Visualization of the course of the sciatic nerve in adult volunteers by ultrasonography.
ABSTRACT The sciatic nerve block by the posterior approaches represents one of the more difficult ultrasound-guided nerve blocks. Our clinical experiences with these blocks indicated a point slightly distal to the subgluteal fold as an advantageous position to allow good ultrasonic visibility. In this study, we systematically scanned the sciatic nerve from the subgluteal fold to the popliteal crease, to determine an optimal point for ultrasonographic visualization.
After institutional approval and written informed consent, we recruited 15 volunteers to visualize the sciatic nerve from the subgluteal fold to the popliteal crease using a linear ultrasound probe in the range of 7-13 MHz. The ultrasonographic visibility of the sciatic nerve, nerve diameter (width and thickness), and skin-to-nerve distance at 20 equidistant points between the subgluteal fold and the popliteal crease were recorded.
The sciatic nerve could be successfully visualized in cross-section as a hyperechoic structure on ultrasound in all volunteers. In the course from subgluteal to the popliteal area, the shape of the sciatic nerve changed from flat to round, while the skin-nerve distance varied with the smallest skin-nerve distances at the popliteal crease and at 5.4 cm (on average) distal to the subgluteal fold. The best ultrasonographic visibility scores were found between 7.2 and 10.8 cm (on average) distal to the gluteal fold.
Between 5.4 and 10.8 cm from the subgluteal fold seems to be the best area to scan the sciatic nerve in terms of superficial nerve position and good ultrasonic visibility.
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ABSTRACT: In 2003 we introduced the concept of a sciatic nerve block performed in the midgluteal area at a fixed distance from the midline in all adults regardless of gender and/or body size. The anatomic basis for that study suggested that a subgluteal block could also be accomplished in a similar fashion. After informed consent, 20 patients were prospectively recruited. Patients were positioned in lateral decubitus. The needle insertion site was located in the subgluteal fold at 10 cm from the midline. The needle was advanced parallel to the midline until a sciatic nerve response was elicited. With a visible response at 0.5 mA, 30 mL 1.5% mepivacaine plus 1:200,000 epinephrine was slowly injected. Sensory anesthesia was tested on the plantar and dorsal aspects of the foot as well as the posterior thigh. Residents performed all blocks. The approach was 100% successful in locating the sciatic nerve with 3 attempts or less from a site located 10 cm from the midline. The block provided successful surgical anesthesia in 90% of the cases; 2 cases required local anesthetic supplementation. Only 3 patients developed anesthesia of the posterior thigh within 30 minutes of injection. This report shows that a sciatic nerve block can be performed in the subgluteal area at 10 cm from the midline in adult patients of both sexes and various sizes. Anesthesia of the posterior thigh is not consistently accomplished with this approach.Regional Anesthesia and Pain Medicine 01/2006; 31(3):215-20. · 3.46 Impact Factor
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ABSTRACT: Ultrasound is a novel method of nerve localization but its use for lower extremity blocks appears limited with only reports for femoral 3-in-1 blocks. We report a case series of popliteal sciatic nerve blocks using ultrasound guidance to illustrate the clinical usefulness of this technology. The sciatic nerve was localized in the popliteal fossa by ultrasound imaging in 10 patients using a 4- to 7-MHz probe and the Philips ATL HDI 5000 unit. Ultrasound imaging showed the sciatic nerve anatomy, the point at which it divides, and the spatial relationship between the peroneal and tibial nerves distally. Needle contact with the nerve(s) was further confirmed with nerve stimulation. Circumferential local anesthetic spread within the fascial sheath after injection appears to correlate with rapid onset and completeness of sciatic nerve block. Our preliminary experience suggests that ultrasound localization of the sciatic nerve in the popliteal fossa is a simple and reliable procedure. It helps guide block needle placement and assess local anesthetic spread pattern at the time of injection.Regional Anesthesia and Pain Medicine 01/2004; 29(2):130-4. · 3.46 Impact Factor
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ABSTRACT: We studied the anatomy of the sciatic nerve and its division into the tibial and peroneal part using handheld ultrasound in adults. We wanted to evaluate the feasibility of ultrasound-guided identification of the sciatic nerve in the popliteal fossa and the correlation of the findings by ultrasound with patients' characteristics. 74 volunteers were randomly selected. Using a handheld ultrasound system with a 5-10 MHz linear array probe the popliteal fossa and the back of the thigh were examined and measured. Using a caliper the distance of the joint line to the nerve division was measured. The sciatic nerve and its division were depicted by ultrasound. We could depict the sciatic nerve in all volunteers and its division in 53 of 74 (72%) volunteers. The position of nerve division showed large anatomic variation. A significant correlation between the width of the knee-joint line and the depth of the nerve division could be demonstrated. We conclude that handheld ultrasound is able to depict the sciatic nerves division. To block the nerve by one injection a more proximal access or visualization by mobile ultrasound is recommended. In addition the surrounding anatomic structures can be depicted as well.Ultraschall in der Medizin 01/2006; 26(6):496-500. · 4.12 Impact Factor