The fascia iliaca compartment approach to lumbar plexus block has the advantage over the Winnie 3-in-1 technique of having a higher success rate than the Winnie technique for blockade of the lateral femoral cutaneous and obturator nerves as well as the femoral branch of the genitofemoral nerve. It also has an advantage over the psoas compartment technique because it is amenable to continuous infusion of local anesthetic by placement of either an 18-gauge intravenous catheter or an overthe-wire central venous catheter into the fascial plane. Lumbar plexus nerve block via the fascia iliaca compartment technique is used primarily for surgical anesthesia of the lower extremity. It is seeing increasing use in the pediatric population. This technique occasionally is used in pain management for the treatment of pain secondary to inflammatory conditions of the lumbar plexus or pain associated with tumor that has invaded the tissues innervated by the lumbar plexus or the plexus itself.

Lumbar plexus nerve block via the fascia iliaca compartment technique with local anesthetic occasionally is used diagnostically when differential neural blockade is performed on an anatomic basis in the evaluation of lower-extremity and groin pain. If destruction of the lumbar plexus is being considered, this technique can be used in a prognostic manner to indicate the degree of motor and sensory impairment that the patient may experience.

Lumbar plexus nerve block via the fascia iliaca compartment technique with local anesthetic may be used for palliation in acute pain emergencies, including groin and lower-extremity trauma or fracture, acute herpes zoster, and cancer pain, during the wait for pharmacologic, surgical, and antiblastic therapies to take effect (Fig. 112.1). Lumbar plexus nerve block via the fascia iliaca compartment technique with local anesthetic and steroid also is useful in the treatment of lumbar plexitis secondary to viral infection or diabetes. For most surgical and pain management applications, epidural or subarachnoid block is a better alternative, although one should expect fewer cardiovascular changes with lumbar plexus block than with epidural or subarachnoid techniques. Destruction of the lumbar plexus is indicated for the palliation of cancer pain, including pain secondary to invasive tumors of the lumbar plexus and the tissues that the plexus innervates. More selective techniques such as radiofrequency lesioning of specific lumbar paravertebral nerve roots may cause less morbidity than lumbar plexus neurolysis.

The lumbar plexus lies within the substance of the psoas muscle. The plexus is made up of the ventral roots of the first four lumbar nerves and, in some patients, a contribution from the 12th thoracic nerve (Fig. 112.2). The nerves lie in front of the transverse processes of their respective vertebrae; as they course inferolaterally, they divide into a number of peripheral nerves. The ilioinguinal and iliohypogastric nerves are branches of the L1 nerves with an occasional contribution of fibers from T12. The genitofemoral nerve is made up of fibers from L1 and L2. The lateral femoral cutaneous nerve is derived from fibers of L2 and L3. The obturator nerve receives fibers from L2 to L4, and the femoral nerve is made up of fibers from L2 to L4. The pain management specialist should be aware of the considerable interpatient variability in terms of the actual spinal nerves that provide fibers to make up these peripheral branches. This variability means that the findings of differential neural blockade on an anatomic basis must be interpreted with caution. Because these nerves pass anteriorly beneath the inguinal ligament, they are accessible to blockade via the lumbar plexus nerve block technique.

The anatomic basis for using the fascia iliaca compartment plane block is to block the femoral and lateral cutaneous nerve as they lie beneath the fascia iliaca (Fig. 112.3). Solutions injected in beneath the fascia iliaca flow cranially to bathe the lateral femoral cutaneous nerve, the femoral nerve, and the obturator nerve as they pass below the inguinal ligament and given the large volumes of local anesthetic used with this technique, the injected solution may flow cranially to block portions of the lumbar plexus.