Lateral cutaneous nerve of thigh block

CHAPTER 29 Lateral cutaneous nerve of thigh block








Sonoanatomy


The LCNT nerve is found below the ASIS between the fascia lata and iliaca. These fascial layers are seen as hyperechoic lines. The appearance of the LCNT on ultrasound is as a round or oval hypoechoic (dark) area. Both branches of the LCNT cross the sartorius superficially. Due to the small size of the nerve and anatomical variability, a scanning routine is paramount. Scan initially with a transverse orientation in the medial thigh to identify the femoral vessels and nerve. With continued transverse scanning, move the transducer lateral and cephalad to identify the sartorius (triangular shape on transverse scan) insertion to the ASIS. Move the transducer caudally from here to the proximal third of the thigh (Fig. 29.3). The LCNT can be seen crossing the sartorius superficially or, alternatively, locate both fascial layers (fascia lata and iliaca) medial or lateral to the sartorius (Fig. 29.4). Injection of 5% dextrose between both fascial layers will help nerve visualization (Fig. 29.5). If the nerve is difficult to identify initially, a good focus point is the space between the sartorius and the more lateral tensor fascia lata. A sagittal oblique transducer orientation obtained by moving the medial aspect of the transducer to a slightly caudal position, parallel to the course of the nerve, can help identify the deep circumflex iliac artery (Fig. 29.6). This can be further identified with Doppler. This artery is crossed by the nerve, and can facilitate its identification (Fig. 29.6).


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Jul 28, 2016 | Posted by in ANESTHESIA | Comments Off on Lateral cutaneous nerve of thigh block
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