GENERAL CONSIDERATIONS


Location

•spinal cord tumors are classified as extradural, intradural-extramedullary, or intramedullary

•extradural tumors are most common and account for 50% of spinal tumors

•intradural-extramedullary account for 30% and intramedullary account for 15% of spinal tumors


Signalment

•90% of spinal tumors occur in large breed dogs

•28% of spinal tumors occur in cats and dogs < 3 years


Canine Spinal Cord Tumors


General Considerations

•spinal cord tumors are uncommon in dogs

•meningioma is the most common with a predilection for the cervical spinal cord

•other primary tumors include LSA, MCT, and intradural-extramedullary spinal cord tumor of young dogs

•HSA is the most common metastatic tumor, but others include pilomatrixoma and pheochromocytoma


Extradural Spinal Cord Tumors

•primary vertebral tumors and multiple myeloma

•other extradural tumors include myxoma, myxosarcoma, LSA, and lipoma or liposarcoma


Intradural-Extramedullary Spinal Cord Tumors

•meningioma and peripheral nerve sheath tumors are the most common intradural-extramedullary tumors

•spinal meningioma accounts for 14% of all CNS meningioma

•spinal meningioma has a predilection for the cervical spinal cord:

•40%-77% cervical spinal cord

•0%-32% thoracic spinal cord

•23%-28% lumbar spinal cord

•peripheral nerve sheath tumors involve the spinal cord in 65% cases

•other intradural-extramedullary tumors include hemangioma (common), myxoma, myxosarcoma, and an unusual case of diffuse meningeal tumor affecting entire meningeal surface of CNS


Intradural-Extramedullary Spinal Cord Tumor of Young Dogs

•uncommon

•synonyms: ependymoma, neuroepithelioma, spinal cord blastoma, medulloepithelioma, hamartoma, and nephroblastoma

•age: 6 months to 3 years

•breed predisposition: GSD, Labrador Retriever, and Golden Retriever

•clinical signs: lateralized with vast majority of lesions between T10-L2

•microscopically similar to nephroblastoma and some believe this tumor may represent extrarenal nephroblastoma arising from ectopic mesonephric or metanephric tissue trapped within the dura during embryologic development

•diagnosis: CSF findings are usually non-specific, but albuminocytologic dissociation may be consistent with a chronic neoplastic process

•treatment: cytologic reduction or removal associated with long-term survival (4 months and > 3 years) ± radiation therapy for incompletely excised tumors


Intramedullary Spinal Cord Tumors

•intramedullary spinal cord tumors are uncommon

•intramedullary spinal cord tumors usually have glial cell origin: astrocytoma, oligodendroglioma, undifferentiated sarcoma, ependymoma, and choroid plexus papilloma

•intramedullary spinal cord tumors are most commonly located between C6-T2

•intramedullary spinal cord metastasis can also occur before evidence of the primary tumor

•primary tumors with a propensity for metastasizing to the spinal cord include HSA and LSA ± mammary ADC and malignant melanoma

•malformation tumors may also affect the spinal cord parenchyma such as epidermoid cyst and hamartoma



CLINICAL FEATURES


History

•extradural spinal cord tumors are usually slow growing and progressive over weeks to months

•acute onset of neurologic signs may be caused by tumor-induced hemorrhage or ischemia

•intramedullary tumors have a more rapid growth rate and have a higher incidence of hemorrhage, ischemia, and necrosis


Clinical Features

•clinical signs depend on the tumor location and are difficult to differentiate from other causes of myelopathy

•extradural tumors may involve the meninges, spinal nerves, or nerve roots which results in varying levels of pain from discomfort to extreme spinal hyperesthesia

•tumors involving the brachial or lumbar intumescence may cause lameness, limb elevation, neurogenic muscle atrophy, and depressed spinal reflexes

•hyperesthesia is associated with extradural and intradural-extramedullary tumors, but not intramedullary tumors

•fundus, lymph node, and rectal examination should be performed for evidence of LSA or metastatic lymphadenopathy



DIAGNOSIS


Survey Radiographs

•thoracic radiographs for evaluation of metastatic disease

•radiographic findings include cortical lysis with collapse of the adjacent intervertebral disk space

•vertebral body and dorsal lamina are more frequently affected than dorsal and transverse spinous processes

•radiographic signs not always visible due to inconsistent vertebral shape, overlying ribs and soft tissue, and improper positioning

•cortical bone destruction is a late event in metastatic vertebral lesions

•radiographic abnormalities associated with non-vertebral spinal cord tumors are rare, but slow and progressive tumor growth may cause enlargement of an intervertebral foramen or vertebral canal with thinning of cortical bone



 From: Withrow SJ & MacEwen EG (eds): Small Animal Clinical Oncology (3rd ed).


