Observations on radiation myelopathy.

Three cases of radiation myelopathy are reported. Corticosteroid therapy was associated with worth-while remissions in 2 patients. Two patients showed swelling of the spinal cord in myelograms and in one it extended below the irradiated part of the spinal cord. Demyelination of the dorsal white columns of the spinal cord unaccompanied by vascular abnormality was seen below the irradiated part of the cord. It is suggested that radiation damages the endothelial cell barrier of capillaries and arterioles after a latent interval. Proteinous oedema fluid spreads through the white matter from the capillaries and also into the arteriolar walls narrowing these vessels enough to cause local ischaemia and infarction. It is further suggested that apart from ischaemia and infarction myelin is also damaged by poor nutrition associated with oedema fluid, and that radiation damage to oligodendroglial cells is not the cause of this additional demyelination in patients with radiation myelopathy.