Page 307 - Atlas of Small Animal CT and MRI

Traumatic and Vascular Disorders 297

of static compression from vertebral column injury. signs also present in some patients. Initial clinical signs
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Cervical cord injury often included central hemorrhagic can include transient pain and can be progressive for
necrosis that was more consistent with transient impact the first 2 hours but are often nonprogressive thereafter.
trauma than static cord compression. The cervicothoracic (C5–T2) and lumbosacral (L3–S3)
MR features of spinal cord contusion include focal to regions appear to be predisposed. Pathology in
regional increased T2 intensity with mild to no enhance­ histologically confirmed patients includes spinal cord
ment following contrast administration (Figure 3.2.18). infarction and hemorrhage with cartilaginous emboli in
T2* sequences reveal parenchymal susceptibility effects meningeal or spinal vessels. In some patients, extensive
when there is a hemorrhagic component. Syringohy­ myelomalacia may also be present, but pathology is
dromyelia is often a late sequela to spinal cord trauma and likely to be more severe in those patients that were euth­
appears as a focal to regional and central to eccentric T2 anized and confirmed as having FCE. 22–24 A poorer
hyperintensity. prognosis is seen in patients with involvement of the
intumescences, symmetrical neurological signs, and
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Vascular disorders decreased deep pain sensation. A recent review of dogs
with ischemic myelopathy found that a combination of
Hematomyelia lesion length greater than twice a vertebral length and
Occasionally frank hematomyelia will be seen as a cross‐sectional involvement of greater than 67% had a
sequela to trauma, primary vascular disease, or an positive correlation with an unsuccessful outcome.
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underlying bleeding diathesis. MR features are similar to Recovery rates for FCE are unclear since patients who
those of spinal cord contusion; however, susceptibility do respond are not definitively diagnosed. However, a
effects may be a predominant sign (Figure 3.2.19). majority of patients with stable disease seem to partially
or fully recover neurologic function. 22
Fibrocartilagenous embolism CT imaging features can be limited to a noncompres­
Early reports indicated that fibrocartilaginous embo­ sive focal increase in spinal cord diameter, indicative of
lism (FCE) occurs primarily in middle‐aged to older, an intrinsic lesion (Figure 3.2.20). MR features include
large‐ and giant‐breed dogs; however, a more recent focal T1 iso‐ to hypointensity and T2 hyperintensity
review in which diagnosis was based on clinical signs within the affected spinal cord segments. Lesions prefer­
and MR imaging findings suggests that small and entially affect gray matter and can be either symmetrical
medium‐sized dogs are also commonly affected. 22–24 The or asymmetrical. Spinal cord diameter can also appear
disorder has also been reported in cats. The clinical locally enlarged but without compression. Intervertebral
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presentation is often a peracute onset of symmetrical or disk T2 signal intensity at the level of the spinal cord
asymmetrical motor dysfunction immediately following lesion is often less than that of adjacent disks
exercise or minor trauma, with lower motor neuron (Figures 3.2.21, 3.2.22). 24

Figure 3.2.1 Three Column Classification Model for Thoracolumbar Vertebral Trauma (Canine)

Cranial view of a thoracic vertebra. The dorsal column (D) includes lamina, pedicles, and
articular facets. The middle column (M) includes the dorsal half of the vertebral body and the
intervertebral disk. The ventral column (V) includes the ventral half of the vertebral body.

(a) GA, CRAN
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