Cerebrospinal Fluid Analysis

•CSF collection and analysis are recommended if survey radiographs are inconclusive

•CSF is collected from a lumbar site and needle left in situ for myelography

•CSF changes include increased protein content and normal to increased white cell count

•CSF findings with LSA include increase white cell count with abnormal lymphocytes

•abnormal CSF findings are more common in dogs with spinal LSA due to leptomeningeal involvement


Myelography

•indications: determining presence, anatomical location and dural site of spinal cord tumor

•spinal cord tumors are classified as extradural, intradural-extramedullary, or intramedullary

•classification may be difficult due to spinal cord edema



 


 From: Withrow SJ & MacEwen EG (eds): Small Animal Clinical Oncology (3rd ed).

Advanced Imaging

•CT is recommended for vertebral tumors due to excellent bone detail

•however, myelography is superior to CT in differentiating intramedullary from intradural-extramedullary

•MRI is recommended for spinal cord tumors due to excellent soft tissue detail

•MRI provides accurate information on anatomic location and bone involvement, but differentiation between intradural, extradural and intramedullary, and extramedullary difficult



TREATMENT


General Considerations

•management options depends on tumor location, extent, and histologic type

•aim: alleviate spinal cord compression

•treatment options include conservative (with corticosteroids) and surgery

•surgery allows decompression ± complete removal or cytoreduction of the mass

•surgical decompression techniques include hemilaminectomy and dorsal laminectomy

•complete resection of spinal meningioma is complicated by adhesions to the pia mater or spinal cord, and friable texture resulting in piecemeal dissection

•rhizotomy can be performed to facilitate tumor resection, but avoided in the brachial and lumbar intumescence

•radiation therapy can be used for LSA, incompletely resected spinal tumors, and when surgery is not feasible

•spinal cord is resistant to the acute effects of radiation due to low replication rate, but late effects (> 2 years) can be seen due to progressive demyelination and malacia of white matter (especially oligodendrocytes, endothelial cells, astrocytes, and microglial cells)



PROGNOSIS


General Considerations

•prognosis depends on resectability, histologic type, location, and severity of neurologic signs

•poor prognosis for metastatic and vertebral tumors


Surgery

•guarded to good prognosis for intradural-extramedullary lesions following surgical resection

•overall MST 240 days for surgically resected spinal cord tumors:

•MST 180 days for malignant spinal tumors

•MST 1,410 days for benign spinal tumors

•56% dogs with spinal meningioma alive > 6 months

•poor prognostic factors for spinal meningioma include tumors located in either the cervical or lumbar intumescence, ventral tumors, and iatrogenic cord trauma during dissection


Radiation Therapy

•guarded to good prognosis for intramedullary tumors treated with radiation therapy with normal spinal cord tolerating radiation well and neurologic signs alleviated > 1 year

•MST 17 month MST for intradural-extramedullary and intramedullary tumors following cytoreductive surgery and radiation therapy

 

SURGICAL ONCOLOGY

SOCIETY

RESEARCH

EDUCATION

LINKS

EMPLOYMENT

 IMAGE LIBRARYImages.html
● HistoryHistory.html
● What is a Surgical OncologistSurgical_Oncology_1.html
● Find a Surgical OncologistSurgical_Oncology_2.html
● Aims and ObjectivesAims.html
● MembershipMembership.html
● CommitteesCommittees.html
● NewsletterNewsletter.html
● Constitution and BylawsConstitution.html
● Research TrialsResearch_Trials.html
● Publications by MembersPublications.html
● Research OpportunitiesResearch_Opportunities.html
● Cancer InformationCancer_Information_1.html
● Conferences and MeetingsConferences.html
● Radiation FacilitiesRadiation_Facilities.html
● CE OpportunitiesCE_Opportunities.html
● Cancer InformationCancer_Information_2.html
● Current OpportunitiesEmployment_Opportunities.html
● Fellowship Training GuidelinesFellowship_Guidelines.html

SPINAL CORD TUMORS

● Surgical Oncology JournalsJournals.html
● Surgical Oncology SocietiesSocieties.html
● Veterinary Surgery CollegesColleges.html