Hospital For Special Surgery: Ultrasound of the Month - Case 29

Patient History •

45 year old male with left anterolateral thigh numbness and tingling with intermittent burning sensation

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Patient also reports extreme sensitivity to heat and cold in this region

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No prior surgery

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MVA 2 months earlier with trauma to left hemipelvis (no fracture)

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Based on the clinical presentation, the diagnosis of meralgia paresthetica was considered most likely

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Ultrasound evaluation of the lateral femoral cutaneous nerve was requested with peri-neural anesthetic injection to confirm the diagnosis

Ultrasound of the Month – Case 29

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Lateral Femoral Cutaneous Nerve Anatomy

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Highly variable anatomy

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Usually passes deep to the inguinal ligament just medial to the anterior superior iliac spine (ASIS)

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Usually passes along the superficial lateral aspect of the proximal sartorius muscle

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The nerve is well visualized by both ultrasound and MRI

Ultrasound of the Month – Case 29

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Lateral Femoral Cutaneous Nerve Entrapment

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LFCN arises from the ventral primary rami of L2-L3

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Condition of LFCN compression is referred to as Meralgia Paresthetica

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Presents as burning, tingling, or numbness in the anterolateral thigh

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Common Causes •

Prior trauma (MVA with seat belt injury)

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Pregnancy

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Pelvic masses (fibroids,etc.)

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Obesity

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Pelvic tilt from leg-length discrepancy

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Diabetes

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Patient Outcome: •

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Following the ultrasound-guided anesthetic injection surrounding the nerve, the patient experienced symptomatic relief for several hours, confirming the diagnosis.

He is currently being treated with a combination of medication and physical therapy, with surgical decompression planned if symptoms persist.

Ultrasound of the Month – Case 29

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