Page 2283 - Cote clinical veterinary advisor dogs and cats 4th

1134.e2 Myelography

of temporalis muscle, make sure that the • Proprioceptive deficits as already described; ADDITIONAL SUGGESTED
frontalis muscle is not collected by mistake. usually self-resolving in 3-4 days; long-term READING
VetBooks.ir mended for routine muscle biopsy collection Alternatives and Their Relative Melmed C, et al: Masticatory muscle myositis:
deficits are extremely uncommon
Percutaneous needle/core biopsy is not recom-
pathogenesis, diagnosis, and treatment. Compend
in dogs and cats:
Contin Educ Pract Vet 26:590-605, 2004.
Merits
• Inadequate sample size
• Difficult to orient tissue • For muscle diseases, there is no alternative Reproduced from the third edition in
• Artifact to the muscle biopsy for determining the unabridged form.
Needle/core biopsies may be beneficial in research specific diagnosis and therapeutic options.
situations where sequential biopsy samples • MRI studies may help localize focal lesions RELATED CLIENT EDUCATION
may be required over time; may be guided by and allow guided muscle biopsies. SHEET
ultrasonographic localization of specific lesions. • Electrophysiologic examinations can provide
important information on peripheral nerve Consent to Perform General Anesthesia
Postprocedure diseases, but a peripheral nerve biopsy should
• Treatment of hemorrhage, swelling, or be collected for histologic evaluation. AUTHOR: G. Diane Shelton, DVM, PhD, DACVIM
hematoma if these occur (rare) EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
• External dressings are not normally required. SUGGESTED READING Thompson, DVM, DABVP
• Animals should be monitored to prevent Dickinson PJ, et al: Muscle and nerve biopsy. Vet
interference with the sutures. Clin North Am Small Anim Pract 32:63-102, 2002.

Myelography Client Education
Sheet

Difficulty level: ♦♦ iohexol or iopamidol (180-300 mg iodine/ • Bradycardia is sometimes seen in animals
mL most commonly used) during injection of the contrast material.
Overview and Goal ○ Full spine dosage is 0.45 mL/kg; regional • Epidural injection may occur with lumbar
Myelography is the introduction of nonionic dosage is 0.3 mL/kg. puncture.
positive-contrast media into the subarachnoid • A 20- to 22-gauge spinal needle with stylet • Subdural injection may result in central canal
space. It is used for demonstrating lesions in and short bevel, 1 2 to 3 2 inches (depend- filling.
1
1
the spinal cord or lesions extrinsic to the spinal ing on size of animal) • Administration of air bubbles
cord that may be causing cord compression. • Appropriately sized syringe (3-35 mL) • Use of the incorrect type of contrast agent
• Flexible extension tubing or T-port (catheter can be fatal. Ionic contrast agents should
Indications cap with side line and port) never be used in any amount in myelography;
• Clinical signs of spinal cord disease (± spinal • Hair clippers only low-osmolar, nonionic, water-soluble
trauma) when magnetic resonance imaging • Surgical scrub solution, rubbing alcohol, and iodine agents are indicated.
(MRI) is not an option gauze/sponge for prepping skin • Lumbar puncture: inability to enter the space
• Spinal pain or neurologic deficits without • Sterile surgical gloves is commonly due to a non-midline location
diagnosis on plain films or laboratory tests of the needle (needle is inadvertently located
• Confirmation of suspected lesion on plain Anticipated Time parallel and lateral to dorsal midline).
films About 45-60 minutes, not including prepro- • Extension of the neck for neck-extended
• Aid in surgical planning (define exact location cedural anesthesia time views can cause permanent cord injury,
of lesion) especially in animals with neck pain before
• Determine amount of spinal cord swelling Preparation: Important the procedure and animals with severe cervi-
• Exclude compressive lesions of the spinal cord; Checkpoints cal intervertebral disc disease (IVDD). These
by process of elimination, make presumptive • CSF analysis to ensure no evidence of infec- views should be preceded by nonextended
diagnosis of noncompressive spinal disorder tion or inflammation views (diagnosis may be apparent without
• Rule out intraspinal lesion • Ensure adequate hydration status to decrease extension) or avoided altogether.
• Disparity between clinical signs and plain risk of neurotoxicosis; IV fluids as appropriate
radiographs • Metastasis imaging (three-view thoracic Procedure
• Recurrence of clinical signs after decompres- radiographs are also indicated if malignancy • Obtain survey radiographs of the area of
sive spinal surgery is part of the differential diagnosis for the interest (ventrodorsal and lateral views).
spinal problem) • Clip a large area of hair near the injection site
Contraindications • Advise owner the hair will be clipped in a (depending on cisternal or lumbar puncture).
• Cerebrospinal fluid (CSF) analysis indicates large area near the injection site(s). • Aseptically prepare the site for injection with
inflammation or infection: condition aggra- surgical scrub solution, isopropyl alcohol,
vated by irritation from contrast medium Possible Complications and and gauze/sponges.
• Increased CSF pressure: possible herniation Common Errors to Avoid • Sterile surgical gloves should be worn from
of cerebellum through foramen magnum • The most common complication of myelog- this point on, and a sterile technique should
• Known hypersensitivity to contrast medium raphy is postprocedure seizures. Recover the be used (nonsterile materials need to be
animal with head elevated to minimize risk. handled by an assistant).
Equipment, Anesthesia If directly induced by contrast, seizures are • Draw correct contrast dose into syringe.
• General anesthesia expected to occur during anesthetic recovery. • Attach flexible extension tubing to the
• Intrathecal contrast material: low osmolar, Seizures occurring thereafter are virtually syringe, and fill with contrast so no air
nonionic, water-soluble iodines, such as never caused by the contrast injection. bubbles are present.

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