Abstract ID: A1
Abstract Title: Ultrasound Localization of the Sciatic Nerve. A preliminary study
Poster Type: Either
ABSTRACT BODY
INTRODUCTION: Real time ultrasound imaging can guide nerve localization and needle placement during brachial plexus blocks (1). Reports of ultrasound imaging of the sciatic nerve, however, have been limited, and with varying success (2,3). This study evaluates the usefulness of ultrasound for anatomical examination and localization of the sciatic nerve in the subgluteal and popliteal regions.
METHODS: After IRB approval and informed consent, 8 volunteers (2 female and 6 male,24-54 years of age, 56-10 kg, 162-185 cm, ASA I physical status) underwent ultrasound examination of the sciatic nerve using a Philips-ATL HDI 5000 unit. In each subject the sciatic nerve was identified at 1)The gluteal fold using a curved C5-2 MHz probe and 2) The popliteal fossa, aproximately 7 cm cephalad to the knee crease with a linear L7-4 MHz probe. After nerve localization and skin sterilization, a 2 inch, 22G insulated needle (Stimuplex Braun medical) was inserted and advanced to contact the sciatic nerve under ultrasound guidance. A nerve stimulator was then turned on, and the minimum stimulating current to elicit a motor response below the knee was recorded. Data are summarized and expresed as mean ± SD.
RESULTS:The sciatic nerve was succesfully identified in 7 of the 8 subjects. In the transverse view, it appeared round or oval and hyperechoic relative to the surrounding tissues. The mean skin-to-nerve dstance was 3.8 ± 1.1 cm at the gluteal fold and 2.7 ± 0.4 cm in the polpliteal fossa. Needle localization was performed in 5 subjects at the gluteal fold and in 2 subjects at the polpliteal fossa. Motor response was elicited in these 7 subjects, but the minimum current required was higher than expected (0.9 ± 0.4 mA, range 0.6-1.5). Following the initial volunteer study, we have further applied ultrasound guided popliteal blocks in 20 patients undergoing elective foot or ankle surgery. Images of the sciatic nerve deviding into the peroneal and tibial components were captured (Fig 1 and 2)
CONCLUSION: Our preliminary data suggest clinical utility of current ultrasound technology in sciatic nerve localization and needle placement.
REFERENCES:
1) Perlas A, Chan V, Simons M. Brachial plexus examination and localization using ultrasound and electrical stimulation. A volunteer study. Anesthesiology 2003; 99:429-35
2) Hullander M, Spillane W, Leivers D, et al. The use of doppler ultrasound to assist with Sciatic Nerve Blocks. Regional Anesthesia 1991; 16:282-84
3) Heinemeyer O, Reimers C. Ultrasound of Radial, Ulnar, Median and Sciatic nerves in healthy subjects and patients with hereditary Motor and sensory neuropathies. Ultrasound in Med and Biol 1999; 25:481-85.
ATTACHED FILES
A1_abstract figures.doc
Reg Anesth Pain Med 2004; 29(2):A1