Ultrasound of the lateral femoral cutaneous nerve in asymptomatic adults

Yunxia Huang,Junjie Shao,Fang liu,Bing Hu,Yiwen Zhao,Jiaan Zhu

doi:10.1186/1471-2474-13-227

Abstract

BackgroundTo define the sites where the lateral femoral cutaneous nerve (LFCN) is more easily visualized and to describe the anatomical variations of the LFCN.MethodsA total of 240 LFCNs in 120 volunteers were evaluated with 18 MHz ultrasound; the intermuscular space between the tensor fasciae latae muscle and the sartorius was used as an initial sonographic landmark. The time taken to identify the nerve was recorded. The number of nerve branches at the level of the inguinal ligament (IL) and the relationship between the LFCN and the IL was assessed. The nerve cross-sectional area (CSA) of the LFCN and the distance between the LFCN and the anterior superior iliac spine was measured.ResultsEach nerve was identified using ultrasound in all participants. The mean time for identifying the nerve was 7s for unilateral LFCNs. The nerve passed under the IL in 198 cases, whereas in 44 cases, it passed through to the IL. The LFCN consisted of 1–4 branches just after its passage under or through the IL. The CSA of the LFCN was 1.04±0.44 mm2, and the mean distance between the LFCN and the anterior superior iliac spine was 15.6 ± 4.2 mm.ConclusionsIt is easier to identify the LFCN if the intermuscular space between the tensor fasciae latae muscle and the sartorius is used as an initial sonographic landmark. The anatomical variation of the LFCN can be viewed with high-frequency ultrasound.

Highlights

To define the sites where the lateral femoral cutaneous nerve (LFCN) is more visualized and to describe the anatomical variations of the LFCN
Our study suggested an easier method for identifying the LFCN in volunteers using the ultrasound technique
Anatomical structures are more differentiated if the different tissues have greater echo differentiation on the sonogram, which is especially important for identifying tiny structures

Summary

Introduction

To define the sites where the lateral femoral cutaneous nerve (LFCN) is more visualized and to describe the anatomical variations of the LFCN. The lateral femoral cutaneous nerve (LFCN) is a pure sensory nerve that arises from the L2 and L3 spinal nerve roots and travels downward lateral to the psoas muscle, and crosses the iliacus muscle. Near the anterior superior iliac spine (ASIS), the LFCN passes under or through the lateral aspect of the inguinal ligament (IL) and over the sartorius muscle into the thigh. The LFCN has received much attention because of its association with meralgia paresthetica [1,2]. The ASIS is a classical landmark for the LFCN in some surgical procedures and in regional anesthesia that involve nerve blocks for the treatment of meralgia paresthetica. The rate of successful anesthesia has only been approximately 40% based on the use of anatomical landmarks [9]

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