The Long Lost Tunnel of the Lateral Femoral Cutaneous Nerve: An Anatomical Description and Surgical Approach to Decompression
Jessica Truong, MD MSc1, Douglas C. Ross, MD, MEd2, Valerie Hurdle, MD3 and Tyler Beveridge, PhD1, (1)Western University, London, ON, Canada, (2)Plastic Surgery/ Hand and Upper limb Centre, St. Joseph's Health Centre University of Western Ontario, London, ON, Canada, (3)University of British Columbia, Kamloops, ON, Canada
Introduction
Meralgia paresthetica (MP), or mononeuropathy of the lateral femoral cutaneous nerve (LFCN) is characterized by pain, paresthesias, and sensory loss within the LFCN distribution of the anterolateral thigh, knee, and buttock. Although decompression is the most common surgical procedure, division and/or transposition have also been advocated. Multiple authors have noted the challenges of identifying the nerve intra-operatively primarily because of anatomic variability. The purpose of this study is to better describe the course of the LFCN in relation to the iliac crest, and in particular, inferior to the inguinal ligament.
Materials & Methods
22 embalmed human cadavers were used to examine the course of 44 LFCNs within the iliac fossa; measurements were taken at 1cm increments along the crest and in relation to the anterior superior iliac spine. Nine cadavers were used to examine 17 LFCNs in the thigh. The LFCN was identified by its cutaneous branches perforating the fascia lata. Cross-sectional samples were excised along its path to characterize its position relative to the fascia and muscles in the thigh using histology.
Results
The distance of the LFCN from the iliac crest decreases as it approaches the inguinal ligament. Specifically, the LFCN was 9.2±12.6mm medial (range -8.4mm to 52.3mm) and 18.3±16.7mm inferior (range 0 to 57mm) from the ASIS. Below the inguinal ligament, the LFCN travels along the lateral border of sartorius, within a fascial plane formed by anterior and posterior leaflets of the fascia lata for a length of 144.0±42.9mm, before perforating through to enter the subcutaneous tissue of the lateral thigh (n=21/21 cross-sectional samples). Inconsistently, the leaflets may fuse lateral to the LFCN creating a distinct fascial tunnel (n=6/21).
Conclusions
There is significant variation in the position of the LFCN within the iliac fossa and may enter the thigh at or medial to the ASIS. Inferior to the inguinal ligament, the LFCN travels a significant distance (144.0±42.9mm) within a fascial plane created by an anterior and posterior leaflet of the fascia lata. The lateral fusion of these layers can form a distinct fascial tunnel in some that may be an important area to decompress during the treatment for neuropathy of the LFCN; a putative approach is offered.
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