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Muscle Biopsy 1134.e1

Muscle Biopsy Client Education
Sheet
VetBooks.ir

in the selection of which muscle and nerve
Difficulty level: ♦♦
direction of the muscle fibers.
should be biopsied. • Make parallel incisions along the longitudinal
Overview and Goal • Knowledge of anatomic localization of • Collect biopsy specimens 0.5 cm (width) ×
Minimally invasive procedure for collec- specific muscle groups 0.5 cm (depth) × 1 cm (length).
tion of muscle specimens for histologic, • It is critical that unfixed biopsy specimens • Transect the ends of the biopsy, handling
histochemical, immunohistochemical, and are kept refrigerated and shipped by courier carefully to minimize artifact.
ultrastructural analyses. A nerve biopsy may for processing within 24-36 hours. Do not • Wrap tissue in a saline-moistened gauze
be performed concurrently, and if so, it should ship biopsy specimens on a Friday. sponge (moistened, not dripping wet).
be performed only by persons trained in the • Place in dry, watertight container, and keep
procedure. Possible Complications and chilled (not frozen).
Common Errors to Avoid • Collect a second, smaller piece of muscle Procedures and Techniques
Indications • Complications (hematoma, swelling) are rare from same site, and place freely in 10%
• Chronic muscle atrophy, hypertrophy after muscle biopsy. buffered formalin.
• Weakness, hypotonia • Transient neurologic dysfunction (knuckling, • Locate the nerve as it passes over the lateral
• Exercise intolerance proprioceptive deficits) possible on the side of head of the gastrocnemius muscle.
• Nonorthopedic gait abnormalities a nerve biopsy. The owner should be warned • Isolate the nerve carefully by blunt
• Contractures before the procedure of the expected short- dissection.
• Chronically elevated creatine kinase activity, term deficits. • A 5-0 or 6-0 silk suture is placed through the
myoglobinuria • Artifacts in histologic specimens due to poor caudal one-third to one-half of the nerve at
• Myalgia, cramping fixation or traumatic collection; handle tissue the proximal end of the biopsy site, allowing
• Clinical evidence of muscle or peripheral carefully minimal gentle traction.
nerve disease • Biopsy of wrong muscle (e.g., frontalis instead • A 3-4 cm fascicular biopsy is excised using
of temporalis for masticatory myositis) fine iris scissors.
Contraindications • Lay nerve specimen on a tongue depressor
• Bleeding disorder Procedure or stick, and pin or tie ends with suture to
• Poor anesthetic risk For biopsy of muscle (biceps femoris) and nerve maintain length. Do not stretch.
(common peroneal) through the same incision, • Immerse nerve biopsy in 10% buffered
Equipment, Anesthesia an open biopsy procedure is necessary: formalin or Karnovsky’s fixative.
• General anesthesia usually is required; muscle • Palpate the location of the common peroneal • The fascial layer is closed with absorbable
biopsies can be taken under heavy sedation nerve on the lateral aspect of the distal femur suture (e.g., polydioxanone).
and local anesthetic if indicated. just caudal to the proximal tibia. • Skin closure with monofilament nylon or
• General surgical pack, including self-retaining • Clip hair, aseptic scrub/prep staples
retractors • Incise skin and overlying fascia to expose • Open muscle biopsy procedures are also
• Containers for biopsy specimens muscle. recommended if a peripheral nerve biopsy is
○ Plain red-top tubes (5-10 mL) for unfixed • Establish orientation of the muscle fibers. not collected at the same time. For collection
biopsy specimens
○ Biopsy jars containing fixatives: 10%
formalin for routine histopathologic evalu-
ation, 2.5% glutaraldehyde in phosphate
buffer or Karnovsky’s fixative for electron
microscopy
• Tongue depressors or wooden sticks and
suture material or pins: for maintaining A
length of nerve specimens
• Method of refrigeration before shipping
specimens
• Styrofoam containers for shipping refrigerated
specimens to a specialized laboratory
Anticipated Time
• About 60-90 minutes if the biopsy is
combined with electrophysiologic evaluations
• About 30-45 minutes if nerve and muscle
biopsy only
Preparation: Important
Checkpoints B
• It is essential that details of fixation and
transportation be obtained from the labora- MUSCLE BIOPSY Biopsies obtained from the temporalis muscle for diagnosis of masticatory myositis.
A, Frontalis muscle (arrow), first muscle encountered after making skin incision. Muscle should be incised and
tory that processes the tissues before taking retracted, allowing visualization of the thick fascia that overlies temporalis muscle. B, Fascia has been incised
biopsies. and retracted, allowing access to temporalis muscle. (A complete description of the masticatory muscles anatomy
• Determine if problem is generalized or local- is provided in Melmed C, et al: Masticatory muscle myositis: pathogenesis, diagnosis, and treatment. Compend
ized to specific muscle groups: this will help Contin Educ Pract Vet 26:590-605, 2004.)

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