Ultrasound of the Lateral Femoral Cutaneous Nerve in Asymptomatic Adults

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

Disclosures

BMC Musculoskelet Disord. 2012;13(227) 

In This Article

Background

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 then crosses the iliacus muscle. Near the anterior superior iliac spine (ASIS), the LFCN then passes under or through the lateral aspect of the inguinal ligament (IL) and over the sartorius muscle into the thigh. Running caudally, the LFCN enters a lenticular compartment between the sartorius muscle and the tensor fasciae lata muscle, formed by a double layer of the fascia lata.[1] The LFCN has received much attention because of its association with meralgia paresthetica.[1,2] Knowledge of its anatomical variations is also crucial for preventing nerve injury during the insertion of needles into the ASIS,[3] the harvesting of the anterior iliac crest bone grafts,[4] and other surgical procedures.[5] LFCN grafts can also be used to repair facial nerve injuries and soft-tissue defects.[6,7]

Because of the anatomical variations in the course of the LFCN, it may be difficult to identify and protect it during surgical dissection.[4,5,8] 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. However, the rate of successful anesthesia has only been approximately 40% based on the use of anatomical landmarks.[9]

It is useful to visualize the LFCN for clinical practice. There are several promising studies about the ability of ultrasound in the evaluation of the LFCN,[10–12] the use of ultrasound guidance in regional anesthesia for blocking the LFCN[13–16] and the use of ultrasound in nerve conduction studies of the LFCN.[17] These ultrasonographic techniques involved the use of the ASIS, the IL, and the sartorius muscle as the landmarks to identify the LFCN. However, because of its small size and the similarities in the echo characteristics between the LFCN and the IL with 10–14 MHz ultrasound, it is not always easy to distinguish the LFCN from the surrounding tissues using ultrasound. In addition, to the best of our knowledge, ultrasound studies on the anatomical variations and the reference values of the LFCN are lacking in the literature. The main objectives of this study are to define the sites where the LFCN is more easily visualized and to describe the anatomical variations of the LFCN.

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