Page 775 - Clinical Small Animal Internal Medicine

69 Central Nervous System Trauma 743

Survey Radiography anesthesia results in the loss of voluntary paraspinal
VetBooks.ir nificant trauma, looking for pleural effusions, contu- muscle contraction, and unstable vertebral segments
Thoracic radiographs should be evaluated after a sig-
may be more likely to subluxate.
It is important to remember that radiographs provide a
sions, pneumomediastinum, and pneumo thorax as well as
the possibility of pericardial effusion and diaphragmatic static record of the location of the vertebrae at the time
herniation. If a vertebral injury is suspected, it is rec- of the study but they do not allow for assessment of how
ommended that survey lateral radiographs are taken of extensive the displacement of the vertebrae was at the
the entire spine prior to additional manipulation of the time of the injury and prior to radiology. As a result of
animal (Figure 69.2). Sites particularly predisposed to the strong paraspinal musculature, vertebrae can be sig-
fracture and luxation include the atlantoaxial junction, nificantly displaced acutely at the time of injury but then
the thoracolumbar junction, and the lumbar and lum- subsequently pulled back into a more normal position.
bosacral spine.
As some fractures can be subtle, good‐quality and Advanced Imaging
well‐positioned radiographs from orthogonal planes are Advanced imaging such as computed tomography (CT)
necessary. This may be accomplished with the animal or magnetic resonance imaging (MRI) is needed to
awake and immobilized; analgesia may be required. Poor evaluate spinal cord compression and to ensure that
radiographic technique resulting in rotation of the spine additional lesions unidentifiable on survey radiographs
(especially in the cervical area) can make assessment for are not present. CT is invaluable in identifying bone
unstable and malaligned vertebral segments difficult. defects that may not be apparent on survey radiography
Extreme care should be taken in positioning the animal (Figure 69.3). Three‐dimensional reconstruction from
for ventrodorsal views; horizontal beam radiographs can CT images may provide additional anatomic informa-
be obtained if the equipment is available. tion regarding bone contour for surgical planning
Sedation may be necessary to achieve accurate posi- (Figure 69.4).
tioning for radiography in some animals. This should not Magnetic resonance imaging is optimal for delineating
be performed if the examiner is unsure of the physical the soft tissues involved in the injury as well as identify-
diagnosis, as sedation often influences the results of the ing spinal cord compression, spinal cord swelling, disk
neurologic examination. Additionally, sedation or herniations, and the presence of intraparenchymal

Figure 69.2 A lateral radiograph of the
thoracic vertebrae confirms a fracture
luxation affecting T6–T7.

Figure 69.3 A sagittal reconstructed CT
scan of the thoracic vertebrae of the case
seen in Fig. 69.2. Although the spinal cord
cannot be seen in detail, compression of
the cord can be inferred from the stenosis
of the canal seen with this image at the
site of the luxation.