Spinal intradural metastases of extraneural origin.

Three cases of intradural extramedullary (spinal subdural) metastases, originating from outside the central nervous system, are presented. Two were located at the cervico-dorsal junction, and one was mid-dorsal. A breast ductus carcinoma, a cervical neuroblastoma, and an apoduma of unknown origin, were the primary neoplasms. All presented clinically with a short history typical of cancerous spinal cord compression. Plain X-rays of the spine did not show areas of destruction. Myelography in two cases clearly suggested that intradural location of the tumour. The relative frequency of these tumours and their pathogenesis are briefly reviewed. It is stressed that primary tumours are mainly in the breast or lung. Their metastases are mainly found in the cervico-dorsal region. It is assumed that they really are metastases of the dura mater itself, growing inward. The importance of the lymphatic and venous pathways in their spread into the dura mater is emphasized.