Intramedullary spinal tumors

Intramedullary spinal tumors are rare, representing 4-10% of all CNS tumors and less than 10% of all pediatric CNS neoplasms . They account for 20% of all intraspinal tumors in adults and 35% of all intraspinal tumors in children .

A long duration of symptoms prior to diagnosis is typical.

Pathology

Classification

They can be classified according to many ways:

• intramedullary neoplastic lesion
  • glial neoplasms: 90-95% of all intramedullary tumors
    • spinal ependymoma: 60% of all glial spinal cord tumors   
    • spinal astrocytoma: 33% of all glial spinal cord tumors
    • spinal ganglioglioma: 1% of all glial spinal cord tumors
    • spinal glioblastoma multiforme (primary): 7.5% of all intramedullary gliomas and only 1.5% of all spinal cord tumors
  • non-glial neoplasms
    • highly vascular lesions
      • spinal hemangioblastoma
      • spinal paraganglioma
    • other rare lesions
      • intramedullary metastasis
      • primary lymphoma of the spinal cord
      • spinal primitive neuroectodermal tumor
      • solitary fibrous tumor
• intramedullary benign masses
  • spinal canal epidermoid cyst
  • spinal canal lipoma

Associations

Intramedullary spinal neoplasms are more common in patients with neurofibromatosis:

• ependymomas occur more often in patients with NF2
• astrocytomas occur more often in patients with NF1

Approximately 70% of intramedullary tumors are associated with cysts . Two types of cysts are recognized:

• tumoral (or intratumoral) cysts
  • contained within the tumor itself
  • typically demonstrate peripheral enhancement
  • may result from necrosis, fluid secretion, or degeneration of the neoplasm
  • need to be resected along with the solid portion of the tumor because there is a high likelihood of neoplastic cells within the cyst wall
  • occurs in association with the following proportion of tumors
    • spinal ganglioglioma: in 46%
    • spinal ependymoma: in 22%
    • spinal astrocytoma: in 21%
    • spinal hemangioblastoma: in 2-4%
• non-tumoral (or reactive) cysts
  • occur rostral or caudal to the solid portion of the tumor
  • occur due to dilatation of the central canal
  • do not enhance
  • present in 60% of all intramedullary spinal tumors
  • may resolve once the neoplasm is resected

Syringomyelia occurs in approximately 50% of all intramedullary tumors but is most frequently associated with hemangioblastomas .

Clinical presentation

The presentation of intramedullary tumors depends on their size and location. The most common presenting symptoms include back/neck pain, radicular pain, weakness, paresthesia, gait disturbance and bowel and bladder dysfunction. Brown-Sequard syndrome may occur. An uncommon presentation is acute headache due to subarachnoid hemorrhage .

In children, progressive scoliosis may be seen. Motor regression and frequent falls may be the presenting features in young children .

Symptoms are usually slowly progressive. Due to their non-specific nature, the diagnosis is often delayed. An exception is intramedullary metastastases, which are diagnosed within one month of symptom onset in up to 75% of cases .

Radiographic features

Plain film

Widening of the interpedicular distance may be seen in less than 10% of cases

CT

Generally not useful because bony changes are relatively rare.

Myelography

• the spinal cord can be enlarged
• gradual subarachnoid space effacement

MRI

3 general characteristics of intramedullary neoplasms are recognized on MRI:

Differential diagnosis

Various lesions may mimic intramedullary tumors. The differential diagnosis of intramedullary tumors includes:

• vascular lesions
  • cavernous malformation (cavernoma)
    • rounded regions of heterogeneous signal intensity on T1 and T2 weighted images due to blood
    • products of varying ages (“popcorn appearance”)
    • low signal intensity rim on T2 weighted images (hemosiderin)
    • hypointense “blooming” on gradient echo sequences (hemosiderin)
    • may demonstrate minimal enhancement on post-contrast images
    • minimal cord expansion or edema unless there has been recent hemorrhage
  • dural arteriovenous fistula (DAVF)-(type I AVM) 
    • spinal cord may be normal size or enlarged
    • hyperintense on T2 weighted images (due to edema)
    • prominent vessels (flow voids) are usually present on the posterior aspect of the cord
    • variable enhancement on post-contrast images
    • typically located in the dorsal aspect of the lower thoracic cord and conus medullaris
  • spinal cord infarction 
    • spinal cord is usually enlarged
    • hyperintense on T2 weighted images and DWI
    • post-contrast enhancement may or may not be present (enhancement is usually present in the subacute stage)
    • signal intensity abnormality may be limited to the central grey matter or may involve most of the cross sectional area of the cord
    • signal abnormality typically extends over multiple vertebral body segments
    • can occur at any location in the cord but has a propensity for the upper thoracic or thoracolumbar regions
    • vertebral body T2 hyperintensity may occasionally be seen (due to concomitant infarction)
• inflammatory lesions
  • demyelination (e.g. multiple sclerosis)
    • usually no spinal cord enlargement (enlargement is seen in 6-14% cases)
    • plaques are generally shorter than two vertebral body segments in length and involve less than half the cross-sectional area of the cord
    • characteristically peripherally located in the dorsal and lateral columns
    • isointense to hypointense on T1 weighted images (unlike brain plaques, cord plaques may not be visible as areas of hypointensity on T1 weighted imaegs)
    • hyperintense on T2 weighted images
    • signal abnormality is typically poorly marginated
    • plaque enhancement correlates with acute lesion activity (usually lasts less than two months)
    • in most patients additional lesions of variable enhancement are present in the brain and spinal cord (MS is solely confined to the spinal cord in 5-24% of patients )
  • transverse myelitis
    • variable enlargement of the spinal cord
    • hyperintense on T2 weighted images and iso- or hypointense on T1 weighted images
    • variable enhancement patterns (none, diffuse, patchy, peripheral)
    • lesions commonly extend for 3-4 spinal segments
    • lesions typically occupy greater than two thirds of the cross-sectional area of the cord
    • acute clinical course
  • spinal cord abscess 
    • core is hypointense on T1 weighted images and hyperintense on T2 weighted images
    • rim enhancement
    • cord expansion
    • may show restricted diffusion on DWI
    • may have adjacent vertebral or disc abnormalities
• spinal cord contusion (acute)
  • isointense to hypointense on T1 weighted images, hyperintense on T2 weighted images
  • cord swelling
  • usually associated with other spinal injuries (osseous, disc, vascular)

See also

• neoplasms of the spinal canal
• intradural extramedullary spinal tumors

Siehe auch:

• Transverse Myelitis
• Encephalomyelitis disseminata
• neoplasms of the spinal canal
• durale AV-Fistel
• Kavernom
• intramedulläres Astrozytom
• spinales Astrozytom
• intradurale extramedulläre Tumoren
• intramedulläres Ependymom
• intramedullary metastases (spinal)

und weiter:

• intramedullary spinal metastasis
• spinale Epidermoidzyste
• spinales Hämangioblastom
• Rückenmarksinfarkt
• intradural spinal mass lesions - an approach
• holocord presentation
• spinale Dermoidzyste
• spinale durale arteriovenöse Fistel
• spinal T2 hyperintense lesions
• intraspinale Tumoren
• Sarkoidose Rückenmark
• intramedulläre spinale Tuberkulose
• Gangliogliom des zervikalen Rückenmarks
• spinales Oligodendrogliom