Nashaat N. Rizk
Patient Position: Supine, with the thigh in a neutral position.
Indications: In the diagnosis and treatment of meralgia paresthetica, a neuritic type of pain in the lateral aspect of the thigh. Also can be used for surgical anesthesia for tourniquet pain in lower limb surgery and for skin graft harvest.
Needle Size: 50-mm insulated needle.
Medication/Volume: 0.25% bupivacaine 7 mL and 40 mg Depo-Medrol (Pharmacia Canada, Inc., Hamilton, Ontario, Canada) for a total of 8 mL.
Anatomic Landmarks: Anterior superior iliac spine, pubic tubercle, and the inguinal ligament.
Approach and Technique: After sterile preparation of the region, the most medial part of the anterior superior iliac spine is palpated, and a point 1 cm medial to it is marked. Next, a vertical line is extended caudally just below the inguinal ligament to determine the site of introduction of the needle (Fig. 71-1). The site is prepared with Betadine (Purdue Pharma L.P., Stamford, CT). Next, a 50-mm insulated needle connected to a nerve stimulator (1.5 mA, 2 Hz, 0.3 ms) is introduced perpendicular to the skin until paresthesia on the lateral border of the thigh is elicited. The needle position is adjusted to maintain the paresthesia with a current of 0.6 mA. After negative blood aspiration, the local anesthetic mixture is slowly injected. The needle is removed, and a Band-Aid (Johnson & Johnson, Somerville, NJ) is applied.
1. This block can be performed without the use of a nerve stimulator, but the nerve stimulator increases the success rate.
Figure 71-1. Introduction of the needle.
Bridenbaugh PO, Wedel DJ. The lower extremity: somatic blockade. In: Cousins MJ, Bridenbaugh PO. Neural blockade in clinical anesthesia and management of pain, 3rd ed. Philadelphia: Lippincott-Raven, 1998.
Waldman SD. Lateral femoral cutaneous nerve block. Atlas of interventional pain management. Philadelphia: WB Saunders, 1998.