UIA - Ultrasound Innovation Award

Ultrasound Innovation Award

Online Abstract Submission

(Author: Marco Fondi )

Abstract

Type: New imaging technique

Title: Sciatic nerve imaging in the gluteal region with linear probe

Disclosure Statements

My research & development of my invention is not supported by a commercial company

Abstract

It is generally agreed thet sciatic nerve may be difficult to be visualized with US in the gluteal region due to its supposed depth, and a low frequency curved probe is mostly preferred. We have found the the sciatic nerve is quite easily visualized even with a linear multifrequency probe(Esaote 5-12 MHz) provided that a fundamental key point be respected: the probe has to be kept at the right proper angle to the nerve, and must follow the convex course of the nerve in the gluteal area toward the greater sciatic notch. In the figure 1. is showed the longitudinal convex course of the sciatic nerve in the gluteal region. In the figure 2. is showed the usual sequence of probe inclinations sliding from subgluteal to parasacral regions, necessary to keep the right beam angle respect to the sciatic nerve for optimal visualization. A the low gluteal level. between ischial tuberosity and greater trochanter, the sciatic nerve is visualized as an hyperechoic oval medially contacting the common hamstring tendon and ischial tuberosity, while liyng on the quadratus femoris m., this latter easy recognizable as a wide hypoechoic band (fig 3) At this level the nerve is noticed as an hyperechoic oval or triangle, flat or inclined rather medially (fig 4). Sliding cranially toward the 3 small rotators mm. region, the sciatic nerve is observed to change inclination in opposite direction, becoming inclined laterally (fig 4), reflecting the the different level and orientation of the gemellus inferior m. as floor. , which attaches at the most prominent ischial tuberosity point (fig 5). Sliding with the probe further step cranially makes the sciatic nerve being observed always laterally inclined, now laying on the obturator internus-gemellus superior muscle, having laterally the piriformis muscleb at Labat level(fig 6). Sliding the probe further up the scietic nerve is seen entering between superior gemellus m. and piriformis m. still contacting the ischial bone (fig 7). Further cranial, at the parasacral region, the sciatic nerve is observed to slide under piriformis muscle, entering the pervis cavity (fig 8). Another key point very useful to recognize the sciatic nerve in difficult cases, is represented by the pulsation of the inferior gluteal artery, which is always medial to the nerve (fig. 9). Videoclips 1 and 2 show noted sonoanatomy from lower gluteal to parasacral region. videoclip 3 demonstrate that sciatic nerve and associate gluteal sonoanatomy ca be oserved and recognised even in the obese patient. Videoclip 4 demonstrate the constant mark of the inferior gluteal artery medial to the sciatic nerve at Labat block level. Videoclip 5 demonstrates the common finding of rich vascularity around the sciatic nerve at the gluteal region. Videoclip 6 shows an US guided Labat sciatic gluteal block: out of plane needle and local anesthetic spread can be observed and the block can be done without nerve stimulator aid.

Clinical Significance

With some practice, sciatic nerve and sorrounding vascular and musculoskeletal sonoanatomy at the gluteal region can be visualized in detail with a multifrequency 5-12 MHz linear probe. Also easy US needle guidance and clear evaluation of adeguate local anesthetic spread allow the gluteal sciatic nerve block to be done very successfully without nerve stimulator assistance.

Ultrasound Equipment

Manufacturer: ESAOTE

Model: MyLab 25

Probe Used

Type: linear

Size: 4 cm

Frequency: 5-12

Files

1. Filename: figure 1.jpg