Page 82 - Zoo Animal Learning and Training

Chapter 7: Advanced Imaging: Spinal Surgery 77

The differential diagnosis for extradural lesions includes primary lesion or from edema secondary to the primary lesion is
intervertebral disc herniation, ligamentous hypertrophy, hemor­ often evident. Intravenous contrast enhancement may be present
rhage, neoplasia (vertebral or soft tissue), abscess, and vertebral with CT or MRI if there is breakdown of the blood–spinal cord bar­
fracture or luxation. rier. The differential diagnosis for intramedullary lesion includes
Intramedullary lesions are characterized by enlargement of the spinal cord edema, ischemic myelopathy, neoplasia, and inflamma­
spinal cord and deviation of the subarachnoid space toward the ver­ tory disease. Neoplasia and ischemia tend to be focal lesions while
tebral canal on all projections (outward deviation) (Figure 7.7C). inflammatory disease is more commonly multifocal.
With myelography and CT, enlargement may be the only finding Intradural–extramedullary lesions (Figure 7.7D) are most
unless there is a tear in the dura resulting in contrast diffusion into evident when there is contrast medium in the subarachnoid
the spinal cord. With MRI, a change in signal intensity due to the space or on heavily T2‐weighted MRI (myelogram‐like images).

A

B

C

D

Figure 7.7 Lateral (sagittal), ventrodorsal (dorsal), and transverse representations of the subarachnoid space in normal (A), extradural (B), intramedullary
(C), and intradural–extramedullary (D) spinal cord lesions.