In the case of the lower extremities, three or more of the lumbar and one or more of the sacral nerve roots are resected within the vertebral canal.

The last three lumbar and the sacral nerves form a sacral plexus, supplying the hind limb.

In the sacrum—the most common site—the tumour implicates the sacral nerves, and causes symptoms of intractable sciatica; and the real nature of the disease is often only detected on making a rectal examination.

In rare cases these injuries are accompanied by damage to the intestine, the rectum, the sacral nerves, or the iliac blood vessels.