In meralgia paresthetica, which nerve and root levels are typically affected?

In meralgia paresthetica, which nerve and root levels are typically affected?

• A. Obturator nerve; L2–L4
• B. Lateral femoral cutaneous nerve; L2–L3
• C. Femoral nerve; L2–L3
• D. Ilioinguinal nerve; L1–L2

Answer: (B)

Meralgia paresthetica is caused by compression of the lateral femoral cutaneous nerve as it passes under the inguinal ligament near the ASIS, leading to sensory symptoms on the outer aspect of the thigh. This nerve is purely sensory and arises from the lumbar plexus at L2–L3 (often with contributions from L1–L3). So the typical root levels involved are L2–L3. The other nerves listed would affect different regions: the obturator nerve supplies the medial thigh, the femoral nerve supplies the anterior thigh, and the ilioinguinal nerve supplies the groin and proximal medial thigh. Thus, the lateral femoral cutaneous nerve with L2–L3 roots best fits the presentation of meralgia paresthetica.

Meralgia paresthetica is caused by compression of the lateral femoral cutaneous nerve as it passes under the inguinal ligament near the ASIS, leading to sensory symptoms on the outer aspect of the thigh. This nerve is purely sensory and arises from the lumbar plexus at L2–L3 (often with contributions from L1–L3). So the typical root levels involved are L2–L3. The other nerves listed would affect different regions: the obturator nerve supplies the medial thigh, the femoral nerve supplies the anterior thigh, and the ilioinguinal nerve supplies the groin and proximal medial thigh. Thus, the lateral femoral cutaneous nerve with L2–L3 roots best fits the presentation of meralgia paresthetica.