E4824. Diagnostic Imaging Features of Intradural Extramedullary Spinal Neoplasms
  1. Ali Hannachi; National Institute of Neurology
  2. Insaf Dkhil; National Institute of Neurology
  3. Soumaya Jelassi; National Institute of Neurology
  4. Sonia Nagi; National Institute of Neurology
Spinal tumors are rare, accounting for approximately 5–10% of all CNS tumors, with an estimated 70–80% being intradural extramedullary in location. Intradural extramedullary spinal neoplasms can arise from a variety of tissue types, including meninges, nerve sheaths, and supporting structures. They are predominantly benign lesions. Meningiomas and schwannomas are the most common of these tumors. Neurofibromas, paragangliomas, and myxopapillary ependymomas are relatively rare. Diagnostic modalities for intradural extramedullary spinal neoplasms include MRI and CT scans. The MRI facilitates precise localization, characterization, and assessment of the extent of the tumor. Additionally, histopathological analysis following surgical resection remains essential to confirm the diagnosis, determining the tumor's grade and type and guiding further treatment strategies.

Educational Goals / Teaching Points
Identify the characteristic imaging patterns of intradural extramedullary spinal neoplasms and learn to differentiate these neoplasms from other spinal cord lesions. Recognize the radiological manifestations of intradural extramedullary spinal neoplasms and understand their correlation with tumor types and locations. Acquire knowledge about the various histological subtypes of intradural extramedullary spinal neoplasms, their distinct features, and their associated clinical behaviors. Appreciate the value of a multidisciplinary approach involving radiologists, neurosurgeons, pathologists, and other specialists in managing intradural extramedullary spinal neoplasms.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Meningioma is the most common intradural extramedullary spinal neoplasm. Approximately 80% of spinal meningiomas arise in the thoracic spine, whereas15% occur in the cervical spine and 5% in the lumbar spine. Meningiomas are typically iso/hypointense on T1 and slightly hyperintense on T2 with intense homogenous enhancement. Schwannoma is the second most frequent intradural extramedullary spinal neoplasm. It develops from dorsal spine nerve roots. It manifests on MRI as a well circumscribed mass, hypointense on T1, and hyperintense on T2 with heterogeneous enhancement. Foraminal extension creates a “dumbbell” morphology. Cystic changes are seen in larger lesions. Multiple Schwannomas are found in neurofibromatosis 2 (NF2) and schwannomatosis. Paraganglioma and myxopapillary ependymoma are the most frequent tumors of the conus medullaris and the cauda equina. Myxopapillary ependymoma is a slow-growing variant of ependymoma. It manifests as a sausage-shape mass, hypointense on T1 and hyperintense on T2 with vivid enhancement. Paraganglioma is rare. Peripheral T2 hypointensity creating a "cap” sign and flow voids help make the diagnosis.

Intradural extramedullary spinal neoplasms represent a challenge in the field of spinal imaging. Their diverse clinical manifestations, intricate anatomical locations, and variable imaging behavior necessitate a multidisciplinary approach involving radiologists, neurosurgeons, and pathologists.