Ultrasound-guided sciatic nerve block in Wistar rat cadavers: Relevant anatomy and injection distribution

The effect of sciatic nerve block on sciatic nerve depth and pain level in patients with ankle fracture based on different approaches under ultrasound guidance

To investigate the clinical efficacy of using different approach sciatic nerve blocks on the sciatic nerve depth and pain degree in patients with ankle fracture. A retrospective analysis was conducted on 151 patients with ankle fractures who were admitted to the hospital from May 2020 to May 2023. The patients were divided into a control group (n=76) using the greater trochanteric plane approach (GTA) and an observation group (n=75) using the suprapopliteal approach (PA). Perioperative related indexes, pain levels, muscle strength, hemodynamic indexes, and adverse reactions were compared between the two groups. There was no significant difference in operation time between the two groups. The nerve block operation time and onset time were lower in the observation group, while the maintenance time of nerve block was higher in the observation group(P<0.05). The visual analogue scale (VAS) scores at 2h, 12h, and 24h postoperatively were lower in the observation group. Muscle strength of the posterior femoral muscle group was significantly better in the observation group at 8h after surgery. Hemodynamic indexes were lower in the observation group at 15minutes and 30minutes after anesthesia. The total incidence of adverse reactions was lower in the observation group compared to the control group. Ultrasound-guided sciatic nerve block using the suprapopliteal approach in patients with ankle fractures can help stabilize muscle strength and hemodynamics, alleviate pain symptoms, and avoid motor block and adverse reactions. This approach is recommended for adoption.

Ultrasound-guided and 'blind' sciatic nerve injection techniques: Comparison in rat cadavers

OBJECTIVE

To compare the success rate and extent of sciatic nerve staining with a bupivacaine-dye solution using two injection techniques: 'blind' or ultrasound-guided approach.

STUDY DESIGN

Prospective, experimental, randomized, cadaveric study.

ANIMALS

Adult female Wistar rat cadavers [n = 24, mass 352 g (323-374)].

METHODS

Each sciatic nerve was randomly allocated to one of two groups: 'blind' (group B) or ultrasound-guided approach (group US) to injection. Following injection of bupivacaine-dye solution (0.1 mL), gross anatomical dissection was performed to visualize nerve staining, categorizing it as either positive or negative. The length of nerve staining was then measured and visual inspection conducted to identify potential nerve damage. Fisher's exact test was used to compare positive or negative nerve staining, and the Wilcoxon signed rank test used to compare the length of nerve staining between groups.

RESULTS

In group B, the bupivacaine-dye solution stained 16/24 sciatic nerves (67% success). In group US, staining was successfully observed in all 24 nerves (100% success, p < 0.004). The length of nerve staining [median (interquartile range)] was 2 (2-3) mm in group B and 5 (4-6) mm in group US (p < 0.001). One sciatic nerve in group B had injectate distributed over 16 mm, suggestive of an intraneural injection. No signs of laceration or nerve damage were visible under 6× magnification in either group.

CONCLUSIONS AND CLINICAL RELEVANCE

The ultrasound-guided approach for sciatic nerve injection demonstrated a higher success rate with superior injectate distribution when compared with the 'blind' approach. Ultrasound guidance is recommended over a 'blind' approach for sciatic nerve block in rats when possible.