An ultrasonographic and histological study of intraneural injection and electrical stimulation in pigs.
BACKGROUND
In this study we evaluated the minimum stimulating current associated with intraneural needle placement and sonographic appearance of intraneural injection.


METHODS
We inserted a needle 2 cm inside 28 pig nerves (brachial plexus in vivo), recorded the minimum current to elicit a motor response, and injected dye (5 mL) under ultrasound (US) imaging.


RESULTS
The minimum current to elicit a motor response was 0.43 mA (range: 0.12-1.8 mA). Nerve expansion was visualized by US in 24 of 28 nerves. Histology revealed penetration of the epineurium in these same 24 nerves. There was no evidence of dysplasia within the fascicle of any nerve.


CONCLUSIONS
US may prove useful to detect intraneural injection, whereas a motor response above 0.5 mA may not exclude intraneural needle placement. The correlation between intraneural injection and neurological dysfunction remains unclear.
Chan
Vincent W S
VW
Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada. vincent.chan@uhn.on.ca
Brull
Richard
R
McCartney
Colin J L
CJ
Xu
Daquan
D
Abbas
Sherif
S
Shannon
Patrick
P
D000818:Animals; D001917:Brachial Plexus / Q000166:cytology* / Q000000981:diagnostic imaging* / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006652:Histological Techniques / Q000379:methods; D007267:Injections; D009339:Needles; D013552:Swine; D014463:Ultrasonography