Compression of the Lateral Femoral Cutaneous Nerve (LFCN)

Background

This condition is also called Meralgia Paresthetica. It remains poorly understood and underdiagnosed. It is characterized by numbness, tingling and burning pain in the outer thigh in the distribution of the lateral femoral cutaneous nerve.

Causes

The causes vary and can range from direct repetitive pressure to the area in the groin from tight clothing or a tool belt, weight fluctuation and direct trauma to the area. Diabetics can develop this nerve compression, similar to other compressions that are common in this patient population such as carpal tunnel and tarsal tunnel syndrome.

Symptoms

Pain and/or numbness and tingling in the anterolateral thigh. The site of compression is usually in the groin area where the inguinal ligament is located. This area can be point tender.

Diagnosis

The diagnosis is made largely clinically based on history and a thorough physical exam, although an MRI or high frequency ultrasound can be very helpful in making an accurate diagnosis. Diagnostic injections can be helpful in confirming the diagnosis, but even when steroids are administered, the effect of the injection will often wear off after several months. Occasionally, physical therapy can be helpful.

Treatment

The more definitive treatment is surgical decompression, which is a relatively simple procedure which is carried out via a short incision near the groin crease. Dr. Dowlatshahi strongly prefers preserving the nerve where possible as opposed to the commonly performed neurectomy which is removal of the nerve with permanent numbness and tingling in the outer thigh, and the possibility of developing a painful neuroma. The nerve preservation approach involves carefully and methodically following the nerve up under the groin/inguinal ligament and decompressing it completely.

This is the example of a standard decompression which resulted in resolution of this patient's pain after 10 years of agony (without exaggeration). The site of compression was obvious. Not all cases are this satisfying, but occasionally, an excellent result can be obtained.

The LFCN is seen being compressed and tethered by two discrete fascial bands. Once they are released, the indentation within the nerve is clearly visible.

In this case, the patient was an adolescent that had undergone prior surgery for a hip issue. During the decompression, there was a very large neuroma that was treated by excision and performing RPNI, see the neuroma section.