The outermost layer is called the dura mater. Beneath the dura is the second layer, the arachnoid. This layer overlies the third layer, the pia mater, which intimately covers the spinal cord surface. Between the arachnoid and the pia mater is a space known as the subarachnoid space. Epidural metastases are the most common form of spinal cord metastases, and typicaly result from tumor spread to the vertebral column with subsequent growth inward toward the spinal cord.
Patients initially present with pain due to cord compression.
Sensory loss, a loss of the sensations of touch, pain, and temperature over the area of the body below the level of the compression. Magnetic resonance imaging of the spinal cord is the best way to diagnose the cause of spinal cord compression. An alternate method is contrast myelography, in which dye is injected into the spinal fuid and X-ray pictures are taken. However, this procedure is invasive and has risks that are not associated with MR imaging. This condition is an emergency situation.