Abstract
Objective
To describe the gross and microscopic anatomy of the sciatic nerve paraneural sheath
and to report an ultrasound (US)-guided subparaneural approach to the sciatic nerve
in dogs, comparing two different volumes of injectate.
Study design
Prospective, randomized, anatomical study.
Animals
A group of nine middle-sized adult Mongrel canine cadavers (18 limbs).
Methods
The sciatic nerves of three pelvic limbs of two canine cadavers were identified, exposed
and isolated between the greater trochanter and the popliteal fossa for gross anatomical
and microscopic examination. An additional three pelvic limbs were surgically dissected
on the lateral surface of the limb; the sciatic nerves were isolated, and a 26 gauge
over-the-needle catheter was inserted through the paraneural sheath under direct visualization.
A methylene blue solution was then slowly injected into the subparaneural compartment
through the catheter under US visualization using an 8–13 MHz linear-array transducer.
Subsequently, 12 pelvic limbs (six cadavers) were randomly allocated to one of two
groups; using US-guided percutaneous subparaneural approach, either 0.1 or 0.05 mL
kg–1of a 1:1 solution of methylene blue and 0.5% bupivacaine was injected. The spread
of the dye solution and the amount of nerve staining were macroscopically scored.
The stained sciatic nerves with their sheaths were then harvested for microscopic
examination.
Results
The paraneural sciatic nerve sheath was easily identified distinct from the nerve
trunk both macroscopically and with US visualization, and microscopically. Complete
staining was achieved in five of six (83.3%) sciatic nerves in each group; no difference
was found in the amount of staining between the two groups. Microscopically, no signs
of sciatic nerve intraneural injection were observed.
Conclusions and clinical relevance
The US-guided subparaneural injection of 0.05 mL kg–1 of a dye injectate resulted in satisfactory nerve staining without evidence of sciatic
nerve intraneural injection.
Keywords
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Article info
Publication history
Published online: October 21, 2020
Accepted:
June 23,
2020
Received:
October 2,
2019
Identification
Copyright
© 2020 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
