Diffuse cord enlargement in radiation myelopathy.

Radiation myelopathy is a well-documented complication of the irradiation of neoplasms adjacent to the spinal cord. Myelography has been used to distinguish intraspinal metastases with the diagnosis of radiation myelopathy being made if the study is normal. Four cases of radiation myelopathy are here described which were associated with swelling of the spinal cord and, in three cases, this was demonstrated at myelography. The fusiform expansion of the cord, which is indistinguishable from an intrinsic tumour or hydromyelia, is maximal in the irradiated zone, but may extend beyond it. The demonstration of swelling was associated with an abrupt clinical deterioration and, in two patients, followed a recent normal examination. The severe degree of damage underlying the cord enlargement was reflected in the poor prognosis.