Classically, lesions involving the spinal canal have been approached by location. The division into extradural (outside the dural sac), intradural-extramedullary (within the dural sac, but outside the spinal cord) and intramedullary (within the spinal cord or filum terminale) has been the classic radiologic grouping. Extradural neoplasia is most common, and are often due to metastases involving the vertebrae, being followed by intradural-extramedullary tumors, with nerve sheath tumors and meningiomas being the most common, and lastly by the intramedullary tumors, which are predominantly astrocytomas and ependymomas.

Epidural Lesions