Lumbar sympathetic blockade is useful for diagnosing and treating pain of sympathetic origin. This includes pain involving the pelvis and lower extremity, secondary to complex regional pain syndrome, vasospastic disorders, and phantom pain.
The spinous process of the second or third lumbar vertebra is palpated, and a point is marked 4 cm lateral to the middle of the spinous process. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 4-in. (10-cm), 22-gauge needle is inserted and advanced cephalad until contact is made with the transverse process. The needle is pulled back to skin level and redirected to pass between the transverse processes and alongside the anterolateral aspect of the vertebral body. After negative aspiration, 20 mL of local anesthetic is injected (Fig. 67-10).
FIGURE 67-10. Lumbar sympathetic approach. Fluoroscopic approach for lumbar sympathetic injection and neural blockade (arrow ).
This technique is commonly used for differential diagnosis and is the preferred treatment of sympathetic mediated pain involving the lower extremity. The lumbar sympathetic ganglia are located along the anterior lateral surface of the lumbar vertebral bodies and anteromedial to the psoas muscle. Autonomic mediated pain does not usually correspond to segmental or peripheral nerve distribution. Lateral and anteroposterior fluoroscopic views are recommended to ensure that the needle is properly positioned. It is recommended that intravenous access be available before the block in the event of local anesthetic toxicity and resulting seizure activity. Rarely are ablative nerve procedures (neurolysis) required in the management of sympathetic mediated pain.
These injections are normally completed with fluoroscopic guidance, as noted in Chapter 68. Performance of this procedure outside of a fully monitored environment is not recommended. Resuscitation equipment and personnel must be readily available. Although appearing technically simple, this block has multiple hazards, owing to the proximity to the aorta, inferior vena cava, kidney, pancreas, and intestines. Intraarterial or intradural injection of local anesthetic may result in death, seizure, respiratory arrest, cardiac arrest, cerebral damage with multiple sequelae, and other lesser complications. The risk for intravascular injection may be reduced if a test dose is given, the total dose is injected incrementally, and aspiration is performed before each injection. Significant hypotension from the sympathetic block is possible but usually does not occur with unilateral block.