Modified Approach for Lateral Femoral Cutaneous Nerve Decompression in Patients with Meralgia Paresthetica

Abstract

Sir: The compression mononeuropathy meralgia paresthetica typically results from a direct entrapment of the lateral femoral cutaneous nerve at the anterior superior iliac spine and inguinal ligament.1–3 Medical management includes antiinflammatory medications, glucose control, and/or weight loss. For patients with refractory symptoms lasting beyond 3 months, surgical decompression of the nerve at the anterior superior iliac spine and inguinal ligament is appropriate to ameliorate symptoms and return the patient to a normal lifestyle.1–4 Current surgical approaches involve lateral femoral cutaneous nerve access by means of direct inguinal ligament dissection, either by radial transection or dissection at the immediately proximal or distal ligament edge.1,4 These techniques may inadvertently injure the nerve because of the inability to directly visualize the nerve and the anatomical variability of the lateral femoral cutaneous nerve during decompression. We have defined a safer and more reliable approach to lateral femoral cutaneous nerve decompression based on studies of relevant lateral femoral cutaneous nerve anatomical variations and our clinical experience. The anterior superior iliac spine and pubic tubercle are marked, indicating the line of the inguinal ligament. A linear incision is made 1 cm medial to the vertical axis of the anterior superior iliac spine, extending from the upper inguinal ligament to 3 cm caudad. After dividing the subcutaneous tissues, the sartorius fascia is identified and the lateral femoral cutaneous nerve is exposed with blunt dissection in the upper thigh (Fig. 1, above). The nerve is defined distally, isolated, and traced proximally toward the inguinal ligament, the anterior superior iliac spine, and the retroperitoneal fascia for decompression. Decompression can require a direct release of the inguinal ligament and a distal portion of the external/internal oblique fascias to release anterior compression (Fig. 1, below) and allow medialization of the nerve, thereby decreasing anterior superior iliac spine compression.Fig. 1.: (Above) Surgical exposure demonstrating the prominent anterior superior iliac spine (semicircular line), the inguinal ligament (dotted line), and the course of the sartorius muscle (double line). After distal identification, the lateral femoral cutaneous nerve is dissected in a retrograde technique to directly visualize points of compression. (Below) Compression of the lateral femoral cutaneous nerve is identified between the anterior superior iliac spine and the inguinal ligament. Distal fibers of the inguinal ligament are released and demonstrate the close and variable relationship of the nerve. After decompression, the lateral femoral cutaneous nerve is easily mobilized medially from the anterior superior iliac spine.Multiple authors have confirmed the high variability of the lateral femoral cutaneous nerve, reporting 44 percent in direct apposition to the anterior superior iliac spine, or 27 percent that pass directly through the inguinal ligament.1,4,5 We identified the lateral femoral cutaneous nerve in an aberrant position along the anterior superior iliac spine in 73 percent of our patients, and found in severe cases the nerve compressed directly by a prominent anterior superior iliac spine and inguinal ligament.2 We previously reported 48 lateral femoral cutaneous nerve decompressions, and have since performed a total of 111, with 77 percent of patients reporting a “most-favorable” surgical outcome and relief of symptoms at a median of 4.5 weeks.2 Analogous to other entrapment syndromes, such as carpal tunnel syndrome, the nerve is at the highest risk of injury at the point of compression because of the pressure of the nerve against the entrapment band. Dissection at the point of maximum compression without first safely identifying and directly visualizing the course of the nerve may endanger the nerve. Also, because of the unpredictability in the point of emergence of the lateral femoral cutaneous nerve at the inguinal ligament, increased risk is incurred if the point of dissection is begun in the region of greatest variability. If instead the distal nerve is identified in the compliant region of the upper thigh, blunt dissection is adequate to appropriately identify the nerve independent of anatomical variability. Appropriate identification and retrograde decompression of the lateral femoral cutaneous nerve may prevent injury of the nerve as it passes through the inguinal tunnel and aids in the identification of the nerve course and points of compression. We have used this technique in a large patient volume for 6 years and find it to be reproducible, safe, and an improvement in the operative management of meralgia paresthetica. Ivica Ducic, M.D., Ph.D. Matthew L. Iorio, M.D. Department of Plastic Surgery Georgetown University Hospital Washington, D.C. DISCLOSURE The authors have no financial interest in the techniques discussed.