Comparing the Anatomy of the Lateral Femoral Cutaneous Nerve in Patients With and Without Meralgia Paresthetica: A Systematic Review and Meta-Analysis.

The anatomical variations of the lateral femoral cutaneous nerve (LFCN) are well documented, with several studies hypothesizing that specific variants may increase the LFCN's susceptibility to meralgia paresthetica (MP). This systematic review and meta-analysis aimed to compare the prevalence of LFCN anatomical variations among limbs with and without MP. It also sought to determine if the LFCN's cross-sectional area (CSA) on ultrasound differed between limbs with and without MP. PubMed, SCOPUS, CINAHL, and Cochrane databases were used to query publications from inception to June 13, 2024. Included studies had a population of living patients, with or without the diagnosis of MP, and reported on the LFCN's exit from the pelvis, branching patterns, distance from the anterior superior iliac spine (ASIS), and/or CSA on ultrasound. Eighteen studies were included, nine retrospective and nine prospective, with a total of 1512 nerves. The LFCN in limbs with MP was closer to the ASIS (p < 0.01) and the MP limbs had a higher percentage of nerves exiting the pelvis lateral to or over the ASIS (p < 0.01) when compared to healthy limbs. The CSA was larger in the nerves affected by MP compared to the unaffected nerves (p < 0.01). The results demonstrate that specific anatomical variations of the LFCN, where the nerve courses in a more lateral or superficial position, may increase its susceptibility to developing MP. The differences in nerve CSA also show the potential utility of ultrasound as a diagnostic adjunct for MP.