Ultrasonographic imaging of the sciatic nerve in the thigh

Ultrasound examinations of the sciatic nerve were performed using high-reso lution transducers (7.5, 10 to 20 MHz) both in anatomical specimens and in healthy volunteers. The ultrasonographic anatomy (sono-anatomy) of the nerve, its course along the thigh and its echogenicity in comparison with muscles, tendons and adip ose tissue were investigated in 10 isolated muscle/nerve preparations. In a ddition, the influence of the angle of the applied transducer on the variou s different tissues was evaluated. In the clinical part of the study, the sciatic nerve was identified ultraso nographically in both thighs of 50 sex-matched healthy volunteers aged betw een 2 and 76 years. The normal sciatic nerve presents as a tubular echogenic structure with par allel linear internal echoes in the longitudinal section, and as a punctifo rm moderately echoic structure in cross-section, with the perineurium produ cing bright boundary echoes. Varying the insonating angle of the transducer reduced echogenicity, but to a smaller degree than in muscles and tendons. Unequivocal identified of th e sciatic nerve from the level of the gluteal fold to its bifurcation in th e distal thigh was possible in all but one case. We conclude that the course of the sciatic nerve along the thigh can be rel iably identified and imaged with high-resolution ultrasound.