meralgia paresthetica is lateral thigh pain in obese patients

Meralgia paresthetica is a common cause of lateral thigh symptoms in obese patients.  It is caused by compression of the lateral femoral cutaneous nerve at the waist and has been linked to tight-fitting clothing.  Patients with meralgia paresthetica may demonstrate altered sensory findings in a specific region at the lateral and anterior thigh, but the knee is spared and no tenderness is noted.

This patient’s clinical presentation is consistent with meralgia paresthetica, a pure sensory syndrome due to lateral femoral cutaneous nerve (LFCN) compression.  This condition is usually seen in patients who are pregnant, obese, diabetic, or who wear tight pants or belts.  Patients typically present with sensory symptoms in the distribution of the LFCN (anterolateral thigh), which originates in the upper lumbosacral plexus (L2-L3) and runs underneath the inguinal ligament where it can frequently be compressed.

The LFCN is a pure sensory nerve, and therefore patients will not present with any symptoms of weakness.  Diagnosis is made clinically, but MRI of the lumbar spine or EMG/NCS may be needed in equivocal cases to rule out other causes.  Since meralgia paresthetica is a benign and self-limited condition, conservative treatment (e.g., avoiding tight garments, weight loss) improves symptoms in > 90% of patients.  Patients with persistent symptoms for > 2 months may respond to anticonvulsants (e.g., gabapentin) or local nerve block.

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