Keywords:
Tissue characterisation, Education and training, Localisation, Diagnostic procedure, Ultrasound-Colour Doppler, Ultrasound, Neuroradiology peripheral nerve, Musculoskeletal system, Anatomy
Authors:
M. De Cesari1, E. Massone1, G. Rebella1, S. Perugin Bernardi2, G. Buonomenna1, V. Picasso2, A. Muda2, D. Orlandi2, E. Silvestri1; 1Genoa/IT, 2Genova/IT
DOI:
10.26044/essr2019/P-0056
Imaging findings OR Procedure Details
For the US examination of the saphenous nerve it is necessary to use transverse images (short axis) and apply the so-called elevator technique which consists of finding landmarks and ‘tracking it’ distally or prossimally.
In this way,
it is possible to assess the nerve as a small round hyperechoic structure,
visualize its surface area and the vasculature; the longitudinal view become important if an abnormality is seen.
A detailed ultrasound approach is:
1.
Place the transducer in a transverse plane at the middle third of the medial aspect of the thigh and identify the sartorius muscle as a thin muscle belly under the subcutaneus layer of adipose tissue.
The saphenous nerve is situated between the sartorius muscle medially and the vastus medialis muscle laterally (Fig.2);
2.
Use color Doppler modules to identify the femoral vessels: the femoral artery runs laterally to the nerve;
3.
Identify Hunter’s canal: the Sartorius muscle forms the “roof” of the adductor canal and runs lateral to medial across the anterior thigh.
The sides of the triangular canal are formed by the vastus medialis laterally and adductor longus (proximally) and magnus (distally) medially; when the patient present deep pain at level of the thigh,
knee pain,
loss of sensation over the medial aspect of the leg,
evaluate the entrapment neuropathy very frequent at this level and often due to a muscular hipertrophy (Fig.3);
4.
Move the probe caudally following the nerve toward the posteromedial aspect of the distal thigh until its emergency from the fascia lata (between sartorius and gracilis) to becomes a subcutaneous nerve;
5.
Place the transducer in a transverse plane on the anteromedial aspect of the knee at the level of the tibial tuberosity; follow the saphenous nerve along the tibial margin adjacent to the large saphenous vein (Fig.4);
6.
Place the probe in a transverse plane just anterior to the medial malleolus: the saphenous nerve is located medially to the saphenous vein which is positioned subcutaneously (Fig.5).