Page 327 - Atlas of Small Animal CT and MRI

3.3

Inflammatory disorders

Noninfectious inflammatory disorders lesser extent, the brain. Although MR features of menin-
geal thickening and contrast enhancement have been
Noninfectious inflammatory spinal disorders that have reported, our experience is that imaging studies in dogs
significant CT or MRI imaging abnormalities are rela- with SRMA are often unremarkable. 6
tively uncommon. Diagnosis of such disorders is often
made from signalment, clinical presentation, cerebro- Infectious inflammatory disorders
spinal fluid analysis, and response to therapy. Brief
descriptions of two of the most common entities follow. Vertebral column
Discospondylitis
Spinal granulomatous Discospondylitis occurs commonly in dogs and is rare
meningoencephalomyelitis in cats. Infection is caused by a wide variety of bacterial
A description of granulomatous meningoencephalomy- and mycotic species. Although the vertebral imaging
elitis (GME) and its intracranial imaging features is features of bacterial and fungal discospondylitis can
included in Chapter 2.6. The disorder involves primarily appear similar, the underlying clinical manifestations
white matter of the brain, the optic nerves, and spinal cord are quite different.
and can manifest as either focal or disseminated disease.
Descriptions of computed tomography features of Bacterial (suppurative) discospondylitis
spinal GME are lacking, but they would be expected to In a large retrospective study involving over 500 canine
be subtle or absent. Focal masses could appear as intrin- patients diagnosed with discospondylitis, two thirds
sic lesions with increased cord diameter with or without were male, older dogs were more likely to be affected,
contrast enhancement. MR features include focal, and Great Danes were overrepresented. Staphylococcus,
8
multifocal, or diffuse parenchymal T1 hypointensity/T2 Brucella, Streptococcus, and Escherichia species are most
hyperintensity and variable contrast enhancement frequently isolated, although many others have been
(Figures 3.3.1, 3.3.2). reported. 8–11 Dogs with bacterial discospondylitis most
often have an underlying infection of the urinary tract,
Steroid responsive meningitis–arteritis skin, or other organ system, which leads to bacteremia
Steroid responsive meningitis–arteritis (SRMA) is a and embolic seeding of vulnerable disks.
systemic immune‐mediated disorder that includes Conventional radiographic examination is an excel-
inflammatory responses of the leptomeninges and asso- lent test for diagnosis and monitoring of discospondylitis.
ciated blood vessels, which has been reported in young CT and MRI are most often employed when neurologic
Bernese Mountain Dogs, Beagles, Nova Scotia Duck deficits are present or the patient has other clinical signs
Tolling Retrievers, Corgis, Boxers, and other breeds. not explained by radiographic findings or other diag-
1–7
The disorder involves the spinal cord primarily and, to a nostic tests.

Atlas of Small Animal CT and MRI, First Edition. Erik R. Wisner and Allison L. Zwingenberger.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.
317