Page 96 - Zoo Animal Learning and Training

9 Muscle and Nerve Biopsy

Michaela Beasley

Introduction rarely, conscious proprioceptive deficits can be seen for a few days
Biopsies of muscles and nerves are indicated for a variety of neuro- following the procedure [5].
muscular diseases, mononeuropathies and polyneuropathies, and
infectious, inflammatory and metabolic myopathies. Biopsies Pelvic Limb
should follow neurological examination, minimum database, and In the pelvic limb, the common peroneal nerve and biceps femoris
electrodiagnostic testing. This information allows the examiner to and gastrocnemius muscles are biopsied through a single curved
select the appropriate biopsy sites: thoracic limb, pelvic limb or incision centered behind the stifle. Alternatively, the tibial nerve
both, proximal or distal sites, or severely affected versus less severely and cranial tibial muscle can be biopsied through two separate but
affected structures. When practical, biopsies are collected contralat- smaller linear incisions. For both options, the leg is clipped and the
eral to the side where a majority of the electrodiagnostics were per- skin surgically prepared with chlorhexidine or betadine. The author
formed. This avoids needle insertion artifacts. In acute disease a prefers to remove the hair and prepare the leg on both the lateral
severely affected muscle should be chosen. However, in chronic and medial surface in a hanging leg type preparation. A sterile towel
disease the most affected muscles may only show fibrotic infiltra- or drape is placed under the leg to give a sterile ventral field, fol-
tion and not the underlying disease process; therefore, less severely lowed by a second towel placed over the foot to allow manipulation
affected muscle are chosen [1–4]. Even the best sample can become of the leg if necessary. A fenestrated paper drape can then be placed
useless without appropriate handling and shipping to a qualified over the leg or a third surgical towel/drape placed over the remain-
pathologist, trained specifically in neuropathology [2–4]. Readers ing hair dorsal to the prepared area (Figure 9.1).
are strongly encouraged to contact their submission laboratory for The cranial tibial muscle and tibial nerve offer a distal muscle
specific instructions on shipment and their comfort level in review- and nerve for biopsy. These can be biopsied through one incision in
ing your samples. At a minimum, formalin‐fixed muscle and nerve some small dogs and cats, but often require two separate incisions.
biopsies and fresh refrigerated muscle biopsies are submitted using The leg is clipped and prepared as described above. A linear proxi-
overnight shipping in an insulated container. Samples are taken on mal to distal incision is made overlying the cranial tibial muscle
a day when their arrival at the laboratory will not fall on a weekend located on the craniolateral aspect of the tibia just distal to the stifle.
or long holiday. The fascia of the cranial tibial muscle is incised in line with the skin
incision and a 1 × 1 × 2 cm block of muscle removed using a #11
scalpel blade. This block of tissue is separated into two 1 cm blocks.
2
One piece should be put in 10% buffered formalin and the other
Techniques wrapped in gauze moistened with physiological saline. After the
Techniques for obtaining muscle and nerve biopsies are described procedure, the muscle is placed in a 10‐mL red‐top tube or similar
in this chapter and include descriptions of performing an open container for shipping. If excessive bleeding from the muscle biopsy
biopsy for the cranial tibial, biceps femoris, gastrocnemius, and tri- site is encountered, absorbable hemostatic gelatin sponge is placed
ceps brachii muscles. Fascicular nerve biopsy techniques are in the defect and the muscle fascia closed over it (Figure 9.2). The
described for the ulnar, common peroneal, and tibial nerves, all subcutaneous tissue and skin are closed in routine fashion.
containing mixed sensory and motor components. This technique, The tibial nerve is located in a nerve/artery/vein (neurovascular)
which samples 30–50% of the nerve diameter, preserves the neuro- bundle between the gastrocnemius tendon and distal tibia. A proxi-
logical function of the nerve while being a representative sample of mal to distal linear incision is made distal to the lateral saphenous
the entire nerve diameter. Nonetheless, owners are warned that, vein extending to the tibiotarsal junction. Here it is important for

Current Techniques in Canine and Feline Neurosurgery, First Edition. Edited by Andy Shores and Brigitte A. Brisson.
© 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/shores/neurosurgery

93