Comparison of percutaneous electrical nerve stimulation and ultrasound imaging for nerve localization.
BACKGROUND
Percutaneous nerve stimulation (PNS) is a non-invasive technique to localize superficial nerves before performing peripheral nerve blocks, but its precision has never been evaluated by high-resolution ultrasound. This study compared stimulating points at the skin with the position of nerve structures determined by ultrasound. Correlations between distances and percutaneous stimulation thresholds were determined.


METHODS
PNS was performed in 20 healthy volunteers systematically with a stimulating pen at the neck after attaching a transparent film with 49 (7×7) perforations. Stimulation thresholds were measured and impedance was controlled. Thereafter, an independent observer measured the depth (D) of the most superficial nerve structure with ultrasound. Distances between stimulating points and the most superficial nerve structure (S) were measured. Correlations between associated stimulating thresholds and distances D and S were calculated.


RESULTS
The stimulating point with the lowest current was identical to the point closest to the nerve in only 10% of measurements. Median S was 12.6 (3.4-32.0) mm and D 7.6 (0.3-28.6) mm. Distances did not correlate with percutaneous stimulation thresholds.


CONCLUSIONS
PNS with a stimulating pen is not a reliable technique for nerve localization in the brachial plexus as verified by high-resolution ultrasound.
Department of Anesthesiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
J T
JT
Wegener
Z J
ZJ
Boender
B
B
Preckel
M W
MW
Hollmann
M F
MF
Stevens
D000328:Adult; D000368:Aged; D001917:Brachial Plexus / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D011446:Prospective Studies; D012867:Skin / Q000294:innervation*; D018084:Ultrasonography, Interventional / Q000379:methods