Page 689 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 31 Tumors of the Nervous System 667

syringomyelic syndrome (see Fig. 31.6). 135 All types of SC tumors Diagnosis of Spinal Cord Tumors
can cause numerous secondary changes within the SC including The minimum database for a patient with a suspected SC neo-
edema, inflammation, gliosis, and hemorrhage. Signs of paraspinal
VetBooks.ir hyperesthesia arise from compression, stretching, inflammation, plasm is identical to that for a brain tumor patient. Although these
laboratory tests will seldom provide a definitive answer regarding
or invasion of the meninges, nerve roots, periosteum, or paraspi-
nal musculature. Early reports have described IM tumors as non- the etiology of SC neoplasia, they can provide valuable informa-
painful because of lack of nociceptors in the parenchyma 126,144 ; tion with respect to hematologic abnormalities, paraneoplastic
however, in one study that specifically reported on the prevalence syndromes, and primary organ dysfunction that is often detected
of paraspinal hyperpathia, 68% of all dogs with IM tumors dis- in patients with metastatic cancers such as lymphoma and mul-
played paraspinal hyperpathia. 135 Development of hyperpathia in tiple myeloma. 132,145
association with IM tumors may be a result of altered neurotrans-
mitter modulation association with destruction of the dorsal horn Diagnostic Imaging
of the gray matter known as syringomyelic syndrome (see Fig. Survey radiographs may identify primary vertebral body tumors
31.6D–F). 135 Another theory postulates that intramedullary mass (see Fig. 31.5A, E), pathologic fractures, osseous metastases, as
expansion may lead to stretching of meninges and stimulation of well as evidence of concurrent malignancy or disease, but are fre-
nociceptive pathways. quently normal (see Fig. 31.5C). 135,145 In cats, radiographically
Primary IM tumors have a protracted clinical course compared apparent lytic lesions are seen more commonly in nonlymphoid
with metastatic IM neoplasms. 135 Acute decompensation can neoplasms. 133,138
occur because of pathologic fracture of neoplastic vertebra, hem- As with brain tumors, MRI is the modality of choice for the
orrhage in or around the tumor or SC, or necrosis of the tumor evaluation of SC tumors. 130–131,135,146,147 However, CT myelogra-
itself. Clinical signs of SC disease, rather than primary organ dys- phy can be helpful for determination of the longitudinal and axial
function, is a frequent chief complaint for animals with second- location of many neoplastic lesions. 147 Irrespective of the imag-
ary SC tumors, occurring in up to 44% of dogs with metastatic ing modality used, in some cases it can be difficult to distinguish
tumors. 135,140 ID-EM from IM origin masses. 146 Similar to what is observed with

A B C

*
*

D E F

• Fig. 31.6 Intradural (A–C) and intramedullary (D–F) canine spinal cord tumors. Dorsal STIR (A) and postcontrast
magnetic resonance image (MRI) (B, C) images of C1 meningioma causing marked spinal cord compression
dural tail (A, arrow). Recurrent tumor is visible 9 months after surgery (C). MRI of heterogeneously contrast
enhancing (D) and T2 hyperintense (E) grade III oligodendroglioma that effaces the spinal cord architecture at
T10. Necropsy specimen demonstrating intramedullary tumor (F, arrow) and syringomyelic cavity (*).