Intradural extramedullary spinal tumors

Last revised by Derek Smith on 26 May 2022

Intradural extramedullary neoplasms are located outside the spinal cord but within the dural sheath. 

The majority (70-80%) of spinal canal tumors are intradural extramedullary 1.

Patients present with signs and symptoms of spinal cord or nerve root compression. Common presentations include weakness, localized back pain, radicular pain, sensory deficits, and gait ataxia.

The most common primary intradural extramedullary neoplasms are meningioma (20-30%) and schwannoma (15-50%), followed by neurofibroma 1. Less common entities include solitary fibrous tumor/hemangiopericytoma and malignant peripheral nerve sheath tumor

Leptomeningeal metastases are frequently seen (5-15%) in the setting of solid tumors (most commonly melanoma, small cell lung cancer, and breast cancer) and hematologic malignancies. In children, the most common intradural extramedullary neoplasms are drop metastases from primary brain tumors (most commonly medulloblastoma). In adults, the most common drop metastases are from glioblastoma.

The category includes primary neoplasms of the cauda equina region, but these have a distinct differential diagnosis, particularly the addition of myxopapillary ependymoma and, less commonly, neuroendocrine tumors (paraganglioma) arising from the filum terminale.

A useful mnemonic can be found here.

In general, a mass lesion is demonstrated within the spinal canal, sometimes with extension into the neural foramina and extradural paraspinal region (which is more suggestive of a nerve sheath tumor). When there is adequate contrast resolution of the cerebrospinal fluid (CSF) space, the mass can be localized within the dura but outside the spinal cord.

  • may be normal
  • may show bone erosion, remodeling, or sclerosis
  • may show a paravertebral mass
  • may show bone erosion, remodeling, or sclerosis
  • may show a paravertebral mass
  • may show tumoral calcifications (especially meningioma)
  • deviation of the spinal cord away from mass
  • ipsilateral cerebrospinal fluid (CSF) space enlargement surrounding the mass and contralateral CSF space effacement
  • intradural filling defect outlined by sharp meniscus of contrast (“meniscus sign”)
  • the subarachnoid space is blocked and CSF above the block remains unopacified

Contrast-enhanced MRI is the modality of choice to fully characterize these masses. The key benefits of MRI are greater sensitivity of detection and the ability to narrow the diagnostic differential by defining signal characteristics and the relationship of the mass to the cord, dura, and nerve roots. In addition, MRI can help in identifying secondary lesions and large feeding/draining vessels.

The appearance will vary depending on the histology and is thus discussed in depth in individual articles (see above list). Distinguishing features include the following 1,4,5:

The differential for intradural extramedullary neoplasms includes non-neoplastic developmental mass lesions in this location:

Uncommon appearances of degenerative disease can mimic a mass:

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1: schwannoma
    Drag here to reorder.
  • Case 2: meningioma
    Drag here to reorder.
  • Case 3: dermoid cyst
    Drag here to reorder.