guided stellate ganglion block can also be used in a prognostic manner to determine the effect of blockade of the lumbar sympathetic chain prior to surgical sympathectomy in the lumbar region. Destruction of the lumbar sympathetic chain is a reasonable next step in the palliation of pain syndromes that have responded to lumbar sympathetic blockade with local anesthetic.

The preganglionic fibers of the lumbar sympathetic nerves exit the intervertebral foramina along with the lumbar paravertebral nerves (Fig. 114.2). After exiting the intervertebral foramen, the lumbar paravertebral nerve gives off a recurrent branch that loops back through the foramen to provide innervation to the spinal ligaments, meninges, and its respective vertebra. The upper lumbar paravertebral nerve also interfaces with the lumbar sympathetic chain via the myelinated preganglionic fibers of the white rami communicantes. All five of the
lumbar nerves interface with the unmyelinated postganglionic fibers of the gray rami communicantes. At the level of the lumbar sympathetic ganglia, preganglionic and postganglionic fibers synapse. Additionally, some of the postganglionic fibers return to their respective somatic nerves via the gray rami communicantes. Other lumbar sympathetic postganglionic fibers travel to the aortic and hypogastric plexus and course up and down the sympathetic trunk to terminate in distant ganglia.

In many patients, the first and second lumbar ganglia are fused. These ganglia and the remainder of the lumbar chain and ganglia lie at the anterolateral margin of the lumbar vertebral bodies (see Figs. 114.2, 114.3 and 114.4). The peritoneal cavity lies lateral and anterior to the lumbar sympathetic chain. Given the proximity of the lumbar somatic nerves to the lumbar sympathetic chain, the potential exists for both neural pathways to be blocked when performing blockade of the lumbar sympathetic ganglion.