Question

What is the root value responsible for Meralgia paresthetica?

• A. T12 and L1
• B. L2 and L3
• C. L2, L3 and L4
• D. L1 and L2

Hint:

Meralgia paresthetica = lateral femoral cutaneous nerve compression = L2, L3.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks for the spinal nerve root values of the nerve whose compression results in the clinical syndrome known as Meralgia paresthetica.
This condition specifically involves the Lateral Femoral Cutaneous Nerve (LFCN).
Step 2: Detailed Explanation:

Definition of Meralgia Paresthetica: This is a sensory mononeuropathy characterized by numbness, tingling, and burning pain in the outer part of the thigh.

Anatomical Cause: It is caused by the compression of the Lateral Femoral Cutaneous Nerve as it passes under the inguinal ligament, often near the anterior superior iliac spine (ASIS).

Origin of the LFCN: The LFCN is a branch of the lumbar plexus. It is formed by the posterior (dorsal) divisions of the anterior rami of the L2 and L3 spinal nerves.

Functional Nature: The LFCN is a purely sensory nerve. This is a critical diagnostic point because Meralgia paresthetica does not involve muscle weakness or reflex changes.

Risk Factors for Compression: Obesity, pregnancy, wearing tight belts or low-rise trousers, and heavy tool belts are common causes for the nerve to become pinched under the inguinal ligament.

Analyzing Options: Based on the lumbar plexus anatomy, L2 and L3 are the only roots contributing to the LFCN. L1 contributes to ilioinguinal/iliohypogastric, and L2-L4 contribute to the Femoral and Obturator nerves.

Step 3: Final Answer:
The lateral femoral cutaneous nerve, which mediates Meralgia paresthetica, originates from the L2 and L3 nerve roots.